From 281ba1c995ddbdfe5e29d0f6fd73534bb79d5937 Mon Sep 17 00:00:00 2001 From: Lizongdi <1210855344@qq.com> Date: Tue, 15 Sep 2026 16:10:16 +0800 Subject: [PATCH] =?UTF-8?q?=E5=B0=9D=E8=AF=95=E7=A7=BB=E6=A4=8Dw25qxx?= =?UTF-8?q?=E9=A9=B1=E5=8A=A8?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- bspMCU/w25qxx.c | 336 ++ bspMCU/w25qxx.h | 77 + library/littlefs/CMakeLists.txt | 16 + library/littlefs/DESIGN.md | 2173 ++++++++ library/littlefs/LICENSE.md | 25 + library/littlefs/SPEC.md | 867 ++++ library/littlefs/include/lfs.h | 802 +++ library/littlefs/include/lfs_config.h | 202 + library/littlefs/include/lfs_filebd.h | 82 + library/littlefs/include/lfs_flashbd.h | 99 + library/littlefs/include/lfs_util.h | 276 + library/littlefs/lfs.c | 6558 ++++++++++++++++++++++++ library/littlefs/lfs_crc.c | 20 + library/littlefs/lfs_filebd.c | 168 + library/littlefs/lfs_flashbd.c | 149 + library/littlefs/lfs_util.c | 37 + 16 files changed, 11887 insertions(+) create mode 100644 bspMCU/w25qxx.c create mode 100644 bspMCU/w25qxx.h create mode 100644 library/littlefs/CMakeLists.txt create mode 100644 library/littlefs/DESIGN.md create mode 100644 library/littlefs/LICENSE.md create mode 100644 library/littlefs/SPEC.md create mode 100644 library/littlefs/include/lfs.h create mode 100644 library/littlefs/include/lfs_config.h create mode 100644 library/littlefs/include/lfs_filebd.h create mode 100644 library/littlefs/include/lfs_flashbd.h create mode 100644 library/littlefs/include/lfs_util.h create mode 100644 library/littlefs/lfs.c create mode 100644 library/littlefs/lfs_crc.c create mode 100644 library/littlefs/lfs_filebd.c create mode 100644 library/littlefs/lfs_flashbd.c create mode 100644 library/littlefs/lfs_util.c diff --git a/bspMCU/w25qxx.c b/bspMCU/w25qxx.c new file mode 100644 index 0000000..299fafe --- /dev/null +++ b/bspMCU/w25qxx.c @@ -0,0 +1,336 @@ +#include "w25qxx.h" +#ifdef USE_W25QXX +#include "spi.h" + +////////////////////////////////////////////////////////////////////////////////// +//本程序只供学习使用，未经作者许可，不得用于其它任何用途 +//ALIENTEK STM32F429开发板 +//W25QXX驱动代码 +//正点原子@ALIENTEK +//技术论坛:www.openedv.com +//创建日期:2016/1/16 +//版本：V1.0 +//版权所有，盗版必究。 +//Copyright(C) 广州市星翼电子科技有限公司 2014-2024 +//All rights reserved +////////////////////////////////////////////////////////////////////////////////// + +uint16_t W25QXX_TYPE=W25Q80; //默认是W25Q80 + +//4Kbytes为一个Sector +//16个扇区为1个Block +//W25Q80 +//容量为1M字节,共有16个Block,256个Sector + +uint8_t SPI2_ReadWriteByte(uint8_t TxData) +{ + uint8_t Rxdata; + HAL_SPI_TransmitReceive(&W25QXXSPI,&TxData,&Rxdata,1, 1000); + return Rxdata; //返回收到的数据 +} + +//初始化SPI FLASH的IO口 +void W25QXX_Init(void) +{ + uint8_t temp; + + SPI2_ReadWriteByte(0Xff); //启动传输 + + W25QXX_CS(1); //SPI FLASH不选中 + + W25QXX_TYPE=W25QXX_ReadID(); //读取FLASH ID + + if(W25QXX_TYPE==W25Q256) + { + temp=W25QXX_ReadSR(3); //读取状态寄存器3，判断地址模式 + if((temp&0X01)==0) //如果不是4字节地址模式,则进入4字节地址模式 + { + W25QXX_CS(0); //选中 + SPI2_ReadWriteByte(W25X_Enable4ByteAddr);//发送进入4字节地址模式指令 + W25QXX_CS(1); //取消片选 + } + } +} + +//读取W25QXX的状态寄存器，W25QXX一共有3个状态寄存器 +//状态寄存器1： +//BIT7 6 5 4 3 2 1 0 +//SPR RV TB BP2 BP1 BP0 WEL BUSY +//SPR:默认0,状态寄存器保护位,配合WP使用 +//TB,BP2,BP1,BP0:FLASH区域写保护设置 +//WEL:写使能锁定 +//BUSY:忙标记位(1,忙;0,空闲) +//默认:0x00 +//状态寄存器2： +//BIT7 6 5 4 3 2 1 0 +//SUS CMP LB3 LB2 LB1 (R) QE SRP1 +//状态寄存器3： +//BIT7 6 5 4 3 2 1 0 +//HOLD/RST DRV1 DRV0 (R) (R) WPS ADP ADS +//regno:状态寄存器号，范:1~3 +//返回值:状态寄存器值 +uint8_t W25QXX_ReadSR(uint8_t regno) +{ + uint8_t byte=0,command=0; + switch(regno) + { + case 1: + command=W25X_ReadStatusReg1; //读状态寄存器1指令 + break; + case 2: + command=W25X_ReadStatusReg2; //读状态寄存器2指令 + break; + case 3: + command=W25X_ReadStatusReg3; //读状态寄存器3指令 + break; + default: + command=W25X_ReadStatusReg1; + break; + } + W25QXX_CS(0); //使能器件 + SPI2_ReadWriteByte(command); //发送读取状态寄存器命令 + byte=SPI2_ReadWriteByte(0Xff); //读取一个字节 + W25QXX_CS(1); //取消片选 + return byte; +} +//写W25QXX状态寄存器 +void W25QXX_Write_SR(uint8_t regno,uint8_t sr) +{ + uint8_t command=0; + switch(regno) + { + case 1: + command=W25X_WriteStatusReg1; //写状态寄存器1指令 + break; + case 2: + command=W25X_WriteStatusReg2; //写状态寄存器2指令 + break; + case 3: + command=W25X_WriteStatusReg3; //写状态寄存器3指令 + break; + default: + command=W25X_WriteStatusReg1; + break; + } + W25QXX_CS(0); //使能器件 + SPI2_ReadWriteByte(command); //发送写取状态寄存器命令 + SPI2_ReadWriteByte(sr); //写入一个字节 + W25QXX_CS(1); //取消片选 +} +//W25QXX写使能 +//将WEL置位 +void W25QXX_Write_Enable(void) +{ + W25QXX_CS(0); //使能器件 + SPI2_ReadWriteByte(W25X_WriteEnable); //发送写使能 + W25QXX_CS(1); //取消片选 +} +//W25QXX写禁止 +//将WEL清零 +void W25QXX_Write_Disable(void) +{ + W25QXX_CS(0); //使能器件 + SPI2_ReadWriteByte(W25X_WriteDisable); //发送写禁止指令 + W25QXX_CS(1); //取消片选 +} + +//读取芯片ID +//返回值如下: +//0XEF13,表示芯片型号为W25Q80 +//0XEF14,表示芯片型号为W25Q16 +//0XEF15,表示芯片型号为W25Q32 +//0XEF16,表示芯片型号为W25Q64 +//0XEF17,表示芯片型号为W25Q128 +//0XEF18,表示芯片型号为W25Q256 +uint16_t W25QXX_ReadID(void) +{ + uint16_t Temp = 0; + W25QXX_CS(0); + SPI2_ReadWriteByte(0x90);//发送读取ID命令 + SPI2_ReadWriteByte(0x00); + SPI2_ReadWriteByte(0x00); + SPI2_ReadWriteByte(0x00); + Temp|=SPI2_ReadWriteByte(0xFF)<<8; + Temp|=SPI2_ReadWriteByte(0xFF); + W25QXX_CS(1); + return Temp; +} +//读取SPI FLASH +//在指定地址开始读取指定长度的数据 +//pBuffer:数据存储区 +//ReadAddr:开始读取的地址(24bit) +//NumByteToRead:要读取的字节数(最大65535) +void W25QXX_Read(uint8_t* pBuffer,uint32_t ReadAddr,uint16_t NumByteToRead) +{ + uint16_t i; + W25QXX_CS(0); //使能器件 + SPI2_ReadWriteByte(W25X_ReadData); //发送读取命令 + if(W25QXX_TYPE==W25Q256) //如果是W25Q256的话地址为4字节的，要发送最高8位 + { + SPI2_ReadWriteByte((uint8_t)((ReadAddr)>>24)); + } + SPI2_ReadWriteByte((uint8_t)((ReadAddr)>>16)); //发送24bit地址 + SPI2_ReadWriteByte((uint8_t)((ReadAddr)>>8)); + SPI2_ReadWriteByte((uint8_t)ReadAddr); + for(i=0;i>24)); + } + SPI2_ReadWriteByte((uint8_t)((WriteAddr)>>16)); //发送24bit地址 + SPI2_ReadWriteByte((uint8_t)((WriteAddr)>>8)); + SPI2_ReadWriteByte((uint8_t)WriteAddr); + for(i=0;ipageremain + { + pBuffer+=pageremain; + WriteAddr+=pageremain; + + NumByteToWrite-=pageremain; //减去已经写入了的字节数 + if(NumByteToWrite>256)pageremain=256; //一次可以写入256个字节 + else pageremain=NumByteToWrite; //不够256个字节了 + } + }; +} +//写SPI FLASH +//在指定地址开始写入指定长度的数据 +//该函数带擦除操作! +//pBuffer:数据存储区 +//WriteAddr:开始写入的地址(24bit) +//NumByteToWrite:要写入的字节数(最大65535) +uint8_t W25QXX_BUFFER[4096]; +void W25QXX_Write(uint8_t* pBuffer,uint32_t WriteAddr,uint16_t NumByteToWrite) +{ + uint32_t secpos; + uint16_t secoff; + uint16_t secremain; + uint16_t i; + uint8_t * W25QXX_BUF; + W25QXX_BUF=W25QXX_BUFFER; + secpos=WriteAddr/4096;//扇区地址 + secoff=WriteAddr%4096;//在扇区内的偏移 + secremain=4096-secoff;//扇区剩余空间大小 + //printf("ad:%X,nb:%X\r\n",WriteAddr,NumByteToWrite);//测试用 + if(NumByteToWrite<=secremain)secremain=NumByteToWrite;//不大于4096个字节 + while(1) + { + W25QXX_Read(W25QXX_BUF,secpos*4096,4096);//读出整个扇区的内容 + for(i=0;i4096)secremain=4096; //下一个扇区还是写不完 + else secremain=NumByteToWrite; //下一个扇区可以写完了 + } + }; +} +//擦除整个芯片 +//等待时间超长... +void W25QXX_Erase_Chip(void) +{ + W25QXX_Write_Enable(); //SET WEL + W25QXX_Wait_Busy(); + W25QXX_CS(0); //使能器件 + SPI2_ReadWriteByte(W25X_ChipErase); //发送片擦除命令 + W25QXX_CS(1); //取消片选 + W25QXX_Wait_Busy(); //等待芯片擦除结束 +} +//擦除一个扇区 +//Dst_Addr:扇区地址 根据实际容量设置 +//擦除一个扇区的最少时间:150ms +void W25QXX_Erase_Sector(uint32_t Dst_Addr) +{ + //监视falsh擦除情况,测试用 + //printf("fe:%x\r\n",Dst_Addr); + Dst_Addr*=4096; + W25QXX_Write_Enable(); //SET WEL + W25QXX_Wait_Busy(); + W25QXX_CS(0); //使能器件 + SPI2_ReadWriteByte(W25X_SectorErase); //发送扇区擦除指令 + if(W25QXX_TYPE==W25Q256) //如果是W25Q256的话地址为4字节的，要发送最高8位 + { + SPI2_ReadWriteByte((uint8_t)((Dst_Addr)>>24)); + } + SPI2_ReadWriteByte((uint8_t)((Dst_Addr)>>16)); //发送24bit地址 + SPI2_ReadWriteByte((uint8_t)((Dst_Addr)>>8)); + SPI2_ReadWriteByte((uint8_t)Dst_Addr); + W25QXX_CS(1); //取消片选 + W25QXX_Wait_Busy(); //等待擦除完成 +} +//等待空闲 +void W25QXX_Wait_Busy(void) +{ + while((W25QXX_ReadSR(1)&0x01)==0x01); // 等待BUSY位清空 +} +//进入掉电模式 +void W25QXX_PowerDown(void) +{ + W25QXX_CS(0); //使能器件 + SPI2_ReadWriteByte(W25X_PowerDown); //发送掉电命令 + W25QXX_CS(1); //取消片选 + HAL_Delay(3); //等待TPD +} +//唤醒 +void W25QXX_WAKEUP(void) +{ + W25QXX_CS(0); //使能器件 + SPI2_ReadWriteByte(W25X_ReleasePowerDown); // send W25X_PowerDown command 0xAB + W25QXX_CS(1); //取消片选 + HAL_Delay(3); //等待TRES1 +} +#endif diff --git a/bspMCU/w25qxx.h b/bspMCU/w25qxx.h new file mode 100644 index 0000000..939147e --- /dev/null +++ b/bspMCU/w25qxx.h @@ -0,0 +1,77 @@ +#ifndef __W25QXX_H +#define __W25QXX_H +#include "common.h" +////////////////////////////////////////////////////////////////////////////////// +//本程序只供学习使用，未经作者许可，不得用于其它任何用途 +//ALIENTEK STM32F429开发板 +//W25QXX驱动代码 +//正点原子@ALIENTEK +//技术论坛:www.openedv.com +//创建日期:2016/1/16 +//版本：V1.0 +//版权所有，盗版必究。 +//Copyright(C) 广州市星翼电子科技有限公司 2014-2024 +//All rights reserved +////////////////////////////////////////////////////////////////////////////////// + +//W25X系列/Q系列芯片列表 +//W25Q80 ID 0XEF13 +//W25Q16 ID 0XEF14 +//W25Q32 ID 0XEF15 +//W25Q64 ID 0XEF16 +//W25Q128 ID 0XEF17 +//W25Q256 ID 0XEF18 +#define W25Q80 0XEF13 +#define W25Q16 0XEF14 +#define W25Q32 0XEF15 +#define W25Q64 0XEF16 +#define W25Q128 0XEF17 +#define W25Q256 0XEF18 + +extern uint16_t W25QXX_TYPE; //定义W25QXX芯片型号 + +//W25QXX的片选信号 +#define W25QXX_CS(n) (n?HAL_GPIO_WritePin(W25QXX_CS_GPIO_Port,W25QXX_CS_Pin,GPIO_PIN_SET):HAL_GPIO_WritePin(W25QXX_CS_GPIO_Port,W25QXX_CS_Pin,GPIO_PIN_RESET)) + +////////////////////////////////////////////////////////////////////////////////// +//指令表 +#define W25X_WriteEnable 0x06 +#define W25X_WriteDisable 0x04 +#define W25X_ReadStatusReg1 0x05 +#define W25X_ReadStatusReg2 0x35 +#define W25X_ReadStatusReg3 0x15 +#define W25X_WriteStatusReg1 0x01 +#define W25X_WriteStatusReg2 0x31 +#define W25X_WriteStatusReg3 0x11 +#define W25X_ReadData 0x03 +#define W25X_FastReadData 0x0B +#define W25X_FastReadDual 0x3B +#define W25X_PageProgram 0x02 +#define W25X_BlockErase 0xD8 +#define W25X_SectorErase 0x20 +#define W25X_ChipErase 0xC7 +#define W25X_PowerDown 0xB9 +#define W25X_ReleasePowerDown 0xAB +#define W25X_DeviceID 0xAB +#define W25X_ManufactDeviceID 0x90 +#define W25X_JedecDeviceID 0x9F +#define W25X_Enable4ByteAddr 0xB7 +#define W25X_Exit4ByteAddr 0xE9 + +void W25QXX_Init(void); +uint16_t W25QXX_ReadID(void); //读取FLASH ID +uint8_t W25QXX_ReadSR(uint8_t regno); //读取状态寄存器 +void W25QXX_4ByteAddr_Enable(void); //使能4字节地址模式 +void W25QXX_Write_SR(uint8_t regno,uint8_t sr); //写状态寄存器 +void W25QXX_Write_Enable(void); //写使能 +void W25QXX_Write_Disable(void); //写保护 +void W25QXX_Write_NoCheck(uint8_t* pBuffer,uint32_t WriteAddr,uint16_t NumByteToWrite); +void W25QXX_Read(uint8_t* pBuffer,uint32_t ReadAddr,uint16_t NumByteToRead); //读取flash +void W25QXX_Write(uint8_t* pBuffer,uint32_t WriteAddr,uint16_t NumByteToWrite);//写入flash +void W25QXX_Erase_Chip(void); //整片擦除 +void W25QXX_Erase_Sector(uint32_t Dst_Addr); //扇区擦除 +void W25QXX_Wait_Busy(void); //等待空闲 +void W25QXX_PowerDown(void); //进入掉电模式 +void W25QXX_WAKEUP(void); //唤醒 + +#endif diff --git a/library/littlefs/CMakeLists.txt b/library/littlefs/CMakeLists.txt new file mode 100644 index 0000000..9cd1a39 --- /dev/null +++ b/library/littlefs/CMakeLists.txt @@ -0,0 +1,16 @@ +cmake_minimum_required(VERSION 3.10) + +get_filename_component(TARGET_NAME "${CMAKE_CURRENT_SOURCE_DIR}" NAME) +set(COMMON_CMAKE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/../CMakeLists.txt") + +if(EXISTS ${COMMON_CMAKE_PATH}) + include(${COMMON_CMAKE_PATH}) +else() + message(FATAL_ERROR "Cannot find common build logic at ${COMMON_CMAKE_PATH}") +endif() + +if(TARGET common) + target_link_libraries(${TARGET_NAME} PUBLIC common) +else() + message(FATAL_ERROR "[${TARGET_NAME}] Dependency 'common' not found.") +endif() \ No newline at end of file diff --git a/library/littlefs/DESIGN.md b/library/littlefs/DESIGN.md new file mode 100644 index 0000000..9c9703a --- /dev/null +++ b/library/littlefs/DESIGN.md @@ -0,0 +1,2173 @@ +## The design of littlefs + +A little fail-safe filesystem designed for microcontrollers. + +``` + | | | .---._____ + .-----. | | +--|o |---| littlefs | +--| |---| | + '-----' '----------' + | | | +``` + +littlefs was originally built as an experiment to learn about filesystem design +in the context of microcontrollers. The question was: How would you build a +filesystem that is resilient to power-loss and flash wear without using +unbounded memory? + +This document covers the high-level design of littlefs, how it is different +than other filesystems, and the design decisions that got us here. For the +low-level details covering every bit on disk, check out [SPEC.md](SPEC.md). + +## The problem + +The embedded systems littlefs targets are usually 32-bit microcontrollers with +around 32 KiB of RAM and 512 KiB of ROM. These are often paired with SPI NOR +flash chips with about 4 MiB of flash storage. These devices are too small for +Linux and most existing filesystems, requiring code written specifically with +size in mind. + +Flash itself is an interesting piece of technology with its own quirks and +nuance. Unlike other forms of storage, writing to flash requires two +operations: erasing and programming. Programming (setting bits to 0) is +relatively cheap and can be very granular. Erasing however (setting bits to 1), +requires an expensive and destructive operation which gives flash its name. +[Wikipedia][wikipedia-flash] has more information on how exactly flash works. + +To make the situation more annoying, it's very common for these embedded +systems to lose power at any time. Usually, microcontroller code is simple and +reactive, with no concept of a shutdown routine. This presents a big challenge +for persistent storage, where an unlucky power loss can corrupt the storage and +leave a device unrecoverable. + +This leaves us with three major requirements for an embedded filesystem. + +1. **Power-loss resilience** - On these systems, power can be lost at any time. + If a power loss corrupts any persistent data structures, this can cause the + device to become unrecoverable. An embedded filesystem must be designed to + recover from a power loss during any write operation. + +1. **Wear leveling** - Writing to flash is destructive. If a filesystem + repeatedly writes to the same block, eventually that block will wear out. + Filesystems that don't take wear into account can easily burn through blocks + used to store frequently updated metadata and cause a device's early death. + +1. **Bounded RAM/ROM** - If the above requirements weren't enough, these + systems also have very limited amounts of memory. This prevents many + existing filesystem designs, which can lean on relatively large amounts of + RAM to temporarily store filesystem metadata. + + For ROM, this means we need to keep our design simple and reuse code paths + where possible. For RAM we have a stronger requirement, all RAM usage is + bounded. This means RAM usage does not grow as the filesystem changes in + size or number of files. This creates a unique challenge as even presumably + simple operations, such as traversing the filesystem, become surprisingly + difficult. + +## Existing designs? + +So, what's already out there? There are, of course, many different filesystems, +however they often share and borrow feature from each other. If we look at +power-loss resilience and wear leveling, we can narrow these down to a handful +of designs. + +1. First we have the non-resilient, block based filesystems, such as [FAT] and + [ext2]. These are the earliest filesystem designs and often the most simple. + Here storage is divided into blocks, with each file being stored in a + collection of blocks. Without modifications, these filesystems are not + power-loss resilient, so updating a file is a simple as rewriting the blocks + in place. + + ``` + .--------. + | root | + | | + | | + '--------' + .-' '-. + v v + .--------. .--------. + | A | | B | + | | | | + | | | | + '--------' '--------' + .-' .-' '-. + v v v + .--------. .--------. .--------. + | C | | D | | E | + | | | | | | + | | | | | | + '--------' '--------' '--------' + ``` + + Because of their simplicity, these filesystems are usually both the fastest + and smallest. However the lack of power resilience is not great, and the + binding relationship of storage location and data removes the filesystem's + ability to manage wear. + +2. In a completely different direction, we have logging filesystems, such as + [JFFS], [YAFFS], and [SPIFFS], storage location is not bound to a piece of + data, instead the entire storage is used for a circular log which is + appended with every change made to the filesystem. Writing appends new + changes, while reading requires traversing the log to reconstruct a file. + Some logging filesystems cache files to avoid the read cost, but this comes + at a tradeoff of RAM. + + ``` + v + .--------.--------.--------.--------.--------.--------.--------.--------. + | C | new B | new A | | A | B | + | | | |-> | | | + | | | | | | | + '--------'--------'--------'--------'--------'--------'--------'--------' + ``` + + Logging filesystem are beautifully elegant. With a checksum, we can easily + detect power-loss and fall back to the previous state by ignoring failed + appends. And if that wasn't good enough, their cyclic nature means that + logging filesystems distribute wear across storage perfectly. + + The main downside is performance. If we look at garbage collection, the + process of cleaning up outdated data from the end of the log, I've yet to + see a pure logging filesystem that does not have one of these two costs: + + 1. _O(n²)_ runtime + 2. _O(n)_ RAM + + SPIFFS is a very interesting case here, as it uses the fact that repeated + programs to NOR flash is both atomic and masking. This is a very neat + solution, however it limits the type of storage you can support. + +3. Perhaps the most common type of filesystem, a journaling filesystem is the + offspring that happens when you mate a block based filesystem with a logging + filesystem. [ext4] and [NTFS] are good examples. Here, we take a normal + block based filesystem and add a bounded log where we note every change + before it occurs. + + ``` + journal + .--------.--------. + .--------. | C'| D'| | E'| + | root |-->| | |-> | | + | | | | | | | + | | '--------'--------' + '--------' + .-' '-. + v v + .--------. .--------. + | A | | B | + | | | | + | | | | + '--------' '--------' + .-' .-' '-. + v v v + .--------. .--------. .--------. + | C | | D | | E | + | | | | | | + | | | | | | + '--------' '--------' '--------' + ``` + + + This sort of filesystem takes the best from both worlds. Performance can be + as fast as a block based filesystem (though updating the journal does have + a small cost), and atomic updates to the journal allow the filesystem to + recover in the event of a power loss. + + Unfortunately, journaling filesystems have a couple of problems. They are + fairly complex, since there are effectively two filesystems running in + parallel, which comes with a code size cost. They also offer no protection + against wear because of the strong relationship between storage location + and data. + +4. Last but not least we have copy-on-write (COW) filesystems, such as + [btrfs] and [ZFS]. These are very similar to other block based filesystems, + but instead of updating block inplace, all updates are performed by creating + a copy with the changes and replacing any references to the old block with + our new block. This recursively pushes all of our problems upwards until we + reach the root of our filesystem, which is often stored in a very small log. + + ``` + .--------. .--------. + | root | write |new root| + | | ==> | | + | | | | + '--------' '--------' + .-' '-. | '-. + | .-------|------------------' v + v v v .--------. + .--------. .--------. | new B | + | A | | B | | | + | | | | | | + | | | | '--------' + '--------' '--------' .-' | + .-' .-' '-. .------------|------' + | | | | v + v v v v .--------. + .--------. .--------. .--------. | new D | + | C | | D | | E | | | + | | | | | | | | + | | | | | | '--------' + '--------' '--------' '--------' + ``` + + COW filesystems are interesting. They offer very similar performance to + block based filesystems while managing to pull off atomic updates without + storing data changes directly in a log. They even disassociate the storage + location of data, which creates an opportunity for wear leveling. + + Well, almost. The unbounded upwards movement of updates causes some + problems. Because updates to a COW filesystem don't stop until they've + reached the root, an update can cascade into a larger set of writes than + would be needed for the original data. On top of this, the upward motion + focuses these writes into the block, which can wear out much earlier than + the rest of the filesystem. + +## littlefs + +So what does littlefs do? + +If we look at existing filesystems, there are two interesting design patterns +that stand out, but each have their own set of problems. Logging, which +provides independent atomicity, has poor runtime performance. And COW data +structures, which perform well, push the atomicity problem upwards. + +Can we work around these limitations? + +Consider logging. It has either a _O(n²)_ runtime or _O(n)_ RAM cost. We +can't avoid these costs, _but_ if we put an upper bound on the size we can at +least prevent the theoretical cost from becoming problem. This relies on the +super secret computer science hack where you can pretend any algorithmic +complexity is _O(1)_ by bounding the input. + +In the case of COW data structures, we can try twisting the definition a bit. +Let's say that our COW structure doesn't copy after a single write, but instead +copies after _n_ writes. This doesn't change most COW properties (assuming you +can write atomically!), but what it does do is prevent the upward motion of +wear. This sort of copy-on-bounded-writes (CObW) still focuses wear, but at +each level we divide the propagation of wear by _n_. With a sufficiently +large _n_ (> branching factor) wear propagation is no longer a problem. + +See where this is going? Separate, logging and COW are imperfect solutions and +have weaknesses that limit their usefulness. But if we merge the two they can +mutually solve each other's limitations. + +This is the idea behind littlefs. At the sub-block level, littlefs is built +out of small, two block logs that provide atomic updates to metadata anywhere +on the filesystem. At the super-block level, littlefs is a CObW tree of blocks +that can be evicted on demand. + +``` + root + .--------.--------. + | A'| B'| | + | | |-> | + | | | | + '--------'--------' + .----' '--------------. + A v B v + .--------.--------. .--------.--------. + | C'| D'| | | E'|new| | + | | |-> | | | E'|-> | + | | | | | | | | + '--------'--------' '--------'--------' + .-' '--. | '------------------. + v v .-' v +.--------. .--------. v .--------. +| C | | D | .--------. write | new E | +| | | | | E | ==> | | +| | | | | | | | +'--------' '--------' | | '--------' + '--------' .-' | + .-' '-. .-------------|------' + v v v v + .--------. .--------. .--------. + | F | | G | | new F | + | | | | | | + | | | | | | + '--------' '--------' '--------' +``` + +There are still some minor issues. Small logs can be expensive in terms of +storage, in the worst case a small log costs 4x the size of the original data. +CObW structures require an efficient block allocator since allocation occurs +every _n_ writes. And there is still the challenge of keeping the RAM usage +constant. + +## Metadata pairs + +Metadata pairs are the backbone of littlefs. These are small, two block logs +that allow atomic updates anywhere in the filesystem. + +Why two blocks? Well, logs work by appending entries to a circular buffer +stored on disk. But remember that flash has limited write granularity. We can +incrementally program new data onto erased blocks, but we need to erase a full +block at a time. This means that in order for our circular buffer to work, we +need more than one block. + +We could make our logs larger than two blocks, but the next challenge is how +do we store references to these logs? Because the blocks themselves are erased +during writes, using a data structure to track these blocks is complicated. +The simple solution here is to store a two block addresses for every metadata +pair. This has the added advantage that we can change out blocks in the +metadata pair independently, and we don't reduce our block granularity for +other operations. + +In order to determine which metadata block is the most recent, we store a +revision count that we compare using [sequence arithmetic][wikipedia-sna] +(very handy for avoiding problems with integer overflow). Conveniently, this +revision count also gives us a rough idea of how many erases have occurred on +the block. + +``` +metadata pair pointer: {block 0, block 1} + | '--------------------. + '-. | +disk v v +.--------.--------.--------.--------.--------.--------.--------.--------. +| | |metadata| |metadata| | +| | |block 0 | |block 1 | | +| | | | | | | +'--------'--------'--------'--------'--------'--------'--------'--------' + '--. .----' + v v + metadata pair .----------------.----------------. + | revision 11 | revision 12 | + block 1 is |----------------|----------------| + most recent | A | A'' | + |----------------|----------------| + | checksum | checksum | + |----------------|----------------| + | B | A''' | <- most recent A + |----------------|----------------| + | A'' | checksum | + |----------------|----------------| + | checksum | | | + |----------------| v | + '----------------'----------------' +``` + +So how do we atomically update our metadata pairs? Atomicity (a type of +power-loss resilience) requires two parts: redundancy and error detection. +Error detection can be provided with a checksum, and in littlefs's case we +use a 32-bit [CRC][wikipedia-crc]. Maintaining redundancy, on the other hand, +requires multiple stages. + +1. If our block is not full and the program size is small enough to let us + append more entries, we can simply append the entries to the log. Because + we don't overwrite the original entries (remember rewriting flash requires + an erase), we still have the original entries if we lose power during the + append. + + ``` + commit A + .----------------.----------------. .----------------.----------------. + | revision 1 | revision 0 | => | revision 1 | revision 0 | + |----------------|----------------| |----------------|----------------| + | | | | | A | | + | v | | |----------------| | + | | | | checksum | | + | | | |----------------| | + | | | | | | | + | | | | v | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + '----------------'----------------' '----------------'----------------' + ``` + + Note that littlefs doesn't maintain a checksum for each entry. Many logging + filesystems do this, but it limits what you can update in a single atomic + operation. What we can do instead is group multiple entries into a commit + that shares a single checksum. This lets us update multiple unrelated pieces + of metadata as long as they reside on the same metadata pair. + + ``` + commit B and A' + .----------------.----------------. .----------------.----------------. + | revision 1 | revision 0 | => | revision 1 | revision 0 | + |----------------|----------------| |----------------|----------------| + | A | | | A | | + |----------------| | |----------------| | + | checksum | | | checksum | | + |----------------| | |----------------| | + | | | | | B | | + | v | | |----------------| | + | | | | A' | | + | | | |----------------| | + | | | | checksum | | + | | | |----------------| | + '----------------'----------------' '----------------'----------------' + ``` + +2. If our block _is_ full of entries, we need to somehow remove outdated + entries to make space for new ones. This process is called garbage + collection, but because littlefs has multiple garbage collectors, we + also call this specific case compaction. + + Compared to other filesystems, littlefs's garbage collector is relatively + simple. We want to avoid RAM consumption, so we use a sort of brute force + solution where for each entry we check to see if a newer entry has been + written. If the entry is the most recent we append it to our new block. This + is where having two blocks becomes important, if we lose power we still have + everything in our original block. + + During this compaction step we also erase the metadata block and increment + the revision count. Because we can commit multiple entries at once, we can + write all of these changes to the second block without worrying about power + loss. It's only when the commit's checksum is written that the compacted + entries and revision count become committed and readable. + + ``` + commit B', need to compact + .----------------.----------------. .----------------.----------------. + | revision 1 | revision 0 | => | revision 1 | revision 2 | + |----------------|----------------| |----------------|----------------| + | A | | | A | A' | + |----------------| | |----------------|----------------| + | checksum | | | checksum | B' | + |----------------| | |----------------|----------------| + | B | | | B | checksum | + |----------------| | |----------------|----------------| + | A' | | | A' | | | + |----------------| | |----------------| v | + | checksum | | | checksum | | + |----------------| | |----------------| | + '----------------'----------------' '----------------'----------------' + ``` + +3. If our block is full of entries _and_ we can't find any garbage, then what? + At this point, most logging filesystems would return an error indicating no + more space is available, but because we have small logs, overflowing a log + isn't really an error condition. + + Instead, we split our original metadata pair into two metadata pairs, each + containing half of the entries, connected by a tail pointer. Instead of + increasing the size of the log and dealing with the scalability issues + associated with larger logs, we form a linked list of small bounded logs. + This is a tradeoff as this approach does use more storage space, but at the + benefit of improved scalability. + + Despite writing to two metadata pairs, we can still maintain power + resilience during this split step by first preparing the new metadata pair, + and then inserting the tail pointer during the commit to the original + metadata pair. + + ``` + commit C and D, need to split + .----------------.----------------. .----------------.----------------. + | revision 1 | revision 2 | => | revision 3 | revision 2 | + |----------------|----------------| |----------------|----------------| + | A | A' | | A' | A' | + |----------------|----------------| |----------------|----------------| + | checksum | B' | | B' | B' | + |----------------|----------------| |----------------|----------------| + | B | checksum | | tail ---------------------. + |----------------|----------------| |----------------|----------------| | + | A' | | | | checksum | | | + |----------------| v | |----------------| | | + | checksum | | | | | | | + |----------------| | | v | | | + '----------------'----------------' '----------------'----------------' | + .----------------.---------' + v v + .----------------.----------------. + | revision 1 | revision 0 | + |----------------|----------------| + | C | | + |----------------| | + | D | | + |----------------| | + | checksum | | + |----------------| | + | | | | + | v | | + | | | + | | | + '----------------'----------------' + ``` + +There is another complexity the crops up when dealing with small logs. The +amortized runtime cost of garbage collection is not only dependent on its +one time cost (_O(n²)_ for littlefs), but also depends on how often +garbage collection occurs. + +Consider two extremes: + +1. Log is empty, garbage collection occurs once every _n_ updates +2. Log is full, garbage collection occurs **every** update + +Clearly we need to be more aggressive than waiting for our metadata pair to +be full. As the metadata pair approaches fullness the frequency of compactions +grows very rapidly. + +Looking at the problem generically, consider a log with ![n] bytes for each +entry, ![d] dynamic entries (entries that are outdated during garbage +collection), and ![s] static entries (entries that need to be copied during +garbage collection). If we look at the amortized runtime complexity of updating +this log we get this formula: + +![cost = n + n (s / d+1)][metadata-formula1] + +If we let ![r] be the ratio of static space to the size of our log in bytes, we +find an alternative representation of the number of static and dynamic entries: + +![s = r (size/n)][metadata-formula2] + +![d = (1 - r) (size/n)][metadata-formula3] + +Substituting these in for ![d] and ![s] gives us a nice formula for the cost of +updating an entry given how full the log is: + +![cost = n + n (r (size/n) / ((1-r) (size/n) + 1))][metadata-formula4] + +Assuming 100 byte entries in a 4 KiB log, we can graph this using the entry +size to find a multiplicative cost: + +![Metadata pair update cost graph][metadata-cost-graph] + +So at 50% usage, we're seeing an average of 2x cost per update, and at 75% +usage, we're already at an average of 4x cost per update. + +To avoid this exponential growth, instead of waiting for our metadata pair +to be full, we split the metadata pair once we exceed 50% capacity. We do this +lazily, waiting until we need to compact before checking if we fit in our 50% +limit. This limits the overhead of garbage collection to 2x the runtime cost, +giving us an amortized runtime complexity of _O(1)_. + +--- + +If we look at metadata pairs and linked-lists of metadata pairs at a high +level, they have fairly nice runtime costs. Assuming _n_ metadata pairs, +each containing _m_ metadata entries, the _lookup_ cost for a specific +entry has a worst case runtime complexity of _O(nm)_. For _updating_ a specific +entry, the worst case complexity is _O(nm²)_, with an amortized complexity +of only _O(nm)_. + +However, splitting at 50% capacity does mean that in the best case our +metadata pairs will only be 1/2 full. If we include the overhead of the second +block in our metadata pair, each metadata entry has an effective storage cost +of 4x the original size. I imagine users would not be happy if they found +that they can only use a quarter of their original storage. Metadata pairs +provide a mechanism for performing atomic updates, but we need a separate +mechanism for storing the bulk of our data. + +## CTZ skip-lists + +Metadata pairs provide efficient atomic updates but unfortunately have a large +storage cost. But we can work around this storage cost by only using the +metadata pairs to store references to more dense, copy-on-write (COW) data +structures. + +[Copy-on-write data structures][wikipedia-cow], also called purely functional +data structures, are a category of data structures where the underlying +elements are immutable. Making changes to the data requires creating new +elements containing a copy of the updated data and replacing any references +with references to the new elements. Generally, the performance of a COW data +structure depends on how many old elements can be reused after replacing parts +of the data. + +littlefs has several requirements of its COW structures. They need to be +efficient to read and write, but most frustrating, they need to be traversable +with a constant amount of RAM. Notably this rules out +[B-trees][wikipedia-B-tree], which can not be traversed with constant RAM, and +[B+-trees][wikipedia-B+-tree], which are not possible to update with COW +operations. + +--- + +So, what can we do? First let's consider storing files in a simple COW +linked-list. Appending a block, which is the basis for writing files, means we +have to update the last block to point to our new block. This requires a COW +operation, which means we need to update the second-to-last block, and then the +third-to-last, and so on until we've copied out the entire file. + +``` +A linked-list +.--------. .--------. .--------. .--------. .--------. .--------. +| data 0 |->| data 1 |->| data 2 |->| data 4 |->| data 5 |->| data 6 | +| | | | | | | | | | | | +| | | | | | | | | | | | +'--------' '--------' '--------' '--------' '--------' '--------' +``` + +To avoid a full copy during appends, we can store the data backwards. Appending +blocks just requires adding the new block and no other blocks need to be +updated. If we update a block in the middle, we still need to copy the +following blocks, but can reuse any blocks before it. Since most file writes +are linear, this design gambles that appends are the most common type of data +update. + +``` +A backwards linked-list +.--------. .--------. .--------. .--------. .--------. .--------. +| data 0 |<-| data 1 |<-| data 2 |<-| data 4 |<-| data 5 |<-| data 6 | +| | | | | | | | | | | | +| | | | | | | | | | | | +'--------' '--------' '--------' '--------' '--------' '--------' +``` + +However, a backwards linked-list does have a rather glaring problem. Iterating +over a file _in order_ has a runtime cost of _O(n²)_. A quadratic runtime +just to read a file! That's awful. + +Fortunately we can do better. Instead of a singly linked list, littlefs +uses a multilayered linked-list often called a +[skip-list][wikipedia-skip-list]. However, unlike the most common type of +skip-list, littlefs's skip-lists are strictly deterministic built around some +interesting properties of the count-trailing-zeros (CTZ) instruction. + +The rules CTZ skip-lists follow are that for every _n_‍th block where _n_ +is divisible by 2‍_ˣ_, that block contains a pointer to block +_n_-2‍_ˣ_. This means that each block contains anywhere from 1 to +log₂_n_ pointers that skip to different preceding elements of the +skip-list. + +The name comes from heavy use of the [CTZ instruction][wikipedia-ctz], which +lets us calculate the power-of-two factors efficiently. For a given block _n_, +that block contains ctz(_n_)+1 pointers. + +``` +A backwards CTZ skip-list +.--------. .--------. .--------. .--------. .--------. .--------. +| data 0 |<-| data 1 |<-| data 2 |<-| data 3 |<-| data 4 |<-| data 5 | +| |<-| |--| |<-| |--| | | | +| |<-| |--| |--| |--| | | | +'--------' '--------' '--------' '--------' '--------' '--------' +``` + +The additional pointers let us navigate the data-structure on disk much more +efficiently than in a singly linked list. + +Consider a path from data block 5 to data block 1. You can see how data block 3 +was completely skipped: +``` +.--------. .--------. .--------. .--------. .--------. .--------. +| data 0 | | data 1 |<-| data 2 | | data 3 | | data 4 |<-| data 5 | +| | | | | |<-| |--| | | | +| | | | | | | | | | | | +'--------' '--------' '--------' '--------' '--------' '--------' +``` + +The path to data block 0 is even faster, requiring only two jumps: +``` +.--------. .--------. .--------. .--------. .--------. .--------. +| data 0 | | data 1 | | data 2 | | data 3 | | data 4 |<-| data 5 | +| | | | | | | | | | | | +| |<-| |--| |--| |--| | | | +'--------' '--------' '--------' '--------' '--------' '--------' +``` + +We can find the runtime complexity by looking at the path to any block from +the block containing the most pointers. Every step along the path divides +the search space for the block in half, giving us a runtime of _O(log n)_. +To get _to_ the block with the most pointers, we can perform the same steps +backwards, which puts the runtime at _O(2 log n)_ = _O(log n)_. An interesting +note is that this optimal path occurs naturally if we greedily choose the +pointer that covers the most distance without passing our target. + +So now we have a [COW] data structure that is cheap to append with a runtime +of _O(1)_, and can be read with a worst case runtime of _O(n log n)_. Given +that this runtime is also divided by the amount of data we can store in a +block, this cost is fairly reasonable. + +--- + +This is a new data structure, so we still have several questions. What is the +storage overhead? Can the number of pointers exceed the size of a block? How do +we store a CTZ skip-list in our metadata pairs? + +To find the storage overhead, we can look at the data structure as multiple +linked-lists. Each linked-list skips twice as many blocks as the previous, +or from another perspective, each linked-list uses half as much storage as +the previous. As we approach infinity, the storage overhead forms a geometric +series. Solving this tells us that on average our storage overhead is only +2 pointers per block. + +![lim,n->inf((1/n)sum,i,0->n(ctz(i)+1)) = sum,i,0->inf(1/2^i) = 2][ctz-formula1] + +Because our file size is limited the word width we use to store sizes, we can +also solve for the maximum number of pointers we would ever need to store in a +block. If we set the overhead of pointers equal to the block size, we get the +following equation. Note that both a smaller block size (![B][bigB]) and larger +word width (![w]) result in more storage overhead. + +![B = (w/8)ceil(log2(2^w / (B-2w/8)))][ctz-formula2] + +Solving the equation for ![B][bigB] gives us the minimum block size for some +common word widths: + +1. 32-bit CTZ skip-list => minimum block size of 104 bytes +2. 64-bit CTZ skip-list => minimum block size of 448 bytes + +littlefs uses a 32-bit word width, so our blocks can only overflow with +pointers if they are smaller than 104 bytes. This is an easy requirement, as +in practice, most block sizes start at 512 bytes. As long as our block size +is larger than 104 bytes, we can avoid the extra logic needed to handle +pointer overflow. + +This last question is how do we store CTZ skip-lists? We need a pointer to the +head block, the size of the skip-list, the index of the head block, and our +offset in the head block. But it's worth noting that each size maps to a unique +index + offset pair. So in theory we can store only a single pointer and size. + +However, calculating the index + offset pair from the size is a bit +complicated. We can start with a summation that loops through all of the blocks +up until our given size. Let ![B][bigB] be the block size in bytes, ![w] be the +word width in bits, ![n] be the index of the block in the skip-list, and +![N][bigN] be the file size in bytes: + +![N = sum,i,0->n(B-(w/8)(ctz(i)+1))][ctz-formula3] + +This works quite well, but requires _O(n)_ to compute, which brings the full +runtime of reading a file up to _O(n² log n)_. Fortunately, that summation +doesn't need to touch the disk, so the practical impact is minimal. + +However, despite the integration of a bitwise operation, we can actually reduce +this equation to a _O(1)_ form. While browsing the amazing resource that is +the [On-Line Encyclopedia of Integer Sequences (OEIS)][oeis], I managed to find +[A001511], which matches the iteration of the CTZ instruction, +and [A005187], which matches its partial summation. Much to my +surprise, these both result from simple equations, leading us to a rather +unintuitive property that ties together two seemingly unrelated bitwise +instructions: + +![sum,i,0->n(ctz(i)+1) = 2n-popcount(n)][ctz-formula4] + +where: + +1. ctz(![x]) = the number of trailing bits that are 0 in ![x] +2. popcount(![x]) = the number of bits that are 1 in ![x] + +Initial tests of this surprising property seem to hold. As ![n] approaches +infinity, we end up with an average overhead of 2 pointers, which matches our +assumption from earlier. During iteration, the popcount function seems to +handle deviations from this average. Of course, just to make sure I wrote a +quick script that verified this property for all 32-bit integers. + +Now we can substitute into our original equation to find a more efficient +equation for file size: + +![N = Bn - (w/8)(2n-popcount(n))][ctz-formula5] + +Unfortunately, the popcount function is non-injective, so we can't solve this +equation for our index. But what we can do is solve for an ![n'] index that +is greater than ![n] with error bounded by the range of the popcount function. +We can repeatedly substitute ![n'] into the original equation until the error +is smaller than our integer resolution. As it turns out, we only need to +perform this substitution once, which gives us this formula for our index: + +![n = floor((N-(w/8)popcount(N/(B-2w/8))) / (B-2w/8))][ctz-formula6] + +Now that we have our index ![n], we can just plug it back into the above +equation to find the offset. We run into a bit of a problem with integer +overflow, but we can avoid this by rearranging the equation a bit: + +![off = N - (B-2w/8)n - (w/8)popcount(n)][ctz-formula7] + +Our solution requires quite a bit of math, but computers are very good at math. +Now we can find both our block index and offset from a size in _O(1)_, letting +us store CTZ skip-lists with only a pointer and size. + +CTZ skip-lists give us a COW data structure that is easily traversable in +_O(n)_, can be appended in _O(1)_, and can be read in _O(n log n)_. All of +these operations work in a bounded amount of RAM and require only two words of +storage overhead per block. In combination with metadata pairs, CTZ skip-lists +provide power resilience and compact storage of data. + +``` + .--------. + .|metadata| + || | + || | + |'--------' + '----|---' + v +.--------. .--------. .--------. .--------. +| data 0 |<-| data 1 |<-| data 2 |<-| data 3 | +| |<-| |--| | | | +| | | | | | | | +'--------' '--------' '--------' '--------' + +write data to disk, create copies +=> + .--------. + .|metadata| + || | + || | + |'--------' + '----|---' + v +.--------. .--------. .--------. .--------. +| data 0 |<-| data 1 |<-| data 2 |<-| data 3 | +| |<-| |--| | | | +| | | | | | | | +'--------' '--------' '--------' '--------' + ^ ^ ^ + | | | .--------. .--------. .--------. .--------. + | | '----| new |<-| new |<-| new |<-| new | + | '----------------| data 2 |<-| data 3 |--| data 4 | | data 5 | + '------------------| |--| |--| | | | + '--------' '--------' '--------' '--------' + +commit to metadata pair +=> + .--------. + .|new | + ||metadata| + || | + |'--------' + '----|---' + | +.--------. .--------. .--------. .--------. | +| data 0 |<-| data 1 |<-| data 2 |<-| data 3 | | +| |<-| |--| | | | | +| | | | | | | | | +'--------' '--------' '--------' '--------' | + ^ ^ ^ v + | | | .--------. .--------. .--------. .--------. + | | '----| new |<-| new |<-| new |<-| new | + | '----------------| data 2 |<-| data 3 |--| data 4 | | data 5 | + '------------------| |--| |--| | | | + '--------' '--------' '--------' '--------' +``` + +## The block allocator + +So we now have the framework for an atomic, wear leveling filesystem. Small two +block metadata pairs provide atomic updates, while CTZ skip-lists provide +compact storage of data in COW blocks. + +But now we need to look at the [elephant] in the room. Where do all these +blocks come from? + +Deciding which block to use next is the responsibility of the block allocator. +In filesystem design, block allocation is often a second-class citizen, but in +a COW filesystem its role becomes much more important as it is needed for +nearly every write to the filesystem. + +Normally, block allocation involves some sort of free list or bitmap stored on +the filesystem that is updated with free blocks. However, with power +resilience, keeping these structures consistent becomes difficult. It doesn't +help that any mistake in updating these structures can result in lost blocks +that are impossible to recover. + +littlefs takes a cautious approach. Instead of trusting a free list on disk, +littlefs relies on the fact that the filesystem on disk is a mirror image of +the free blocks on the disk. The block allocator operates much like a garbage +collector in a scripting language, scanning for unused blocks on demand. + +``` + .----. + |root| + | | + '----' + v-------' '-------v +.----. . . .----. +| A | . . | B | +| | . . | | +'----' . . '----' +. . . . v--' '------------v---------v +. . . .----. . .----. .----. +. . . | C | . | D | | E | +. . . | | . | | | | +. . . '----' . '----' '----' +. . . . . . . . . . +.----.----.----.----.----.----.----.----.----.----.----.----. +| A | |root| C | B | | D | | E | | +| | | | | | | | | | | +'----'----'----'----'----'----'----'----'----'----'----'----' + ^ ^ ^ ^ ^ + '-------------------'----'-------------------'----'-- free blocks +``` + +While this approach may sound complicated, the decision to not maintain a free +list greatly simplifies the overall design of littlefs. Unlike programming +languages, there are only a handful of data structures we need to traverse. +And block deallocation, which occurs nearly as often as block allocation, +is simply a noop. This "drop it on the floor" strategy greatly reduces the +complexity of managing on disk data structures, especially when handling +high-risk error conditions. + +--- + +Our block allocator needs to find free blocks efficiently. You could traverse +through every block on storage and check each one against our filesystem tree; +however, the runtime would be abhorrent. We need to somehow collect multiple +blocks per traversal. + +Looking at existing designs, some larger filesystems that use a similar "drop +it on the floor" strategy store a bitmap of the entire storage in [RAM]. This +works well because bitmaps are surprisingly compact. We can't use the same +strategy here, as it violates our constant RAM requirement, but we may be able +to modify the idea into a workable solution. + +``` +.----.----.----.----.----.----.----.----.----.----.----.----. +| A | |root| C | B | | D | | E | | +| | | | | | | | | | | +'----'----'----'----'----'----'----'----'----'----'----'----' + 1 0 1 1 1 0 0 1 0 1 0 0 + \---------------------------+----------------------------/ + v + bitmap: 0xb94 (0b101110010100) +``` + +The block allocator in littlefs is a compromise between a disk-sized bitmap and +a brute force traversal. Instead of a bitmap the size of storage, we keep track +of a small, fixed-size bitmap called the lookahead buffer. During block +allocation, we take blocks from the lookahead buffer. If the lookahead buffer +is empty, we scan the filesystem for more free blocks, populating our lookahead +buffer. In each scan we use an increasing offset, circling the storage as +blocks are allocated. + +Here's what it might look like to allocate 4 blocks on a decently busy +filesystem with a 32 bit lookahead and a total of 128 blocks (512 KiB +of storage if blocks are 4 KiB): +``` +boot... lookahead: + fs blocks: fffff9fffffffffeffffffffffff0000 +scanning... lookahead: fffff9ff + fs blocks: fffff9fffffffffeffffffffffff0000 +alloc = 21 lookahead: fffffdff + fs blocks: fffffdfffffffffeffffffffffff0000 +alloc = 22 lookahead: ffffffff + fs blocks: fffffffffffffffeffffffffffff0000 +scanning... lookahead: fffffffe + fs blocks: fffffffffffffffeffffffffffff0000 +alloc = 63 lookahead: ffffffff + fs blocks: ffffffffffffffffffffffffffff0000 +scanning... lookahead: ffffffff + fs blocks: ffffffffffffffffffffffffffff0000 +scanning... lookahead: ffffffff + fs blocks: ffffffffffffffffffffffffffff0000 +scanning... lookahead: ffff0000 + fs blocks: ffffffffffffffffffffffffffff0000 +alloc = 112 lookahead: ffff8000 + fs blocks: ffffffffffffffffffffffffffff8000 +``` + +This lookahead approach has a runtime complexity of _O(n²)_ to completely +scan storage; however, bitmaps are surprisingly compact, and in practice only +one or two passes are usually needed to find free blocks. Additionally, the +performance of the allocator can be optimized by adjusting the block size or +size of the lookahead buffer, trading either write granularity or RAM for +allocator performance. + +## Wear leveling + +The block allocator has a secondary role: wear leveling. + +Wear leveling is the process of distributing wear across all blocks in the +storage to prevent the filesystem from experiencing an early death due to +wear on a single block in the storage. + +littlefs has two methods of protecting against wear: +1. Detection and recovery from bad blocks +2. Evenly distributing wear across dynamic blocks + +--- + +Recovery from bad blocks doesn't actually have anything to do with the block +allocator itself. Instead, it relies on the ability of the filesystem to detect +and evict bad blocks when they occur. + +In littlefs, it is fairly straightforward to detect bad blocks at write time. +All writes must be sourced by some form of data in RAM, so immediately after we +write to a block, we can read the data back and verify that it was written +correctly. If we find that the data on disk does not match the copy we have in +RAM, a write error has occurred and we most likely have a bad block. + +Once we detect a bad block, we need to recover from it. In the case of write +errors, we have a copy of the corrupted data in RAM, so all we need to do is +evict the bad block, allocate a new, hopefully good block, and repeat the write +that previously failed. + +The actual act of evicting the bad block and replacing it with a new block is +left up to the filesystem's copy-on-bounded-writes (CObW) data structures. One +property of CObW data structures is that any block can be replaced during a +COW operation. The bounded-writes part is normally triggered by a counter, but +nothing prevents us from triggering a COW operation as soon as we find a bad +block. + +``` + .----. + |root| + | | + '----' + v--' '----------------------v +.----. .----. +| A | | B | +| | | | +'----' '----' +. . v---' . +. . .----. . +. . | C | . +. . | | . +. . '----' . +. . . . . +.----.----.----.----.----.----.----.----.----.----. +| A |root| | C | B | | +| | | | | | | +'----'----'----'----'----'----'----'----'----'----' + +update C +=> + .----. + |root| + | | + '----' + v--' '----------------------v +.----. .----. +| A | | B | +| | | | +'----' '----' +. . v---' . +. . .----. . +. . |bad | . +. . |blck| . +. . '----' . +. . . . . +.----.----.----.----.----.----.----.----.----.----. +| A |root| |bad | B | | +| | | |blck| | | +'----'----'----'----'----'----'----'----'----'----' + +oh no! bad block! relocate C +=> + .----. + |root| + | | + '----' + v--' '----------------------v +.----. .----. +| A | | B | +| | | | +'----' '----' +. . v---' . +. . .----. . +. . |bad | . +. . |blck| . +. . '----' . +. . . . . +.----.----.----.----.----.----.----.----.----.----. +| A |root| |bad | B |bad | | +| | | |blck| |blck| | +'----'----'----'----'----'----'----'----'----'----' + ---------> +oh no! bad block! relocate C +=> + .----. + |root| + | | + '----' + v--' '----------------------v +.----. .----. +| A | | B | +| | | | +'----' '----' +. . v---' . +. . .----. . .----. +. . |bad | . | C' | +. . |blck| . | | +. . '----' . '----' +. . . . . . . +.----.----.----.----.----.----.----.----.----.----. +| A |root| |bad | B |bad | C' | | +| | | |blck| |blck| | | +'----'----'----'----'----'----'----'----'----'----' + --------------> +successfully relocated C, update B +=> + .----. + |root| + | | + '----' + v--' '----------------------v +.----. .----. +| A | |bad | +| | |blck| +'----' '----' +. . v---' . +. . .----. . .----. +. . |bad | . | C' | +. . |blck| . | | +. . '----' . '----' +. . . . . . . +.----.----.----.----.----.----.----.----.----.----. +| A |root| |bad |bad |bad | C' | | +| | | |blck|blck|blck| | | +'----'----'----'----'----'----'----'----'----'----' + +oh no! bad block! relocate B +=> + .----. + |root| + | | + '----' + v--' '----------------------v +.----. .----. .----. +| A | |bad | |bad | +| | |blck| |blck| +'----' '----' '----' +. . v---' . . . +. . .----. . .----. . +. . |bad | . | C' | . +. . |blck| . | | . +. . '----' . '----' . +. . . . . . . . +.----.----.----.----.----.----.----.----.----.----. +| A |root| |bad |bad |bad | C' |bad | +| | | |blck|blck|blck| |blck| +'----'----'----'----'----'----'----'----'----'----' + --------------> +oh no! bad block! relocate B +=> + .----. + |root| + | | + '----' + v--' '----------------------v +.----. .----. .----. +| A | | B' | |bad | +| | | | |blck| +'----' '----' '----' +. . . | . .---' . +. . . '--------------v-------------v +. . . . .----. . .----. +. . . . |bad | . | C' | +. . . . |blck| . | | +. . . . '----' . '----' +. . . . . . . . . +.----.----.----.----.----.----.----.----.----.----. +| A |root| B' | |bad |bad |bad | C' |bad | +| | | | |blck|blck|blck| |blck| +'----'----'----'----'----'----'----'----'----'----' +------------> ------------------ +successfully relocated B, update root +=> + .----. + |root| + | | + '----' + v--' '--v +.----. .----. +| A | | B' | +| | | | +'----' '----' +. . . '---------------------------v +. . . . .----. +. . . . | C' | +. . . . | | +. . . . '----' +. . . . . . +.----.----.----.----.----.----.----.----.----.----. +| A |root| B' | |bad |bad |bad | C' |bad | +| | | | |blck|blck|blck| |blck| +'----'----'----'----'----'----'----'----'----'----' +``` + +We may find that the new block is also bad, but hopefully after repeating this +cycle we'll eventually find a new block where a write succeeds. If we don't, +that means that all blocks in our storage are bad, and we've reached the end of +our device's usable life. At this point, littlefs will return an "out of space" +error. This is technically true, as there are no more good blocks, but as an +added benefit it also matches the error condition expected by users of +dynamically sized data. + +--- + +Read errors, on the other hand, are quite a bit more complicated. We don't have +a copy of the data lingering around in RAM, so we need a way to reconstruct the +original data even after it has been corrupted. One such mechanism for this is +[error-correction-codes (ECC)][wikipedia-ecc]. + +ECC is an extension to the idea of a checksum. Where a checksum such as CRC can +detect that an error has occurred in the data, ECC can detect and actually +correct some amount of errors. However, there is a limit to how many errors ECC +can detect: the [Hamming bound][wikipedia-hamming-bound]. As the number of +errors approaches the Hamming bound, we may still be able to detect errors, but +can no longer fix the data. If we've reached this point the block is +unrecoverable. + +littlefs by itself does **not** provide ECC. The block nature and relatively +large footprint of ECC does not work well with the dynamically sized data of +filesystems, correcting errors without RAM is complicated, and ECC fits better +with the geometry of block devices. In fact, several NOR flash chips have extra +storage intended for ECC, and many NAND chips can even calculate ECC on the +chip itself. + +In littlefs, ECC is entirely optional. Read errors can instead be prevented +proactively by wear leveling. But it's important to note that ECC can be used +at the block device level to modestly extend the life of a device. littlefs +respects any errors reported by the block device, allowing a block device to +provide additional aggressive error detection. + +--- + +To avoid read errors, we need to be proactive, as opposed to reactive as we +were with write errors. + +One way to do this is to detect when the number of errors in a block exceeds +some threshold, but is still recoverable. With ECC we can do this at write +time, and treat the error as a write error, evicting the block before fatal +read errors have a chance to develop. + +A different, more generic strategy, is to proactively distribute wear across +all blocks in the storage, with the hope that no single block fails before the +rest of storage is approaching the end of its usable life. This is called +wear leveling. + +Generally, wear leveling algorithms fall into one of two categories: + +1. [Dynamic wear leveling][wikipedia-dynamic-wear-leveling], where we + distribute wear over "dynamic" blocks. The can be accomplished by + only considering unused blocks. + +2. [Static wear leveling][wikipedia-static-wear-leveling], where we + distribute wear over both "dynamic" and "static" blocks. To make this work, + we need to consider all blocks, including blocks that already contain data. + +As a tradeoff for code size and complexity, littlefs (currently) only provides +dynamic wear leveling. This is a best effort solution. Wear is not distributed +perfectly, but it is distributed among the free blocks and greatly extends the +life of a device. + +On top of this, littlefs uses a statistical wear leveling algorithm. What this +means is that we don’t actively track wear, instead we rely on a uniform +distribution of wear across storage to approximate a dynamic wear leveling +algorithm. Despite the long name, this is actually a simplification of dynamic +wear leveling. + +The uniform distribution of wear is left up to the block allocator, which +creates a uniform distribution in two parts. The easy part is when the device +is powered, in which case we allocate the blocks linearly, circling the device. +The harder part is what to do when the device loses power. We can't just +restart the allocator at the beginning of storage, as this would bias the wear. +Instead, we start the allocator as a random offset every time we mount the +filesystem. As long as this random offset is uniform, the combined allocation +pattern is also a uniform distribution. + +![Cumulative wear distribution graph][wear-distribution-graph] + +Initially, this approach to wear leveling looks like it creates a difficult +dependency on a power-independent random number generator, which must return +different random numbers on each boot. However, the filesystem is in a +relatively unique situation in that it is sitting on top of a large of amount +of entropy that persists across power loss. + +We can actually use the data on disk to directly drive our random number +generator. In practice, this is implemented by xoring the checksums of each +metadata pair, which is already calculated to fetch and mount the filesystem. + +``` + .--------. \ probably random + .|metadata| | ^ + || | +-> crc ----------------------> xor + || | | ^ + |'--------' / | + '---|--|-' | + .-' '-------------------------. | + | | | + | .--------------> xor ------------> xor + | | ^ | ^ + v crc crc v crc + .--------. \ ^ .--------. \ ^ .--------. \ ^ + .|metadata|-|--|-->|metadata| | | .|metadata| | | + || | +--' || | +--' || | +--' + || | | || | | || | | + |'--------' / |'--------' / |'--------' / + '---|--|-' '----|---' '---|--|-' + .-' '-. | .-' '-. + v v v v v +.--------. .--------. .--------. .--------. .--------. +| data | | data | | data | | data | | data | +| | | | | | | | | | +| | | | | | | | | | +'--------' '--------' '--------' '--------' '--------' +``` + +Note that this random number generator is not perfect. It only returns unique +random numbers when the filesystem is modified. This is exactly what we want +for distributing wear in the allocator, but means this random number generator +is not useful for general use. + +--- + +Together, bad block detection and dynamic wear leveling provide a best effort +solution for avoiding the early death of a filesystem due to wear. Importantly, +littlefs's wear leveling algorithm provides a key feature: You can increase the +life of a device simply by increasing the size of storage. And if more +aggressive wear leveling is desired, you can always combine littlefs with a +[flash translation layer (FTL)][wikipedia-ftl] to get a small power resilient +filesystem with static wear leveling. + +## Files + +Now that we have our building blocks out of the way, we can start looking at +our filesystem as a whole. + +The first step: How do we actually store our files? + +We've determined that CTZ skip-lists are pretty good at storing data compactly, +so following the precedent found in other filesystems we could give each file +a skip-list stored in a metadata pair that acts as an inode for the file. + + +``` + .--------. + .|metadata| + || | + || | + |'--------' + '----|---' + v +.--------. .--------. .--------. .--------. +| data 0 |<-| data 1 |<-| data 2 |<-| data 3 | +| |<-| |--| | | | +| | | | | | | | +'--------' '--------' '--------' '--------' +``` + +However, this doesn't work well when files are small, which is common for +embedded systems. Compared to PCs, _all_ data in an embedded system is small. + +Consider a small 4-byte file. With a two block metadata-pair and one block for +the CTZ skip-list, we find ourselves using a full 3 blocks. On most NOR flash +with 4 KiB blocks, this is 12 KiB of overhead. A ridiculous 3072x increase. + +``` +file stored as inode, 4 bytes costs ~12 KiB + + .----------------. \ +.| revision | | +||----------------| \ | +|| skiplist ---. +- metadata | +||----------------| | / 4x8 bytes | +|| checksum | | 32 bytes | +||----------------| | | +|| | | | +- metadata pair +|| v | | | 2x4 KiB +|| | | | 8 KiB +|| | | | +|| | | | +|| | | | +|'----------------' | | +'----------------' | / + .--------' + v + .----------------. \ \ + | data | +- data | + |----------------| / 4 bytes | + | | | + | | | + | | | + | | +- data block + | | | 4 KiB + | | | + | | | + | | | + | | | + | | | + '----------------' / +``` + +We can make several improvements. First, instead of giving each file its own +metadata pair, we can store multiple files in a single metadata pair. One way +to do this is to directly associate a directory with a metadata pair (or a +linked list of metadata pairs). This makes it easy for multiple files to share +the directory's metadata pair for logging and reduces the collective storage +overhead. + +The strict binding of metadata pairs and directories also gives users +direct control over storage utilization depending on how they organize their +directories. + +``` +multiple files stored in metadata pair, 4 bytes costs ~4 KiB + + .----------------. + .| revision | + ||----------------| + || A name | + || A skiplist -----. + ||----------------| | \ + || B name | | +- metadata + || B skiplist ---. | | 4x8 bytes + ||----------------| | | / 32 bytes + || checksum | | | + ||----------------| | | + || | | | | + || v | | | + |'----------------' | | + '----------------' | | + .----------------' | + v v +.----------------. .----------------. \ \ +| A data | | B data | +- data | +| | |----------------| / 4 bytes | +| | | | | +| | | | | +| | | | | +| | | | + data block +| | | | | 4 KiB +| | | | | +|----------------| | | | +| | | | | +| | | | | +| | | | | +'----------------' '----------------' / +``` + +The second improvement we can make is noticing that for very small files, our +attempts to use CTZ skip-lists for compact storage backfires. Metadata pairs +have a ~4x storage cost, so if our file is smaller than 1/4 the block size, +there's actually no benefit in storing our file outside of our metadata pair. + +In this case, we can store the file directly in our directory's metadata pair. +We call this an inline file, and it allows a directory to store many small +files quite efficiently. Our previous 4 byte file now only takes up a +theoretical 16 bytes on disk. + +``` +inline files stored in metadata pair, 4 bytes costs ~16 bytes + + .----------------. +.| revision | +||----------------| +|| A name | +|| A skiplist ---. +||----------------| | \ +|| B name | | +- data +|| B data | | | 4x4 bytes +||----------------| | / 16 bytes +|| checksum | | +||----------------| | +|| | | | +|| v | | +|'----------------' | +'----------------' | + .---------' + v + .----------------. + | A data | + | | + | | + | | + | | + | | + | | + | | + |----------------| + | | + | | + | | + '----------------' +``` + +Once the file exceeds 1/4 the block size, we switch to a CTZ skip-list. This +means that our files never use more than 4x storage overhead, decreasing as +the file grows in size. + +![File storage cost graph][file-cost-graph] + +## Directories + +Now we just need directories to store our files. As mentioned above we want +a strict binding of directories and metadata pairs, but there are a few +complications we need to sort out. + +On their own, each directory is a linked-list of metadata pairs. This lets us +store an unlimited number of files in each directory, and we don't need to +worry about the runtime complexity of unbounded logs. We can store other +directory pointers in our metadata pairs, which gives us a directory tree, much +like what you find on other filesystems. + +``` + .--------. + .| root | + || | + || | + |'--------' + '---|--|-' + .-' '-------------------------. + v v + .--------. .--------. .--------. + .| dir A |------->| dir A | .| dir B | + || | || | || | + || | || | || | + |'--------' |'--------' |'--------' + '---|--|-' '----|---' '---|--|-' + .-' '-. | .-' '-. + v v v v v +.--------. .--------. .--------. .--------. .--------. +| file C | | file D | | file E | | file F | | file G | +| | | | | | | | | | +| | | | | | | | | | +'--------' '--------' '--------' '--------' '--------' +``` + +The main complication is, once again, traversal with a constant amount of +[RAM]. The directory tree is a tree, and the unfortunate fact is you can't +traverse a tree with constant RAM. + +Fortunately, the elements of our tree are metadata pairs, so unlike CTZ +skip-lists, we're not limited to strict COW operations. One thing we can do is +thread a linked-list through our tree, explicitly enabling cheap traversal +over the entire filesystem. + +``` + .--------. + .| root |-. + || | | + .-------|| |-' + | |'--------' + | '---|--|-' + | .-' '-------------------------. + | v v + | .--------. .--------. .--------. + '->| dir A |------->| dir A |------->| dir B | + || | || | || | + || | || | || | + |'--------' |'--------' |'--------' + '---|--|-' '----|---' '---|--|-' + .-' '-. | .-' '-. + v v v v v +.--------. .--------. .--------. .--------. .--------. +| file C | | file D | | file E | | file F | | file G | +| | | | | | | | | | +| | | | | | | | | | +'--------' '--------' '--------' '--------' '--------' +``` + +Unfortunately, not sticking to pure COW operations creates some problems. Now, +whenever we want to manipulate the directory tree, multiple pointers need to be +updated. If you're familiar with designing atomic data structures this should +set off a bunch of red flags. + +To work around this, our threaded linked-list has a bit of leeway. Instead of +only containing metadata pairs found in our filesystem, it is allowed to +contain metadata pairs that have no parent because of a power loss. These are +called orphaned metadata pairs. + +With the possibility of orphans, we can build power loss resilient operations +that maintain a filesystem tree threaded with a linked-list for traversal. + +Adding a directory to our tree: + +``` + .--------. + .| root |-. + || | | +.-------|| |-' +| |'--------' +| '---|--|-' +| .-' '-. +| v v +| .--------. .--------. +'->| dir A |->| dir C | + || | || | + || | || | + |'--------' |'--------' + '--------' '--------' + +allocate dir B +=> + .--------. + .| root |-. + || | | +.-------|| |-' +| |'--------' +| '---|--|-' +| .-' '-. +| v v +| .--------. .--------. +'->| dir A |--->| dir C | + || | .->| | + || | | || | + |'--------' | |'--------' + '--------' | '--------' + | + .--------. | + .| dir B |-' + || | + || | + |'--------' + '--------' + +insert dir B into threaded linked-list, creating an orphan +=> + .--------. + .| root |-. + || | | +.-------|| |-' +| |'--------' +| '---|--|-' +| .-' '-------------. +| v v +| .--------. .--------. .--------. +'->| dir A |->| dir B |->| dir C | + || | || orphan!| || | + || | || | || | + |'--------' |'--------' |'--------' + '--------' '--------' '--------' + +add dir B to parent directory +=> + .--------. + .| root |-. + || | | +.-------------|| |-' +| |'--------' +| '--|-|-|-' +| .------' | '-------. +| v v v +| .--------. .--------. .--------. +'->| dir A |->| dir B |->| dir C | + || | || | || | + || | || | || | + |'--------' |'--------' |'--------' + '--------' '--------' '--------' +``` + +Removing a directory: + +``` + .--------. + .| root |-. + || | | +.-------------|| |-' +| |'--------' +| '--|-|-|-' +| .------' | '-------. +| v v v +| .--------. .--------. .--------. +'->| dir A |->| dir B |->| dir C | + || | || | || | + || | || | || | + |'--------' |'--------' |'--------' + '--------' '--------' '--------' + +remove dir B from parent directory, creating an orphan +=> + .--------. + .| root |-. + || | | +.-------|| |-' +| |'--------' +| '---|--|-' +| .-' '-------------. +| v v +| .--------. .--------. .--------. +'->| dir A |->| dir B |->| dir C | + || | || orphan!| || | + || | || | || | + |'--------' |'--------' |'--------' + '--------' '--------' '--------' + +remove dir B from threaded linked-list, returning dir B to free blocks +=> + .--------. + .| root |-. + || | | +.-------|| |-' +| |'--------' +| '---|--|-' +| .-' '-. +| v v +| .--------. .--------. +'->| dir A |->| dir C | + || | || | + || | || | + |'--------' |'--------' + '--------' '--------' +``` + +In addition to normal directory tree operations, we can use orphans to evict +blocks in a metadata pair when the block goes bad or exceeds its allocated +erases. If we lose power while evicting a metadata block we may end up with +a situation where the filesystem references the replacement block while the +threaded linked-list still contains the evicted block. We call this a +half-orphan. + +``` + .--------. + .| root |-. + || | | +.-------------|| |-' +| |'--------' +| '--|-|-|-' +| .------' | '-------. +| v v v +| .--------. .--------. .--------. +'->| dir A |->| dir B |->| dir C | + || | || | || | + || | || | || | + |'--------' |'--------' |'--------' + '--------' '--------' '--------' + +try to write to dir B +=> + .--------. + .| root |-. + || | | +.----------------|| |-' +| |'--------' +| '-|-||-|-' +| .--------' || '-----. +| v |v v +| .--------. .--------. .--------. +'->| dir A |---->| dir B |->| dir C | + || |-. | | || | + || | | | | || | + |'--------' | '--------' |'--------' + '--------' | v '--------' + | .--------. + '->| dir B | + | bad | + | block! | + '--------' + +oh no! bad block detected, allocate replacement +=> + .--------. + .| root |-. + || | | +.----------------|| |-' +| |'--------' +| '-|-||-|-' +| .--------' || '-------. +| v |v v +| .--------. .--------. .--------. +'->| dir A |---->| dir B |--->| dir C | + || |-. | | .->| | + || | | | | | || | + |'--------' | '--------' | |'--------' + '--------' | v | '--------' + | .--------. | + '->| dir B | | + | bad | | + | block! | | + '--------' | + | + .--------. | + | dir B |--' + | | + | | + '--------' + +insert replacement in threaded linked-list, creating a half-orphan +=> + .--------. + .| root |-. + || | | +.----------------|| |-' +| |'--------' +| '-|-||-|-' +| .--------' || '-------. +| v |v v +| .--------. .--------. .--------. +'->| dir A |---->| dir B |--->| dir C | + || |-. | | .->| | + || | | | | | || | + |'--------' | '--------' | |'--------' + '--------' | v | '--------' + | .--------. | + | | dir B | | + | | bad | | + | | block! | | + | '--------' | + | | + | .--------. | + '->| dir B |--' + | half | + | orphan!| + '--------' + +fix reference in parent directory +=> + .--------. + .| root |-. + || | | +.-------------|| |-' +| |'--------' +| '--|-|-|-' +| .------' | '-------. +| v v v +| .--------. .--------. .--------. +'->| dir A |->| dir B |->| dir C | + || | || | || | + || | || | || | + |'--------' |'--------' |'--------' + '--------' '--------' '--------' +``` + +Finding orphans and half-orphans is expensive, requiring a _O(n²)_ +comparison of every metadata pair with every directory entry. But the tradeoff +is a power resilient filesystem that works with only a bounded amount of RAM. +Fortunately, we only need to check for orphans on the first allocation after +boot, and a read-only littlefs can ignore the threaded linked-list entirely. + +If we only had some sort of global state, then we could also store a flag and +avoid searching for orphans unless we knew we were specifically interrupted +while manipulating the directory tree (foreshadowing!). + +## The move problem + +We have one last challenge: the move problem. Phrasing the problem is simple: + +How do you atomically move a file between two directories? + +In littlefs we can atomically commit to directories, but we can't create +an atomic commit that spans multiple directories. The filesystem must go +through a minimum of two distinct states to complete a move. + +To make matters worse, file moves are a common form of synchronization for +filesystems. As a filesystem designed for power-loss, it's important we get +atomic moves right. + +So what can we do? + +- We definitely can't just let power-loss result in duplicated or lost files. + This could easily break users' code and would only reveal itself in extreme + cases. We were only able to be lazy about the threaded linked-list because + it isn't user facing and we can handle the corner cases internally. + +- Some filesystems propagate COW operations up the tree until a common parent + is found. Unfortunately this interacts poorly with our threaded tree and + brings back the issue of upward propagation of wear. + +- In a previous version of littlefs we tried to solve this problem by going + back and forth between the source and destination, marking and unmarking the + file as moving in order to make the move atomic from the user perspective. + This worked, but not well. Finding failed moves was expensive and required + a unique identifier for each file. + +In the end, solving the move problem required creating a new mechanism for +sharing knowledge between multiple metadata pairs. In littlefs this led to the +introduction of a mechanism called "global state". + +--- + +Global state is a small set of state that can be updated from _any_ metadata +pair. Combining global state with metadata pairs' ability to update multiple +entries in one commit gives us a powerful tool for crafting complex atomic +operations. + +How does global state work? + +Global state exists as a set of deltas that are distributed across the metadata +pairs in the filesystem. The actual global state can be built out of these +deltas by xoring together all of the deltas in the filesystem. + +``` + .--------. .--------. .--------. .--------. .--------. +.| |->| gdelta |->| |->| gdelta |->| gdelta | +|| | || 0x23 | || | || 0xff | || 0xce | +|| | || | || | || | || | +|'--------' |'--------' |'--------' |'--------' |'--------' +'--------' '----|---' '--------' '----|---' '----|---' + v v v + 0x00 --> xor ------------------> xor ------> xor --> gstate 0x12 +``` + +To update the global state from a metadata pair, we take the global state we +know and xor it with both our changes and any existing delta in the metadata +pair. Committing this new delta to the metadata pair commits the changes to +the filesystem's global state. + +``` + .--------. .--------. .--------. .--------. .--------. +.| |->| gdelta |->| |->| gdelta |->| gdelta | +|| | || 0x23 | || | || 0xff | || 0xce | +|| | || | || | || | || | +|'--------' |'--------' |'--------' |'--------' |'--------' +'--------' '----|---' '--------' '--|---|-' '----|---' + v v | v + 0x00 --> xor ----------------> xor -|------> xor --> gstate = 0x12 + | | + | | +change gstate to 0xab --> xor <------------|--------------------------' +=> | v + '------------> xor + | + v + .--------. .--------. .--------. .--------. .--------. +.| |->| gdelta |->| |->| gdelta |->| gdelta | +|| | || 0x23 | || | || 0x46 | || 0xce | +|| | || | || | || | || | +|'--------' |'--------' |'--------' |'--------' |'--------' +'--------' '----|---' '--------' '----|---' '----|---' + v v v + 0x00 --> xor ------------------> xor ------> xor --> gstate = 0xab +``` + +To make this efficient, we always keep a copy of the global state in RAM. We +only need to iterate over our metadata pairs and build the global state when +the filesystem is mounted. + +You may have noticed that global state is very expensive. We keep a copy in +RAM and a delta in an unbounded number of metadata pairs. Even if we reset +the global state to its initial value, we can't easily clean up the deltas on +disk. For this reason, it's very important that we keep the size of global +state bounded and extremely small. But, even with a strict budget, global +state is incredibly valuable. + +--- + +Now we can solve the move problem. We can create global state describing our +move atomically with the creation of the new file, and we can clear this move +state atomically with the removal of the old file. + +``` + .--------. gstate = no move + .| root |-. + || | | +.-------------|| |-' +| |'--------' +| '--|-|-|-' +| .------' | '-------. +| v v v +| .--------. .--------. .--------. +'->| dir A |->| dir B |->| dir C | + || | || | || | + || | || | || | + |'--------' |'--------' |'--------' + '----|---' '--------' '--------' + v + .--------. + | file D | + | | + | | + '--------' + +begin move, add reference in dir C, change gstate to have move +=> + .--------. gstate = moving file D in dir A (m1) + .| root |-. + || | | +.-------------|| |-' +| |'--------' +| '--|-|-|-' +| .------' | '-------. +| v v v +| .--------. .--------. .--------. +'->| dir A |->| dir B |->| dir C | + || | || | || gdelta | + || | || | || =m1 | + |'--------' |'--------' |'--------' + '----|---' '--------' '----|---' + | .----------------' + v v + .--------. + | file D | + | | + | | + '--------' + +complete move, remove reference in dir A, change gstate to no move +=> + .--------. gstate = no move (m1^~m1) + .| root |-. + || | | +.-------------|| |-' +| |'--------' +| '--|-|-|-' +| .------' | '-------. +| v v v +| .--------. .--------. .--------. +'->| dir A |->| dir B |->| dir C | + || gdelta | || | || gdelta | + || =~m1 | || | || =m1 | + |'--------' |'--------' |'--------' + '--------' '--------' '----|---' + v + .--------. + | file D | + | | + | | + '--------' +``` + + +If, after building our global state during mount, we find information +describing an ongoing move, we know we lost power during a move and the file +is duplicated in both the source and destination directories. If this happens, +we can resolve the move using the information in the global state to remove +one of the files. + +``` + .--------. gstate = moving file D in dir A (m1) + .| root |-. ^ + || |------------> xor +.---------------|| |-' ^ +| |'--------' | +| '--|-|-|-' | +| .--------' | '---------. | +| | | | | +| | .----------> xor --------> xor +| v | v ^ v ^ +| .--------. | .--------. | .--------. | +'->| dir A |-|->| dir B |-|->| dir C | | + || |-' || |-' || gdelta |-' + || | || | || =m1 | + |'--------' |'--------' |'--------' + '----|---' '--------' '----|---' + | .---------------------' + v v + .--------. + | file D | + | | + | | + '--------' +``` + +We can also move directories the same way we move files. There is the threaded +linked-list to consider, but leaving the threaded linked-list unchanged works +fine as the order doesn't really matter. + +``` + .--------. gstate = no move (m1^~m1) + .| root |-. + || | | +.-------------|| |-' +| |'--------' +| '--|-|-|-' +| .------' | '-------. +| v v v +| .--------. .--------. .--------. +'->| dir A |->| dir B |->| dir C | + || gdelta | || | || gdelta | + || =~m1 | || | || =m1 | + |'--------' |'--------' |'--------' + '--------' '--------' '----|---' + v + .--------. + | file D | + | | + | | + '--------' + +begin move, add reference in dir C, change gstate to have move +=> + .--------. gstate = moving dir B in root (m1^~m1^m2) + .| root |-. + || | | +.--------------|| |-' +| |'--------' +| '--|-|-|-' +| .-------' | '----------. +| v | v +| .--------. | .--------. +'->| dir A |-. | .->| dir C | + || gdelta | | | | || gdelta | + || =~m1 | | | | || =m1^m2 | + |'--------' | | | |'--------' + '--------' | | | '---|--|-' + | | .-------' | + | v v | v + | .--------. | .--------. + '->| dir B |-' | file D | + || | | | + || | | | + |'--------' '--------' + '--------' + +complete move, remove reference in root, change gstate to no move +=> + .--------. gstate = no move (m1^~m1^m2^~m2) + .| root |-. + || gdelta | | +.-----------|| =~m2 |-' +| |'--------' +| '---|--|-' +| .-----' '-----. +| v v +| .--------. .--------. +'->| dir A |-. .->| dir C | + || gdelta | | | || gdelta | + || =~m1 | | '-|| =m1^m2 |-------. + |'--------' | |'--------' | + '--------' | '---|--|-' | + | .-' '-. | + | v v | + | .--------. .--------. | + '->| dir B |--| file D |-' + || | | | + || | | | + |'--------' '--------' + '--------' +``` + +Global state gives us a powerful tool we can use to solve the move problem. +And the result is surprisingly performant, only needing the minimum number +of states and using the same number of commits as a naive move. Additionally, +global state gives us a bit of persistent state we can use for some other +small improvements. + +## Conclusion + +And that's littlefs, thanks for reading! + + +[wikipedia-flash]: https://en.wikipedia.org/wiki/Flash_memory +[wikipedia-sna]: https://en.wikipedia.org/wiki/Serial_number_arithmetic +[wikipedia-crc]: https://en.wikipedia.org/wiki/Cyclic_redundancy_check +[wikipedia-cow]: https://en.wikipedia.org/wiki/Copy-on-write +[wikipedia-B-tree]: https://en.wikipedia.org/wiki/B-tree +[wikipedia-B+-tree]: https://en.wikipedia.org/wiki/B%2B_tree +[wikipedia-skip-list]: https://en.wikipedia.org/wiki/Skip_list +[wikipedia-ctz]: https://en.wikipedia.org/wiki/Count_trailing_zeros +[wikipedia-ecc]: https://en.wikipedia.org/wiki/Error_correction_code +[wikipedia-hamming-bound]: https://en.wikipedia.org/wiki/Hamming_bound +[wikipedia-dynamic-wear-leveling]: https://en.wikipedia.org/wiki/Wear_leveling#Dynamic_wear_leveling +[wikipedia-static-wear-leveling]: https://en.wikipedia.org/wiki/Wear_leveling#Static_wear_leveling +[wikipedia-ftl]: https://en.wikipedia.org/wiki/Flash_translation_layer + +[oeis]: https://oeis.org +[A001511]: https://oeis.org/A001511 +[A005187]: https://oeis.org/A005187 + +[fat]: https://en.wikipedia.org/wiki/Design_of_the_FAT_file_system +[ext2]: http://e2fsprogs.sourceforge.net/ext2intro.html +[jffs]: https://www.sourceware.org/jffs2/jffs2-html +[yaffs]: https://yaffs.net/documents/how-yaffs-works +[spiffs]: https://github.com/pellepl/spiffs/blob/master/docs/TECH_SPEC +[ext4]: https://ext4.wiki.kernel.org/index.php/Ext4_Design +[ntfs]: https://en.wikipedia.org/wiki/NTFS +[btrfs]: https://btrfs.wiki.kernel.org/index.php/Btrfs_design +[zfs]: https://en.wikipedia.org/wiki/ZFS + +[cow]: https://upload.wikimedia.org/wikipedia/commons/0/0c/Cow_female_black_white.jpg +[elephant]: https://upload.wikimedia.org/wikipedia/commons/3/37/African_Bush_Elephant.jpg +[ram]: https://upload.wikimedia.org/wikipedia/commons/9/97/New_Mexico_Bighorn_Sheep.JPG + +[metadata-formula1]: https://latex.codecogs.com/svg.latex?cost%20%3D%20n%20+%20n%20%5Cfrac%7Bs%7D%7Bd+1%7D +[metadata-formula2]: https://latex.codecogs.com/svg.latex?s%20%3D%20r%20%5Cfrac%7Bsize%7D%7Bn%7D +[metadata-formula3]: https://latex.codecogs.com/svg.latex?d%20%3D%20%281-r%29%20%5Cfrac%7Bsize%7D%7Bn%7D +[metadata-formula4]: https://latex.codecogs.com/svg.latex?cost%20%3D%20n%20+%20n%20%5Cfrac%7Br%5Cfrac%7Bsize%7D%7Bn%7D%7D%7B%281-r%29%5Cfrac%7Bsize%7D%7Bn%7D+1%7D + +[ctz-formula1]: https://latex.codecogs.com/svg.latex?%5Clim_%7Bn%5Cto%5Cinfty%7D%5Cfrac%7B1%7D%7Bn%7D%5Csum_%7Bi%3D0%7D%5E%7Bn%7D%5Cleft%28%5Ctext%7Bctz%7D%28i%29+1%5Cright%29%20%3D%20%5Csum_%7Bi%3D0%7D%5Cfrac%7B1%7D%7B2%5Ei%7D%20%3D%202 +[ctz-formula2]: https://latex.codecogs.com/svg.latex?B%20%3D%20%5Cfrac%7Bw%7D%7B8%7D%5Cleft%5Clceil%5Clog_2%5Cleft%28%5Cfrac%7B2%5Ew%7D%7BB-2%5Cfrac%7Bw%7D%7B8%7D%7D%5Cright%29%5Cright%5Crceil +[ctz-formula3]: https://latex.codecogs.com/svg.latex?N%20%3D%20%5Csum_i%5En%5Cleft%5BB-%5Cfrac%7Bw%7D%7B8%7D%5Cleft%28%5Ctext%7Bctz%7D%28i%29+1%5Cright%29%5Cright%5D +[ctz-formula4]: https://latex.codecogs.com/svg.latex?%5Csum_i%5En%5Cleft%28%5Ctext%7Bctz%7D%28i%29+1%5Cright%29%20%3D%202n-%5Ctext%7Bpopcount%7D%28n%29 +[ctz-formula5]: https://latex.codecogs.com/svg.latex?N%20%3D%20Bn%20-%20%5Cfrac%7Bw%7D%7B8%7D%5Cleft%282n-%5Ctext%7Bpopcount%7D%28n%29%5Cright%29 +[ctz-formula6]: https://latex.codecogs.com/svg.latex?n%20%3D%20%5Cleft%5Clfloor%5Cfrac%7BN-%5Cfrac%7Bw%7D%7B8%7D%5Cleft%28%5Ctext%7Bpopcount%7D%5Cleft%28%5Cfrac%7BN%7D%7BB-2%5Cfrac%7Bw%7D%7B8%7D%7D-1%5Cright%29+2%5Cright%29%7D%7BB-2%5Cfrac%7Bw%7D%7B8%7D%7D%5Cright%5Crfloor +[ctz-formula7]: https://latex.codecogs.com/svg.latex?%5Cmathit%7Boff%7D%20%3D%20N%20-%20%5Cleft%28B-2%5Cfrac%7Bw%7D%7B8%7D%5Cright%29n%20-%20%5Cfrac%7Bw%7D%7B8%7D%5Ctext%7Bpopcount%7D%28n%29 + +[bigB]: https://latex.codecogs.com/svg.latex?B +[d]: https://latex.codecogs.com/svg.latex?d +[m]: https://latex.codecogs.com/svg.latex?m +[bigN]: https://latex.codecogs.com/svg.latex?N +[n]: https://latex.codecogs.com/svg.latex?n +[n']: https://latex.codecogs.com/svg.latex?n%27 +[r]: https://latex.codecogs.com/svg.latex?r +[s]: https://latex.codecogs.com/svg.latex?s +[w]: https://latex.codecogs.com/svg.latex?w +[x]: https://latex.codecogs.com/svg.latex?x + +[metadata-cost-graph]: https://raw.githubusercontent.com/geky/littlefs/gh-images/metadata-cost.svg?sanitize=true +[wear-distribution-graph]: https://raw.githubusercontent.com/geky/littlefs/gh-images/wear-distribution.svg?sanitize=true +[file-cost-graph]: https://raw.githubusercontent.com/geky/littlefs/gh-images/file-cost.svg?sanitize=true diff --git a/library/littlefs/LICENSE.md b/library/littlefs/LICENSE.md new file mode 100644 index 0000000..e6c3a7b --- /dev/null +++ b/library/littlefs/LICENSE.md @@ -0,0 +1,25 @@ +Copyright (c) 2022, The littlefs authors. +Copyright (c) 2017, Arm Limited. All rights reserved. + +Redistribution and use in source and binary forms, with or without modification, +are permitted provided that the following conditions are met: + +- Redistributions of source code must retain the above copyright notice, this + list of conditions and the following disclaimer. +- Redistributions in binary form must reproduce the above copyright notice, this + list of conditions and the following disclaimer in the documentation and/or + other materials provided with the distribution. +- Neither the name of ARM nor the names of its contributors may be used to + endorse or promote products derived from this software without specific prior + written permission. + +THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND +ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED +WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE +DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR +ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES +(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; +LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON +ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS +SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. diff --git a/library/littlefs/SPEC.md b/library/littlefs/SPEC.md new file mode 100644 index 0000000..6682c74 --- /dev/null +++ b/library/littlefs/SPEC.md @@ -0,0 +1,867 @@ +## littlefs technical specification + +This is the technical specification of the little filesystem with on-disk +version lfs2.1. This document covers the technical details of how the littlefs +is stored on disk for introspection and tooling. This document assumes you are +familiar with the design of the littlefs, for more info on how littlefs works +check out [DESIGN.md](DESIGN.md). + +``` + | | | .---._____ + .-----. | | +--|o |---| littlefs | +--| |---| | + '-----' '----------' + | | | +``` + +## Some quick notes + +- littlefs is a block-based filesystem. The disk is divided into an array of + evenly sized blocks that are used as the logical unit of storage. + +- Block pointers are stored in 32 bits, with the special value `0xffffffff` + representing a null block address. + +- In addition to the logical block size (which usually matches the erase + block size), littlefs also uses a program block size and read block size. + These determine the alignment of block device operations, but don't need + to be consistent for portability. + +- By default, all values in littlefs are stored in little-endian byte order. + +## Directories / Metadata pairs + +Metadata pairs form the backbone of littlefs and provide a system for +distributed atomic updates. Even the superblock is stored in a metadata pair. + +As their name suggests, a metadata pair is stored in two blocks, with one block +providing a backup during erase cycles in case power is lost. These two blocks +are not necessarily sequential and may be anywhere on disk, so a "pointer" to a +metadata pair is stored as two block pointers. + +On top of this, each metadata block behaves as an appendable log, containing a +variable number of commits. Commits can be appended to the metadata log in +order to update the metadata without requiring an erase cycles. Note that +successive commits may supersede the metadata in previous commits. Only the +most recent metadata should be considered valid. + +The high-level layout of a metadata block is fairly simple: + +``` + .---------------------------------------. +.-| revision count | entries | \ +| |-------------------+ | | +| | | | +| | | +-- 1st commit +| | | | +| | +-------------------| | +| | | CRC | / +| |-------------------+-------------------| +| | entries | \ +| | | | +| | | +-- 2nd commit +| | +-------------------+--------------| | +| | | CRC | padding | / +| |----+-------------------+--------------| +| | entries | \ +| | | | +| | | +-- 3rd commit +| | +-------------------+---------| | +| | | CRC | | / +| |---------+-------------------+ | +| | unwritten storage | more commits +| | | | +| | | v +| | | +| | | +| '---------------------------------------' +'---------------------------------------' +``` + +Each metadata block contains a 32-bit revision count followed by a number of +commits. Each commit contains a variable number of metadata entries followed +by a 32-bit CRC. + +Note also that entries aren't necessarily word-aligned. This allows us to +store metadata more compactly, however we can only write to addresses that are +aligned to our program block size. This means each commit may have padding for +alignment. + +Metadata block fields: + +1. **Revision count (32-bits)** - Incremented every erase cycle. If both blocks + contain valid commits, only the block with the most recent revision count + should be used. Sequence comparison must be used to avoid issues with + integer overflow. + +2. **CRC (32-bits)** - Detects corruption from power-loss or other write + issues. Uses a CRC-32 with a polynomial of `0x04c11db7` initialized + with `0xffffffff`. + +Entries themselves are stored as a 32-bit tag followed by a variable length +blob of data. But exactly how these tags are stored is a little bit tricky. + +Metadata blocks support both forward and backward iteration. In order to do +this without duplicating the space for each tag, neighboring entries have their +tags XORed together, starting with `0xffffffff`. + +``` + Forward iteration Backward iteration + +.-------------------. 0xffffffff .-------------------. +| revision count | | | revision count | +|-------------------| v |-------------------| +| tag ~A |---> xor -> tag A | tag ~A |---> xor -> 0xffffffff +|-------------------| | |-------------------| ^ +| data A | | | data A | | +| | | | | | +| | | | | | +|-------------------| v |-------------------| | +| tag AxB |---> xor -> tag B | tag AxB |---> xor -> tag A +|-------------------| | |-------------------| ^ +| data B | | | data B | | +| | | | | | +| | | | | | +|-------------------| v |-------------------| | +| tag BxC |---> xor -> tag C | tag BxC |---> xor -> tag B +|-------------------| |-------------------| ^ +| data C | | data C | | +| | | | tag C +| | | | +| | | | +'-------------------' '-------------------' +``` + +Here's a more complete example of metadata block containing 4 entries: + +``` + .---------------------------------------. +.-| revision count | tag ~A | \ +| |-------------------+-------------------| | +| | data A | | +| | | | +| |-------------------+-------------------| | +| | tag AxB | data B | <--. | +| |-------------------+ | | | +| | | | +-- 1st commit +| | +-------------------+---------| | | +| | | tag BxC | | <-.| | +| |---------+-------------------+ | || | +| | data C | || | +| | | || | +| |-------------------+-------------------| || | +| | tag CxCRC | CRC | || / +| |-------------------+-------------------| || +| | tag CRCxA' | data A' | || \ +| |-------------------+ | || | +| | | || | +| | +-------------------+----| || +-- 2nd commit +| | | tag CRCxA' | | || | +| |--------------+-------------------+----| || | +| | CRC | padding | || / +| |--------------+----+-------------------| || +| | tag CRCxA'' | data A'' | <---. \ +| |-------------------+ | ||| | +| | | ||| | +| | +-------------------+---------| ||| | +| | | tag A''xD | | < ||| | +| |---------+-------------------+ | |||| +-- 3rd commit +| | data D | |||| | +| | +---------| |||| | +| | | tag Dx| |||| | +| |---------+-------------------+---------| |||| | +| |CRC | CRC | | |||| / +| |---------+-------------------+ | |||| +| | unwritten storage | |||| more commits +| | | |||| | +| | | |||| v +| | | |||| +| | | |||| +| '---------------------------------------' |||| +'---------------------------------------' |||'- most recent A + ||'-- most recent B + |'--- most recent C + '---- most recent D +``` + +Two things to note before we get into the details around tag encoding: + +1. Each tag contains a valid bit used to indicate if the tag and containing + commit is valid. After XORing, this bit should always be zero. + + At the end of each commit, the valid bit of the previous tag is XORed + with the lowest bit in the type field of the CRC tag. This allows + the CRC tag to force the next commit to fail the valid bit test if it + has not yet been written to. + +2. The valid bit alone is not enough info to know if the next commit has been + erased. We don't know the order bits will be programmed in a program block, + so it's possible that the next commit had an attempted program that left the + valid bit unchanged. + + To ensure we only ever program erased bytes, each commit can contain an + optional forward-CRC (FCRC). An FCRC contains a checksum of some amount of + bytes in the next commit at the time it was erased. + + ``` + .-------------------. \ \ + | revision count | | | + |-------------------| | | + | metadata | | | + | | +---. +-- current commit + | | | | | + |-------------------| | | | + | FCRC ---|-. | | + |-------------------| / | | | + | CRC -----|-' / + |-------------------| | + | padding | | padding (does't need CRC) + | | | + |-------------------| \ | \ + | erased? | +-' | + | | | | +-- next commit + | v | / | + | | / + | | + '-------------------' + ``` + + If the FCRC is missing or the checksum does not match, we must assume a + commit was attempted but failed due to power-loss. + + Note that end-of-block commits do not need an FCRC. + +## Metadata tags + +So in littlefs, 32-bit tags describe every type of metadata. And this means +_every_ type of metadata, including file entries, directory fields, and +global state. Even the CRCs used to mark the end of commits get their own tag. + +Because of this, the tag format contains some densely packed information. Note +that there are multiple levels of types which break down into more info: + +``` +[---- 32 ----] +[1|-- 11 --|-- 10 --|-- 10 --] + ^. ^ . ^ ^- length + |. | . '------------ id + |. '-----.------------------ type (type3) + '.-----------.------------------ valid bit + [-3-|-- 8 --] + ^ ^- chunk + '------- type (type1) +``` + + +Before we go further, there's one important thing to note. These tags are +**not** stored in little-endian. Tags stored in commits are actually stored +in big-endian (and is the only thing in littlefs stored in big-endian). This +little bit of craziness comes from the fact that the valid bit must be the +first bit in a commit, and when converted to little-endian, the valid bit finds +itself in byte 4. We could restructure the tag to store the valid bit lower, +but, because none of the fields are byte-aligned, this would be more +complicated than just storing the tag in big-endian. + +Another thing to note is that both the tags `0x00000000` and `0xffffffff` are +invalid and can be used for null values. + +Metadata tag fields: + +1. **Valid bit (1-bit)** - Indicates if the tag is valid. + +2. **Type3 (11-bits)** - Type of the tag. This field is broken down further + into a 3-bit abstract type and an 8-bit chunk field. Note that the value + `0x000` is invalid and not assigned a type. + + 1. **Type1 (3-bits)** - Abstract type of the tag. Groups the tags into + 8 categories that facilitate bitmasked lookups. + + 2. **Chunk (8-bits)** - Chunk field used for various purposes by the different + abstract types. type1+chunk+id form a unique identifier for each tag in the + metadata block. + +3. **Id (10-bits)** - File id associated with the tag. Each file in a metadata + block gets a unique id which is used to associate tags with that file. The + special value `0x3ff` is used for any tags that are not associated with a + file, such as directory and global metadata. + +4. **Length (10-bits)** - Length of the data in bytes. The special value + `0x3ff` indicates that this tag has been deleted. + +## Metadata types + +What follows is an exhaustive list of metadata in littlefs. + +--- +#### `0x401` LFS_TYPE_CREATE + +Creates a new file with this id. Note that files in a metadata block +don't necessarily need a create tag. All a create does is move over any +files using this id. In this sense a create is similar to insertion into +an imaginary array of files. + +The create and delete tags allow littlefs to keep files in a directory +ordered alphabetically by filename. + +--- +#### `0x4ff` LFS_TYPE_DELETE + +Deletes the file with this id. An inverse to create, this tag moves over +any files neighboring this id similar to a deletion from an imaginary +array of files. + +--- +#### `0x0xx` LFS_TYPE_NAME + +Associates the id with a file name and file type. + +The data contains the file name stored as an ASCII string (may be expanded to +UTF8 in the future). + +The chunk field in this tag indicates an 8-bit file type which can be one of +the following. + +Currently, the name tag must precede any other tags associated with the id and +can not be reassigned without deleting the file. + +Layout of the name tag: + +``` + tag data +[-- 32 --][--- variable length ---] +[1| 3| 8 | 10 | 10 ][--- (size * 8) ---] + ^ ^ ^ ^ ^- size ^- file name + | | | '------ id + | | '----------- file type + | '-------------- type1 (0x0) + '----------------- valid bit +``` + +Name fields: + +1. **file type (8-bits)** - Type of the file. + +2. **file name** - File name stored as an ASCII string. + +--- +#### `0x001` LFS_TYPE_REG + +Initializes the id + name as a regular file. + +How each file is stored depends on its struct tag, which is described below. + +--- +#### `0x002` LFS_TYPE_DIR + +Initializes the id + name as a directory. + +Directories in littlefs are stored on disk as a linked-list of metadata pairs, +each pair containing any number of files in alphabetical order. A pointer to +the directory is stored in the struct tag, which is described below. + +--- +#### `0x0ff` LFS_TYPE_SUPERBLOCK + +Initializes the id as a superblock entry. + +The superblock entry is a special entry used to store format-time configuration +and identify the filesystem. + +The name is a bit of a misnomer. While the superblock entry serves the same +purpose as a superblock found in other filesystems, in littlefs the superblock +does not get a dedicated block. Instead, the superblock entry is duplicated +across a linked-list of metadata pairs rooted on the blocks 0 and 1. The last +metadata pair doubles as the root directory of the filesystem. + +``` + .--------. .--------. .--------. .--------. .--------. +.| super |->| super |->| super |->| super |->| file B | +|| block | || block | || block | || block | || file C | +|| | || | || | || file A | || file D | +|'--------' |'--------' |'--------' |'--------' |'--------' +'--------' '--------' '--------' '--------' '--------' + +\----------------+----------------/ \----------+----------/ + superblock pairs root directory +``` + +The filesystem starts with only the root directory. The superblock metadata +pairs grow every time the root pair is compacted in order to prolong the +life of the device exponentially. + +The contents of the superblock entry are stored in a name tag with the +superblock type and an inline-struct tag. The name tag contains the magic +string "littlefs", while the inline-struct tag contains version and +configuration information. + +Layout of the superblock name tag and inline-struct tag: + +``` + tag data +[-- 32 --][-- 32 --|-- 32 --] +[1|- 11 -| 10 | 10 ][--- 64 ---] + ^ ^ ^ ^- size (8) ^- magic string ("littlefs") + | | '------ id (0) + | '------------ type (0x0ff) + '----------------- valid bit + + tag data +[-- 32 --][-- 32 --|-- 32 --|-- 32 --] +[1|- 11 -| 10 | 10 ][-- 32 --|-- 32 --|-- 32 --] + ^ ^ ^ ^ ^- version ^- block size ^- block count + | | | | [-- 32 --|-- 32 --|-- 32 --] + | | | | [-- 32 --|-- 32 --|-- 32 --] + | | | | ^- name max ^- file max ^- attr max + | | | '- size (24) + | | '------ id (0) + | '------------ type (0x201) + '----------------- valid bit +``` + +Superblock fields: + +1. **Magic string (8-bytes)** - Magic string indicating the presence of + littlefs on the device. Must be the string "littlefs". + +2. **Version (32-bits)** - The version of littlefs at format time. The version + is encoded in a 32-bit value with the upper 16-bits containing the major + version, and the lower 16-bits containing the minor version. + + This specification describes version 2.0 (`0x00020000`). + +3. **Block size (32-bits)** - Size of the logical block size used by the + filesystem in bytes. + +4. **Block count (32-bits)** - Number of blocks in the filesystem. + +5. **Name max (32-bits)** - Maximum size of file names in bytes. + +6. **File max (32-bits)** - Maximum size of files in bytes. + +7. **Attr max (32-bits)** - Maximum size of file attributes in bytes. + +The superblock must always be the first entry (id 0) in the metadata pair, and +the name tag must always be the first tag in the metadata pair. This makes it +so that the magic string "littlefs" will always reside at offset=8 in a valid +littlefs superblock. + +--- +#### `0x2xx` LFS_TYPE_STRUCT + +Associates the id with an on-disk data structure. + +The exact layout of the data depends on the data structure type stored in the +chunk field and can be one of the following. + +Any type of struct supersedes all other structs associated with the id. For +example, appending a ctz-struct replaces an inline-struct on the same file. + +--- +#### `0x200` LFS_TYPE_DIRSTRUCT + +Gives the id a directory data structure. + +Directories in littlefs are stored on disk as a linked-list of metadata pairs, +each pair containing any number of files in alphabetical order. + +``` + | + v + .--------. .--------. .--------. .--------. .--------. .--------. +.| file A |->| file D |->| file G |->| file I |->| file J |->| file M | +|| file B | || file E | || file H | || | || file K | || file N | +|| file C | || file F | || | || | || file L | || | +|'--------' |'--------' |'--------' |'--------' |'--------' |'--------' +'--------' '--------' '--------' '--------' '--------' '--------' +``` + +The dir-struct tag contains only the pointer to the first metadata-pair in the +directory. The directory size is not known without traversing the directory. + +The pointer to the next metadata-pair in the directory is stored in a tail tag, +which is described below. + +Layout of the dir-struct tag: + +``` + tag data +[-- 32 --][-- 32 --|-- 32 --] +[1|- 11 -| 10 | 10 ][--- 64 ---] + ^ ^ ^ ^- size (8) ^- metadata pair + | | '------ id + | '------------ type (0x200) + '----------------- valid bit +``` + +Dir-struct fields: + +1. **Metadata pair (8-bytes)** - Pointer to the first metadata-pair + in the directory. + +--- +#### `0x201` LFS_TYPE_INLINESTRUCT + +Gives the id an inline data structure. + +Inline structs store small files that can fit in the metadata pair. In this +case, the file data is stored directly in the tag's data area. + +Layout of the inline-struct tag: + +``` + tag data +[-- 32 --][--- variable length ---] +[1|- 11 -| 10 | 10 ][--- (size * 8) ---] + ^ ^ ^ ^- size ^- inline data + | | '------ id + | '------------ type (0x201) + '----------------- valid bit +``` + +Inline-struct fields: + +1. **Inline data** - File data stored directly in the metadata-pair. + +--- +#### `0x202` LFS_TYPE_CTZSTRUCT + +Gives the id a CTZ skip-list data structure. + +CTZ skip-lists store files that can not fit in the metadata pair. These files +are stored in a skip-list in reverse, with a pointer to the head of the +skip-list. Note that the head of the skip-list and the file size is enough +information to read the file. + +How exactly CTZ skip-lists work is a bit complicated. A full explanation can be +found in the [DESIGN.md](DESIGN.md#ctz-skip-lists). + +A quick summary: For every _n_‍th block where _n_ is divisible by +2‍_ˣ_, that block contains a pointer to block _n_-2‍_ˣ_. +These pointers are stored in increasing order of _x_ in each block of the file +before the actual data. + +``` + | + v +.--------. .--------. .--------. .--------. .--------. .--------. +| A |<-| D |<-| G |<-| J |<-| M |<-| P | +| B |<-| E |--| H |<-| K |--| N | | Q | +| C |<-| F |--| I |--| L |--| O | | | +'--------' '--------' '--------' '--------' '--------' '--------' + block 0 block 1 block 2 block 3 block 4 block 5 + 1 skip 2 skips 1 skip 3 skips 1 skip +``` + +Note that the maximum number of pointers in a block is bounded by the maximum +file size divided by the block size. With 32 bits for file size, this results +in a minimum block size of 104 bytes. + +Layout of the CTZ-struct tag: + +``` + tag data +[-- 32 --][-- 32 --|-- 32 --] +[1|- 11 -| 10 | 10 ][-- 32 --|-- 32 --] + ^ ^ ^ ^ ^ ^- file size + | | | | '-------------------- file head + | | | '- size (8) + | | '------ id + | '------------ type (0x202) + '----------------- valid bit +``` + +CTZ-struct fields: + +1. **File head (32-bits)** - Pointer to the block that is the head of the + file's CTZ skip-list. + +2. **File size (32-bits)** - Size of the file in bytes. + +--- +#### `0x3xx` LFS_TYPE_USERATTR + +Attaches a user attribute to an id. + +littlefs has a concept of "user attributes". These are small user-provided +attributes that can be used to store things like timestamps, hashes, +permissions, etc. + +Each user attribute is uniquely identified by an 8-bit type which is stored in +the chunk field, and the user attribute itself can be found in the tag's data. + +There are currently no standard user attributes and a portable littlefs +implementation should work with any user attributes missing. + +Layout of the user-attr tag: + +``` + tag data +[-- 32 --][--- variable length ---] +[1| 3| 8 | 10 | 10 ][--- (size * 8) ---] + ^ ^ ^ ^ ^- size ^- attr data + | | | '------ id + | | '----------- attr type + | '-------------- type1 (0x3) + '----------------- valid bit +``` + +User-attr fields: + +1. **Attr type (8-bits)** - Type of the user attributes. + +2. **Attr data** - The data associated with the user attribute. + +--- +#### `0x6xx` LFS_TYPE_TAIL + +Provides the tail pointer for the metadata pair itself. + +The metadata pair's tail pointer is used in littlefs for a linked-list +containing all metadata pairs. The chunk field contains the type of the tail, +which indicates if the following metadata pair is a part of the directory +(hard-tail) or only used to traverse the filesystem (soft-tail). + +``` + .--------. + .| dir A |-. + ||softtail| | +.--------| |-' +| |'--------' +| '---|--|-' +| .-' '-------------. +| v v +| .--------. .--------. .--------. +'->| dir B |->| dir B |->| dir C | + ||hardtail| ||softtail| || | + || | || | || | + |'--------' |'--------' |'--------' + '--------' '--------' '--------' +``` + +Currently any type supersedes any other preceding tails in the metadata pair, +but this may change if additional metadata pair state is added. + +A note about the metadata pair linked-list: Normally, this linked-list contains +every metadata pair in the filesystem. However, there are some operations that +can cause this linked-list to become out of sync if a power-loss were to occur. +When this happens, littlefs sets the "sync" flag in the global state. How +exactly this flag is stored is described below. + +When the sync flag is set: + +1. The linked-list may contain an orphaned directory that has been removed in + the filesystem. +2. The linked-list may contain a metadata pair with a bad block that has been + replaced in the filesystem. + +If the sync flag is set, the threaded linked-list must be checked for these +errors before it can be used reliably. Note that the threaded linked-list can +be ignored if littlefs is mounted read-only. + +Layout of the tail tag: + +``` + tag data +[-- 32 --][-- 32 --|-- 32 --] +[1| 3| 8 | 10 | 10 ][--- 64 ---] + ^ ^ ^ ^ ^- size (8) ^- metadata pair + | | | '------ id + | | '---------- tail type + | '------------- type1 (0x6) + '---------------- valid bit +``` + +Tail fields: + +1. **Tail type (8-bits)** - Type of the tail pointer. + +2. **Metadata pair (8-bytes)** - Pointer to the next metadata-pair. + +--- +#### `0x600` LFS_TYPE_SOFTTAIL + +Provides a tail pointer that points to the next metadata pair in the +filesystem. + +In this case, the next metadata pair is not a part of our current directory +and should only be followed when traversing the entire filesystem. + +--- +#### `0x601` LFS_TYPE_HARDTAIL + +Provides a tail pointer that points to the next metadata pair in the +directory. + +In this case, the next metadata pair belongs to the current directory. Note +that because directories in littlefs are sorted alphabetically, the next +metadata pair should only contain filenames greater than any filename in the +current pair. + +--- +#### `0x7xx` LFS_TYPE_GSTATE + +Provides delta bits for global state entries. + +littlefs has a concept of "global state". This is a small set of state that +can be updated by a commit to _any_ metadata pair in the filesystem. + +The way this works is that the global state is stored as a set of deltas +distributed across the filesystem such that the global state can be found by +the xor-sum of these deltas. + +``` + .--------. .--------. .--------. .--------. .--------. +.| |->| gdelta |->| |->| gdelta |->| gdelta | +|| | || 0x23 | || | || 0xff | || 0xce | +|| | || | || | || | || | +|'--------' |'--------' |'--------' |'--------' |'--------' +'--------' '----|---' '--------' '----|---' '----|---' + v v v + 0x00 --> xor ------------------> xor ------> xor --> gstate = 0x12 +``` + +Note that storing globals this way is very expensive in terms of storage usage, +so any global state should be kept very small. + +The size and format of each piece of global state depends on the type, which +is stored in the chunk field. Currently, the only global state is move state, +which is outlined below. + +--- +#### `0x7ff` LFS_TYPE_MOVESTATE + +Provides delta bits for the global move state. + +The move state in littlefs is used to store info about operations that could +cause to filesystem to go out of sync if the power is lost. The operations +where this could occur is moves of files between metadata pairs and any +operation that changes metadata pairs on the threaded linked-list. + +In the case of moves, the move state contains a tag + metadata pair describing +the source of the ongoing move. If this tag is non-zero, that means that power +was lost during a move, and the file exists in two different locations. If this +happens, the source of the move should be considered deleted, and the move +should be completed (the source should be deleted) before any other write +operations to the filesystem. + +In the case of operations to the threaded linked-list, a single "sync" bit is +used to indicate that a modification is ongoing. If this sync flag is set, the +threaded linked-list will need to be checked for errors before it can be used +reliably. The exact cases to check for are described above in the tail tag. + +Layout of the move state: + +``` + tag data +[-- 32 --][-- 32 --|-- 32 --|-- 32 --] +[1|- 11 -| 10 | 10 ][1|- 11 -| 10 | 10 |--- 64 ---] + ^ ^ ^ ^ ^ ^ ^ ^- padding (0) ^- metadata pair + | | | | | | '------ move id + | | | | | '------------ move type + | | | | '----------------- sync bit + | | | | + | | | '- size (12) + | | '------ id (0x3ff) + | '------------ type (0x7ff) + '----------------- valid bit +``` + +Move state fields: + +1. **Sync bit (1-bit)** - Indicates if the metadata pair threaded linked-list + is in-sync. If set, the threaded linked-list should be checked for errors. + +2. **Move type (11-bits)** - Type of move being performed. Must be either + `0x000`, indicating no move, or `0x4ff` indicating the source file should + be deleted. + +3. **Move id (10-bits)** - The file id being moved. + +4. **Metadata pair (8-bytes)** - Pointer to the metadata-pair containing + the move. + +--- +#### `0x5xx` LFS_TYPE_CRC + +Last but not least, the CRC tag marks the end of a commit and provides a +checksum for any commits to the metadata block. + +The first 32-bits of the data contain a CRC-32 with a polynomial of +`0x04c11db7` initialized with `0xffffffff`. This CRC provides a checksum for +all metadata since the previous CRC tag, including the CRC tag itself. For +the first commit, this includes the revision count for the metadata block. + +However, the size of the data is not limited to 32-bits. The data field may +larger to pad the commit to the next program-aligned boundary. + +In addition, the CRC tag's chunk field contains a set of flags which can +change the behaviour of commits. Currently the only flag in use is the lowest +bit, which determines the expected state of the valid bit for any following +tags. This is used to guarantee that unwritten storage in a metadata block +will be detected as invalid. + +Layout of the CRC tag: + +``` + tag data +[-- 32 --][-- 32 --|--- variable length ---] +[1| 3| 8 | 10 | 10 ][-- 32 --|--- (size * 8 - 32) ---] + ^ ^ ^ ^ ^ ^- crc ^- padding + | | | | '- size + | | | '------ id (0x3ff) + | | '----------- valid state + | '-------------- type1 (0x5) + '----------------- valid bit +``` + +CRC fields: + +1. **Valid state (1-bit)** - Indicates the expected value of the valid bit for + any tags in the next commit. + +2. **CRC (32-bits)** - CRC-32 with a polynomial of `0x04c11db7` initialized + with `0xffffffff`. + +3. **Padding** - Padding to the next program-aligned boundary. No guarantees + are made about the contents. + +--- +#### `0x5ff` LFS_TYPE_FCRC + +Added in lfs2.1, the optional FCRC tag contains a checksum of some amount of +bytes in the next commit at the time it was erased. This allows us to ensure +that we only ever program erased bytes, even if a previous commit failed due +to power-loss. + +When programming a commit, the FCRC size must be at least as large as the +program block size. However, the program block is not saved on disk, and can +change between mounts, so the FCRC size on disk may be different than the +current program block size. + +If the FCRC is missing or the checksum does not match, we must assume a +commit was attempted but failed due to power-loss. + +Layout of the FCRC tag: + +``` + tag data +[-- 32 --][-- 32 --|-- 32 --] +[1|- 11 -| 10 | 10 ][-- 32 --|-- 32 --] + ^ ^ ^ ^ ^- fcrc size ^- fcrc + | | | '- size (8) + | | '------ id (0x3ff) + | '------------ type (0x5ff) + '----------------- valid bit +``` + +FCRC fields: + +1. **FCRC size (32-bits)** - Number of bytes after this commit's CRC tag's + padding to include in the FCRC. + +2. **FCRC (32-bits)** - CRC of the bytes after this commit's CRC tag's padding + when erased. Like the CRC tag, this uses a CRC-32 with a polynomial of + `0x04c11db7` initialized with `0xffffffff`. + +--- diff --git a/library/littlefs/include/lfs.h b/library/littlefs/include/lfs.h new file mode 100644 index 0000000..8fbd5b4 --- /dev/null +++ b/library/littlefs/include/lfs.h @@ -0,0 +1,802 @@ +/* + * The little filesystem + * + * Copyright (c) 2022, The littlefs authors. + * Copyright (c) 2017, Arm Limited. All rights reserved. + * SPDX-License-Identifier: BSD-3-Clause + */ +#ifndef LFS_H +#define LFS_H + +#include "lfs_util.h" + +#ifdef __cplusplus +extern "C" +{ +#endif + + +/// Version info /// + +// Software library version +// Major (top-nibble), incremented on backwards incompatible changes +// Minor (bottom-nibble), incremented on feature additions +#define LFS_VERSION 0x0002000b +#define LFS_VERSION_MAJOR (0xffff & (LFS_VERSION >> 16)) +#define LFS_VERSION_MINOR (0xffff & (LFS_VERSION >> 0)) + +// Version of On-disk data structures +// Major (top-nibble), incremented on backwards incompatible changes +// Minor (bottom-nibble), incremented on feature additions +#define LFS_DISK_VERSION 0x00020001 +#define LFS_DISK_VERSION_MAJOR (0xffff & (LFS_DISK_VERSION >> 16)) +#define LFS_DISK_VERSION_MINOR (0xffff & (LFS_DISK_VERSION >> 0)) + + +/// Definitions /// + +// Type definitions +typedef uint32_t lfs_size_t; +typedef uint32_t lfs_off_t; + +typedef int32_t lfs_ssize_t; +typedef int32_t lfs_soff_t; + +typedef uint32_t lfs_block_t; + +// Maximum name size in bytes, may be redefined to reduce the size of the +// info struct. Limited to <= 1022. Stored in superblock and must be +// respected by other littlefs drivers. +#ifndef LFS_NAME_MAX +#define LFS_NAME_MAX 255 +#endif + +// Maximum size of a file in bytes, may be redefined to limit to support other +// drivers. Limited on disk to <= 2147483647. Stored in superblock and must be +// respected by other littlefs drivers. +#ifndef LFS_FILE_MAX +#define LFS_FILE_MAX 2147483647 +#endif + +// Maximum size of custom attributes in bytes, may be redefined, but there is +// no real benefit to using a smaller LFS_ATTR_MAX. Limited to <= 1022. Stored +// in superblock and must be respected by other littlefs drivers. +#ifndef LFS_ATTR_MAX +#define LFS_ATTR_MAX 1022 +#endif + +// Possible error codes, these are negative to allow +// valid positive return values +enum lfs_error { + LFS_ERR_OK = 0, // No error + LFS_ERR_IO = -5, // Error during device operation + LFS_ERR_CORRUPT = -84, // Corrupted + LFS_ERR_NOENT = -2, // No directory entry + LFS_ERR_EXIST = -17, // Entry already exists + LFS_ERR_NOTDIR = -20, // Entry is not a dir + LFS_ERR_ISDIR = -21, // Entry is a dir + LFS_ERR_NOTEMPTY = -39, // Dir is not empty + LFS_ERR_BADF = -9, // Bad file number + LFS_ERR_FBIG = -27, // File too large + LFS_ERR_INVAL = -22, // Invalid parameter + LFS_ERR_NOSPC = -28, // No space left on device + LFS_ERR_NOMEM = -12, // No more memory available + LFS_ERR_NOATTR = -61, // No data/attr available + LFS_ERR_NAMETOOLONG = -36, // File name too long +}; + +// File types +enum lfs_type { + // file types + LFS_TYPE_REG = 0x001, + LFS_TYPE_DIR = 0x002, + + // internally used types + LFS_TYPE_SPLICE = 0x400, + LFS_TYPE_NAME = 0x000, + LFS_TYPE_STRUCT = 0x200, + LFS_TYPE_USERATTR = 0x300, + LFS_TYPE_FROM = 0x100, + LFS_TYPE_TAIL = 0x600, + LFS_TYPE_GLOBALS = 0x700, + LFS_TYPE_CRC = 0x500, + + // internally used type specializations + LFS_TYPE_CREATE = 0x401, + LFS_TYPE_DELETE = 0x4ff, + LFS_TYPE_SUPERBLOCK = 0x0ff, + LFS_TYPE_DIRSTRUCT = 0x200, + LFS_TYPE_CTZSTRUCT = 0x202, + LFS_TYPE_INLINESTRUCT = 0x201, + LFS_TYPE_SOFTTAIL = 0x600, + LFS_TYPE_HARDTAIL = 0x601, + LFS_TYPE_MOVESTATE = 0x7ff, + LFS_TYPE_CCRC = 0x500, + LFS_TYPE_FCRC = 0x5ff, + + // internal chip sources + LFS_FROM_NOOP = 0x000, + LFS_FROM_MOVE = 0x101, + LFS_FROM_USERATTRS = 0x102, +}; + +// File open flags +enum lfs_open_flags { + // open flags + LFS_O_RDONLY = 1, // Open a file as read only +#ifndef LFS_READONLY + LFS_O_WRONLY = 2, // Open a file as write only + LFS_O_RDWR = 3, // Open a file as read and write + LFS_O_CREAT = 0x0100, // Create a file if it does not exist + LFS_O_EXCL = 0x0200, // Fail if a file already exists + LFS_O_TRUNC = 0x0400, // Truncate the existing file to zero size + LFS_O_APPEND = 0x0800, // Move to end of file on every write +#endif + + // internally used flags +#ifndef LFS_READONLY + LFS_F_DIRTY = 0x00010000, // File does not match storage due to write + LFS_F_DUSTY = 0x00020000, // File does not match storage due to desync + LFS_F_WRITING = 0x00040000, // File has been written since last flush +#endif + LFS_F_READING = 0x00080000, // File has been read since last flush +#ifndef LFS_READONLY + LFS_F_ERRED = 0x00100000, // An error occurred during write +#endif + LFS_F_INLINE = 0x01000000, // Currently inlined in directory entry +}; + +// File seek flags +enum lfs_whence_flags { + LFS_SEEK_SET = 0, // Seek relative to an absolute position + LFS_SEEK_CUR = 1, // Seek relative to the current file position + LFS_SEEK_END = 2, // Seek relative to the end of the file +}; + + +// Configuration provided during initialization of the littlefs +struct lfs_config { + // Opaque user provided context that can be used to pass + // information to the block device operations + void *context; + + // Read a region in a block. Negative error codes are propagated + // to the user. + int (*read)(const struct lfs_config *c, lfs_block_t block, + lfs_off_t off, void *buffer, lfs_size_t size); + + // Program a region in a block. The block must have previously + // been erased. Negative error codes are propagated to the user. + // May return LFS_ERR_CORRUPT if the block should be considered bad. + int (*prog)(const struct lfs_config *c, lfs_block_t block, + lfs_off_t off, const void *buffer, lfs_size_t size); + + // Erase a block. A block must be erased before being programmed. + // The state of an erased block is undefined. Negative error codes + // are propagated to the user. + // May return LFS_ERR_CORRUPT if the block should be considered bad. + int (*erase)(const struct lfs_config *c, lfs_block_t block); + + // Sync the state of the underlying block device. Negative error codes + // are propagated to the user. + int (*sync)(const struct lfs_config *c); + +#ifdef LFS_THREADSAFE + // Lock the underlying block device. Negative error codes + // are propagated to the user. + int (*lock)(const struct lfs_config *c); + + // Unlock the underlying block device. Negative error codes + // are propagated to the user. + int (*unlock)(const struct lfs_config *c); +#endif + + // Minimum size of a block read in bytes. All read operations will be a + // multiple of this value. + lfs_size_t read_size; + + // Minimum size of a block program in bytes. All program operations will be + // a multiple of this value. + lfs_size_t prog_size; + + // Size of an erasable block in bytes. This does not impact ram consumption + // and may be larger than the physical erase size. However, non-inlined + // files take up at minimum one block. Must be a multiple of the read and + // program sizes. + lfs_size_t block_size; + + // Number of erasable blocks on the device. Defaults to block_count stored + // on disk when zero. + lfs_size_t block_count; + + // Number of erase cycles before littlefs evicts metadata logs and moves + // the metadata to another block. Suggested values are in the + // range 100-1000, with large values having better performance at the cost + // of less consistent wear distribution. + // + // Set to -1 to disable block-level wear-leveling. + int32_t block_cycles; + + // Size of block caches in bytes. Each cache buffers a portion of a block in + // RAM. The littlefs needs a read cache, a program cache, and one additional + // cache per file. Larger caches can improve performance by storing more + // data and reducing the number of disk accesses. Must be a multiple of the + // read and program sizes, and a factor of the block size. + lfs_size_t cache_size; + + // Size of the lookahead buffer in bytes. A larger lookahead buffer + // increases the number of blocks found during an allocation pass. The + // lookahead buffer is stored as a compact bitmap, so each byte of RAM + // can track 8 blocks. + lfs_size_t lookahead_size; + + // Threshold for metadata compaction during lfs_fs_gc in bytes. Metadata + // pairs that exceed this threshold will be compacted during lfs_fs_gc. + // Defaults to ~88% block_size when zero, though the default may change + // in the future. + // + // Note this only affects lfs_fs_gc. Normal compactions still only occur + // when full. + // + // Set to -1 to disable metadata compaction during lfs_fs_gc. + lfs_size_t compact_thresh; + + // Optional statically allocated read buffer. Must be cache_size. + // By default lfs_malloc is used to allocate this buffer. + void *read_buffer; + + // Optional statically allocated program buffer. Must be cache_size. + // By default lfs_malloc is used to allocate this buffer. + void *prog_buffer; + + // Optional statically allocated lookahead buffer. Must be lookahead_size. + // By default lfs_malloc is used to allocate this buffer. + void *lookahead_buffer; + + // Optional upper limit on length of file names in bytes. No downside for + // larger names except the size of the info struct which is controlled by + // the LFS_NAME_MAX define. Defaults to LFS_NAME_MAX or name_max stored on + // disk when zero. + lfs_size_t name_max; + + // Optional upper limit on files in bytes. No downside for larger files + // but must be <= LFS_FILE_MAX. Defaults to LFS_FILE_MAX or file_max stored + // on disk when zero. + lfs_size_t file_max; + + // Optional upper limit on custom attributes in bytes. No downside for + // larger attributes size but must be <= LFS_ATTR_MAX. Defaults to + // LFS_ATTR_MAX or attr_max stored on disk when zero. + lfs_size_t attr_max; + + // Optional upper limit on total space given to metadata pairs in bytes. On + // devices with large blocks (e.g. 128kB) setting this to a low size (2-8kB) + // can help bound the metadata compaction time. Must be <= block_size. + // Defaults to block_size when zero. + lfs_size_t metadata_max; + + // Optional upper limit on inlined files in bytes. Inlined files live in + // metadata and decrease storage requirements, but may be limited to + // improve metadata-related performance. Must be <= cache_size, <= + // attr_max, and <= block_size/8. Defaults to the largest possible + // inline_max when zero. + // + // Set to -1 to disable inlined files. + lfs_size_t inline_max; + +#ifdef LFS_MULTIVERSION + // On-disk version to use when writing in the form of 16-bit major version + // + 16-bit minor version. This limiting metadata to what is supported by + // older minor versions. Note that some features will be lost. Defaults to + // to the most recent minor version when zero. + uint32_t disk_version; +#endif +}; + +// File info structure +struct lfs_info { + // Type of the file, either LFS_TYPE_REG or LFS_TYPE_DIR + uint8_t type; + + // Size of the file, only valid for REG files. Limited to 32-bits. + lfs_size_t size; + + // Name of the file stored as a null-terminated string. Limited to + // LFS_NAME_MAX+1, which can be changed by redefining LFS_NAME_MAX to + // reduce RAM. LFS_NAME_MAX is stored in superblock and must be + // respected by other littlefs drivers. + char name[LFS_NAME_MAX+1]; +}; + +// Filesystem info structure +struct lfs_fsinfo { + // On-disk version. + uint32_t disk_version; + + // Size of a logical block in bytes. + lfs_size_t block_size; + + // Number of logical blocks in filesystem. + lfs_size_t block_count; + + // Upper limit on the length of file names in bytes. + lfs_size_t name_max; + + // Upper limit on the size of files in bytes. + lfs_size_t file_max; + + // Upper limit on the size of custom attributes in bytes. + lfs_size_t attr_max; +}; + +// Custom attribute structure, used to describe custom attributes +// committed atomically during file writes. +struct lfs_attr { + // 8-bit type of attribute, provided by user and used to + // identify the attribute + uint8_t type; + + // Pointer to buffer containing the attribute + void *buffer; + + // Size of attribute in bytes, limited to LFS_ATTR_MAX + lfs_size_t size; +}; + +// Optional configuration provided during lfs_file_opencfg +struct lfs_file_config { + // Optional statically allocated file buffer. Must be cache_size. + // By default lfs_malloc is used to allocate this buffer. + void *buffer; + + // Optional list of custom attributes related to the file. If the file + // is opened with read access, these attributes will be read from disk + // during the open call. If the file is opened with write access, the + // attributes will be written to disk every file sync or close. This + // write occurs atomically with update to the file's contents. + // + // Custom attributes are uniquely identified by an 8-bit type and limited + // to LFS_ATTR_MAX bytes. When read, if the stored attribute is smaller + // than the buffer, it will be padded with zeros. If the stored attribute + // is larger, then it will be silently truncated. If the attribute is not + // found, it will be created implicitly. + struct lfs_attr *attrs; + + // Number of custom attributes in the list + lfs_size_t attr_count; +}; + + +/// internal littlefs data structures /// +typedef struct lfs_cache { + lfs_block_t block; + lfs_off_t off; + lfs_size_t size; + uint8_t *buffer; +} lfs_cache_t; + +typedef struct lfs_mdir { + lfs_block_t pair[2]; + uint32_t rev; + lfs_off_t off; + uint32_t etag; + uint16_t count; + bool erased; + bool split; + lfs_block_t tail[2]; +} lfs_mdir_t; + +// littlefs directory type +typedef struct lfs_dir { + struct lfs_dir *next; + uint16_t id; + uint8_t type; + lfs_mdir_t m; + + lfs_off_t pos; + lfs_block_t head[2]; +} lfs_dir_t; + +// littlefs file type +typedef struct lfs_file { + struct lfs_file *next; + uint16_t id; + uint8_t type; + lfs_mdir_t m; + + struct lfs_ctz { + lfs_block_t head; + lfs_size_t size; + } ctz; + + uint32_t flags; + lfs_off_t pos; + lfs_block_t block; + lfs_off_t off; + lfs_cache_t cache; + + const struct lfs_file_config *cfg; +} lfs_file_t; + +typedef struct lfs_superblock { + uint32_t version; + lfs_size_t block_size; + lfs_size_t block_count; + lfs_size_t name_max; + lfs_size_t file_max; + lfs_size_t attr_max; +} lfs_superblock_t; + +typedef struct lfs_gstate { + uint32_t tag; + lfs_block_t pair[2]; +} lfs_gstate_t; + +// The littlefs filesystem type +typedef struct lfs { + lfs_cache_t rcache; + lfs_cache_t pcache; + + lfs_block_t root[2]; + struct lfs_mlist { + struct lfs_mlist *next; + uint16_t id; + uint8_t type; + lfs_mdir_t m; + } *mlist; + uint32_t seed; + + lfs_gstate_t gstate; + lfs_gstate_t gdisk; + lfs_gstate_t gdelta; + + struct lfs_lookahead { + lfs_block_t start; + lfs_block_t size; + lfs_block_t next; + lfs_block_t ckpoint; + uint8_t *buffer; + } lookahead; + + const struct lfs_config *cfg; + lfs_size_t block_count; + lfs_size_t name_max; + lfs_size_t file_max; + lfs_size_t attr_max; + lfs_size_t inline_max; + +#ifdef LFS_MIGRATE + struct lfs1 *lfs1; +#endif +} lfs_t; + + +/// Filesystem functions /// + +#ifndef LFS_READONLY +// Format a block device with the littlefs +// +// Requires a littlefs object and config struct. This clobbers the littlefs +// object, and does not leave the filesystem mounted. The config struct must +// be zeroed for defaults and backwards compatibility. +// +// Returns a negative error code on failure. +int lfs_format(lfs_t *lfs, const struct lfs_config *config); +#endif + +// Mounts a littlefs +// +// Requires a littlefs object and config struct. Multiple filesystems +// may be mounted simultaneously with multiple littlefs objects. Both +// lfs and config must be allocated while mounted. The config struct must +// be zeroed for defaults and backwards compatibility. +// +// Returns a negative error code on failure. +int lfs_mount(lfs_t *lfs, const struct lfs_config *config); + +// Unmounts a littlefs +// +// Does nothing besides releasing any allocated resources. +// Returns a negative error code on failure. +int lfs_unmount(lfs_t *lfs); + +/// General operations /// + +#ifndef LFS_READONLY +// Removes a file or directory +// +// If removing a directory, the directory must be empty. +// Returns a negative error code on failure. +int lfs_remove(lfs_t *lfs, const char *path); +#endif + +#ifndef LFS_READONLY +// Rename or move a file or directory +// +// If the destination exists, it must match the source in type. +// If the destination is a directory, the directory must be empty. +// +// Returns a negative error code on failure. +int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath); +#endif + +// Find info about a file or directory +// +// Fills out the info structure, based on the specified file or directory. +// Returns a negative error code on failure. +int lfs_stat(lfs_t *lfs, const char *path, struct lfs_info *info); + +// Get a custom attribute +// +// Custom attributes are uniquely identified by an 8-bit type and limited +// to LFS_ATTR_MAX bytes. When read, if the stored attribute is smaller than +// the buffer, it will be padded with zeros. If the stored attribute is larger, +// then it will be silently truncated. If no attribute is found, the error +// LFS_ERR_NOATTR is returned and the buffer is filled with zeros. +// +// Returns the size of the attribute, or a negative error code on failure. +// Note, the returned size is the size of the attribute on disk, irrespective +// of the size of the buffer. This can be used to dynamically allocate a buffer +// or check for existence. +lfs_ssize_t lfs_getattr(lfs_t *lfs, const char *path, + uint8_t type, void *buffer, lfs_size_t size); + +#ifndef LFS_READONLY +// Set custom attributes +// +// Custom attributes are uniquely identified by an 8-bit type and limited +// to LFS_ATTR_MAX bytes. If an attribute is not found, it will be +// implicitly created. +// +// Returns a negative error code on failure. +int lfs_setattr(lfs_t *lfs, const char *path, + uint8_t type, const void *buffer, lfs_size_t size); +#endif + +#ifndef LFS_READONLY +// Removes a custom attribute +// +// If an attribute is not found, nothing happens. +// +// Returns a negative error code on failure. +int lfs_removeattr(lfs_t *lfs, const char *path, uint8_t type); +#endif + + +/// File operations /// + +#ifndef LFS_NO_MALLOC +// Open a file +// +// The mode that the file is opened in is determined by the flags, which +// are values from the enum lfs_open_flags that are bitwise-ored together. +// +// Returns a negative error code on failure. +int lfs_file_open(lfs_t *lfs, lfs_file_t *file, + const char *path, int flags); + +// if LFS_NO_MALLOC is defined, lfs_file_open() will fail with LFS_ERR_NOMEM +// thus use lfs_file_opencfg() with config.buffer set. +#endif + +// Open a file with extra configuration +// +// The mode that the file is opened in is determined by the flags, which +// are values from the enum lfs_open_flags that are bitwise-ored together. +// +// The config struct provides additional config options per file as described +// above. The config struct must remain allocated while the file is open, and +// the config struct must be zeroed for defaults and backwards compatibility. +// +// Returns a negative error code on failure. +int lfs_file_opencfg(lfs_t *lfs, lfs_file_t *file, + const char *path, int flags, + const struct lfs_file_config *config); + +// Close a file +// +// Any pending writes are written out to storage as though +// sync had been called and releases any allocated resources. +// +// Returns a negative error code on failure. +int lfs_file_close(lfs_t *lfs, lfs_file_t *file); + +// Synchronize a file on storage +// +// Any pending writes are written out to storage. +// Returns a negative error code on failure. +int lfs_file_sync(lfs_t *lfs, lfs_file_t *file); + +// Read data from file +// +// Takes a buffer and size indicating where to store the read data. +// Returns the number of bytes read, or a negative error code on failure. +lfs_ssize_t lfs_file_read(lfs_t *lfs, lfs_file_t *file, + void *buffer, lfs_size_t size); + +#ifndef LFS_READONLY +// Write data to file +// +// Takes a buffer and size indicating the data to write. The file will not +// actually be updated on the storage until either sync or close is called. +// +// Returns the number of bytes written, or a negative error code on failure. +lfs_ssize_t lfs_file_write(lfs_t *lfs, lfs_file_t *file, + const void *buffer, lfs_size_t size); +#endif + +// Change the position of the file +// +// The change in position is determined by the offset and whence flag. +// Returns the new position of the file, or a negative error code on failure. +lfs_soff_t lfs_file_seek(lfs_t *lfs, lfs_file_t *file, + lfs_soff_t off, int whence); + +#ifndef LFS_READONLY +// Truncates the size of the file to the specified size +// +// Returns a negative error code on failure. +int lfs_file_truncate(lfs_t *lfs, lfs_file_t *file, lfs_off_t size); +#endif + +// Return the position of the file +// +// Equivalent to lfs_file_seek(lfs, file, 0, LFS_SEEK_CUR) +// Returns the position of the file, or a negative error code on failure. +lfs_soff_t lfs_file_tell(lfs_t *lfs, lfs_file_t *file); + +// Change the position of the file to the beginning of the file +// +// Equivalent to lfs_file_seek(lfs, file, 0, LFS_SEEK_SET) +// Returns a negative error code on failure. +int lfs_file_rewind(lfs_t *lfs, lfs_file_t *file); + +// Return the size of the file +// +// Similar to lfs_file_seek(lfs, file, 0, LFS_SEEK_END) +// Returns the size of the file, or a negative error code on failure. +lfs_soff_t lfs_file_size(lfs_t *lfs, lfs_file_t *file); + + +/// Directory operations /// + +#ifndef LFS_READONLY +// Create a directory +// +// Returns a negative error code on failure. +int lfs_mkdir(lfs_t *lfs, const char *path); +#endif + +// Open a directory +// +// Once open a directory can be used with read to iterate over files. +// Returns a negative error code on failure. +int lfs_dir_open(lfs_t *lfs, lfs_dir_t *dir, const char *path); + +// Close a directory +// +// Releases any allocated resources. +// Returns a negative error code on failure. +int lfs_dir_close(lfs_t *lfs, lfs_dir_t *dir); + +// Read an entry in the directory +// +// Fills out the info structure, based on the specified file or directory. +// Returns a positive value on success, 0 at the end of directory, +// or a negative error code on failure. +int lfs_dir_read(lfs_t *lfs, lfs_dir_t *dir, struct lfs_info *info); + +// Change the position of the directory +// +// The new off must be a value previous returned from tell and specifies +// an absolute offset in the directory seek. +// +// Returns a negative error code on failure. +int lfs_dir_seek(lfs_t *lfs, lfs_dir_t *dir, lfs_off_t off); + +// Return the position of the directory +// +// The returned offset is only meant to be consumed by seek and may not make +// sense, but does indicate the current position in the directory iteration. +// +// Returns the position of the directory, or a negative error code on failure. +lfs_soff_t lfs_dir_tell(lfs_t *lfs, lfs_dir_t *dir); + +// Change the position of the directory to the beginning of the directory +// +// Returns a negative error code on failure. +int lfs_dir_rewind(lfs_t *lfs, lfs_dir_t *dir); + + +/// Filesystem-level filesystem operations + +// Find on-disk info about the filesystem +// +// Fills out the fsinfo structure based on the filesystem found on-disk. +// Returns a negative error code on failure. +int lfs_fs_stat(lfs_t *lfs, struct lfs_fsinfo *fsinfo); + +// Finds the current size of the filesystem +// +// Note: Result is best effort. If files share COW structures, the returned +// size may be larger than the filesystem actually is. +// +// Returns the number of allocated blocks, or a negative error code on failure. +lfs_ssize_t lfs_fs_size(lfs_t *lfs); + +// Traverse through all blocks in use by the filesystem +// +// The provided callback will be called with each block address that is +// currently in use by the filesystem. This can be used to determine which +// blocks are in use or how much of the storage is available. +// +// Returns a negative error code on failure. +int lfs_fs_traverse(lfs_t *lfs, int (*cb)(void*, lfs_block_t), void *data); + +#ifndef LFS_READONLY +// Attempt to make the filesystem consistent and ready for writing +// +// Calling this function is not required, consistency will be implicitly +// enforced on the first operation that writes to the filesystem, but this +// function allows the work to be performed earlier and without other +// filesystem changes. +// +// Returns a negative error code on failure. +int lfs_fs_mkconsistent(lfs_t *lfs); +#endif + +#ifndef LFS_READONLY +// Attempt any janitorial work +// +// This currently: +// 1. Calls mkconsistent if not already consistent +// 2. Compacts metadata > compact_thresh +// 3. Populates the block allocator +// +// Though additional janitorial work may be added in the future. +// +// Calling this function is not required, but may allow the offloading of +// expensive janitorial work to a less time-critical code path. +// +// Returns a negative error code on failure. Accomplishing nothing is not +// an error. +int lfs_fs_gc(lfs_t *lfs); +#endif + +#ifndef LFS_READONLY +// Grows the filesystem to a new size, updating the superblock with the new +// block count. +// +// If LFS_SHRINKNONRELOCATING is defined, this function will also accept +// block_counts smaller than the current configuration, after checking +// that none of the blocks that are being removed are in use. +// Note that littlefs's pseudorandom block allocation means that +// this is very unlikely to work in the general case. +// +// Returns a negative error code on failure. +int lfs_fs_grow(lfs_t *lfs, lfs_size_t block_count); +#endif + +#ifndef LFS_READONLY +#ifdef LFS_MIGRATE +// Attempts to migrate a previous version of littlefs +// +// Behaves similarly to the lfs_format function. Attempts to mount +// the previous version of littlefs and update the filesystem so it can be +// mounted with the current version of littlefs. +// +// Requires a littlefs object and config struct. This clobbers the littlefs +// object, and does not leave the filesystem mounted. The config struct must +// be zeroed for defaults and backwards compatibility. +// +// Returns a negative error code on failure. +int lfs_migrate(lfs_t *lfs, const struct lfs_config *cfg); +#endif +#endif + + +#ifdef __cplusplus +} /* extern "C" */ +#endif + +#endif diff --git a/library/littlefs/include/lfs_config.h b/library/littlefs/include/lfs_config.h new file mode 100644 index 0000000..056dd98 --- /dev/null +++ b/library/littlefs/include/lfs_config.h @@ -0,0 +1,202 @@ +#ifndef _LFS_CONFIG_H_ +#define _LFS_CONFIG_H_ + +#include "common.h" + +// System includes +#include +#include +#include +#include + +#ifdef __cplusplus +extern "C" +{ +#endif +// Macros, may be replaced by system specific wrappers. Arguments to these +// macros must not have side-effects as the macros can be removed for a smaller +// code footprint + +// Logging functions +#ifdef LFS_YES_TRACE +#define LFS_TRACE(fmt, ...) \ + RD_PRINTF("%s:%d:trace: " fmt "%s\n", __FILE__, __LINE__, __VA_ARGS__) +#define LFS_TRACE(...) LFS_TRACE_(__VA_ARGS__, "") +#else +#define LFS_TRACE(...) +#endif + +#ifndef LFS_NO_DEBUG +#define LFS_DEBUG_(fmt, ...) \ + RD_PRINTF("%s:%d:debug: " fmt "%s\n", __FILE__, __LINE__, __VA_ARGS__) +#define LFS_DEBUG(...) LFS_DEBUG_(__VA_ARGS__, "") +#else +#define LFS_DEBUG(...) +#endif + +#ifndef LFS_NO_WARN +#define LFS_WARN_(fmt, ...) \ + RD_PRINTF("%s:%d:warn: " fmt "%s\n", __FILE__, __LINE__, __VA_ARGS__) +#define LFS_WARN(...) LFS_WARN_(__VA_ARGS__, "") +#else +#define LFS_WARN(...) +#endif + +#ifndef LFS_NO_ERROR +#define LFS_ERROR_(fmt, ...) \ + RD_PRINTF("%s:%d:error: " fmt "%s\n", __FILE__, __LINE__, __VA_ARGS__) +#define LFS_ERROR(...) LFS_ERROR_(__VA_ARGS__, "") +#else +#define LFS_ERROR(...) +#endif + +// Runtime assertions +#ifndef LFS_NO_ASSERT +#define LFS_ASSERT(test) assert(test) +#else +#define LFS_ASSERT(test) +#endif + + +// Builtin functions, these may be replaced by more efficient +// toolchain-specific implementations. LFS_NO_INTRINSICS falls back to a more +// expensive basic C implementation for debugging purposes + +// Min/max functions for unsigned 32-bit numbers +static inline uint32_t lfs_max(uint32_t a, uint32_t b) { + return (a > b) ? a : b; +} + +static inline uint32_t lfs_min(uint32_t a, uint32_t b) { + return (a < b) ? a : b; +} + +// Align to nearest multiple of a size +static inline uint32_t lfs_aligndown(uint32_t a, uint32_t alignment) { + return a - (a % alignment); +} + +static inline uint32_t lfs_alignup(uint32_t a, uint32_t alignment) { + return lfs_aligndown(a + alignment-1, alignment); +} + +// Find the smallest power of 2 greater than or equal to a +static inline uint32_t lfs_npw2(uint32_t a) { +#if !defined(LFS_NO_INTRINSICS) && (defined(__GNUC__) || defined(__CC_ARM)) + return 32 - __builtin_clz(a-1); +#else + uint32_t r = 0; + uint32_t s; + a -= 1; + s = (a > 0xffff) << 4; a >>= s; r |= s; + s = (a > 0xff ) << 3; a >>= s; r |= s; + s = (a > 0xf ) << 2; a >>= s; r |= s; + s = (a > 0x3 ) << 1; a >>= s; r |= s; + return (r | (a >> 1)) + 1; +#endif +} + +// Count the number of trailing binary zeros in a +// lfs_ctz(0) may be undefined +static inline uint32_t lfs_ctz(uint32_t a) { +#if !defined(LFS_NO_INTRINSICS) && defined(__GNUC__) + return __builtin_ctz(a); +#else + return lfs_npw2((a & -a) + 1) - 1; +#endif +} + +// Count the number of binary ones in a +static inline uint32_t lfs_popc(uint32_t a) { +#if !defined(LFS_NO_INTRINSICS) && (defined(__GNUC__) || defined(__CC_ARM)) + return __builtin_popcount(a); +#else + a = a - ((a >> 1) & 0x55555555); + a = (a & 0x33333333) + ((a >> 2) & 0x33333333); + return (((a + (a >> 4)) & 0xf0f0f0f) * 0x1010101) >> 24; +#endif +} + +// Find the sequence comparison of a and b, this is the distance +// between a and b ignoring overflow +static inline int lfs_scmp(uint32_t a, uint32_t b) { + return (int)(unsigned)(a - b); +} + +// Convert between 32-bit little-endian and native order +static inline uint32_t lfs_fromle32(uint32_t a) { +#if !defined(LFS_NO_INTRINSICS) && ( \ + (defined( BYTE_ORDER ) && defined( ORDER_LITTLE_ENDIAN ) && BYTE_ORDER == ORDER_LITTLE_ENDIAN ) || \ + (defined(__BYTE_ORDER ) && defined(__ORDER_LITTLE_ENDIAN ) && __BYTE_ORDER == __ORDER_LITTLE_ENDIAN ) || \ + (defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)) + return a; +#elif !defined(LFS_NO_INTRINSICS) && ( \ + (defined( BYTE_ORDER ) && defined( ORDER_BIG_ENDIAN ) && BYTE_ORDER == ORDER_BIG_ENDIAN ) || \ + (defined(__BYTE_ORDER ) && defined(__ORDER_BIG_ENDIAN ) && __BYTE_ORDER == __ORDER_BIG_ENDIAN ) || \ + (defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)) + return __builtin_bswap32(a); +#else + return (((uint8_t*)&a)[0] << 0) | + (((uint8_t*)&a)[1] << 8) | + (((uint8_t*)&a)[2] << 16) | + (((uint8_t*)&a)[3] << 24); +#endif +} + +static inline uint32_t lfs_tole32(uint32_t a) { + return lfs_fromle32(a); +} + +// Convert between 32-bit big-endian and native order +static inline uint32_t lfs_frombe32(uint32_t a) { +#if !defined(LFS_NO_INTRINSICS) && ( \ + (defined( BYTE_ORDER ) && defined( ORDER_LITTLE_ENDIAN ) && BYTE_ORDER == ORDER_LITTLE_ENDIAN ) || \ + (defined(__BYTE_ORDER ) && defined(__ORDER_LITTLE_ENDIAN ) && __BYTE_ORDER == __ORDER_LITTLE_ENDIAN ) || \ + (defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)) + return __builtin_bswap32(a); +#elif !defined(LFS_NO_INTRINSICS) && ( \ + (defined( BYTE_ORDER ) && defined( ORDER_BIG_ENDIAN ) && BYTE_ORDER == ORDER_BIG_ENDIAN ) || \ + (defined(__BYTE_ORDER ) && defined(__ORDER_BIG_ENDIAN ) && __BYTE_ORDER == __ORDER_BIG_ENDIAN ) || \ + (defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)) + return a; +#else + return (((uint8_t*)&a)[0] << 24) | + (((uint8_t*)&a)[1] << 16) | + (((uint8_t*)&a)[2] << 8) | + (((uint8_t*)&a)[3] << 0); +#endif +} + +static inline uint32_t lfs_tobe32(uint32_t a) { + return lfs_frombe32(a); +} + +// Calculate CRC-32 with polynomial = 0x04c11db7 +uint32_t lfs_crc(uint32_t crc, const void *buffer, size_t size); + +// Allocate memory, only used if buffers are not provided to littlefs +// Note, memory must be 64-bit aligned +static inline void *lfs_malloc(size_t size) { +#ifndef LFS_NO_MALLOC + return RD_MALLOC(size); +#else + (void)size; + return NULL; +#endif +} + +// Deallocate memory, only used if buffers are not provided to littlefs +static inline void lfs_free(void *p) { +#ifndef LFS_NO_MALLOC + RD_FREE(p); +#else + (void)p; +#endif +} + + +#ifdef __cplusplus +} /* extern "C" */ +#endif + +#endif diff --git a/library/littlefs/include/lfs_filebd.h b/library/littlefs/include/lfs_filebd.h new file mode 100644 index 0000000..d7d2fd9 --- /dev/null +++ b/library/littlefs/include/lfs_filebd.h @@ -0,0 +1,82 @@ +/* + * Block device emulated in a file + * + * Copyright (c) 2022, The littlefs authors. + * Copyright (c) 2017, Arm Limited. All rights reserved. + * SPDX-License-Identifier: BSD-3-Clause + */ +#ifndef LFS_FILEBD_H +#define LFS_FILEBD_H + +#include "lfs.h" +#include "lfs_util.h" + +#ifdef __cplusplus +extern "C" +{ +#endif + + +// Block device specific tracing +#ifndef LFS_FILEBD_TRACE +#ifdef LFS_FILEBD_YES_TRACE +#define LFS_FILEBD_TRACE(...) LFS_TRACE(__VA_ARGS__) +#else +#define LFS_FILEBD_TRACE(...) +#endif +#endif + +// filebd config +struct lfs_filebd_config { + // Minimum size of a read operation in bytes. + lfs_size_t read_size; + + // Minimum size of a program operation in bytes. + lfs_size_t prog_size; + + // Size of an erase operation in bytes. + lfs_size_t erase_size; + + // Number of erase blocks on the device. + lfs_size_t erase_count; +}; + +// filebd state +typedef struct lfs_filebd { + int fd; + const struct lfs_filebd_config *cfg; +} lfs_filebd_t; + + +// Create a file block device +int lfs_filebd_create(const struct lfs_config *cfg, const char *path, + const struct lfs_filebd_config *bdcfg); + +// Clean up memory associated with block device +int lfs_filebd_destroy(const struct lfs_config *cfg); + +// Read a block +int lfs_filebd_read(const struct lfs_config *cfg, lfs_block_t block, + lfs_off_t off, void *buffer, lfs_size_t size); + +// Program a block +// +// The block must have previously been erased. +int lfs_filebd_prog(const struct lfs_config *cfg, lfs_block_t block, + lfs_off_t off, const void *buffer, lfs_size_t size); + +// Erase a block +// +// A block must be erased before being programmed. The +// state of an erased block is undefined. +int lfs_filebd_erase(const struct lfs_config *cfg, lfs_block_t block); + +// Sync the block device +int lfs_filebd_sync(const struct lfs_config *cfg); + + +#ifdef __cplusplus +} /* extern "C" */ +#endif + +#endif diff --git a/library/littlefs/include/lfs_flashbd.h b/library/littlefs/include/lfs_flashbd.h new file mode 100644 index 0000000..d87efbe --- /dev/null +++ b/library/littlefs/include/lfs_flashbd.h @@ -0,0 +1,99 @@ +/* + * LittleFS block device adapter for W25QXX SPI Flash + * + * Maps littlefs read/prog/erase/sync callbacks to the W25QXX driver: + * read -> W25QXX_Read + * prog -> W25QXX_Write_NoCheck (littleFS guarantees erase-before-prog) + * erase -> W25QXX_Erase_Sector (4 KiB sector) + * sync -> W25QXX_Wait_Busy + */ +#ifndef LFS_FLASHBD_H +#define LFS_FLASHBD_H + +#include "lfs.h" +#include "lfs_util.h" +#include + +#ifdef __cplusplus +extern "C" { +#endif + +/* W25QXX 扇区大小固定为 4096 字节 */ +#define LFS_FLASHBD_SECTOR_SIZE 4096 + +/* Flash 块设备配置 */ +struct lfs_flashbd_config { + /* Flash 起始偏移地址（字节），必须 4096 对齐 */ + uint32_t base_addr; + + /* 使用的块（扇区）数量 */ + uint32_t block_count; +}; + +/* Flash 块设备状态 */ +typedef struct lfs_flashbd { + const struct lfs_flashbd_config *cfg; +} lfs_flashbd_t; + + +/* 初始化块设备（内部调用 W25QXX_Init） */ +int lfs_flashbd_create(const struct lfs_config *cfg, + const struct lfs_flashbd_config *bdcfg); + +/* 销毁块设备（当前为空操作） */ +int lfs_flashbd_destroy(const struct lfs_config *cfg); + +/* 读取一个块的区域 */ +int lfs_flashbd_read(const struct lfs_config *cfg, lfs_block_t block, + lfs_off_t off, void *buffer, lfs_size_t size); + +/* 编程一个块的区域（块必须已擦除） */ +int lfs_flashbd_prog(const struct lfs_config *cfg, lfs_block_t block, + lfs_off_t off, const void *buffer, lfs_size_t size); + +/* 擦除一个块（4 KiB 扇区） */ +int lfs_flashbd_erase(const struct lfs_config *cfg, lfs_block_t block); + +/* 同步块设备（等待 Flash 空闲） */ +int lfs_flashbd_sync(const struct lfs_config *cfg); + + +/* + * 便捷函数：用 W25QXX 默认参数填充 lfs_config 和 flashbd 配置。 + * + * 调用者需提供 lfs_config、lfs_flashbd_t、lfs_flashbd_config 结构体 + * （可以是在栈上或静态分配），以及 Flash 起始地址和使用的块数量。 + * + * 如果 read_buffer / prog_buffer / lookahead_buffer 为 NULL， + * littleFS 会通过 lfs_malloc 动态分配缓存。 + * 静态 lookahead_buffer 大小需 >= lookahead_size = ceil(block_count / 8) 字节。 + * + * 典型用法（W25Q80，从地址 0 开始使用全部 1 MB）： + * + * lfs_t lfs; + * lfs_flashbd_t bd; + * struct lfs_flashbd_config bd_cfg; + * struct lfs_config cfg; + * uint8_t read_buf[256], prog_buf[256], lookahead_buf[32]; // 256 块 -> 32 字节 + * + * lfs_flashbd_default_config(&cfg, &bd, &bd_cfg, 0, 256, + * read_buf, prog_buf, lookahead_buf); + * lfs_format(&lfs, &cfg); // 首次使用需格式化 + * lfs_mount(&lfs, &cfg); + */ +void lfs_flashbd_default_config( + struct lfs_config *cfg, + lfs_flashbd_t *bd, + struct lfs_flashbd_config *bdcfg, + uint32_t base_addr, + uint32_t block_count, + void *read_buffer, + void *prog_buffer, + void *lookahead_buffer); + + +#ifdef __cplusplus +} /* extern "C" */ +#endif + +#endif /* LFS_FLASHBD_H */ diff --git a/library/littlefs/include/lfs_util.h b/library/littlefs/include/lfs_util.h new file mode 100644 index 0000000..e8f78a9 --- /dev/null +++ b/library/littlefs/include/lfs_util.h @@ -0,0 +1,276 @@ +/* + * lfs utility functions + * + * Copyright (c) 2022, The littlefs authors. + * Copyright (c) 2017, Arm Limited. All rights reserved. + * SPDX-License-Identifier: BSD-3-Clause + */ +#ifndef LFS_UTIL_H +#define LFS_UTIL_H + +#define LFS_STRINGIZE(x) LFS_STRINGIZE2(x) +#define LFS_STRINGIZE2(x) #x + +// Users can override lfs_util.h with their own configuration by defining +// LFS_CONFIG as a header file to include (-DLFS_CONFIG=lfs_config.h). +// +// If LFS_CONFIG is used, none of the default utils will be emitted and must be +// provided by the config file. To start, I would suggest copying lfs_util.h +// and modifying as needed. + +#define LFS_CONFIG lfs_config.h + +#ifdef LFS_CONFIG +#include LFS_STRINGIZE(LFS_CONFIG) +#else + +// Alternatively, users can provide a header file which defines +// macros and other things consumed by littlefs. +// +// For example, provide my_defines.h, which contains +// something like: +// +// #include +// extern void *my_malloc(size_t sz); +// #define LFS_MALLOC(sz) my_malloc(sz) +// +// And build littlefs with the header by defining LFS_DEFINES. +// (-DLFS_DEFINES=my_defines.h) + +#ifdef LFS_DEFINES +#include LFS_STRINGIZE(LFS_DEFINES) +#endif + +// System includes +#include +#include +#include +#include + +#ifndef LFS_NO_MALLOC +#include +#endif +#ifndef LFS_NO_ASSERT +#include +#endif +#if !defined(LFS_NO_DEBUG) || \ + !defined(LFS_NO_WARN) || \ + !defined(LFS_NO_ERROR) || \ + defined(LFS_YES_TRACE) +#include +#endif + +#ifdef __cplusplus +extern "C" +{ +#endif + + +// Macros, may be replaced by system specific wrappers. Arguments to these +// macros must not have side-effects as the macros can be removed for a smaller +// code footprint + +// Logging functions +#ifndef LFS_TRACE +#ifdef LFS_YES_TRACE +#define LFS_TRACE_(fmt, ...) \ + printf("%s:%d:trace: " fmt "%s\n", __FILE__, __LINE__, __VA_ARGS__) +#define LFS_TRACE(...) LFS_TRACE_(__VA_ARGS__, "") +#else +#define LFS_TRACE(...) +#endif +#endif + +#ifndef LFS_DEBUG +#ifndef LFS_NO_DEBUG +#define LFS_DEBUG_(fmt, ...) \ + printf("%s:%d:debug: " fmt "%s\n", __FILE__, __LINE__, __VA_ARGS__) +#define LFS_DEBUG(...) LFS_DEBUG_(__VA_ARGS__, "") +#else +#define LFS_DEBUG(...) +#endif +#endif + +#ifndef LFS_WARN +#ifndef LFS_NO_WARN +#define LFS_WARN_(fmt, ...) \ + printf("%s:%d:warn: " fmt "%s\n", __FILE__, __LINE__, __VA_ARGS__) +#define LFS_WARN(...) LFS_WARN_(__VA_ARGS__, "") +#else +#define LFS_WARN(...) +#endif +#endif + +#ifndef LFS_ERROR +#ifndef LFS_NO_ERROR +#define LFS_ERROR_(fmt, ...) \ + printf("%s:%d:error: " fmt "%s\n", __FILE__, __LINE__, __VA_ARGS__) +#define LFS_ERROR(...) LFS_ERROR_(__VA_ARGS__, "") +#else +#define LFS_ERROR(...) +#endif +#endif + +// Runtime assertions +#ifndef LFS_ASSERT +#ifndef LFS_NO_ASSERT +#define LFS_ASSERT(test) assert(test) +#else +#define LFS_ASSERT(test) +#endif +#endif + + +// Builtin functions, these may be replaced by more efficient +// toolchain-specific implementations. LFS_NO_INTRINSICS falls back to a more +// expensive basic C implementation for debugging purposes + +// Min/max functions for unsigned 32-bit numbers +static inline uint32_t lfs_max(uint32_t a, uint32_t b) { + return (a > b) ? a : b; +} + +static inline uint32_t lfs_min(uint32_t a, uint32_t b) { + return (a < b) ? a : b; +} + +// Align to nearest multiple of a size +static inline uint32_t lfs_aligndown(uint32_t a, uint32_t alignment) { + return a - (a % alignment); +} + +static inline uint32_t lfs_alignup(uint32_t a, uint32_t alignment) { + return lfs_aligndown(a + alignment-1, alignment); +} + +// Find the smallest power of 2 greater than or equal to a +static inline uint32_t lfs_npw2(uint32_t a) { +#if !defined(LFS_NO_INTRINSICS) && (defined(__GNUC__) || defined(__CC_ARM)) + return 32 - __builtin_clz(a-1); +#else + uint32_t r = 0; + uint32_t s; + a -= 1; + s = (a > 0xffff) << 4; a >>= s; r |= s; + s = (a > 0xff ) << 3; a >>= s; r |= s; + s = (a > 0xf ) << 2; a >>= s; r |= s; + s = (a > 0x3 ) << 1; a >>= s; r |= s; + return (r | (a >> 1)) + 1; +#endif +} + +// Count the number of trailing binary zeros in a +// lfs_ctz(0) may be undefined +static inline uint32_t lfs_ctz(uint32_t a) { +#if !defined(LFS_NO_INTRINSICS) && defined(__GNUC__) + return __builtin_ctz(a); +#else + return lfs_npw2((a & -a) + 1) - 1; +#endif +} + +// Count the number of binary ones in a +static inline uint32_t lfs_popc(uint32_t a) { +#if !defined(LFS_NO_INTRINSICS) && (defined(__GNUC__) || defined(__CC_ARM)) + return __builtin_popcount(a); +#else + a = a - ((a >> 1) & 0x55555555); + a = (a & 0x33333333) + ((a >> 2) & 0x33333333); + return (((a + (a >> 4)) & 0xf0f0f0f) * 0x1010101) >> 24; +#endif +} + +// Find the sequence comparison of a and b, this is the distance +// between a and b ignoring overflow +static inline int lfs_scmp(uint32_t a, uint32_t b) { + return (int)(unsigned)(a - b); +} + +// Convert between 32-bit little-endian and native order +static inline uint32_t lfs_fromle32(uint32_t a) { +#if (defined( BYTE_ORDER ) && defined( ORDER_LITTLE_ENDIAN ) && BYTE_ORDER == ORDER_LITTLE_ENDIAN ) || \ + (defined(__BYTE_ORDER ) && defined(__ORDER_LITTLE_ENDIAN ) && __BYTE_ORDER == __ORDER_LITTLE_ENDIAN ) || \ + (defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__) + return a; +#elif !defined(LFS_NO_INTRINSICS) && ( \ + (defined( BYTE_ORDER ) && defined( ORDER_BIG_ENDIAN ) && BYTE_ORDER == ORDER_BIG_ENDIAN ) || \ + (defined(__BYTE_ORDER ) && defined(__ORDER_BIG_ENDIAN ) && __BYTE_ORDER == __ORDER_BIG_ENDIAN ) || \ + (defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)) + return __builtin_bswap32(a); +#else + return ((uint32_t)((uint8_t*)&a)[0] << 0) | + ((uint32_t)((uint8_t*)&a)[1] << 8) | + ((uint32_t)((uint8_t*)&a)[2] << 16) | + ((uint32_t)((uint8_t*)&a)[3] << 24); +#endif +} + +static inline uint32_t lfs_tole32(uint32_t a) { + return lfs_fromle32(a); +} + +// Convert between 32-bit big-endian and native order +static inline uint32_t lfs_frombe32(uint32_t a) { +#if !defined(LFS_NO_INTRINSICS) && ( \ + (defined( BYTE_ORDER ) && defined( ORDER_LITTLE_ENDIAN ) && BYTE_ORDER == ORDER_LITTLE_ENDIAN ) || \ + (defined(__BYTE_ORDER ) && defined(__ORDER_LITTLE_ENDIAN ) && __BYTE_ORDER == __ORDER_LITTLE_ENDIAN ) || \ + (defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)) + return __builtin_bswap32(a); +#elif (defined( BYTE_ORDER ) && defined( ORDER_BIG_ENDIAN ) && BYTE_ORDER == ORDER_BIG_ENDIAN ) || \ + (defined(__BYTE_ORDER ) && defined(__ORDER_BIG_ENDIAN ) && __BYTE_ORDER == __ORDER_BIG_ENDIAN ) || \ + (defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__) + return a; +#else + return ((uint32_t)((uint8_t*)&a)[0] << 24) | + ((uint32_t)((uint8_t*)&a)[1] << 16) | + ((uint32_t)((uint8_t*)&a)[2] << 8) | + ((uint32_t)((uint8_t*)&a)[3] << 0); +#endif +} + +static inline uint32_t lfs_tobe32(uint32_t a) { + return lfs_frombe32(a); +} + +// Calculate CRC-32 with polynomial = 0x04c11db7 +#ifdef LFS_CRC +static inline uint32_t lfs_crc(uint32_t crc, const void *buffer, size_t size) { + return LFS_CRC(crc, buffer, size); +} +#else +uint32_t lfs_crc(uint32_t crc, const void *buffer, size_t size); +#endif + +// Allocate memory, only used if buffers are not provided to littlefs +// +// littlefs current has no alignment requirements, as it only allocates +// byte-level buffers. +static inline void *lfs_malloc(size_t size) { +#if defined(LFS_MALLOC) + return LFS_MALLOC(size); +#elif !defined(LFS_NO_MALLOC) + return malloc(size); +#else + (void)size; + return NULL; +#endif +} + +// Deallocate memory, only used if buffers are not provided to littlefs +static inline void lfs_free(void *p) { +#if defined(LFS_FREE) + LFS_FREE(p); +#elif !defined(LFS_NO_MALLOC) + free(p); +#else + (void)p; +#endif +} + + +#ifdef __cplusplus +} /* extern "C" */ +#endif + +#endif +#endif diff --git a/library/littlefs/lfs.c b/library/littlefs/lfs.c new file mode 100644 index 0000000..c83c7e0 --- /dev/null +++ b/library/littlefs/lfs.c @@ -0,0 +1,6558 @@ +/* + * The little filesystem + * + * Copyright (c) 2022, The littlefs authors. + * Copyright (c) 2017, Arm Limited. All rights reserved. + * SPDX-License-Identifier: BSD-3-Clause + */ +#include "lfs.h" +#include "lfs_util.h" + + +// some constants used throughout the code +#define LFS_BLOCK_NULL ((lfs_block_t)-1) +#define LFS_BLOCK_INLINE ((lfs_block_t)-2) + +enum { + LFS_OK_RELOCATED = 1, + LFS_OK_DROPPED = 2, + LFS_OK_ORPHANED = 3, +}; + +enum { + LFS_CMP_EQ = 0, + LFS_CMP_LT = 1, + LFS_CMP_GT = 2, +}; + + +/// Caching block device operations /// + +static inline void lfs_cache_drop(lfs_t *lfs, lfs_cache_t *rcache) { + // do not zero, cheaper if cache is readonly or only going to be + // written with identical data (during relocates) + (void)lfs; + rcache->block = LFS_BLOCK_NULL; +} + +static inline void lfs_cache_zero(lfs_t *lfs, lfs_cache_t *pcache) { + // zero to avoid information leak + memset(pcache->buffer, 0xff, lfs->cfg->cache_size); + pcache->block = LFS_BLOCK_NULL; +} + +static int lfs_bd_read(lfs_t *lfs, + const lfs_cache_t *pcache, lfs_cache_t *rcache, lfs_size_t hint, + lfs_block_t block, lfs_off_t off, + void *buffer, lfs_size_t size) { + uint8_t *data = buffer; + if (off+size > lfs->cfg->block_size + || (lfs->block_count && block >= lfs->block_count)) { + return LFS_ERR_CORRUPT; + } + + while (size > 0) { + lfs_size_t diff = size; + + if (pcache && block == pcache->block && + off < pcache->off + pcache->size) { + if (off >= pcache->off) { + // is already in pcache? + diff = lfs_min(diff, pcache->size - (off-pcache->off)); + memcpy(data, &pcache->buffer[off-pcache->off], diff); + + data += diff; + off += diff; + size -= diff; + continue; + } + + // pcache takes priority + diff = lfs_min(diff, pcache->off-off); + } + + if (block == rcache->block && + off < rcache->off + rcache->size) { + if (off >= rcache->off) { + // is already in rcache? + diff = lfs_min(diff, rcache->size - (off-rcache->off)); + memcpy(data, &rcache->buffer[off-rcache->off], diff); + + data += diff; + off += diff; + size -= diff; + continue; + } + + // rcache takes priority + diff = lfs_min(diff, rcache->off-off); + } + + if (size >= hint && off % lfs->cfg->read_size == 0 && + size >= lfs->cfg->read_size) { + // bypass cache? + diff = lfs_aligndown(diff, lfs->cfg->read_size); + int err = lfs->cfg->read(lfs->cfg, block, off, data, diff); + LFS_ASSERT(err <= 0); + if (err) { + return err; + } + + data += diff; + off += diff; + size -= diff; + continue; + } + + // load to cache, first condition can no longer fail + LFS_ASSERT(!lfs->block_count || block < lfs->block_count); + rcache->block = block; + rcache->off = lfs_aligndown(off, lfs->cfg->read_size); + rcache->size = lfs_min( + lfs_min( + lfs_alignup(off+hint, lfs->cfg->read_size), + lfs->cfg->block_size) + - rcache->off, + lfs->cfg->cache_size); + int err = lfs->cfg->read(lfs->cfg, rcache->block, + rcache->off, rcache->buffer, rcache->size); + LFS_ASSERT(err <= 0); + if (err) { + return err; + } + } + + return 0; +} + +static int lfs_bd_cmp(lfs_t *lfs, + const lfs_cache_t *pcache, lfs_cache_t *rcache, lfs_size_t hint, + lfs_block_t block, lfs_off_t off, + const void *buffer, lfs_size_t size) { + const uint8_t *data = buffer; + lfs_size_t diff = 0; + + for (lfs_off_t i = 0; i < size; i += diff) { + uint8_t dat[8]; + + diff = lfs_min(size-i, sizeof(dat)); + int err = lfs_bd_read(lfs, + pcache, rcache, hint-i, + block, off+i, &dat, diff); + if (err) { + return err; + } + + int res = memcmp(dat, data + i, diff); + if (res) { + return res < 0 ? LFS_CMP_LT : LFS_CMP_GT; + } + } + + return LFS_CMP_EQ; +} + +static int lfs_bd_crc(lfs_t *lfs, + const lfs_cache_t *pcache, lfs_cache_t *rcache, lfs_size_t hint, + lfs_block_t block, lfs_off_t off, lfs_size_t size, uint32_t *crc) { + lfs_size_t diff = 0; + + for (lfs_off_t i = 0; i < size; i += diff) { + uint8_t dat[8]; + diff = lfs_min(size-i, sizeof(dat)); + int err = lfs_bd_read(lfs, + pcache, rcache, hint-i, + block, off+i, &dat, diff); + if (err) { + return err; + } + + *crc = lfs_crc(*crc, &dat, diff); + } + + return 0; +} + +#ifndef LFS_READONLY +static int lfs_bd_flush(lfs_t *lfs, + lfs_cache_t *pcache, lfs_cache_t *rcache, bool validate) { + if (pcache->block != LFS_BLOCK_NULL && pcache->block != LFS_BLOCK_INLINE) { + LFS_ASSERT(pcache->block < lfs->block_count); + lfs_size_t diff = lfs_alignup(pcache->size, lfs->cfg->prog_size); + int err = lfs->cfg->prog(lfs->cfg, pcache->block, + pcache->off, pcache->buffer, diff); + LFS_ASSERT(err <= 0); + if (err) { + return err; + } + + if (validate) { + // check data on disk + lfs_cache_drop(lfs, rcache); + int res = lfs_bd_cmp(lfs, + NULL, rcache, diff, + pcache->block, pcache->off, pcache->buffer, diff); + if (res < 0) { + return res; + } + + if (res != LFS_CMP_EQ) { + return LFS_ERR_CORRUPT; + } + } + + lfs_cache_zero(lfs, pcache); + } + + return 0; +} +#endif + +#ifndef LFS_READONLY +static int lfs_bd_sync(lfs_t *lfs, + lfs_cache_t *pcache, lfs_cache_t *rcache, bool validate) { + lfs_cache_drop(lfs, rcache); + + int err = lfs_bd_flush(lfs, pcache, rcache, validate); + if (err) { + return err; + } + + err = lfs->cfg->sync(lfs->cfg); + LFS_ASSERT(err <= 0); + return err; +} +#endif + +#ifndef LFS_READONLY +static int lfs_bd_prog(lfs_t *lfs, + lfs_cache_t *pcache, lfs_cache_t *rcache, bool validate, + lfs_block_t block, lfs_off_t off, + const void *buffer, lfs_size_t size) { + const uint8_t *data = buffer; + LFS_ASSERT(block == LFS_BLOCK_INLINE || block < lfs->block_count); + LFS_ASSERT(off + size <= lfs->cfg->block_size); + + while (size > 0) { + if (block == pcache->block && + off >= pcache->off && + off < pcache->off + lfs->cfg->cache_size) { + // already fits in pcache? + lfs_size_t diff = lfs_min(size, + lfs->cfg->cache_size - (off-pcache->off)); + memcpy(&pcache->buffer[off-pcache->off], data, diff); + + data += diff; + off += diff; + size -= diff; + + pcache->size = lfs_max(pcache->size, off - pcache->off); + if (pcache->size == lfs->cfg->cache_size) { + // eagerly flush out pcache if we fill up + int err = lfs_bd_flush(lfs, pcache, rcache, validate); + if (err) { + return err; + } + } + + continue; + } + + // pcache must have been flushed, either by programming an + // entire block or manually flushing the pcache + LFS_ASSERT(pcache->block == LFS_BLOCK_NULL); + + // prepare pcache, first condition can no longer fail + pcache->block = block; + pcache->off = lfs_aligndown(off, lfs->cfg->prog_size); + pcache->size = 0; + } + + return 0; +} +#endif + +#ifndef LFS_READONLY +static int lfs_bd_erase(lfs_t *lfs, lfs_block_t block) { + LFS_ASSERT(block < lfs->block_count); + int err = lfs->cfg->erase(lfs->cfg, block); + LFS_ASSERT(err <= 0); + return err; +} +#endif + + +/// Small type-level utilities /// + +// some operations on paths +static inline lfs_size_t lfs_path_namelen(const char *path) { + return (lfs_size_t)strcspn(path, "/"); +} + +static inline bool lfs_path_islast(const char *path) { + lfs_size_t namelen = lfs_path_namelen(path); + return path[namelen + strspn(path + namelen, "/")] == '\0'; +} + +static inline bool lfs_path_isdir(const char *path) { + return path[lfs_path_namelen(path)] != '\0'; +} + +// operations on block pairs +static inline void lfs_pair_swap(lfs_block_t pair[2]) { + lfs_block_t t = pair[0]; + pair[0] = pair[1]; + pair[1] = t; +} + +static inline bool lfs_pair_isnull(const lfs_block_t pair[2]) { + return pair[0] == LFS_BLOCK_NULL || pair[1] == LFS_BLOCK_NULL; +} + +static inline int lfs_pair_cmp( + const lfs_block_t paira[2], + const lfs_block_t pairb[2]) { + return !(paira[0] == pairb[0] || paira[1] == pairb[1] || + paira[0] == pairb[1] || paira[1] == pairb[0]); +} + +static inline bool lfs_pair_issync( + const lfs_block_t paira[2], + const lfs_block_t pairb[2]) { + return (paira[0] == pairb[0] && paira[1] == pairb[1]) || + (paira[0] == pairb[1] && paira[1] == pairb[0]); +} + +static inline void lfs_pair_fromle32(lfs_block_t pair[2]) { + pair[0] = lfs_fromle32(pair[0]); + pair[1] = lfs_fromle32(pair[1]); +} + +#ifndef LFS_READONLY +static inline void lfs_pair_tole32(lfs_block_t pair[2]) { + pair[0] = lfs_tole32(pair[0]); + pair[1] = lfs_tole32(pair[1]); +} +#endif + +// operations on 32-bit entry tags +typedef uint32_t lfs_tag_t; +typedef int32_t lfs_stag_t; + +#define LFS_MKTAG(type, id, size) \ + (((lfs_tag_t)(type) << 20) | ((lfs_tag_t)(id) << 10) | (lfs_tag_t)(size)) + +#define LFS_MKTAG_IF(cond, type, id, size) \ + ((cond) ? LFS_MKTAG(type, id, size) : LFS_MKTAG(LFS_FROM_NOOP, 0, 0)) + +#define LFS_MKTAG_IF_ELSE(cond, type1, id1, size1, type2, id2, size2) \ + ((cond) ? LFS_MKTAG(type1, id1, size1) : LFS_MKTAG(type2, id2, size2)) + +static inline bool lfs_tag_isvalid(lfs_tag_t tag) { + return !(tag & 0x80000000); +} + +static inline bool lfs_tag_isdelete(lfs_tag_t tag) { + return ((int32_t)(tag << 22) >> 22) == -1; +} + +static inline uint16_t lfs_tag_type1(lfs_tag_t tag) { + return (tag & 0x70000000) >> 20; +} + +static inline uint16_t lfs_tag_type2(lfs_tag_t tag) { + return (tag & 0x78000000) >> 20; +} + +static inline uint16_t lfs_tag_type3(lfs_tag_t tag) { + return (tag & 0x7ff00000) >> 20; +} + +static inline uint8_t lfs_tag_chunk(lfs_tag_t tag) { + return (tag & 0x0ff00000) >> 20; +} + +static inline int8_t lfs_tag_splice(lfs_tag_t tag) { + return (int8_t)lfs_tag_chunk(tag); +} + +static inline uint16_t lfs_tag_id(lfs_tag_t tag) { + return (tag & 0x000ffc00) >> 10; +} + +static inline lfs_size_t lfs_tag_size(lfs_tag_t tag) { + return tag & 0x000003ff; +} + +static inline lfs_size_t lfs_tag_dsize(lfs_tag_t tag) { + return sizeof(tag) + lfs_tag_size(tag + lfs_tag_isdelete(tag)); +} + +// operations on attributes in attribute lists +struct lfs_mattr { + lfs_tag_t tag; + const void *buffer; +}; + +struct lfs_diskoff { + lfs_block_t block; + lfs_off_t off; +}; + +#define LFS_MKATTRS(...) \ + (struct lfs_mattr[]){__VA_ARGS__}, \ + sizeof((struct lfs_mattr[]){__VA_ARGS__}) / sizeof(struct lfs_mattr) + +// operations on global state +static inline void lfs_gstate_xor(lfs_gstate_t *a, const lfs_gstate_t *b) { + a->tag ^= b->tag; + a->pair[0] ^= b->pair[0]; + a->pair[1] ^= b->pair[1]; +} + +static inline bool lfs_gstate_iszero(const lfs_gstate_t *a) { + return a->tag == 0 + && a->pair[0] == 0 + && a->pair[1] == 0; +} + +#ifndef LFS_READONLY +static inline bool lfs_gstate_hasorphans(const lfs_gstate_t *a) { + return lfs_tag_size(a->tag); +} + +static inline uint8_t lfs_gstate_getorphans(const lfs_gstate_t *a) { + return lfs_tag_size(a->tag) & 0x1ff; +} + +static inline bool lfs_gstate_hasmove(const lfs_gstate_t *a) { + return lfs_tag_type1(a->tag); +} +#endif + +static inline bool lfs_gstate_needssuperblock(const lfs_gstate_t *a) { + return lfs_tag_size(a->tag) >> 9; +} + +static inline bool lfs_gstate_hasmovehere(const lfs_gstate_t *a, + const lfs_block_t *pair) { + return lfs_tag_type1(a->tag) && lfs_pair_cmp(a->pair, pair) == 0; +} + +static inline void lfs_gstate_fromle32(lfs_gstate_t *a) { + a->tag = lfs_fromle32(a->tag); + a->pair[0] = lfs_fromle32(a->pair[0]); + a->pair[1] = lfs_fromle32(a->pair[1]); +} + +#ifndef LFS_READONLY +static inline void lfs_gstate_tole32(lfs_gstate_t *a) { + a->tag = lfs_tole32(a->tag); + a->pair[0] = lfs_tole32(a->pair[0]); + a->pair[1] = lfs_tole32(a->pair[1]); +} +#endif + +// operations on forward-CRCs used to track erased state +struct lfs_fcrc { + lfs_size_t size; + uint32_t crc; +}; + +static void lfs_fcrc_fromle32(struct lfs_fcrc *fcrc) { + fcrc->size = lfs_fromle32(fcrc->size); + fcrc->crc = lfs_fromle32(fcrc->crc); +} + +#ifndef LFS_READONLY +static void lfs_fcrc_tole32(struct lfs_fcrc *fcrc) { + fcrc->size = lfs_tole32(fcrc->size); + fcrc->crc = lfs_tole32(fcrc->crc); +} +#endif + +// other endianness operations +static void lfs_ctz_fromle32(struct lfs_ctz *ctz) { + ctz->head = lfs_fromle32(ctz->head); + ctz->size = lfs_fromle32(ctz->size); +} + +#ifndef LFS_READONLY +static void lfs_ctz_tole32(struct lfs_ctz *ctz) { + ctz->head = lfs_tole32(ctz->head); + ctz->size = lfs_tole32(ctz->size); +} +#endif + +static inline void lfs_superblock_fromle32(lfs_superblock_t *superblock) { + superblock->version = lfs_fromle32(superblock->version); + superblock->block_size = lfs_fromle32(superblock->block_size); + superblock->block_count = lfs_fromle32(superblock->block_count); + superblock->name_max = lfs_fromle32(superblock->name_max); + superblock->file_max = lfs_fromle32(superblock->file_max); + superblock->attr_max = lfs_fromle32(superblock->attr_max); +} + +#ifndef LFS_READONLY +static inline void lfs_superblock_tole32(lfs_superblock_t *superblock) { + superblock->version = lfs_tole32(superblock->version); + superblock->block_size = lfs_tole32(superblock->block_size); + superblock->block_count = lfs_tole32(superblock->block_count); + superblock->name_max = lfs_tole32(superblock->name_max); + superblock->file_max = lfs_tole32(superblock->file_max); + superblock->attr_max = lfs_tole32(superblock->attr_max); +} +#endif + +#ifndef LFS_NO_ASSERT +static bool lfs_mlist_isopen(struct lfs_mlist *head, + struct lfs_mlist *node) { + for (struct lfs_mlist **p = &head; *p; p = &(*p)->next) { + if (*p == (struct lfs_mlist*)node) { + return true; + } + } + + return false; +} +#endif + +static void lfs_mlist_remove(lfs_t *lfs, struct lfs_mlist *mlist) { + for (struct lfs_mlist **p = &lfs->mlist; *p; p = &(*p)->next) { + if (*p == mlist) { + *p = (*p)->next; + break; + } + } +} + +static void lfs_mlist_append(lfs_t *lfs, struct lfs_mlist *mlist) { + mlist->next = lfs->mlist; + lfs->mlist = mlist; +} + +// some other filesystem operations +static uint32_t lfs_fs_disk_version(lfs_t *lfs) { + (void)lfs; +#ifdef LFS_MULTIVERSION + if (lfs->cfg->disk_version) { + return lfs->cfg->disk_version; + } else +#endif + { + return LFS_DISK_VERSION; + } +} + +static uint16_t lfs_fs_disk_version_major(lfs_t *lfs) { + return 0xffff & (lfs_fs_disk_version(lfs) >> 16); + +} + +static uint16_t lfs_fs_disk_version_minor(lfs_t *lfs) { + return 0xffff & (lfs_fs_disk_version(lfs) >> 0); +} + + +/// Internal operations predeclared here /// +#ifndef LFS_READONLY +static int lfs_dir_commit(lfs_t *lfs, lfs_mdir_t *dir, + const struct lfs_mattr *attrs, int attrcount); +static int lfs_dir_compact(lfs_t *lfs, + lfs_mdir_t *dir, const struct lfs_mattr *attrs, int attrcount, + lfs_mdir_t *source, uint16_t begin, uint16_t end); +static lfs_ssize_t lfs_file_flushedwrite(lfs_t *lfs, lfs_file_t *file, + const void *buffer, lfs_size_t size); +static lfs_ssize_t lfs_file_write_(lfs_t *lfs, lfs_file_t *file, + const void *buffer, lfs_size_t size); +static int lfs_file_sync_(lfs_t *lfs, lfs_file_t *file); +static int lfs_file_outline(lfs_t *lfs, lfs_file_t *file); +static int lfs_file_flush(lfs_t *lfs, lfs_file_t *file); + +static int lfs_fs_deorphan(lfs_t *lfs, bool powerloss); +static int lfs_fs_preporphans(lfs_t *lfs, int8_t orphans); +static void lfs_fs_prepmove(lfs_t *lfs, + uint16_t id, const lfs_block_t pair[2]); +static int lfs_fs_pred(lfs_t *lfs, const lfs_block_t dir[2], + lfs_mdir_t *pdir); +static lfs_stag_t lfs_fs_parent(lfs_t *lfs, const lfs_block_t dir[2], + lfs_mdir_t *parent); +static int lfs_fs_forceconsistency(lfs_t *lfs); +#endif + +static void lfs_fs_prepsuperblock(lfs_t *lfs, bool needssuperblock); + +#ifdef LFS_MIGRATE +static int lfs1_traverse(lfs_t *lfs, + int (*cb)(void*, lfs_block_t), void *data); +#endif + +static int lfs_dir_rewind_(lfs_t *lfs, lfs_dir_t *dir); + +static lfs_ssize_t lfs_file_flushedread(lfs_t *lfs, lfs_file_t *file, + void *buffer, lfs_size_t size); +static lfs_ssize_t lfs_file_read_(lfs_t *lfs, lfs_file_t *file, + void *buffer, lfs_size_t size); +static int lfs_file_close_(lfs_t *lfs, lfs_file_t *file); +static lfs_soff_t lfs_file_size_(lfs_t *lfs, lfs_file_t *file); + +static lfs_ssize_t lfs_fs_size_(lfs_t *lfs); +static int lfs_fs_traverse_(lfs_t *lfs, + int (*cb)(void *data, lfs_block_t block), void *data, + bool includeorphans); + +static int lfs_deinit(lfs_t *lfs); +static int lfs_unmount_(lfs_t *lfs); + + +/// Block allocator /// + +// allocations should call this when all allocated blocks are committed to +// the filesystem +// +// after a checkpoint, the block allocator may realloc any untracked blocks +static void lfs_alloc_ckpoint(lfs_t *lfs) { + lfs->lookahead.ckpoint = lfs->block_count; +} + +// drop the lookahead buffer, this is done during mounting and failed +// traversals in order to avoid invalid lookahead state +static void lfs_alloc_drop(lfs_t *lfs) { + lfs->lookahead.size = 0; + lfs->lookahead.next = 0; + lfs_alloc_ckpoint(lfs); +} + +#ifndef LFS_READONLY +static int lfs_alloc_lookahead(void *p, lfs_block_t block) { + lfs_t *lfs = (lfs_t*)p; + lfs_block_t off = ((block - lfs->lookahead.start) + + lfs->block_count) % lfs->block_count; + + if (off < lfs->lookahead.size) { + lfs->lookahead.buffer[off / 8] |= 1U << (off % 8); + } + + return 0; +} +#endif + +#ifndef LFS_READONLY +static int lfs_alloc_scan(lfs_t *lfs) { + // move lookahead buffer to the first unused block + // + // note we limit the lookahead buffer to at most the amount of blocks + // checkpointed, this prevents the math in lfs_alloc from underflowing + lfs->lookahead.start = (lfs->lookahead.start + lfs->lookahead.next) + % lfs->block_count; + lfs->lookahead.next = 0; + lfs->lookahead.size = lfs_min( + 8*lfs->cfg->lookahead_size, + lfs->lookahead.ckpoint); + + // find mask of free blocks from tree + memset(lfs->lookahead.buffer, 0, lfs->cfg->lookahead_size); + int err = lfs_fs_traverse_(lfs, lfs_alloc_lookahead, lfs, true); + if (err) { + lfs_alloc_drop(lfs); + return err; + } + + return 0; +} +#endif + +#ifndef LFS_READONLY +static int lfs_alloc(lfs_t *lfs, lfs_block_t *block) { + while (true) { + // scan our lookahead buffer for free blocks + while (lfs->lookahead.next < lfs->lookahead.size) { + if (!(lfs->lookahead.buffer[lfs->lookahead.next / 8] + & (1U << (lfs->lookahead.next % 8)))) { + // found a free block + *block = (lfs->lookahead.start + lfs->lookahead.next) + % lfs->block_count; + + // eagerly find next free block to maximize how many blocks + // lfs_alloc_ckpoint makes available for scanning + while (true) { + lfs->lookahead.next += 1; + lfs->lookahead.ckpoint -= 1; + + if (lfs->lookahead.next >= lfs->lookahead.size + || !(lfs->lookahead.buffer[lfs->lookahead.next / 8] + & (1U << (lfs->lookahead.next % 8)))) { + return 0; + } + } + } + + lfs->lookahead.next += 1; + lfs->lookahead.ckpoint -= 1; + } + + // In order to keep our block allocator from spinning forever when our + // filesystem is full, we mark points where there are no in-flight + // allocations with a checkpoint before starting a set of allocations. + // + // If we've looked at all blocks since the last checkpoint, we report + // the filesystem as out of storage. + // + if (lfs->lookahead.ckpoint <= 0) { + LFS_ERROR("No more free space 0x%"PRIx32, + (lfs->lookahead.start + lfs->lookahead.next) + % lfs->block_count); + return LFS_ERR_NOSPC; + } + + // No blocks in our lookahead buffer, we need to scan the filesystem for + // unused blocks in the next lookahead window. + int err = lfs_alloc_scan(lfs); + if(err) { + return err; + } + } +} +#endif + +/// Metadata pair and directory operations /// +static lfs_stag_t lfs_dir_getslice(lfs_t *lfs, const lfs_mdir_t *dir, + lfs_tag_t gmask, lfs_tag_t gtag, + lfs_off_t goff, void *gbuffer, lfs_size_t gsize) { + lfs_off_t off = dir->off; + lfs_tag_t ntag = dir->etag; + lfs_stag_t gdiff = 0; + + // synthetic moves + if (lfs_gstate_hasmovehere(&lfs->gdisk, dir->pair) && + lfs_tag_id(gmask) != 0) { + if (lfs_tag_id(lfs->gdisk.tag) == lfs_tag_id(gtag)) { + return LFS_ERR_NOENT; + } else if (lfs_tag_id(lfs->gdisk.tag) < lfs_tag_id(gtag)) { + gdiff -= LFS_MKTAG(0, 1, 0); + } + } + + // iterate over dir block backwards (for faster lookups) + while (off >= sizeof(lfs_tag_t) + lfs_tag_dsize(ntag)) { + off -= lfs_tag_dsize(ntag); + lfs_tag_t tag = ntag; + int err = lfs_bd_read(lfs, + NULL, &lfs->rcache, sizeof(ntag), + dir->pair[0], off, &ntag, sizeof(ntag)); + LFS_ASSERT(err <= 0); + if (err) { + return err; + } + + ntag = (lfs_frombe32(ntag) ^ tag) & 0x7fffffff; + + if (lfs_tag_id(gmask) != 0 && + lfs_tag_type1(tag) == LFS_TYPE_SPLICE && + lfs_tag_id(tag) <= lfs_tag_id(gtag - gdiff)) { + if (tag == (LFS_MKTAG(LFS_TYPE_CREATE, 0, 0) | + (LFS_MKTAG(0, 0x3ff, 0) & (gtag - gdiff)))) { + // found where we were created + return LFS_ERR_NOENT; + } + + // move around splices + gdiff += LFS_MKTAG(0, lfs_tag_splice(tag), 0); + } + + if ((gmask & tag) == (gmask & (gtag - gdiff))) { + if (lfs_tag_isdelete(tag)) { + return LFS_ERR_NOENT; + } + + lfs_size_t diff = lfs_min(lfs_tag_size(tag), gsize); + err = lfs_bd_read(lfs, + NULL, &lfs->rcache, diff, + dir->pair[0], off+sizeof(tag)+goff, gbuffer, diff); + LFS_ASSERT(err <= 0); + if (err) { + return err; + } + + memset((uint8_t*)gbuffer + diff, 0, gsize - diff); + + return tag + gdiff; + } + } + + return LFS_ERR_NOENT; +} + +static lfs_stag_t lfs_dir_get(lfs_t *lfs, const lfs_mdir_t *dir, + lfs_tag_t gmask, lfs_tag_t gtag, void *buffer) { + return lfs_dir_getslice(lfs, dir, + gmask, gtag, + 0, buffer, lfs_tag_size(gtag)); +} + +static int lfs_dir_getread(lfs_t *lfs, const lfs_mdir_t *dir, + const lfs_cache_t *pcache, lfs_cache_t *rcache, lfs_size_t hint, + lfs_tag_t gmask, lfs_tag_t gtag, + lfs_off_t off, void *buffer, lfs_size_t size) { + uint8_t *data = buffer; + if (off+size > lfs->cfg->block_size) { + return LFS_ERR_CORRUPT; + } + + while (size > 0) { + lfs_size_t diff = size; + + if (pcache && pcache->block == LFS_BLOCK_INLINE && + off < pcache->off + pcache->size) { + if (off >= pcache->off) { + // is already in pcache? + diff = lfs_min(diff, pcache->size - (off-pcache->off)); + memcpy(data, &pcache->buffer[off-pcache->off], diff); + + data += diff; + off += diff; + size -= diff; + continue; + } + + // pcache takes priority + diff = lfs_min(diff, pcache->off-off); + } + + if (rcache->block == LFS_BLOCK_INLINE && + off < rcache->off + rcache->size) { + if (off >= rcache->off) { + // is already in rcache? + diff = lfs_min(diff, rcache->size - (off-rcache->off)); + memcpy(data, &rcache->buffer[off-rcache->off], diff); + + data += diff; + off += diff; + size -= diff; + continue; + } + } + + // load to cache, first condition can no longer fail + rcache->block = LFS_BLOCK_INLINE; + rcache->off = lfs_aligndown(off, lfs->cfg->read_size); + rcache->size = lfs_min(lfs_alignup(off+hint, lfs->cfg->read_size), + lfs->cfg->cache_size); + int err = lfs_dir_getslice(lfs, dir, gmask, gtag, + rcache->off, rcache->buffer, rcache->size); + if (err < 0) { + return err; + } + } + + return 0; +} + +#ifndef LFS_READONLY +static int lfs_dir_traverse_filter(void *p, + lfs_tag_t tag, const void *buffer) { + lfs_tag_t *filtertag = p; + (void)buffer; + + // which mask depends on unique bit in tag structure + uint32_t mask = (tag & LFS_MKTAG(0x100, 0, 0)) + ? LFS_MKTAG(0x7ff, 0x3ff, 0) + : LFS_MKTAG(0x700, 0x3ff, 0); + + // check for redundancy + if ((mask & tag) == (mask & *filtertag) || + lfs_tag_isdelete(*filtertag) || + (LFS_MKTAG(0x7ff, 0x3ff, 0) & tag) == ( + LFS_MKTAG(LFS_TYPE_DELETE, 0, 0) | + (LFS_MKTAG(0, 0x3ff, 0) & *filtertag))) { + *filtertag = LFS_MKTAG(LFS_FROM_NOOP, 0, 0); + return true; + } + + // check if we need to adjust for created/deleted tags + if (lfs_tag_type1(tag) == LFS_TYPE_SPLICE && + lfs_tag_id(tag) <= lfs_tag_id(*filtertag)) { + *filtertag += LFS_MKTAG(0, lfs_tag_splice(tag), 0); + } + + return false; +} +#endif + +#ifndef LFS_READONLY +// maximum recursive depth of lfs_dir_traverse, the deepest call: +// +// traverse with commit +// '-> traverse with move +// '-> traverse with filter +// +#define LFS_DIR_TRAVERSE_DEPTH 3 + +struct lfs_dir_traverse { + const lfs_mdir_t *dir; + lfs_off_t off; + lfs_tag_t ptag; + const struct lfs_mattr *attrs; + int attrcount; + + lfs_tag_t tmask; + lfs_tag_t ttag; + uint16_t begin; + uint16_t end; + int16_t diff; + + int (*cb)(void *data, lfs_tag_t tag, const void *buffer); + void *data; + + lfs_tag_t tag; + const void *buffer; + struct lfs_diskoff disk; +}; + +static int lfs_dir_traverse(lfs_t *lfs, + const lfs_mdir_t *dir, lfs_off_t off, lfs_tag_t ptag, + const struct lfs_mattr *attrs, int attrcount, + lfs_tag_t tmask, lfs_tag_t ttag, + uint16_t begin, uint16_t end, int16_t diff, + int (*cb)(void *data, lfs_tag_t tag, const void *buffer), void *data) { + // This function in inherently recursive, but bounded. To allow tool-based + // analysis without unnecessary code-cost we use an explicit stack + struct lfs_dir_traverse stack[LFS_DIR_TRAVERSE_DEPTH-1]; + unsigned sp = 0; + int res; + + // iterate over directory and attrs + lfs_tag_t tag; + const void *buffer; + struct lfs_diskoff disk = {0}; + while (true) { + { + if (off+lfs_tag_dsize(ptag) < dir->off) { + off += lfs_tag_dsize(ptag); + int err = lfs_bd_read(lfs, + NULL, &lfs->rcache, sizeof(tag), + dir->pair[0], off, &tag, sizeof(tag)); + if (err) { + return err; + } + + tag = (lfs_frombe32(tag) ^ ptag) | 0x80000000; + disk.block = dir->pair[0]; + disk.off = off+sizeof(lfs_tag_t); + buffer = &disk; + ptag = tag; + } else if (attrcount > 0) { + tag = attrs[0].tag; + buffer = attrs[0].buffer; + attrs += 1; + attrcount -= 1; + } else { + // finished traversal, pop from stack? + res = 0; + break; + } + + // do we need to filter? + lfs_tag_t mask = LFS_MKTAG(0x7ff, 0, 0); + if ((mask & tmask & tag) != (mask & tmask & ttag)) { + continue; + } + + if (lfs_tag_id(tmask) != 0) { + LFS_ASSERT(sp < LFS_DIR_TRAVERSE_DEPTH); + // recurse, scan for duplicates, and update tag based on + // creates/deletes + stack[sp] = (struct lfs_dir_traverse){ + .dir = dir, + .off = off, + .ptag = ptag, + .attrs = attrs, + .attrcount = attrcount, + .tmask = tmask, + .ttag = ttag, + .begin = begin, + .end = end, + .diff = diff, + .cb = cb, + .data = data, + .tag = tag, + .buffer = buffer, + .disk = disk, + }; + sp += 1; + + tmask = 0; + ttag = 0; + begin = 0; + end = 0; + diff = 0; + cb = lfs_dir_traverse_filter; + data = &stack[sp-1].tag; + continue; + } + } + +popped: + // in filter range? + if (lfs_tag_id(tmask) != 0 && + !(lfs_tag_id(tag) >= begin && lfs_tag_id(tag) < end)) { + continue; + } + + // handle special cases for mcu-side operations + if (lfs_tag_type3(tag) == LFS_FROM_NOOP) { + // do nothing + } else if (lfs_tag_type3(tag) == LFS_FROM_MOVE) { + // Without this condition, lfs_dir_traverse can exhibit an + // extremely expensive O(n^3) of nested loops when renaming. + // This happens because lfs_dir_traverse tries to filter tags by + // the tags in the source directory, triggering a second + // lfs_dir_traverse with its own filter operation. + // + // traverse with commit + // '-> traverse with filter + // '-> traverse with move + // '-> traverse with filter + // + // However we don't actually care about filtering the second set of + // tags, since duplicate tags have no effect when filtering. + // + // This check skips this unnecessary recursive filtering explicitly, + // reducing this runtime from O(n^3) to O(n^2). + if (cb == lfs_dir_traverse_filter) { + continue; + } + + // recurse into move + stack[sp] = (struct lfs_dir_traverse){ + .dir = dir, + .off = off, + .ptag = ptag, + .attrs = attrs, + .attrcount = attrcount, + .tmask = tmask, + .ttag = ttag, + .begin = begin, + .end = end, + .diff = diff, + .cb = cb, + .data = data, + .tag = LFS_MKTAG(LFS_FROM_NOOP, 0, 0), + }; + sp += 1; + + uint16_t fromid = lfs_tag_size(tag); + uint16_t toid = lfs_tag_id(tag); + dir = buffer; + off = 0; + ptag = 0xffffffff; + attrs = NULL; + attrcount = 0; + tmask = LFS_MKTAG(0x600, 0x3ff, 0); + ttag = LFS_MKTAG(LFS_TYPE_STRUCT, 0, 0); + begin = fromid; + end = fromid+1; + diff = toid-fromid+diff; + } else if (lfs_tag_type3(tag) == LFS_FROM_USERATTRS) { + for (unsigned i = 0; i < lfs_tag_size(tag); i++) { + const struct lfs_attr *a = buffer; + res = cb(data, LFS_MKTAG(LFS_TYPE_USERATTR + a[i].type, + lfs_tag_id(tag) + diff, a[i].size), a[i].buffer); + if (res < 0) { + return res; + } + + if (res) { + break; + } + } + } else { + res = cb(data, tag + LFS_MKTAG(0, diff, 0), buffer); + if (res < 0) { + return res; + } + + if (res) { + break; + } + } + } + + if (sp > 0) { + // pop from the stack and return, fortunately all pops share + // a destination + dir = stack[sp-1].dir; + off = stack[sp-1].off; + ptag = stack[sp-1].ptag; + attrs = stack[sp-1].attrs; + attrcount = stack[sp-1].attrcount; + tmask = stack[sp-1].tmask; + ttag = stack[sp-1].ttag; + begin = stack[sp-1].begin; + end = stack[sp-1].end; + diff = stack[sp-1].diff; + cb = stack[sp-1].cb; + data = stack[sp-1].data; + tag = stack[sp-1].tag; + buffer = stack[sp-1].buffer; + disk = stack[sp-1].disk; + sp -= 1; + goto popped; + } else { + return res; + } +} +#endif + +static lfs_stag_t lfs_dir_fetchmatch(lfs_t *lfs, + lfs_mdir_t *dir, const lfs_block_t pair[2], + lfs_tag_t fmask, lfs_tag_t ftag, uint16_t *id, + int (*cb)(void *data, lfs_tag_t tag, const void *buffer), void *data) { + // we can find tag very efficiently during a fetch, since we're already + // scanning the entire directory + lfs_stag_t besttag = -1; + + // if either block address is invalid we return LFS_ERR_CORRUPT here, + // otherwise later writes to the pair could fail + if (lfs->block_count + && (pair[0] >= lfs->block_count || pair[1] >= lfs->block_count)) { + return LFS_ERR_CORRUPT; + } + + // find the block with the most recent revision + uint32_t revs[2] = {0, 0}; + int r = 0; + for (int i = 0; i < 2; i++) { + int err = lfs_bd_read(lfs, + NULL, &lfs->rcache, sizeof(revs[i]), + pair[i], 0, &revs[i], sizeof(revs[i])); + revs[i] = lfs_fromle32(revs[i]); + if (err && err != LFS_ERR_CORRUPT) { + return err; + } + + if (err != LFS_ERR_CORRUPT && + lfs_scmp(revs[i], revs[(i+1)%2]) > 0) { + r = i; + } + } + + dir->pair[0] = pair[(r+0)%2]; + dir->pair[1] = pair[(r+1)%2]; + dir->rev = revs[(r+0)%2]; + dir->off = 0; // nonzero = found some commits + + // now scan tags to fetch the actual dir and find possible match + for (int i = 0; i < 2; i++) { + lfs_off_t off = 0; + lfs_tag_t ptag = 0xffffffff; + + uint16_t tempcount = 0; + lfs_block_t temptail[2] = {LFS_BLOCK_NULL, LFS_BLOCK_NULL}; + bool tempsplit = false; + lfs_stag_t tempbesttag = besttag; + + // assume not erased until proven otherwise + bool maybeerased = false; + bool hasfcrc = false; + struct lfs_fcrc fcrc; + + dir->rev = lfs_tole32(dir->rev); + uint32_t crc = lfs_crc(0xffffffff, &dir->rev, sizeof(dir->rev)); + dir->rev = lfs_fromle32(dir->rev); + + while (true) { + // extract next tag + lfs_tag_t tag; + off += lfs_tag_dsize(ptag); + int err = lfs_bd_read(lfs, + NULL, &lfs->rcache, lfs->cfg->block_size, + dir->pair[0], off, &tag, sizeof(tag)); + if (err) { + if (err == LFS_ERR_CORRUPT) { + // can't continue? + break; + } + return err; + } + + crc = lfs_crc(crc, &tag, sizeof(tag)); + tag = lfs_frombe32(tag) ^ ptag; + + // next commit not yet programmed? + if (!lfs_tag_isvalid(tag)) { + // we only might be erased if the last tag was a crc + maybeerased = (lfs_tag_type2(ptag) == LFS_TYPE_CCRC); + break; + // out of range? + } else if (off + lfs_tag_dsize(tag) > lfs->cfg->block_size) { + break; + } + + ptag = tag; + + if (lfs_tag_type2(tag) == LFS_TYPE_CCRC) { + // check the crc attr + uint32_t dcrc; + err = lfs_bd_read(lfs, + NULL, &lfs->rcache, lfs->cfg->block_size, + dir->pair[0], off+sizeof(tag), &dcrc, sizeof(dcrc)); + if (err) { + if (err == LFS_ERR_CORRUPT) { + break; + } + return err; + } + dcrc = lfs_fromle32(dcrc); + + if (crc != dcrc) { + break; + } + + // reset the next bit if we need to + ptag ^= (lfs_tag_t)(lfs_tag_chunk(tag) & 1U) << 31; + + // toss our crc into the filesystem seed for + // pseudorandom numbers, note we use another crc here + // as a collection function because it is sufficiently + // random and convenient + lfs->seed = lfs_crc(lfs->seed, &crc, sizeof(crc)); + + // update with what's found so far + besttag = tempbesttag; + dir->off = off + lfs_tag_dsize(tag); + dir->etag = ptag; + dir->count = tempcount; + dir->tail[0] = temptail[0]; + dir->tail[1] = temptail[1]; + dir->split = tempsplit; + + // reset crc, hasfcrc + crc = 0xffffffff; + continue; + } + + // crc the entry first, hopefully leaving it in the cache + err = lfs_bd_crc(lfs, + NULL, &lfs->rcache, lfs->cfg->block_size, + dir->pair[0], off+sizeof(tag), + lfs_tag_dsize(tag)-sizeof(tag), &crc); + if (err) { + if (err == LFS_ERR_CORRUPT) { + break; + } + return err; + } + + // directory modification tags? + if (lfs_tag_type1(tag) == LFS_TYPE_NAME) { + // increase count of files if necessary + if (lfs_tag_id(tag) >= tempcount) { + tempcount = lfs_tag_id(tag) + 1; + } + } else if (lfs_tag_type1(tag) == LFS_TYPE_SPLICE) { + tempcount += lfs_tag_splice(tag); + + if (tag == (LFS_MKTAG(LFS_TYPE_DELETE, 0, 0) | + (LFS_MKTAG(0, 0x3ff, 0) & tempbesttag))) { + tempbesttag |= 0x80000000; + } else if (tempbesttag != -1 && + lfs_tag_id(tag) <= lfs_tag_id(tempbesttag)) { + tempbesttag += LFS_MKTAG(0, lfs_tag_splice(tag), 0); + } + } else if (lfs_tag_type1(tag) == LFS_TYPE_TAIL) { + tempsplit = (lfs_tag_chunk(tag) & 1); + + err = lfs_bd_read(lfs, + NULL, &lfs->rcache, lfs->cfg->block_size, + dir->pair[0], off+sizeof(tag), &temptail, 8); + if (err) { + if (err == LFS_ERR_CORRUPT) { + break; + } + return err; + } + lfs_pair_fromle32(temptail); + } else if (lfs_tag_type3(tag) == LFS_TYPE_FCRC) { + err = lfs_bd_read(lfs, + NULL, &lfs->rcache, lfs->cfg->block_size, + dir->pair[0], off+sizeof(tag), + &fcrc, sizeof(fcrc)); + if (err) { + if (err == LFS_ERR_CORRUPT) { + break; + } + return err; + } + + lfs_fcrc_fromle32(&fcrc); + hasfcrc = true; + } + + // found a match for our fetcher? + if ((fmask & tag) == (fmask & ftag)) { + LFS_ASSERT(cb != NULL); + int res = cb(data, tag, &(struct lfs_diskoff){ + dir->pair[0], off+sizeof(tag)}); + if (res < 0) { + if (res == LFS_ERR_CORRUPT) { + break; + } + return res; + } + + if (res == LFS_CMP_EQ) { + // found a match + tempbesttag = tag; + } else if ((LFS_MKTAG(0x7ff, 0x3ff, 0) & tag) == + (LFS_MKTAG(0x7ff, 0x3ff, 0) & tempbesttag)) { + // found an identical tag, but contents didn't match + // this must mean that our besttag has been overwritten + tempbesttag = -1; + } else if (res == LFS_CMP_GT && + lfs_tag_id(tag) <= lfs_tag_id(tempbesttag)) { + // found a greater match, keep track to keep things sorted + tempbesttag = tag | 0x80000000; + } + } + } + + // found no valid commits? + if (dir->off == 0) { + // try the other block? + lfs_pair_swap(dir->pair); + dir->rev = revs[(r+1)%2]; + continue; + } + + // did we end on a valid commit? we may have an erased block + dir->erased = false; + if (maybeerased && dir->off % lfs->cfg->prog_size == 0) { + #ifdef LFS_MULTIVERSION + // note versions < lfs2.1 did not have fcrc tags, if + // we're < lfs2.1 treat missing fcrc as erased data + // + // we don't strictly need to do this, but otherwise writing + // to lfs2.0 disks becomes very inefficient + if (lfs_fs_disk_version(lfs) < 0x00020001) { + dir->erased = true; + + } else + #endif + if (hasfcrc) { + // check for an fcrc matching the next prog's erased state, if + // this failed most likely a previous prog was interrupted, we + // need a new erase + uint32_t fcrc_ = 0xffffffff; + int err = lfs_bd_crc(lfs, + NULL, &lfs->rcache, lfs->cfg->block_size, + dir->pair[0], dir->off, fcrc.size, &fcrc_); + if (err && err != LFS_ERR_CORRUPT) { + return err; + } + + // found beginning of erased part? + dir->erased = (fcrc_ == fcrc.crc); + } + } + + // synthetic move + if (lfs_gstate_hasmovehere(&lfs->gdisk, dir->pair)) { + if (lfs_tag_id(lfs->gdisk.tag) == lfs_tag_id(besttag)) { + besttag |= 0x80000000; + } else if (besttag != -1 && + lfs_tag_id(lfs->gdisk.tag) < lfs_tag_id(besttag)) { + besttag -= LFS_MKTAG(0, 1, 0); + } + } + + // found tag? or found best id? + if (id) { + *id = lfs_min(lfs_tag_id(besttag), dir->count); + } + + if (lfs_tag_isvalid(besttag)) { + return besttag; + } else if (lfs_tag_id(besttag) < dir->count) { + return LFS_ERR_NOENT; + } else { + return 0; + } + } + + LFS_ERROR("Corrupted dir pair at {0x%"PRIx32", 0x%"PRIx32"}", + dir->pair[0], dir->pair[1]); + return LFS_ERR_CORRUPT; +} + +static int lfs_dir_fetch(lfs_t *lfs, + lfs_mdir_t *dir, const lfs_block_t pair[2]) { + // note, mask=-1, tag=-1 can never match a tag since this + // pattern has the invalid bit set + return (int)lfs_dir_fetchmatch(lfs, dir, pair, + (lfs_tag_t)-1, (lfs_tag_t)-1, NULL, NULL, NULL); +} + +static int lfs_dir_getgstate(lfs_t *lfs, const lfs_mdir_t *dir, + lfs_gstate_t *gstate) { + lfs_gstate_t temp; + lfs_stag_t res = lfs_dir_get(lfs, dir, LFS_MKTAG(0x7ff, 0, 0), + LFS_MKTAG(LFS_TYPE_MOVESTATE, 0, sizeof(temp)), &temp); + if (res < 0 && res != LFS_ERR_NOENT) { + return res; + } + + if (res != LFS_ERR_NOENT) { + // xor together to find resulting gstate + lfs_gstate_fromle32(&temp); + lfs_gstate_xor(gstate, &temp); + } + + return 0; +} + +static int lfs_dir_getinfo(lfs_t *lfs, lfs_mdir_t *dir, + uint16_t id, struct lfs_info *info) { + if (id == 0x3ff) { + // special case for root + strcpy(info->name, "/"); + info->type = LFS_TYPE_DIR; + return 0; + } + + lfs_stag_t tag = lfs_dir_get(lfs, dir, LFS_MKTAG(0x780, 0x3ff, 0), + LFS_MKTAG(LFS_TYPE_NAME, id, lfs->name_max+1), info->name); + if (tag < 0) { + return (int)tag; + } + + info->type = lfs_tag_type3(tag); + + struct lfs_ctz ctz; + tag = lfs_dir_get(lfs, dir, LFS_MKTAG(0x700, 0x3ff, 0), + LFS_MKTAG(LFS_TYPE_STRUCT, id, sizeof(ctz)), &ctz); + if (tag < 0) { + return (int)tag; + } + lfs_ctz_fromle32(&ctz); + + if (lfs_tag_type3(tag) == LFS_TYPE_CTZSTRUCT) { + info->size = ctz.size; + } else if (lfs_tag_type3(tag) == LFS_TYPE_INLINESTRUCT) { + info->size = lfs_tag_size(tag); + } + + return 0; +} + +struct lfs_dir_find_match { + lfs_t *lfs; + const void *name; + lfs_size_t size; +}; + +static int lfs_dir_find_match(void *data, + lfs_tag_t tag, const void *buffer) { + struct lfs_dir_find_match *name = data; + lfs_t *lfs = name->lfs; + const struct lfs_diskoff *disk = buffer; + + // compare with disk + lfs_size_t diff = lfs_min(name->size, lfs_tag_size(tag)); + int res = lfs_bd_cmp(lfs, + NULL, &lfs->rcache, diff, + disk->block, disk->off, name->name, diff); + if (res != LFS_CMP_EQ) { + return res; + } + + // only equal if our size is still the same + if (name->size != lfs_tag_size(tag)) { + return (name->size < lfs_tag_size(tag)) ? LFS_CMP_LT : LFS_CMP_GT; + } + + // found a match! + return LFS_CMP_EQ; +} + +// lfs_dir_find tries to set path and id even if file is not found +// +// returns: +// - 0 if file is found +// - LFS_ERR_NOENT if file or parent is not found +// - LFS_ERR_NOTDIR if parent is not a dir +static lfs_stag_t lfs_dir_find(lfs_t *lfs, lfs_mdir_t *dir, + const char **path, uint16_t *id) { + // we reduce path to a single name if we can find it + const char *name = *path; + + // default to root dir + lfs_stag_t tag = LFS_MKTAG(LFS_TYPE_DIR, 0x3ff, 0); + dir->tail[0] = lfs->root[0]; + dir->tail[1] = lfs->root[1]; + + // empty paths are not allowed + if (*name == '\0') { + return LFS_ERR_INVAL; + } + + while (true) { +nextname: + // skip slashes if we're a directory + if (lfs_tag_type3(tag) == LFS_TYPE_DIR) { + name += strspn(name, "/"); + } + lfs_size_t namelen = (lfs_size_t)strcspn(name, "/"); + + // skip '.' + if (namelen == 1 && memcmp(name, ".", 1) == 0) { + name += namelen; + goto nextname; + } + + // error on unmatched '..', trying to go above root? + if (namelen == 2 && memcmp(name, "..", 2) == 0) { + return LFS_ERR_INVAL; + } + + // skip if matched by '..' in name + const char *suffix = name + namelen; + lfs_size_t sufflen; + int depth = 1; + while (true) { + suffix += strspn(suffix, "/"); + sufflen = (lfs_size_t)strcspn(suffix, "/"); + if (sufflen == 0) { + break; + } + + if (sufflen == 1 && memcmp(suffix, ".", 1) == 0) { + // noop + } else if (sufflen == 2 && memcmp(suffix, "..", 2) == 0) { + depth -= 1; + if (depth == 0) { + name = suffix + sufflen; + goto nextname; + } + } else { + depth += 1; + } + + suffix += sufflen; + } + + // found path + if (*name == '\0') { + return tag; + } + + // update what we've found so far + *path = name; + + // only continue if we're a directory + if (lfs_tag_type3(tag) != LFS_TYPE_DIR) { + return LFS_ERR_NOTDIR; + } + + // grab the entry data + if (lfs_tag_id(tag) != 0x3ff) { + lfs_stag_t res = lfs_dir_get(lfs, dir, LFS_MKTAG(0x700, 0x3ff, 0), + LFS_MKTAG(LFS_TYPE_STRUCT, lfs_tag_id(tag), 8), dir->tail); + if (res < 0) { + return res; + } + lfs_pair_fromle32(dir->tail); + } + + // find entry matching name + while (true) { + tag = lfs_dir_fetchmatch(lfs, dir, dir->tail, + LFS_MKTAG(0x780, 0, 0), + LFS_MKTAG(LFS_TYPE_NAME, 0, namelen), + id, + lfs_dir_find_match, &(struct lfs_dir_find_match){ + lfs, name, namelen}); + if (tag < 0) { + return tag; + } + + if (tag) { + break; + } + + if (!dir->split) { + return LFS_ERR_NOENT; + } + } + + // to next name + name += namelen; + } +} + +// commit logic +struct lfs_commit { + lfs_block_t block; + lfs_off_t off; + lfs_tag_t ptag; + uint32_t crc; + + lfs_off_t begin; + lfs_off_t end; +}; + +#ifndef LFS_READONLY +static int lfs_dir_commitprog(lfs_t *lfs, struct lfs_commit *commit, + const void *buffer, lfs_size_t size) { + int err = lfs_bd_prog(lfs, + &lfs->pcache, &lfs->rcache, false, + commit->block, commit->off , + (const uint8_t*)buffer, size); + if (err) { + return err; + } + + commit->crc = lfs_crc(commit->crc, buffer, size); + commit->off += size; + return 0; +} +#endif + +#ifndef LFS_READONLY +static int lfs_dir_commitattr(lfs_t *lfs, struct lfs_commit *commit, + lfs_tag_t tag, const void *buffer) { + // check if we fit + lfs_size_t dsize = lfs_tag_dsize(tag); + if (commit->off + dsize > commit->end) { + return LFS_ERR_NOSPC; + } + + // write out tag + lfs_tag_t ntag = lfs_tobe32((tag & 0x7fffffff) ^ commit->ptag); + int err = lfs_dir_commitprog(lfs, commit, &ntag, sizeof(ntag)); + if (err) { + return err; + } + + if (!(tag & 0x80000000)) { + // from memory + err = lfs_dir_commitprog(lfs, commit, buffer, dsize-sizeof(tag)); + if (err) { + return err; + } + } else { + // from disk + const struct lfs_diskoff *disk = buffer; + for (lfs_off_t i = 0; i < dsize-sizeof(tag); i++) { + // rely on caching to make this efficient + uint8_t dat; + err = lfs_bd_read(lfs, + NULL, &lfs->rcache, dsize-sizeof(tag)-i, + disk->block, disk->off+i, &dat, 1); + if (err) { + return err; + } + + err = lfs_dir_commitprog(lfs, commit, &dat, 1); + if (err) { + return err; + } + } + } + + commit->ptag = tag & 0x7fffffff; + return 0; +} +#endif + +#ifndef LFS_READONLY + +static int lfs_dir_commitcrc(lfs_t *lfs, struct lfs_commit *commit) { + // align to program units + // + // this gets a bit complex as we have two types of crcs: + // - 5-word crc with fcrc to check following prog (middle of block) + // - 2-word crc with no following prog (end of block) + const lfs_off_t end = lfs_alignup( + lfs_min(commit->off + 5*sizeof(uint32_t), lfs->cfg->block_size), + lfs->cfg->prog_size); + + lfs_off_t off1 = 0; + uint32_t crc1 = 0; + + // create crc tags to fill up remainder of commit, note that + // padding is not crced, which lets fetches skip padding but + // makes committing a bit more complicated + while (commit->off < end) { + lfs_off_t noff = ( + lfs_min(end - (commit->off+sizeof(lfs_tag_t)), 0x3fe) + + (commit->off+sizeof(lfs_tag_t))); + // too large for crc tag? need padding commits + if (noff < end) { + noff = lfs_min(noff, end - 5*sizeof(uint32_t)); + } + + // space for fcrc? + uint8_t eperturb = (uint8_t)-1; + if (noff >= end && noff <= lfs->cfg->block_size - lfs->cfg->prog_size) { + // first read the leading byte, this always contains a bit + // we can perturb to avoid writes that don't change the fcrc + int err = lfs_bd_read(lfs, + NULL, &lfs->rcache, lfs->cfg->prog_size, + commit->block, noff, &eperturb, 1); + if (err && err != LFS_ERR_CORRUPT) { + return err; + } + + #ifdef LFS_MULTIVERSION + // unfortunately fcrcs break mdir fetching < lfs2.1, so only write + // these if we're a >= lfs2.1 filesystem + if (lfs_fs_disk_version(lfs) <= 0x00020000) { + // don't write fcrc + } else + #endif + { + // find the expected fcrc, don't bother avoiding a reread + // of the eperturb, it should still be in our cache + struct lfs_fcrc fcrc = { + .size = lfs->cfg->prog_size, + .crc = 0xffffffff + }; + err = lfs_bd_crc(lfs, + NULL, &lfs->rcache, lfs->cfg->prog_size, + commit->block, noff, fcrc.size, &fcrc.crc); + if (err && err != LFS_ERR_CORRUPT) { + return err; + } + + lfs_fcrc_tole32(&fcrc); + err = lfs_dir_commitattr(lfs, commit, + LFS_MKTAG(LFS_TYPE_FCRC, 0x3ff, sizeof(struct lfs_fcrc)), + &fcrc); + if (err) { + return err; + } + } + } + + // build commit crc + struct { + lfs_tag_t tag; + uint32_t crc; + } ccrc; + lfs_tag_t ntag = LFS_MKTAG( + LFS_TYPE_CCRC + (((uint8_t)~eperturb) >> 7), 0x3ff, + noff - (commit->off+sizeof(lfs_tag_t))); + ccrc.tag = lfs_tobe32(ntag ^ commit->ptag); + commit->crc = lfs_crc(commit->crc, &ccrc.tag, sizeof(lfs_tag_t)); + ccrc.crc = lfs_tole32(commit->crc); + + int err = lfs_bd_prog(lfs, + &lfs->pcache, &lfs->rcache, false, + commit->block, commit->off, &ccrc, sizeof(ccrc)); + if (err) { + return err; + } + + // keep track of non-padding checksum to verify + if (off1 == 0) { + off1 = commit->off + sizeof(lfs_tag_t); + crc1 = commit->crc; + } + + commit->off = noff; + // perturb valid bit? + commit->ptag = ntag ^ ((lfs_tag_t)(0x80 & ~eperturb) << 24); + // reset crc for next commit + commit->crc = 0xffffffff; + + // manually flush here since we don't prog the padding, this confuses + // the caching layer + if (noff >= end || noff >= lfs->pcache.off + lfs->cfg->cache_size) { + // flush buffers + int err = lfs_bd_sync(lfs, &lfs->pcache, &lfs->rcache, false); + if (err) { + return err; + } + } + } + + // successful commit, check checksums to make sure + // + // note that we don't need to check padding commits, worst + // case if they are corrupted we would have had to compact anyways + lfs_off_t off = commit->begin; + uint32_t crc = 0xffffffff; + int err = lfs_bd_crc(lfs, + NULL, &lfs->rcache, off1+sizeof(uint32_t), + commit->block, off, off1-off, &crc); + if (err) { + return err; + } + + // check non-padding commits against known crc + if (crc != crc1) { + return LFS_ERR_CORRUPT; + } + + // make sure to check crc in case we happen to pick + // up an unrelated crc (frozen block?) + err = lfs_bd_crc(lfs, + NULL, &lfs->rcache, sizeof(uint32_t), + commit->block, off1, sizeof(uint32_t), &crc); + if (err) { + return err; + } + + if (crc != 0) { + return LFS_ERR_CORRUPT; + } + + return 0; +} +#endif + +#ifndef LFS_READONLY +static int lfs_dir_alloc(lfs_t *lfs, lfs_mdir_t *dir) { + // allocate pair of dir blocks (backwards, so we write block 1 first) + for (int i = 0; i < 2; i++) { + int err = lfs_alloc(lfs, &dir->pair[(i+1)%2]); + if (err) { + return err; + } + } + + // zero for reproducibility in case initial block is unreadable + dir->rev = 0; + + // rather than clobbering one of the blocks we just pretend + // the revision may be valid + int err = lfs_bd_read(lfs, + NULL, &lfs->rcache, sizeof(dir->rev), + dir->pair[0], 0, &dir->rev, sizeof(dir->rev)); + dir->rev = lfs_fromle32(dir->rev); + if (err && err != LFS_ERR_CORRUPT) { + return err; + } + + // to make sure we don't immediately evict, align the new revision count + // to our block_cycles modulus, see lfs_dir_compact for why our modulus + // is tweaked this way + if (lfs->cfg->block_cycles > 0) { + dir->rev = lfs_alignup(dir->rev, ((lfs->cfg->block_cycles+1)|1)); + } + + // set defaults + dir->off = sizeof(dir->rev); + dir->etag = 0xffffffff; + dir->count = 0; + dir->tail[0] = LFS_BLOCK_NULL; + dir->tail[1] = LFS_BLOCK_NULL; + dir->erased = false; + dir->split = false; + + // don't write out yet, let caller take care of that + return 0; +} +#endif + +#ifndef LFS_READONLY +static int lfs_dir_drop(lfs_t *lfs, lfs_mdir_t *dir, lfs_mdir_t *tail) { + // steal state + int err = lfs_dir_getgstate(lfs, tail, &lfs->gdelta); + if (err) { + return err; + } + + // steal tail + lfs_pair_tole32(tail->tail); + err = lfs_dir_commit(lfs, dir, LFS_MKATTRS( + {LFS_MKTAG(LFS_TYPE_TAIL + tail->split, 0x3ff, 8), tail->tail})); + lfs_pair_fromle32(tail->tail); + if (err) { + return err; + } + + return 0; +} +#endif + +#ifndef LFS_READONLY +static int lfs_dir_split(lfs_t *lfs, + lfs_mdir_t *dir, const struct lfs_mattr *attrs, int attrcount, + lfs_mdir_t *source, uint16_t split, uint16_t end) { + // create tail metadata pair + lfs_mdir_t tail; + int err = lfs_dir_alloc(lfs, &tail); + if (err) { + return err; + } + + tail.split = dir->split; + tail.tail[0] = dir->tail[0]; + tail.tail[1] = dir->tail[1]; + + // note we don't care about LFS_OK_RELOCATED + int res = lfs_dir_compact(lfs, &tail, attrs, attrcount, source, split, end); + if (res < 0) { + return res; + } + + dir->tail[0] = tail.pair[0]; + dir->tail[1] = tail.pair[1]; + dir->split = true; + + // update root if needed + if (lfs_pair_cmp(dir->pair, lfs->root) == 0 && split == 0) { + lfs->root[0] = tail.pair[0]; + lfs->root[1] = tail.pair[1]; + } + + return 0; +} +#endif + +#ifndef LFS_READONLY +static int lfs_dir_commit_size(void *p, lfs_tag_t tag, const void *buffer) { + lfs_size_t *size = p; + (void)buffer; + + *size += lfs_tag_dsize(tag); + return 0; +} +#endif + +#ifndef LFS_READONLY +struct lfs_dir_commit_commit { + lfs_t *lfs; + struct lfs_commit *commit; +}; +#endif + +#ifndef LFS_READONLY +static int lfs_dir_commit_commit(void *p, lfs_tag_t tag, const void *buffer) { + struct lfs_dir_commit_commit *commit = p; + return lfs_dir_commitattr(commit->lfs, commit->commit, tag, buffer); +} +#endif + +#ifndef LFS_READONLY +static bool lfs_dir_needsrelocation(lfs_t *lfs, lfs_mdir_t *dir) { + // If our revision count == n * block_cycles, we should force a relocation, + // this is how littlefs wear-levels at the metadata-pair level. Note that we + // actually use (block_cycles+1)|1, this is to avoid two corner cases: + // 1. block_cycles = 1, which would prevent relocations from terminating + // 2. block_cycles = 2n, which, due to aliasing, would only ever relocate + // one metadata block in the pair, effectively making this useless + return (lfs->cfg->block_cycles > 0 + && ((dir->rev + 1) % ((lfs->cfg->block_cycles+1)|1) == 0)); +} +#endif + +#ifndef LFS_READONLY +static int lfs_dir_compact(lfs_t *lfs, + lfs_mdir_t *dir, const struct lfs_mattr *attrs, int attrcount, + lfs_mdir_t *source, uint16_t begin, uint16_t end) { + // save some state in case block is bad + bool relocated = false; + bool tired = lfs_dir_needsrelocation(lfs, dir); + + // increment revision count + dir->rev += 1; + + // do not proactively relocate blocks during migrations, this + // can cause a number of failure states such: clobbering the + // v1 superblock if we relocate root, and invalidating directory + // pointers if we relocate the head of a directory. On top of + // this, relocations increase the overall complexity of + // lfs_migration, which is already a delicate operation. +#ifdef LFS_MIGRATE + if (lfs->lfs1) { + tired = false; + } +#endif + + if (tired && lfs_pair_cmp(dir->pair, (const lfs_block_t[2]){0, 1}) != 0) { + // we're writing too much, time to relocate + goto relocate; + } + + // begin loop to commit compaction to blocks until a compact sticks + while (true) { + { + // setup commit state + struct lfs_commit commit = { + .block = dir->pair[1], + .off = 0, + .ptag = 0xffffffff, + .crc = 0xffffffff, + + .begin = 0, + .end = (lfs->cfg->metadata_max ? + lfs->cfg->metadata_max : lfs->cfg->block_size) - 8, + }; + + // erase block to write to + int err = lfs_bd_erase(lfs, dir->pair[1]); + if (err) { + if (err == LFS_ERR_CORRUPT) { + goto relocate; + } + return err; + } + + // write out header + dir->rev = lfs_tole32(dir->rev); + err = lfs_dir_commitprog(lfs, &commit, + &dir->rev, sizeof(dir->rev)); + dir->rev = lfs_fromle32(dir->rev); + if (err) { + if (err == LFS_ERR_CORRUPT) { + goto relocate; + } + return err; + } + + // traverse the directory, this time writing out all unique tags + err = lfs_dir_traverse(lfs, + source, 0, 0xffffffff, attrs, attrcount, + LFS_MKTAG(0x400, 0x3ff, 0), + LFS_MKTAG(LFS_TYPE_NAME, 0, 0), + begin, end, -begin, + lfs_dir_commit_commit, &(struct lfs_dir_commit_commit){ + lfs, &commit}); + if (err) { + if (err == LFS_ERR_CORRUPT) { + goto relocate; + } + return err; + } + + // commit tail, which may be new after last size check + if (!lfs_pair_isnull(dir->tail)) { + lfs_pair_tole32(dir->tail); + err = lfs_dir_commitattr(lfs, &commit, + LFS_MKTAG(LFS_TYPE_TAIL + dir->split, 0x3ff, 8), + dir->tail); + lfs_pair_fromle32(dir->tail); + if (err) { + if (err == LFS_ERR_CORRUPT) { + goto relocate; + } + return err; + } + } + + // bring over gstate? + lfs_gstate_t delta = {0}; + if (!relocated) { + lfs_gstate_xor(&delta, &lfs->gdisk); + lfs_gstate_xor(&delta, &lfs->gstate); + } + lfs_gstate_xor(&delta, &lfs->gdelta); + delta.tag &= ~LFS_MKTAG(0, 0, 0x3ff); + + err = lfs_dir_getgstate(lfs, dir, &delta); + if (err) { + return err; + } + + if (!lfs_gstate_iszero(&delta)) { + lfs_gstate_tole32(&delta); + err = lfs_dir_commitattr(lfs, &commit, + LFS_MKTAG(LFS_TYPE_MOVESTATE, 0x3ff, + sizeof(delta)), &delta); + if (err) { + if (err == LFS_ERR_CORRUPT) { + goto relocate; + } + return err; + } + } + + // complete commit with crc + err = lfs_dir_commitcrc(lfs, &commit); + if (err) { + if (err == LFS_ERR_CORRUPT) { + goto relocate; + } + return err; + } + + // successful compaction, swap dir pair to indicate most recent + LFS_ASSERT(commit.off % lfs->cfg->prog_size == 0); + lfs_pair_swap(dir->pair); + dir->count = end - begin; + dir->off = commit.off; + dir->etag = commit.ptag; + // update gstate + lfs->gdelta = (lfs_gstate_t){0}; + if (!relocated) { + lfs->gdisk = lfs->gstate; + } + } + break; + +relocate: + // commit was corrupted, drop caches and prepare to relocate block + relocated = true; + lfs_cache_drop(lfs, &lfs->pcache); + if (!tired) { + LFS_DEBUG("Bad block at 0x%"PRIx32, dir->pair[1]); + } + + // can't relocate superblock, filesystem is now frozen + if (lfs_pair_cmp(dir->pair, (const lfs_block_t[2]){0, 1}) == 0) { + LFS_WARN("Superblock 0x%"PRIx32" has become unwritable", + dir->pair[1]); + return LFS_ERR_NOSPC; + } + + // relocate half of pair + int err = lfs_alloc(lfs, &dir->pair[1]); + if (err && (err != LFS_ERR_NOSPC || !tired)) { + return err; + } + + tired = false; + continue; + } + + return relocated ? LFS_OK_RELOCATED : 0; +} +#endif + +#ifndef LFS_READONLY +static int lfs_dir_splittingcompact(lfs_t *lfs, lfs_mdir_t *dir, + const struct lfs_mattr *attrs, int attrcount, + lfs_mdir_t *source, uint16_t begin, uint16_t end) { + while (true) { + // find size of first split, we do this by halving the split until + // the metadata is guaranteed to fit + // + // Note that this isn't a true binary search, we never increase the + // split size. This may result in poorly distributed metadata but isn't + // worth the extra code size or performance hit to fix. + lfs_size_t split = begin; + while (end - split > 1) { + lfs_size_t size = 0; + int err = lfs_dir_traverse(lfs, + source, 0, 0xffffffff, attrs, attrcount, + LFS_MKTAG(0x400, 0x3ff, 0), + LFS_MKTAG(LFS_TYPE_NAME, 0, 0), + split, end, -split, + lfs_dir_commit_size, &size); + if (err) { + return err; + } + + // space is complicated, we need room for: + // + // - tail: 4+2*4 = 12 bytes + // - gstate: 4+3*4 = 16 bytes + // - move delete: 4 = 4 bytes + // - crc: 4+4 = 8 bytes + // total = 40 bytes + // + // And we cap at half a block to avoid degenerate cases with + // nearly-full metadata blocks. + // + lfs_size_t metadata_max = (lfs->cfg->metadata_max) + ? lfs->cfg->metadata_max + : lfs->cfg->block_size; + if (end - split < 0xff + && size <= lfs_min( + metadata_max - 40, + lfs_alignup( + metadata_max/2, + lfs->cfg->prog_size))) { + break; + } + + split = split + ((end - split) / 2); + } + + if (split == begin) { + // no split needed + break; + } + + // split into two metadata pairs and continue + int err = lfs_dir_split(lfs, dir, attrs, attrcount, + source, split, end); + if (err && err != LFS_ERR_NOSPC) { + return err; + } + + if (err) { + // we can't allocate a new block, try to compact with degraded + // performance + LFS_WARN("Unable to split {0x%"PRIx32", 0x%"PRIx32"}", + dir->pair[0], dir->pair[1]); + break; + } else { + end = split; + } + } + + if (lfs_dir_needsrelocation(lfs, dir) + && lfs_pair_cmp(dir->pair, (const lfs_block_t[2]){0, 1}) == 0) { + // oh no! we're writing too much to the superblock, + // should we expand? + lfs_ssize_t size = lfs_fs_size_(lfs); + if (size < 0) { + return size; + } + + // littlefs cannot reclaim expanded superblocks, so expand cautiously + // + // if our filesystem is more than ~88% full, don't expand, this is + // somewhat arbitrary + if (lfs->block_count - size > lfs->block_count/8) { + LFS_DEBUG("Expanding superblock at rev %"PRIu32, dir->rev); + int err = lfs_dir_split(lfs, dir, attrs, attrcount, + source, begin, end); + if (err && err != LFS_ERR_NOSPC) { + return err; + } + + if (err) { + // welp, we tried, if we ran out of space there's not much + // we can do, we'll error later if we've become frozen + LFS_WARN("Unable to expand superblock"); + } else { + // duplicate the superblock entry into the new superblock + end = 1; + } + } + } + + return lfs_dir_compact(lfs, dir, attrs, attrcount, source, begin, end); +} +#endif + +#ifndef LFS_READONLY +static int lfs_dir_relocatingcommit(lfs_t *lfs, lfs_mdir_t *dir, + const lfs_block_t pair[2], + const struct lfs_mattr *attrs, int attrcount, + lfs_mdir_t *pdir) { + int state = 0; + + // calculate changes to the directory + bool hasdelete = false; + for (int i = 0; i < attrcount; i++) { + if (lfs_tag_type3(attrs[i].tag) == LFS_TYPE_CREATE) { + dir->count += 1; + } else if (lfs_tag_type3(attrs[i].tag) == LFS_TYPE_DELETE) { + LFS_ASSERT(dir->count > 0); + dir->count -= 1; + hasdelete = true; + } else if (lfs_tag_type1(attrs[i].tag) == LFS_TYPE_TAIL) { + dir->tail[0] = ((lfs_block_t*)attrs[i].buffer)[0]; + dir->tail[1] = ((lfs_block_t*)attrs[i].buffer)[1]; + dir->split = (lfs_tag_chunk(attrs[i].tag) & 1); + lfs_pair_fromle32(dir->tail); + } + } + + // should we actually drop the directory block? + if (hasdelete && dir->count == 0) { + LFS_ASSERT(pdir); + int err = lfs_fs_pred(lfs, dir->pair, pdir); + if (err && err != LFS_ERR_NOENT) { + return err; + } + + if (err != LFS_ERR_NOENT && pdir->split) { + state = LFS_OK_DROPPED; + goto fixmlist; + } + } + + if (dir->erased && dir->count < 0xff) { + // try to commit + struct lfs_commit commit = { + .block = dir->pair[0], + .off = dir->off, + .ptag = dir->etag, + .crc = 0xffffffff, + + .begin = dir->off, + .end = (lfs->cfg->metadata_max ? + lfs->cfg->metadata_max : lfs->cfg->block_size) - 8, + }; + + // traverse attrs that need to be written out + lfs_pair_tole32(dir->tail); + int err = lfs_dir_traverse(lfs, + dir, dir->off, dir->etag, attrs, attrcount, + 0, 0, 0, 0, 0, + lfs_dir_commit_commit, &(struct lfs_dir_commit_commit){ + lfs, &commit}); + lfs_pair_fromle32(dir->tail); + if (err) { + if (err == LFS_ERR_NOSPC || err == LFS_ERR_CORRUPT) { + goto compact; + } + return err; + } + + // commit any global diffs if we have any + lfs_gstate_t delta = {0}; + lfs_gstate_xor(&delta, &lfs->gstate); + lfs_gstate_xor(&delta, &lfs->gdisk); + lfs_gstate_xor(&delta, &lfs->gdelta); + delta.tag &= ~LFS_MKTAG(0, 0, 0x3ff); + if (!lfs_gstate_iszero(&delta)) { + err = lfs_dir_getgstate(lfs, dir, &delta); + if (err) { + return err; + } + + lfs_gstate_tole32(&delta); + err = lfs_dir_commitattr(lfs, &commit, + LFS_MKTAG(LFS_TYPE_MOVESTATE, 0x3ff, + sizeof(delta)), &delta); + if (err) { + if (err == LFS_ERR_NOSPC || err == LFS_ERR_CORRUPT) { + goto compact; + } + return err; + } + } + + // finalize commit with the crc + err = lfs_dir_commitcrc(lfs, &commit); + if (err) { + if (err == LFS_ERR_NOSPC || err == LFS_ERR_CORRUPT) { + goto compact; + } + return err; + } + + // successful commit, update dir + LFS_ASSERT(commit.off % lfs->cfg->prog_size == 0); + dir->off = commit.off; + dir->etag = commit.ptag; + // and update gstate + lfs->gdisk = lfs->gstate; + lfs->gdelta = (lfs_gstate_t){0}; + + goto fixmlist; + } + +compact: + // fall back to compaction + lfs_cache_drop(lfs, &lfs->pcache); + + state = lfs_dir_splittingcompact(lfs, dir, attrs, attrcount, + dir, 0, dir->count); + if (state < 0) { + return state; + } + + goto fixmlist; + +fixmlist:; + // this complicated bit of logic is for fixing up any active + // metadata-pairs that we may have affected + // + // note we have to make two passes since the mdir passed to + // lfs_dir_commit could also be in this list, and even then + // we need to copy the pair so they don't get clobbered if we refetch + // our mdir. + lfs_block_t oldpair[2] = {pair[0], pair[1]}; + for (struct lfs_mlist *d = lfs->mlist; d; d = d->next) { + if (lfs_pair_cmp(d->m.pair, oldpair) == 0) { + d->m = *dir; + if (d->m.pair != pair) { + for (int i = 0; i < attrcount; i++) { + if (lfs_tag_type3(attrs[i].tag) == LFS_TYPE_DELETE && + d->id == lfs_tag_id(attrs[i].tag) && + d->type != LFS_TYPE_DIR) { + d->m.pair[0] = LFS_BLOCK_NULL; + d->m.pair[1] = LFS_BLOCK_NULL; + } else if (lfs_tag_type3(attrs[i].tag) == LFS_TYPE_DELETE && + d->id > lfs_tag_id(attrs[i].tag)) { + d->id -= 1; + if (d->type == LFS_TYPE_DIR) { + ((lfs_dir_t*)d)->pos -= 1; + } + } else if (lfs_tag_type3(attrs[i].tag) == LFS_TYPE_CREATE && + d->id >= lfs_tag_id(attrs[i].tag)) { + d->id += 1; + if (d->type == LFS_TYPE_DIR) { + ((lfs_dir_t*)d)->pos += 1; + } + } + } + } + + while (d->id >= d->m.count && d->m.split) { + // we split and id is on tail now + if (lfs_pair_cmp(d->m.tail, lfs->root) != 0) { + d->id -= d->m.count; + } + int err = lfs_dir_fetch(lfs, &d->m, d->m.tail); + if (err) { + return err; + } + } + } + } + + return state; +} +#endif + +#ifndef LFS_READONLY +static int lfs_dir_orphaningcommit(lfs_t *lfs, lfs_mdir_t *dir, + const struct lfs_mattr *attrs, int attrcount) { + // check for any inline files that aren't RAM backed and + // forcefully evict them, needed for filesystem consistency + for (lfs_file_t *f = (lfs_file_t*)lfs->mlist; f; f = f->next) { + if (dir != &f->m && lfs_pair_cmp(f->m.pair, dir->pair) == 0 && + f->type == LFS_TYPE_REG && (f->flags & LFS_F_INLINE) && + f->ctz.size > lfs->cfg->cache_size) { + int err = lfs_file_outline(lfs, f); + if (err) { + return err; + } + + err = lfs_file_flush(lfs, f); + if (err) { + return err; + } + } + } + + lfs_block_t lpair[2] = {dir->pair[0], dir->pair[1]}; + lfs_mdir_t ldir = *dir; + lfs_mdir_t pdir; + int state = lfs_dir_relocatingcommit(lfs, &ldir, dir->pair, + attrs, attrcount, &pdir); + if (state < 0) { + return state; + } + + // update if we're not in mlist, note we may have already been + // updated if we are in mlist + if (lfs_pair_cmp(dir->pair, lpair) == 0) { + *dir = ldir; + } + + // commit was successful, but may require other changes in the + // filesystem, these would normally be tail recursive, but we have + // flattened them here avoid unbounded stack usage + + // need to drop? + if (state == LFS_OK_DROPPED) { + // steal state + int err = lfs_dir_getgstate(lfs, dir, &lfs->gdelta); + if (err) { + return err; + } + + // steal tail, note that this can't create a recursive drop + lpair[0] = pdir.pair[0]; + lpair[1] = pdir.pair[1]; + lfs_pair_tole32(dir->tail); + state = lfs_dir_relocatingcommit(lfs, &pdir, lpair, LFS_MKATTRS( + {LFS_MKTAG(LFS_TYPE_TAIL + dir->split, 0x3ff, 8), + dir->tail}), + NULL); + lfs_pair_fromle32(dir->tail); + if (state < 0) { + return state; + } + + ldir = pdir; + } + + // need to relocate? + bool orphans = false; + while (state == LFS_OK_RELOCATED) { + LFS_DEBUG("Relocating {0x%"PRIx32", 0x%"PRIx32"} " + "-> {0x%"PRIx32", 0x%"PRIx32"}", + lpair[0], lpair[1], ldir.pair[0], ldir.pair[1]); + state = 0; + + // update internal root + if (lfs_pair_cmp(lpair, lfs->root) == 0) { + lfs->root[0] = ldir.pair[0]; + lfs->root[1] = ldir.pair[1]; + } + + // update internally tracked dirs + for (struct lfs_mlist *d = lfs->mlist; d; d = d->next) { + if (lfs_pair_cmp(lpair, d->m.pair) == 0) { + d->m.pair[0] = ldir.pair[0]; + d->m.pair[1] = ldir.pair[1]; + } + + if (d->type == LFS_TYPE_DIR && + lfs_pair_cmp(lpair, ((lfs_dir_t*)d)->head) == 0) { + ((lfs_dir_t*)d)->head[0] = ldir.pair[0]; + ((lfs_dir_t*)d)->head[1] = ldir.pair[1]; + } + } + + // find parent + lfs_stag_t tag = lfs_fs_parent(lfs, lpair, &pdir); + if (tag < 0 && tag != LFS_ERR_NOENT) { + return tag; + } + + bool hasparent = (tag != LFS_ERR_NOENT); + if (tag != LFS_ERR_NOENT) { + // note that if we have a parent, we must have a pred, so this will + // always create an orphan + int err = lfs_fs_preporphans(lfs, +1); + if (err) { + return err; + } + + // fix pending move in this pair? this looks like an optimization but + // is in fact _required_ since relocating may outdate the move. + uint16_t moveid = 0x3ff; + if (lfs_gstate_hasmovehere(&lfs->gstate, pdir.pair)) { + moveid = lfs_tag_id(lfs->gstate.tag); + LFS_DEBUG("Fixing move while relocating " + "{0x%"PRIx32", 0x%"PRIx32"} 0x%"PRIx16"\n", + pdir.pair[0], pdir.pair[1], moveid); + lfs_fs_prepmove(lfs, 0x3ff, NULL); + if (moveid < lfs_tag_id(tag)) { + tag -= LFS_MKTAG(0, 1, 0); + } + } + + lfs_block_t ppair[2] = {pdir.pair[0], pdir.pair[1]}; + lfs_pair_tole32(ldir.pair); + state = lfs_dir_relocatingcommit(lfs, &pdir, ppair, LFS_MKATTRS( + {LFS_MKTAG_IF(moveid != 0x3ff, + LFS_TYPE_DELETE, moveid, 0), NULL}, + {tag, ldir.pair}), + NULL); + lfs_pair_fromle32(ldir.pair); + if (state < 0) { + return state; + } + + if (state == LFS_OK_RELOCATED) { + lpair[0] = ppair[0]; + lpair[1] = ppair[1]; + ldir = pdir; + orphans = true; + continue; + } + } + + // find pred + int err = lfs_fs_pred(lfs, lpair, &pdir); + if (err && err != LFS_ERR_NOENT) { + return err; + } + LFS_ASSERT(!(hasparent && err == LFS_ERR_NOENT)); + + // if we can't find dir, it must be new + if (err != LFS_ERR_NOENT) { + if (lfs_gstate_hasorphans(&lfs->gstate)) { + // next step, clean up orphans + err = lfs_fs_preporphans(lfs, -(int8_t)hasparent); + if (err) { + return err; + } + } + + // fix pending move in this pair? this looks like an optimization + // but is in fact _required_ since relocating may outdate the move. + uint16_t moveid = 0x3ff; + if (lfs_gstate_hasmovehere(&lfs->gstate, pdir.pair)) { + moveid = lfs_tag_id(lfs->gstate.tag); + LFS_DEBUG("Fixing move while relocating " + "{0x%"PRIx32", 0x%"PRIx32"} 0x%"PRIx16"\n", + pdir.pair[0], pdir.pair[1], moveid); + lfs_fs_prepmove(lfs, 0x3ff, NULL); + } + + // replace bad pair, either we clean up desync, or no desync occured + lpair[0] = pdir.pair[0]; + lpair[1] = pdir.pair[1]; + lfs_pair_tole32(ldir.pair); + state = lfs_dir_relocatingcommit(lfs, &pdir, lpair, LFS_MKATTRS( + {LFS_MKTAG_IF(moveid != 0x3ff, + LFS_TYPE_DELETE, moveid, 0), NULL}, + {LFS_MKTAG(LFS_TYPE_TAIL + pdir.split, 0x3ff, 8), + ldir.pair}), + NULL); + lfs_pair_fromle32(ldir.pair); + if (state < 0) { + return state; + } + + ldir = pdir; + } + } + + return orphans ? LFS_OK_ORPHANED : 0; +} +#endif + +#ifndef LFS_READONLY +static int lfs_dir_commit(lfs_t *lfs, lfs_mdir_t *dir, + const struct lfs_mattr *attrs, int attrcount) { + int orphans = lfs_dir_orphaningcommit(lfs, dir, attrs, attrcount); + if (orphans < 0) { + return orphans; + } + + if (orphans) { + // make sure we've removed all orphans, this is a noop if there + // are none, but if we had nested blocks failures we may have + // created some + int err = lfs_fs_deorphan(lfs, false); + if (err) { + return err; + } + } + + return 0; +} +#endif + + +/// Top level directory operations /// +#ifndef LFS_READONLY +static int lfs_mkdir_(lfs_t *lfs, const char *path) { + // deorphan if we haven't yet, needed at most once after poweron + int err = lfs_fs_forceconsistency(lfs); + if (err) { + return err; + } + + struct lfs_mlist cwd; + cwd.next = lfs->mlist; + uint16_t id; + err = lfs_dir_find(lfs, &cwd.m, &path, &id); + if (!(err == LFS_ERR_NOENT && lfs_path_islast(path))) { + return (err < 0) ? err : LFS_ERR_EXIST; + } + + // check that name fits + lfs_size_t nlen = lfs_path_namelen(path); + if (nlen > lfs->name_max) { + return LFS_ERR_NAMETOOLONG; + } + + // build up new directory + lfs_alloc_ckpoint(lfs); + lfs_mdir_t dir; + err = lfs_dir_alloc(lfs, &dir); + if (err) { + return err; + } + + // find end of list + lfs_mdir_t pred = cwd.m; + while (pred.split) { + err = lfs_dir_fetch(lfs, &pred, pred.tail); + if (err) { + return err; + } + } + + // setup dir + lfs_pair_tole32(pred.tail); + err = lfs_dir_commit(lfs, &dir, LFS_MKATTRS( + {LFS_MKTAG(LFS_TYPE_SOFTTAIL, 0x3ff, 8), pred.tail})); + lfs_pair_fromle32(pred.tail); + if (err) { + return err; + } + + // current block not end of list? + if (cwd.m.split) { + // update tails, this creates a desync + err = lfs_fs_preporphans(lfs, +1); + if (err) { + return err; + } + + // it's possible our predecessor has to be relocated, and if + // our parent is our predecessor's predecessor, this could have + // caused our parent to go out of date, fortunately we can hook + // ourselves into littlefs to catch this + cwd.type = 0; + cwd.id = 0; + lfs->mlist = &cwd; + + lfs_pair_tole32(dir.pair); + err = lfs_dir_commit(lfs, &pred, LFS_MKATTRS( + {LFS_MKTAG(LFS_TYPE_SOFTTAIL, 0x3ff, 8), dir.pair})); + lfs_pair_fromle32(dir.pair); + if (err) { + lfs->mlist = cwd.next; + return err; + } + + lfs->mlist = cwd.next; + err = lfs_fs_preporphans(lfs, -1); + if (err) { + return err; + } + } + + // now insert into our parent block + lfs_pair_tole32(dir.pair); + err = lfs_dir_commit(lfs, &cwd.m, LFS_MKATTRS( + {LFS_MKTAG(LFS_TYPE_CREATE, id, 0), NULL}, + {LFS_MKTAG(LFS_TYPE_DIR, id, nlen), path}, + {LFS_MKTAG(LFS_TYPE_DIRSTRUCT, id, 8), dir.pair}, + {LFS_MKTAG_IF(!cwd.m.split, + LFS_TYPE_SOFTTAIL, 0x3ff, 8), dir.pair})); + lfs_pair_fromle32(dir.pair); + if (err) { + return err; + } + + return 0; +} +#endif + +static int lfs_dir_open_(lfs_t *lfs, lfs_dir_t *dir, const char *path) { + lfs_stag_t tag = lfs_dir_find(lfs, &dir->m, &path, NULL); + if (tag < 0) { + return tag; + } + + if (lfs_tag_type3(tag) != LFS_TYPE_DIR) { + return LFS_ERR_NOTDIR; + } + + lfs_block_t pair[2]; + if (lfs_tag_id(tag) == 0x3ff) { + // handle root dir separately + pair[0] = lfs->root[0]; + pair[1] = lfs->root[1]; + } else { + // get dir pair from parent + lfs_stag_t res = lfs_dir_get(lfs, &dir->m, LFS_MKTAG(0x700, 0x3ff, 0), + LFS_MKTAG(LFS_TYPE_STRUCT, lfs_tag_id(tag), 8), pair); + if (res < 0) { + return res; + } + lfs_pair_fromle32(pair); + } + + // fetch first pair + int err = lfs_dir_fetch(lfs, &dir->m, pair); + if (err) { + return err; + } + + // setup entry + dir->head[0] = dir->m.pair[0]; + dir->head[1] = dir->m.pair[1]; + dir->id = 0; + dir->pos = 0; + + // add to list of mdirs + dir->type = LFS_TYPE_DIR; + lfs_mlist_append(lfs, (struct lfs_mlist *)dir); + + return 0; +} + +static int lfs_dir_close_(lfs_t *lfs, lfs_dir_t *dir) { + // remove from list of mdirs + lfs_mlist_remove(lfs, (struct lfs_mlist *)dir); + + return 0; +} + +static int lfs_dir_read_(lfs_t *lfs, lfs_dir_t *dir, struct lfs_info *info) { + memset(info, 0, sizeof(*info)); + + // special offset for '.' and '..' + if (dir->pos == 0) { + info->type = LFS_TYPE_DIR; + strcpy(info->name, "."); + dir->pos += 1; + return true; + } else if (dir->pos == 1) { + info->type = LFS_TYPE_DIR; + strcpy(info->name, ".."); + dir->pos += 1; + return true; + } + + while (true) { + if (dir->id == dir->m.count) { + if (!dir->m.split) { + return false; + } + + int err = lfs_dir_fetch(lfs, &dir->m, dir->m.tail); + if (err) { + return err; + } + + dir->id = 0; + } + + int err = lfs_dir_getinfo(lfs, &dir->m, dir->id, info); + if (err && err != LFS_ERR_NOENT) { + return err; + } + + dir->id += 1; + if (err != LFS_ERR_NOENT) { + break; + } + } + + dir->pos += 1; + return true; +} + +static int lfs_dir_seek_(lfs_t *lfs, lfs_dir_t *dir, lfs_off_t off) { + // simply walk from head dir + int err = lfs_dir_rewind_(lfs, dir); + if (err) { + return err; + } + + // first two for ./.. + dir->pos = lfs_min(2, off); + off -= dir->pos; + + // skip superblock entry + dir->id = (off > 0 && lfs_pair_cmp(dir->head, lfs->root) == 0); + + while (off > 0) { + if (dir->id == dir->m.count) { + if (!dir->m.split) { + return LFS_ERR_INVAL; + } + + err = lfs_dir_fetch(lfs, &dir->m, dir->m.tail); + if (err) { + return err; + } + + dir->id = 0; + } + + int diff = lfs_min(dir->m.count - dir->id, off); + dir->id += diff; + dir->pos += diff; + off -= diff; + } + + return 0; +} + +static lfs_soff_t lfs_dir_tell_(lfs_t *lfs, lfs_dir_t *dir) { + (void)lfs; + return dir->pos; +} + +static int lfs_dir_rewind_(lfs_t *lfs, lfs_dir_t *dir) { + // reload the head dir + int err = lfs_dir_fetch(lfs, &dir->m, dir->head); + if (err) { + return err; + } + + dir->id = 0; + dir->pos = 0; + return 0; +} + + +/// File index list operations /// +static int lfs_ctz_index(lfs_t *lfs, lfs_off_t *off) { + lfs_off_t size = *off; + lfs_off_t b = lfs->cfg->block_size - 2*4; + lfs_off_t i = size / b; + if (i == 0) { + return 0; + } + + i = (size - 4*(lfs_popc(i-1)+2)) / b; + *off = size - b*i - 4*lfs_popc(i); + return i; +} + +static int lfs_ctz_find(lfs_t *lfs, + const lfs_cache_t *pcache, lfs_cache_t *rcache, + lfs_block_t head, lfs_size_t size, + lfs_size_t pos, lfs_block_t *block, lfs_off_t *off) { + if (size == 0) { + *block = LFS_BLOCK_NULL; + *off = 0; + return 0; + } + + lfs_off_t current = lfs_ctz_index(lfs, &(lfs_off_t){size-1}); + lfs_off_t target = lfs_ctz_index(lfs, &pos); + + while (current > target) { + lfs_size_t skip = lfs_min( + lfs_npw2(current-target+1) - 1, + lfs_ctz(current)); + + int err = lfs_bd_read(lfs, + pcache, rcache, sizeof(head), + head, 4*skip, &head, sizeof(head)); + head = lfs_fromle32(head); + if (err) { + return err; + } + + current -= 1 << skip; + } + + *block = head; + *off = pos; + return 0; +} + +#ifndef LFS_READONLY +static int lfs_ctz_extend(lfs_t *lfs, + lfs_cache_t *pcache, lfs_cache_t *rcache, + lfs_block_t head, lfs_size_t size, + lfs_block_t *block, lfs_off_t *off) { + while (true) { + // go ahead and grab a block + lfs_block_t nblock; + int err = lfs_alloc(lfs, &nblock); + if (err) { + return err; + } + + { + err = lfs_bd_erase(lfs, nblock); + if (err) { + if (err == LFS_ERR_CORRUPT) { + goto relocate; + } + return err; + } + + if (size == 0) { + *block = nblock; + *off = 0; + return 0; + } + + lfs_size_t noff = size - 1; + lfs_off_t index = lfs_ctz_index(lfs, &noff); + noff = noff + 1; + + // just copy out the last block if it is incomplete + if (noff != lfs->cfg->block_size) { + for (lfs_off_t i = 0; i < noff; i++) { + uint8_t data; + err = lfs_bd_read(lfs, + NULL, rcache, noff-i, + head, i, &data, 1); + if (err) { + return err; + } + + err = lfs_bd_prog(lfs, + pcache, rcache, true, + nblock, i, &data, 1); + if (err) { + if (err == LFS_ERR_CORRUPT) { + goto relocate; + } + return err; + } + } + + *block = nblock; + *off = noff; + return 0; + } + + // append block + index += 1; + lfs_size_t skips = lfs_ctz(index) + 1; + lfs_block_t nhead = head; + for (lfs_off_t i = 0; i < skips; i++) { + nhead = lfs_tole32(nhead); + err = lfs_bd_prog(lfs, pcache, rcache, true, + nblock, 4*i, &nhead, 4); + nhead = lfs_fromle32(nhead); + if (err) { + if (err == LFS_ERR_CORRUPT) { + goto relocate; + } + return err; + } + + if (i != skips-1) { + err = lfs_bd_read(lfs, + NULL, rcache, sizeof(nhead), + nhead, 4*i, &nhead, sizeof(nhead)); + nhead = lfs_fromle32(nhead); + if (err) { + return err; + } + } + } + + *block = nblock; + *off = 4*skips; + return 0; + } + +relocate: + LFS_DEBUG("Bad block at 0x%"PRIx32, nblock); + + // just clear cache and try a new block + lfs_cache_drop(lfs, pcache); + } +} +#endif + +static int lfs_ctz_traverse(lfs_t *lfs, + const lfs_cache_t *pcache, lfs_cache_t *rcache, + lfs_block_t head, lfs_size_t size, + int (*cb)(void*, lfs_block_t), void *data) { + if (size == 0) { + return 0; + } + + lfs_off_t index = lfs_ctz_index(lfs, &(lfs_off_t){size-1}); + + while (true) { + int err = cb(data, head); + if (err) { + return err; + } + + if (index == 0) { + return 0; + } + + lfs_block_t heads[2]; + int count = 2 - (index & 1); + err = lfs_bd_read(lfs, + pcache, rcache, count*sizeof(head), + head, 0, &heads, count*sizeof(head)); + heads[0] = lfs_fromle32(heads[0]); + heads[1] = lfs_fromle32(heads[1]); + if (err) { + return err; + } + + for (int i = 0; i < count-1; i++) { + err = cb(data, heads[i]); + if (err) { + return err; + } + } + + head = heads[count-1]; + index -= count; + } +} + + +/// Top level file operations /// +static int lfs_file_opencfg_(lfs_t *lfs, lfs_file_t *file, + const char *path, int flags, + const struct lfs_file_config *cfg) { +#ifndef LFS_READONLY + // deorphan if we haven't yet, needed at most once after poweron + if ((flags & LFS_O_WRONLY) == LFS_O_WRONLY) { + int err = lfs_fs_forceconsistency(lfs); + if (err) { + return err; + } + } +#else + LFS_ASSERT((flags & LFS_O_RDONLY) == LFS_O_RDONLY); +#endif + + // setup simple file details + int err; + file->cfg = cfg; + file->flags = flags; + file->pos = 0; + file->off = 0; + file->cache.buffer = NULL; + + // allocate entry for file if it doesn't exist + lfs_stag_t tag = lfs_dir_find(lfs, &file->m, &path, &file->id); + if (tag < 0 && !(tag == LFS_ERR_NOENT && lfs_path_islast(path))) { + err = tag; + goto cleanup; + } + + // get id, add to list of mdirs to catch update changes + file->type = LFS_TYPE_REG; + lfs_mlist_append(lfs, (struct lfs_mlist *)file); + +#ifdef LFS_READONLY + if (tag == LFS_ERR_NOENT) { + err = LFS_ERR_NOENT; + goto cleanup; +#else + if (tag == LFS_ERR_NOENT) { + if (!(flags & LFS_O_CREAT)) { + err = LFS_ERR_NOENT; + goto cleanup; + } + + // don't allow trailing slashes + if (lfs_path_isdir(path)) { + err = LFS_ERR_NOTDIR; + goto cleanup; + } + + // check that name fits + lfs_size_t nlen = lfs_path_namelen(path); + if (nlen > lfs->name_max) { + err = LFS_ERR_NAMETOOLONG; + goto cleanup; + } + + // get next slot and create entry to remember name + err = lfs_dir_commit(lfs, &file->m, LFS_MKATTRS( + {LFS_MKTAG(LFS_TYPE_CREATE, file->id, 0), NULL}, + {LFS_MKTAG(LFS_TYPE_REG, file->id, nlen), path}, + {LFS_MKTAG(LFS_TYPE_INLINESTRUCT, file->id, 0), NULL})); + + // it may happen that the file name doesn't fit in the metadata blocks, e.g., a 256 byte file name will + // not fit in a 128 byte block. + err = (err == LFS_ERR_NOSPC) ? LFS_ERR_NAMETOOLONG : err; + if (err) { + goto cleanup; + } + + tag = LFS_MKTAG(LFS_TYPE_INLINESTRUCT, 0, 0); + } else if (flags & LFS_O_EXCL) { + err = LFS_ERR_EXIST; + goto cleanup; +#endif + } else if (lfs_tag_type3(tag) != LFS_TYPE_REG) { + err = LFS_ERR_ISDIR; + goto cleanup; +#ifndef LFS_READONLY + } else if (flags & LFS_O_TRUNC) { + // truncate if requested + tag = LFS_MKTAG(LFS_TYPE_INLINESTRUCT, file->id, 0); + file->flags |= LFS_F_DIRTY; +#endif + } else { + // try to load what's on disk, if it's inlined we'll fix it later + tag = lfs_dir_get(lfs, &file->m, LFS_MKTAG(0x700, 0x3ff, 0), + LFS_MKTAG(LFS_TYPE_STRUCT, file->id, 8), &file->ctz); + if (tag < 0) { + err = tag; + goto cleanup; + } + lfs_ctz_fromle32(&file->ctz); + } + + // fetch attrs + for (unsigned i = 0; i < file->cfg->attr_count; i++) { + // if opened for read / read-write operations + if ((file->flags & LFS_O_RDONLY) == LFS_O_RDONLY) { + lfs_stag_t res = lfs_dir_get(lfs, &file->m, + LFS_MKTAG(0x7ff, 0x3ff, 0), + LFS_MKTAG(LFS_TYPE_USERATTR + file->cfg->attrs[i].type, + file->id, file->cfg->attrs[i].size), + file->cfg->attrs[i].buffer); + if (res < 0 && res != LFS_ERR_NOENT) { + err = res; + goto cleanup; + } + } + +#ifndef LFS_READONLY + // if opened for write / read-write operations + if ((file->flags & LFS_O_WRONLY) == LFS_O_WRONLY) { + if (file->cfg->attrs[i].size > lfs->attr_max) { + err = LFS_ERR_NOSPC; + goto cleanup; + } + + file->flags |= LFS_F_DIRTY; + } +#endif + } + + // allocate buffer if needed + if (file->cfg->buffer) { + file->cache.buffer = file->cfg->buffer; + } else { + file->cache.buffer = lfs_malloc(lfs->cfg->cache_size); + if (!file->cache.buffer) { + err = LFS_ERR_NOMEM; + goto cleanup; + } + } + + // zero to avoid information leak + lfs_cache_zero(lfs, &file->cache); + + if (lfs_tag_type3(tag) == LFS_TYPE_INLINESTRUCT) { + // load inline files + file->ctz.head = LFS_BLOCK_INLINE; + file->ctz.size = lfs_tag_size(tag); + file->flags |= LFS_F_INLINE; + file->cache.block = file->ctz.head; + file->cache.off = 0; + file->cache.size = lfs->cfg->cache_size; + + // don't always read (may be new/trunc file) + if (file->ctz.size > 0) { + lfs_stag_t res = lfs_dir_get(lfs, &file->m, + LFS_MKTAG(0x700, 0x3ff, 0), + LFS_MKTAG(LFS_TYPE_STRUCT, file->id, + lfs_min(file->cache.size, 0x3fe)), + file->cache.buffer); + if (res < 0) { + err = res; + goto cleanup; + } + } + } + + return 0; + +cleanup: + // clean up lingering resources +#ifndef LFS_READONLY + file->flags |= LFS_F_ERRED; +#endif + lfs_file_close_(lfs, file); + return err; +} + +#ifndef LFS_NO_MALLOC +static int lfs_file_open_(lfs_t *lfs, lfs_file_t *file, + const char *path, int flags) { + static const struct lfs_file_config defaults = {0}; + int err = lfs_file_opencfg_(lfs, file, path, flags, &defaults); + return err; +} +#endif + +static int lfs_file_close_(lfs_t *lfs, lfs_file_t *file) { + int err = 0; +#ifndef LFS_READONLY + // it's not safe to do anything if our file errored + if (!(file->flags & LFS_F_ERRED)) { + err = lfs_file_sync_(lfs, file); + } +#endif + + // remove from list of mdirs + lfs_mlist_remove(lfs, (struct lfs_mlist*)file); + + // clean up memory + if (!file->cfg->buffer) { + lfs_free(file->cache.buffer); + } + + return err; +} + + +#ifndef LFS_READONLY +static int lfs_file_relocate(lfs_t *lfs, lfs_file_t *file) { + while (true) { + // just relocate what exists into new block + lfs_block_t nblock; + int err = lfs_alloc(lfs, &nblock); + if (err) { + return err; + } + + err = lfs_bd_erase(lfs, nblock); + if (err) { + if (err == LFS_ERR_CORRUPT) { + goto relocate; + } + return err; + } + + // either read from dirty cache or disk + for (lfs_off_t i = 0; i < file->off; i++) { + uint8_t data; + if (file->flags & LFS_F_INLINE) { + err = lfs_dir_getread(lfs, &file->m, + // note we evict inline files before they can be dirty + NULL, &file->cache, file->off-i, + LFS_MKTAG(0xfff, 0x1ff, 0), + LFS_MKTAG(LFS_TYPE_INLINESTRUCT, file->id, 0), + i, &data, 1); + if (err) { + return err; + } + } else { + err = lfs_bd_read(lfs, + &file->cache, &lfs->rcache, file->off-i, + file->block, i, &data, 1); + if (err) { + return err; + } + } + + err = lfs_bd_prog(lfs, + &lfs->pcache, &lfs->rcache, true, + nblock, i, &data, 1); + if (err) { + if (err == LFS_ERR_CORRUPT) { + goto relocate; + } + return err; + } + } + + // copy over new state of file + memcpy(file->cache.buffer, lfs->pcache.buffer, lfs->cfg->cache_size); + file->cache.block = lfs->pcache.block; + file->cache.off = lfs->pcache.off; + file->cache.size = lfs->pcache.size; + lfs_cache_zero(lfs, &lfs->pcache); + + file->block = nblock; + file->flags |= LFS_F_WRITING; + return 0; + +relocate: + LFS_DEBUG("Bad block at 0x%"PRIx32, nblock); + + // just clear cache and try a new block + lfs_cache_drop(lfs, &lfs->pcache); + } +} +#endif + +#ifndef LFS_READONLY +static int lfs_file_outline(lfs_t *lfs, lfs_file_t *file) { + file->off = file->pos; + lfs_alloc_ckpoint(lfs); + int err = lfs_file_relocate(lfs, file); + if (err) { + return err; + } + + file->flags &= ~LFS_F_INLINE; + return 0; +} +#endif + +static int lfs_file_flush(lfs_t *lfs, lfs_file_t *file) { + if (file->flags & LFS_F_READING) { + if (!(file->flags & LFS_F_INLINE)) { + lfs_cache_drop(lfs, &file->cache); + } + file->flags &= ~LFS_F_READING; + } + +#ifndef LFS_READONLY + if (file->flags & LFS_F_WRITING) { + lfs_off_t pos = file->pos; + + if (!(file->flags & LFS_F_INLINE)) { + // copy over anything after current branch + lfs_file_t orig = { + .ctz.head = file->ctz.head, + .ctz.size = file->ctz.size, + .flags = LFS_O_RDONLY, + .pos = file->pos, + .cache = lfs->rcache, + }; + lfs_cache_drop(lfs, &lfs->rcache); + + while (file->pos < file->ctz.size) { + // copy over a byte at a time, leave it up to caching + // to make this efficient + uint8_t data; + lfs_ssize_t res = lfs_file_flushedread(lfs, &orig, &data, 1); + if (res < 0) { + return res; + } + + res = lfs_file_flushedwrite(lfs, file, &data, 1); + if (res < 0) { + return res; + } + + // keep our reference to the rcache in sync + if (lfs->rcache.block != LFS_BLOCK_NULL) { + lfs_cache_drop(lfs, &orig.cache); + lfs_cache_drop(lfs, &lfs->rcache); + } + } + + // write out what we have + while (true) { + int err = lfs_bd_flush(lfs, &file->cache, &lfs->rcache, true); + if (err) { + if (err == LFS_ERR_CORRUPT) { + goto relocate; + } + return err; + } + + break; + +relocate: + LFS_DEBUG("Bad block at 0x%"PRIx32, file->block); + err = lfs_file_relocate(lfs, file); + if (err) { + return err; + } + } + } else { + file->pos = lfs_max(file->pos, file->ctz.size); + } + + // actual file updates + file->ctz.head = file->block; + file->ctz.size = file->pos; + file->flags &= ~LFS_F_WRITING; + file->flags |= LFS_F_DIRTY; + + file->pos = pos; + } +#endif + + return 0; +} + +#ifndef LFS_READONLY +static int lfs_file_sync_(lfs_t *lfs, lfs_file_t *file) { + int err = lfs_file_flush(lfs, file); + if (err) { + file->flags |= LFS_F_ERRED; + return err; + } + + if ((file->flags & LFS_F_DIRTY) && + !lfs_pair_isnull(file->m.pair)) { + // before we commit metadata, we need sync the disk to make sure + // data writes don't complete after metadata writes + if (!(file->flags & LFS_F_INLINE)) { + err = lfs_bd_sync(lfs, &lfs->pcache, &lfs->rcache, false); + if (err) { + return err; + } + } + + // update dir entry + uint16_t type; + const void *buffer; + lfs_size_t size; + struct lfs_ctz ctz; + if (file->flags & LFS_F_INLINE) { + // inline the whole file + type = LFS_TYPE_INLINESTRUCT; + buffer = file->cache.buffer; + size = file->ctz.size; + } else { + // update the ctz reference + type = LFS_TYPE_CTZSTRUCT; + // copy ctz so alloc will work during a relocate + ctz = file->ctz; + lfs_ctz_tole32(&ctz); + buffer = &ctz; + size = sizeof(ctz); + } + + // commit file data and attributes + err = lfs_dir_commit(lfs, &file->m, LFS_MKATTRS( + {LFS_MKTAG(type, file->id, size), buffer}, + {LFS_MKTAG(LFS_FROM_USERATTRS, file->id, + file->cfg->attr_count), file->cfg->attrs})); + if (err) { + file->flags |= LFS_F_ERRED; + return err; + } + + file->flags &= ~LFS_F_DIRTY; + } + + // mark any other file handles as dirty + desync + for (lfs_file_t *f = (lfs_file_t*)lfs->mlist; f; f = f->next) { + if (file != f + && f->type == LFS_TYPE_REG + && lfs_pair_cmp(f->m.pair, file->m.pair) == 0 + && f->id == file->id) { + f->flags |= LFS_F_DUSTY; + } + } + + file->flags &= ~LFS_F_ERRED & ~LFS_F_DUSTY; + return 0; +} +#endif + +static lfs_ssize_t lfs_file_flushedread(lfs_t *lfs, lfs_file_t *file, + void *buffer, lfs_size_t size) { + uint8_t *data = buffer; + lfs_size_t nsize = size; + + if (file->pos >= file->ctz.size) { + // eof if past end + return 0; + } + + size = lfs_min(size, file->ctz.size - file->pos); + nsize = size; + + while (nsize > 0) { + // check if we need a new block + if (!(file->flags & LFS_F_READING) || + file->off == lfs->cfg->block_size) { + if (!(file->flags & LFS_F_INLINE)) { + int err = lfs_ctz_find(lfs, NULL, &file->cache, + file->ctz.head, file->ctz.size, + file->pos, &file->block, &file->off); + if (err) { + return err; + } + } else { + file->block = LFS_BLOCK_INLINE; + file->off = file->pos; + } + + file->flags |= LFS_F_READING; + } + + // read as much as we can in current block + lfs_size_t diff = lfs_min(nsize, lfs->cfg->block_size - file->off); + if (file->flags & LFS_F_INLINE) { + int err = lfs_dir_getread(lfs, &file->m, + NULL, &file->cache, lfs->cfg->block_size, + LFS_MKTAG(0xfff, 0x1ff, 0), + LFS_MKTAG(LFS_TYPE_INLINESTRUCT, file->id, 0), + file->off, data, diff); + if (err) { + return err; + } + } else { + int err = lfs_bd_read(lfs, + NULL, &file->cache, lfs->cfg->block_size, + file->block, file->off, data, diff); + if (err) { + return err; + } + } + + file->pos += diff; + file->off += diff; + data += diff; + nsize -= diff; + } + + return size; +} + +static lfs_ssize_t lfs_file_read_(lfs_t *lfs, lfs_file_t *file, + void *buffer, lfs_size_t size) { + LFS_ASSERT((file->flags & LFS_O_RDONLY) == LFS_O_RDONLY); + +#ifndef LFS_READONLY + if (file->flags & LFS_F_WRITING) { + // flush out any writes + int err = lfs_file_flush(lfs, file); + if (err) { + return err; + } + } +#endif + + return lfs_file_flushedread(lfs, file, buffer, size); +} + + +#ifndef LFS_READONLY +static lfs_ssize_t lfs_file_flushedwrite(lfs_t *lfs, lfs_file_t *file, + const void *buffer, lfs_size_t size) { + const uint8_t *data = buffer; + lfs_size_t nsize = size; + + if ((file->flags & LFS_F_INLINE) && + lfs_max(file->pos+nsize, file->ctz.size) > lfs->inline_max) { + // inline file doesn't fit anymore + int err = lfs_file_outline(lfs, file); + if (err) { + file->flags |= LFS_F_ERRED; + return err; + } + } + + while (nsize > 0) { + // check if we need a new block + if (!(file->flags & LFS_F_WRITING) || + file->off == lfs->cfg->block_size) { + if (!(file->flags & LFS_F_INLINE)) { + if (!(file->flags & LFS_F_WRITING) && file->pos > 0) { + // find out which block we're extending from + int err = lfs_ctz_find(lfs, NULL, &file->cache, + file->ctz.head, file->ctz.size, + file->pos-1, &file->block, &(lfs_off_t){0}); + if (err) { + file->flags |= LFS_F_ERRED; + return err; + } + + // mark cache as dirty since we may have read data into it + lfs_cache_zero(lfs, &file->cache); + } + + // extend file with new blocks + lfs_alloc_ckpoint(lfs); + int err = lfs_ctz_extend(lfs, &file->cache, &lfs->rcache, + file->block, file->pos, + &file->block, &file->off); + if (err) { + file->flags |= LFS_F_ERRED; + return err; + } + } else { + file->block = LFS_BLOCK_INLINE; + file->off = file->pos; + } + + file->flags |= LFS_F_WRITING; + } + + // program as much as we can in current block + lfs_size_t diff = lfs_min(nsize, lfs->cfg->block_size - file->off); + while (true) { + int err = lfs_bd_prog(lfs, &file->cache, &lfs->rcache, true, + file->block, file->off, data, diff); + if (err) { + if (err == LFS_ERR_CORRUPT) { + goto relocate; + } + file->flags |= LFS_F_ERRED; + return err; + } + + break; +relocate: + err = lfs_file_relocate(lfs, file); + if (err) { + file->flags |= LFS_F_ERRED; + return err; + } + } + + file->pos += diff; + file->off += diff; + data += diff; + nsize -= diff; + + lfs_alloc_ckpoint(lfs); + } + + return size; +} + +static lfs_ssize_t lfs_file_write_(lfs_t *lfs, lfs_file_t *file, + const void *buffer, lfs_size_t size) { + LFS_ASSERT((file->flags & LFS_O_WRONLY) == LFS_O_WRONLY); + + if (file->flags & LFS_F_READING) { + // drop any reads + int err = lfs_file_flush(lfs, file); + if (err) { + return err; + } + } + + if ((file->flags & LFS_O_APPEND) && file->pos < file->ctz.size) { + file->pos = file->ctz.size; + } + + if (file->pos + size > lfs->file_max) { + // Larger than file limit? + return LFS_ERR_FBIG; + } + + if (!(file->flags & LFS_F_WRITING) && file->pos > file->ctz.size) { + // fill with zeros + lfs_off_t pos = file->pos; + file->pos = file->ctz.size; + + while (file->pos < pos) { + lfs_ssize_t res = lfs_file_flushedwrite(lfs, file, &(uint8_t){0}, 1); + if (res < 0) { + return res; + } + } + } + + lfs_ssize_t nsize = lfs_file_flushedwrite(lfs, file, buffer, size); + if (nsize < 0) { + return nsize; + } + + file->flags &= ~LFS_F_ERRED & ~LFS_F_DUSTY; + return nsize; +} +#endif + +static lfs_soff_t lfs_file_seek_(lfs_t *lfs, lfs_file_t *file, + lfs_soff_t off, int whence) { + // find new pos + // + // fortunately for us, littlefs is limited to 31-bit file sizes, so we + // don't have to worry too much about integer overflow + lfs_off_t npos = file->pos; + if (whence == LFS_SEEK_SET) { + npos = off; + } else if (whence == LFS_SEEK_CUR) { + npos = file->pos + (lfs_off_t)off; + } else if (whence == LFS_SEEK_END) { + npos = (lfs_off_t)lfs_file_size_(lfs, file) + (lfs_off_t)off; + } + + if (npos > lfs->file_max) { + // file position out of range + return LFS_ERR_INVAL; + } + + if (file->pos == npos) { + // noop - position has not changed + return npos; + } + + // if we're only reading and our new offset is still in the file's cache + // we can avoid flushing and needing to reread the data + if ((file->flags & LFS_F_READING) + && file->off != lfs->cfg->block_size) { + int oindex = lfs_ctz_index(lfs, &(lfs_off_t){file->pos}); + lfs_off_t noff = npos; + int nindex = lfs_ctz_index(lfs, &noff); + if (oindex == nindex + && noff >= file->cache.off + && noff < file->cache.off + file->cache.size) { + file->pos = npos; + file->off = noff; + return npos; + } + } + + // write out everything beforehand, may be noop if rdonly + int err = lfs_file_flush(lfs, file); + if (err) { + return err; + } + + // update pos + file->pos = npos; + return npos; +} + +#ifndef LFS_READONLY +static int lfs_file_truncate_(lfs_t *lfs, lfs_file_t *file, lfs_off_t size) { + LFS_ASSERT((file->flags & LFS_O_WRONLY) == LFS_O_WRONLY); + + if (size > LFS_FILE_MAX) { + return LFS_ERR_INVAL; + } + + lfs_off_t pos = file->pos; + lfs_off_t oldsize = lfs_file_size_(lfs, file); + if (size < oldsize) { + // revert to inline file? + if (size <= lfs->inline_max) { + // flush+seek to head + lfs_soff_t res = lfs_file_seek_(lfs, file, 0, LFS_SEEK_SET); + if (res < 0) { + return (int)res; + } + + // read our data into rcache temporarily + lfs_cache_drop(lfs, &lfs->rcache); + res = lfs_file_flushedread(lfs, file, + lfs->rcache.buffer, size); + if (res < 0) { + return (int)res; + } + + file->ctz.head = LFS_BLOCK_INLINE; + file->ctz.size = size; + file->flags |= LFS_F_DIRTY | LFS_F_READING | LFS_F_INLINE; + file->cache.block = file->ctz.head; + file->cache.off = 0; + file->cache.size = lfs->cfg->cache_size; + memcpy(file->cache.buffer, lfs->rcache.buffer, size); + + } else { + // need to flush since directly changing metadata + int err = lfs_file_flush(lfs, file); + if (err) { + return err; + } + + // lookup new head in ctz skip list + err = lfs_ctz_find(lfs, NULL, &file->cache, + file->ctz.head, file->ctz.size, + size-1, &file->block, &(lfs_off_t){0}); + if (err) { + return err; + } + + // need to set pos/block/off consistently so seeking back to + // the old position does not get confused + file->pos = size; + file->ctz.head = file->block; + file->ctz.size = size; + file->flags |= LFS_F_DIRTY | LFS_F_READING; + } + } else if (size > oldsize) { + // flush+seek if not already at end + lfs_soff_t res = lfs_file_seek_(lfs, file, 0, LFS_SEEK_END); + if (res < 0) { + return (int)res; + } + + // fill with zeros + while (file->pos < size) { + res = lfs_file_write_(lfs, file, &(uint8_t){0}, 1); + if (res < 0) { + return (int)res; + } + } + } + + // restore pos + lfs_soff_t res = lfs_file_seek_(lfs, file, pos, LFS_SEEK_SET); + if (res < 0) { + return (int)res; + } + + return 0; +} +#endif + +static lfs_soff_t lfs_file_tell_(lfs_t *lfs, lfs_file_t *file) { + (void)lfs; + return file->pos; +} + +static int lfs_file_rewind_(lfs_t *lfs, lfs_file_t *file) { + lfs_soff_t res = lfs_file_seek_(lfs, file, 0, LFS_SEEK_SET); + if (res < 0) { + return (int)res; + } + + return 0; +} + +static lfs_soff_t lfs_file_size_(lfs_t *lfs, lfs_file_t *file) { + (void)lfs; + +#ifndef LFS_READONLY + if (file->flags & LFS_F_WRITING) { + return lfs_max(file->pos, file->ctz.size); + } +#endif + + return file->ctz.size; +} + + +/// General fs operations /// +static int lfs_stat_(lfs_t *lfs, const char *path, struct lfs_info *info) { + lfs_mdir_t cwd; + lfs_stag_t tag = lfs_dir_find(lfs, &cwd, &path, NULL); + if (tag < 0) { + return (int)tag; + } + + // only allow trailing slashes on dirs + if (strchr(path, '/') != NULL + && lfs_tag_type3(tag) != LFS_TYPE_DIR) { + return LFS_ERR_NOTDIR; + } + + return lfs_dir_getinfo(lfs, &cwd, lfs_tag_id(tag), info); +} + +#ifndef LFS_READONLY +static int lfs_remove_(lfs_t *lfs, const char *path) { + // deorphan if we haven't yet, needed at most once after poweron + int err = lfs_fs_forceconsistency(lfs); + if (err) { + return err; + } + + lfs_mdir_t cwd; + lfs_stag_t tag = lfs_dir_find(lfs, &cwd, &path, NULL); + if (tag < 0 || lfs_tag_id(tag) == 0x3ff) { + return (tag < 0) ? (int)tag : LFS_ERR_INVAL; + } + + struct lfs_mlist dir; + dir.next = lfs->mlist; + if (lfs_tag_type3(tag) == LFS_TYPE_DIR) { + // must be empty before removal + lfs_block_t pair[2]; + lfs_stag_t res = lfs_dir_get(lfs, &cwd, LFS_MKTAG(0x700, 0x3ff, 0), + LFS_MKTAG(LFS_TYPE_STRUCT, lfs_tag_id(tag), 8), pair); + if (res < 0) { + return (int)res; + } + lfs_pair_fromle32(pair); + + err = lfs_dir_fetch(lfs, &dir.m, pair); + if (err) { + return err; + } + + if (dir.m.count > 0 || dir.m.split) { + return LFS_ERR_NOTEMPTY; + } + + // mark fs as orphaned + err = lfs_fs_preporphans(lfs, +1); + if (err) { + return err; + } + + // I know it's crazy but yes, dir can be changed by our parent's + // commit (if predecessor is child) + dir.type = 0; + dir.id = 0; + lfs->mlist = &dir; + } + + // delete the entry + err = lfs_dir_commit(lfs, &cwd, LFS_MKATTRS( + {LFS_MKTAG(LFS_TYPE_DELETE, lfs_tag_id(tag), 0), NULL})); + if (err) { + lfs->mlist = dir.next; + return err; + } + + lfs->mlist = dir.next; + if (lfs_gstate_hasorphans(&lfs->gstate)) { + LFS_ASSERT(lfs_tag_type3(tag) == LFS_TYPE_DIR); + + // fix orphan + err = lfs_fs_preporphans(lfs, -1); + if (err) { + return err; + } + + err = lfs_fs_pred(lfs, dir.m.pair, &cwd); + if (err) { + return err; + } + + err = lfs_dir_drop(lfs, &cwd, &dir.m); + if (err) { + return err; + } + } + + return 0; +} +#endif + +#ifndef LFS_READONLY +static int lfs_rename_(lfs_t *lfs, const char *oldpath, const char *newpath) { + // deorphan if we haven't yet, needed at most once after poweron + int err = lfs_fs_forceconsistency(lfs); + if (err) { + return err; + } + + // find old entry + lfs_mdir_t oldcwd; + lfs_stag_t oldtag = lfs_dir_find(lfs, &oldcwd, &oldpath, NULL); + if (oldtag < 0 || lfs_tag_id(oldtag) == 0x3ff) { + return (oldtag < 0) ? (int)oldtag : LFS_ERR_INVAL; + } + + // find new entry + lfs_mdir_t newcwd; + uint16_t newid; + lfs_stag_t prevtag = lfs_dir_find(lfs, &newcwd, &newpath, &newid); + if ((prevtag < 0 || lfs_tag_id(prevtag) == 0x3ff) && + !(prevtag == LFS_ERR_NOENT && lfs_path_islast(newpath))) { + return (prevtag < 0) ? (int)prevtag : LFS_ERR_INVAL; + } + + // if we're in the same pair there's a few special cases... + bool samepair = (lfs_pair_cmp(oldcwd.pair, newcwd.pair) == 0); + uint16_t newoldid = lfs_tag_id(oldtag); + + struct lfs_mlist prevdir; + prevdir.next = lfs->mlist; + if (prevtag == LFS_ERR_NOENT) { + // if we're a file, don't allow trailing slashes + if (lfs_path_isdir(newpath) + && lfs_tag_type3(oldtag) != LFS_TYPE_DIR) { + return LFS_ERR_NOTDIR; + } + + // check that name fits + lfs_size_t nlen = lfs_path_namelen(newpath); + if (nlen > lfs->name_max) { + return LFS_ERR_NAMETOOLONG; + } + + // there is a small chance we are being renamed in the same + // directory/ to an id less than our old id, the global update + // to handle this is a bit messy + if (samepair && newid <= newoldid) { + newoldid += 1; + } + } else if (lfs_tag_type3(prevtag) != lfs_tag_type3(oldtag)) { + return (lfs_tag_type3(prevtag) == LFS_TYPE_DIR) + ? LFS_ERR_ISDIR + : LFS_ERR_NOTDIR; + } else if (samepair && newid == newoldid) { + // we're renaming to ourselves?? + return 0; + } else if (lfs_tag_type3(prevtag) == LFS_TYPE_DIR) { + // must be empty before removal + lfs_block_t prevpair[2]; + lfs_stag_t res = lfs_dir_get(lfs, &newcwd, LFS_MKTAG(0x700, 0x3ff, 0), + LFS_MKTAG(LFS_TYPE_STRUCT, newid, 8), prevpair); + if (res < 0) { + return (int)res; + } + lfs_pair_fromle32(prevpair); + + // must be empty before removal + err = lfs_dir_fetch(lfs, &prevdir.m, prevpair); + if (err) { + return err; + } + + if (prevdir.m.count > 0 || prevdir.m.split) { + return LFS_ERR_NOTEMPTY; + } + + // mark fs as orphaned + err = lfs_fs_preporphans(lfs, +1); + if (err) { + return err; + } + + // I know it's crazy but yes, dir can be changed by our parent's + // commit (if predecessor is child) + prevdir.type = 0; + prevdir.id = 0; + lfs->mlist = &prevdir; + } + + if (!samepair) { + lfs_fs_prepmove(lfs, newoldid, oldcwd.pair); + } + + // move over all attributes + err = lfs_dir_commit(lfs, &newcwd, LFS_MKATTRS( + {LFS_MKTAG_IF(prevtag != LFS_ERR_NOENT, + LFS_TYPE_DELETE, newid, 0), NULL}, + {LFS_MKTAG(LFS_TYPE_CREATE, newid, 0), NULL}, + {LFS_MKTAG(lfs_tag_type3(oldtag), + newid, lfs_path_namelen(newpath)), newpath}, + {LFS_MKTAG(LFS_FROM_MOVE, newid, lfs_tag_id(oldtag)), &oldcwd}, + {LFS_MKTAG_IF(samepair, + LFS_TYPE_DELETE, newoldid, 0), NULL})); + if (err) { + lfs->mlist = prevdir.next; + return err; + } + + // let commit clean up after move (if we're different! otherwise move + // logic already fixed it for us) + if (!samepair && lfs_gstate_hasmove(&lfs->gstate)) { + // prep gstate and delete move id + lfs_fs_prepmove(lfs, 0x3ff, NULL); + err = lfs_dir_commit(lfs, &oldcwd, LFS_MKATTRS( + {LFS_MKTAG(LFS_TYPE_DELETE, lfs_tag_id(oldtag), 0), NULL})); + if (err) { + lfs->mlist = prevdir.next; + return err; + } + } + + lfs->mlist = prevdir.next; + if (lfs_gstate_hasorphans(&lfs->gstate)) { + LFS_ASSERT(prevtag != LFS_ERR_NOENT + && lfs_tag_type3(prevtag) == LFS_TYPE_DIR); + + // fix orphan + err = lfs_fs_preporphans(lfs, -1); + if (err) { + return err; + } + + err = lfs_fs_pred(lfs, prevdir.m.pair, &newcwd); + if (err) { + return err; + } + + err = lfs_dir_drop(lfs, &newcwd, &prevdir.m); + if (err) { + return err; + } + } + + return 0; +} +#endif + +static lfs_ssize_t lfs_getattr_(lfs_t *lfs, const char *path, + uint8_t type, void *buffer, lfs_size_t size) { + lfs_mdir_t cwd; + lfs_stag_t tag = lfs_dir_find(lfs, &cwd, &path, NULL); + if (tag < 0) { + return tag; + } + + uint16_t id = lfs_tag_id(tag); + if (id == 0x3ff) { + // special case for root + id = 0; + int err = lfs_dir_fetch(lfs, &cwd, lfs->root); + if (err) { + return err; + } + } + + tag = lfs_dir_get(lfs, &cwd, LFS_MKTAG(0x7ff, 0x3ff, 0), + LFS_MKTAG(LFS_TYPE_USERATTR + type, + id, lfs_min(size, lfs->attr_max)), + buffer); + if (tag < 0) { + if (tag == LFS_ERR_NOENT) { + return LFS_ERR_NOATTR; + } + + return tag; + } + + return lfs_tag_size(tag); +} + +#ifndef LFS_READONLY +static int lfs_commitattr(lfs_t *lfs, const char *path, + uint8_t type, const void *buffer, lfs_size_t size) { + lfs_mdir_t cwd; + lfs_stag_t tag = lfs_dir_find(lfs, &cwd, &path, NULL); + if (tag < 0) { + return tag; + } + + uint16_t id = lfs_tag_id(tag); + if (id == 0x3ff) { + // special case for root + id = 0; + int err = lfs_dir_fetch(lfs, &cwd, lfs->root); + if (err) { + return err; + } + } + + return lfs_dir_commit(lfs, &cwd, LFS_MKATTRS( + {LFS_MKTAG(LFS_TYPE_USERATTR + type, id, size), buffer})); +} +#endif + +#ifndef LFS_READONLY +static int lfs_setattr_(lfs_t *lfs, const char *path, + uint8_t type, const void *buffer, lfs_size_t size) { + if (size > lfs->attr_max) { + return LFS_ERR_NOSPC; + } + + return lfs_commitattr(lfs, path, type, buffer, size); +} +#endif + +#ifndef LFS_READONLY +static int lfs_removeattr_(lfs_t *lfs, const char *path, uint8_t type) { + return lfs_commitattr(lfs, path, type, NULL, 0x3ff); +} +#endif + + +/// Filesystem operations /// + +// compile time checks, see lfs.h for why these limits exist +#if LFS_NAME_MAX > 1022 +#error "Invalid LFS_NAME_MAX, must be <= 1022" +#endif + +#if LFS_FILE_MAX > 2147483647 +#error "Invalid LFS_FILE_MAX, must be <= 2147483647" +#endif + +#if LFS_ATTR_MAX > 1022 +#error "Invalid LFS_ATTR_MAX, must be <= 1022" +#endif + +// common filesystem initialization +static int lfs_init(lfs_t *lfs, const struct lfs_config *cfg) { + lfs->cfg = cfg; + lfs->block_count = cfg->block_count; // May be 0 + int err = 0; + +#ifdef LFS_MULTIVERSION + // this driver only supports minor version < current minor version + LFS_ASSERT(!lfs->cfg->disk_version || ( + (0xffff & (lfs->cfg->disk_version >> 16)) + == LFS_DISK_VERSION_MAJOR + && (0xffff & (lfs->cfg->disk_version >> 0)) + <= LFS_DISK_VERSION_MINOR)); +#endif + + // check that bool is a truthy-preserving type + // + // note the most common reason for this failure is a before-c99 compiler, + // which littlefs currently does not support + LFS_ASSERT((bool)0x80000000); + + // check that the required io functions are provided + LFS_ASSERT(lfs->cfg->read != NULL); +#ifndef LFS_READONLY + LFS_ASSERT(lfs->cfg->prog != NULL); + LFS_ASSERT(lfs->cfg->erase != NULL); + LFS_ASSERT(lfs->cfg->sync != NULL); +#endif + + // validate that the lfs-cfg sizes were initiated properly before + // performing any arithmetic logics with them + LFS_ASSERT(lfs->cfg->read_size != 0); + LFS_ASSERT(lfs->cfg->prog_size != 0); + LFS_ASSERT(lfs->cfg->cache_size != 0); + + // check that block size is a multiple of cache size is a multiple + // of prog and read sizes + LFS_ASSERT(lfs->cfg->cache_size % lfs->cfg->read_size == 0); + LFS_ASSERT(lfs->cfg->cache_size % lfs->cfg->prog_size == 0); + LFS_ASSERT(lfs->cfg->block_size % lfs->cfg->cache_size == 0); + + // check that the block size is large enough to fit all ctz pointers + LFS_ASSERT(lfs->cfg->block_size >= 128); + // this is the exact calculation for all ctz pointers, if this fails + // and the simpler assert above does not, math must be broken + LFS_ASSERT(4*lfs_npw2(0xffffffff / (lfs->cfg->block_size-2*4)) + <= lfs->cfg->block_size); + + // block_cycles = 0 is no longer supported. + // + // block_cycles is the number of erase cycles before littlefs evicts + // metadata logs as a part of wear leveling. Suggested values are in the + // range of 100-1000, or set block_cycles to -1 to disable block-level + // wear-leveling. + LFS_ASSERT(lfs->cfg->block_cycles != 0); + + // check that compact_thresh makes sense + // + // metadata can't be compacted below block_size/2, and metadata can't + // exceed a block_size + LFS_ASSERT(lfs->cfg->compact_thresh == 0 + || lfs->cfg->compact_thresh >= lfs->cfg->block_size/2); + LFS_ASSERT(lfs->cfg->compact_thresh == (lfs_size_t)-1 + || lfs->cfg->compact_thresh <= lfs->cfg->block_size); + + // check that metadata_max is a multiple of read_size and prog_size, + // and a factor of the block_size + LFS_ASSERT(!lfs->cfg->metadata_max + || lfs->cfg->metadata_max % lfs->cfg->read_size == 0); + LFS_ASSERT(!lfs->cfg->metadata_max + || lfs->cfg->metadata_max % lfs->cfg->prog_size == 0); + LFS_ASSERT(!lfs->cfg->metadata_max + || lfs->cfg->block_size % lfs->cfg->metadata_max == 0); + + // setup read cache + if (lfs->cfg->read_buffer) { + lfs->rcache.buffer = lfs->cfg->read_buffer; + } else { + lfs->rcache.buffer = lfs_malloc(lfs->cfg->cache_size); + if (!lfs->rcache.buffer) { + err = LFS_ERR_NOMEM; + goto cleanup; + } + } + + // setup program cache + if (lfs->cfg->prog_buffer) { + lfs->pcache.buffer = lfs->cfg->prog_buffer; + } else { + lfs->pcache.buffer = lfs_malloc(lfs->cfg->cache_size); + if (!lfs->pcache.buffer) { + err = LFS_ERR_NOMEM; + goto cleanup; + } + } + + // zero to avoid information leaks + lfs_cache_zero(lfs, &lfs->rcache); + lfs_cache_zero(lfs, &lfs->pcache); + + // setup lookahead buffer, note mount finishes initializing this after + // we establish a decent pseudo-random seed + LFS_ASSERT(lfs->cfg->lookahead_size > 0); + if (lfs->cfg->lookahead_buffer) { + lfs->lookahead.buffer = lfs->cfg->lookahead_buffer; + } else { + lfs->lookahead.buffer = lfs_malloc(lfs->cfg->lookahead_size); + if (!lfs->lookahead.buffer) { + err = LFS_ERR_NOMEM; + goto cleanup; + } + } + + // check that the size limits are sane + LFS_ASSERT(lfs->cfg->name_max <= LFS_NAME_MAX); + lfs->name_max = lfs->cfg->name_max; + if (!lfs->name_max) { + lfs->name_max = LFS_NAME_MAX; + } + + LFS_ASSERT(lfs->cfg->file_max <= LFS_FILE_MAX); + lfs->file_max = lfs->cfg->file_max; + if (!lfs->file_max) { + lfs->file_max = LFS_FILE_MAX; + } + + LFS_ASSERT(lfs->cfg->attr_max <= LFS_ATTR_MAX); + lfs->attr_max = lfs->cfg->attr_max; + if (!lfs->attr_max) { + lfs->attr_max = LFS_ATTR_MAX; + } + + LFS_ASSERT(lfs->cfg->metadata_max <= lfs->cfg->block_size); + + LFS_ASSERT(lfs->cfg->inline_max == (lfs_size_t)-1 + || lfs->cfg->inline_max <= lfs->cfg->cache_size); + LFS_ASSERT(lfs->cfg->inline_max == (lfs_size_t)-1 + || lfs->cfg->inline_max <= lfs->attr_max); + LFS_ASSERT(lfs->cfg->inline_max == (lfs_size_t)-1 + || lfs->cfg->inline_max <= ((lfs->cfg->metadata_max) + ? lfs->cfg->metadata_max + : lfs->cfg->block_size)/8); + lfs->inline_max = lfs->cfg->inline_max; + if (lfs->inline_max == (lfs_size_t)-1) { + lfs->inline_max = 0; + } else if (lfs->inline_max == 0) { + lfs->inline_max = lfs_min( + lfs->cfg->cache_size, + lfs_min( + lfs->attr_max, + ((lfs->cfg->metadata_max) + ? lfs->cfg->metadata_max + : lfs->cfg->block_size)/8)); + } + + // setup default state + lfs->root[0] = LFS_BLOCK_NULL; + lfs->root[1] = LFS_BLOCK_NULL; + lfs->mlist = NULL; + lfs->seed = 0; + lfs->gdisk = (lfs_gstate_t){0}; + lfs->gstate = (lfs_gstate_t){0}; + lfs->gdelta = (lfs_gstate_t){0}; +#ifdef LFS_MIGRATE + lfs->lfs1 = NULL; +#endif + + return 0; + +cleanup: + lfs_deinit(lfs); + return err; +} + +static int lfs_deinit(lfs_t *lfs) { + // free allocated memory + if (!lfs->cfg->read_buffer) { + lfs_free(lfs->rcache.buffer); + } + + if (!lfs->cfg->prog_buffer) { + lfs_free(lfs->pcache.buffer); + } + + if (!lfs->cfg->lookahead_buffer) { + lfs_free(lfs->lookahead.buffer); + } + + return 0; +} + + + +#ifndef LFS_READONLY +static int lfs_format_(lfs_t *lfs, const struct lfs_config *cfg) { + int err = 0; + { + err = lfs_init(lfs, cfg); + if (err) { + return err; + } + + LFS_ASSERT(cfg->block_count != 0); + + // create free lookahead + memset(lfs->lookahead.buffer, 0, lfs->cfg->lookahead_size); + lfs->lookahead.start = 0; + lfs->lookahead.size = lfs_min(8*lfs->cfg->lookahead_size, + lfs->block_count); + lfs->lookahead.next = 0; + lfs_alloc_ckpoint(lfs); + + // create root dir + lfs_mdir_t root; + err = lfs_dir_alloc(lfs, &root); + if (err) { + goto cleanup; + } + + // write one superblock + lfs_superblock_t superblock = { + .version = lfs_fs_disk_version(lfs), + .block_size = lfs->cfg->block_size, + .block_count = lfs->block_count, + .name_max = lfs->name_max, + .file_max = lfs->file_max, + .attr_max = lfs->attr_max, + }; + + lfs_superblock_tole32(&superblock); + err = lfs_dir_commit(lfs, &root, LFS_MKATTRS( + {LFS_MKTAG(LFS_TYPE_CREATE, 0, 0), NULL}, + {LFS_MKTAG(LFS_TYPE_SUPERBLOCK, 0, 8), "littlefs"}, + {LFS_MKTAG(LFS_TYPE_INLINESTRUCT, 0, sizeof(superblock)), + &superblock})); + if (err) { + goto cleanup; + } + + // force compaction to prevent accidentally mounting any + // older version of littlefs that may live on disk + root.erased = false; + err = lfs_dir_commit(lfs, &root, NULL, 0); + if (err) { + goto cleanup; + } + + // sanity check that fetch works + err = lfs_dir_fetch(lfs, &root, (const lfs_block_t[2]){0, 1}); + if (err) { + goto cleanup; + } + } + +cleanup: + lfs_deinit(lfs); + return err; + +} +#endif + +struct lfs_tortoise_t { + lfs_block_t pair[2]; + lfs_size_t i; + lfs_size_t period; +}; + +static int lfs_tortoise_detectcycles( + const lfs_mdir_t *dir, struct lfs_tortoise_t *tortoise) { + // detect cycles with Brent's algorithm + if (lfs_pair_issync(dir->tail, tortoise->pair)) { + LFS_WARN("Cycle detected in tail list"); + return LFS_ERR_CORRUPT; + } + if (tortoise->i == tortoise->period) { + tortoise->pair[0] = dir->tail[0]; + tortoise->pair[1] = dir->tail[1]; + tortoise->i = 0; + tortoise->period *= 2; + } + tortoise->i += 1; + + return LFS_ERR_OK; +} + +static int lfs_mount_(lfs_t *lfs, const struct lfs_config *cfg) { + int err = lfs_init(lfs, cfg); + if (err) { + return err; + } + + // scan directory blocks for superblock and any global updates + lfs_mdir_t dir = {.tail = {0, 1}}; + struct lfs_tortoise_t tortoise = { + .pair = {LFS_BLOCK_NULL, LFS_BLOCK_NULL}, + .i = 1, + .period = 1, + }; + while (!lfs_pair_isnull(dir.tail)) { + err = lfs_tortoise_detectcycles(&dir, &tortoise); + if (err < 0) { + goto cleanup; + } + + // fetch next block in tail list + lfs_stag_t tag = lfs_dir_fetchmatch(lfs, &dir, dir.tail, + LFS_MKTAG(0x7ff, 0x3ff, 0), + LFS_MKTAG(LFS_TYPE_SUPERBLOCK, 0, 8), + NULL, + lfs_dir_find_match, &(struct lfs_dir_find_match){ + lfs, "littlefs", 8}); + if (tag < 0) { + err = tag; + goto cleanup; + } + + // has superblock? + if (tag && !lfs_tag_isdelete(tag)) { + // update root + lfs->root[0] = dir.pair[0]; + lfs->root[1] = dir.pair[1]; + + // grab superblock + lfs_superblock_t superblock; + tag = lfs_dir_get(lfs, &dir, LFS_MKTAG(0x7ff, 0x3ff, 0), + LFS_MKTAG(LFS_TYPE_INLINESTRUCT, 0, sizeof(superblock)), + &superblock); + if (tag < 0) { + err = tag; + goto cleanup; + } + lfs_superblock_fromle32(&superblock); + + // check version + uint16_t major_version = (0xffff & (superblock.version >> 16)); + uint16_t minor_version = (0xffff & (superblock.version >> 0)); + if (major_version != lfs_fs_disk_version_major(lfs) + || minor_version > lfs_fs_disk_version_minor(lfs)) { + LFS_ERROR("Invalid version " + "v%"PRIu16".%"PRIu16" != v%"PRIu16".%"PRIu16, + major_version, + minor_version, + lfs_fs_disk_version_major(lfs), + lfs_fs_disk_version_minor(lfs)); + err = LFS_ERR_INVAL; + goto cleanup; + } + + // found older minor version? set an in-device only bit in the + // gstate so we know we need to rewrite the superblock before + // the first write + bool needssuperblock = false; + if (minor_version < lfs_fs_disk_version_minor(lfs)) { + LFS_DEBUG("Found older minor version " + "v%"PRIu16".%"PRIu16" < v%"PRIu16".%"PRIu16, + major_version, + minor_version, + lfs_fs_disk_version_major(lfs), + lfs_fs_disk_version_minor(lfs)); + needssuperblock = true; + } + // note this bit is reserved on disk, so fetching more gstate + // will not interfere here + lfs_fs_prepsuperblock(lfs, needssuperblock); + + // check superblock configuration + if (superblock.name_max) { + if (superblock.name_max > lfs->name_max) { + LFS_ERROR("Unsupported name_max (%"PRIu32" > %"PRIu32")", + superblock.name_max, lfs->name_max); + err = LFS_ERR_INVAL; + goto cleanup; + } + + lfs->name_max = superblock.name_max; + } + + if (superblock.file_max) { + if (superblock.file_max > lfs->file_max) { + LFS_ERROR("Unsupported file_max (%"PRIu32" > %"PRIu32")", + superblock.file_max, lfs->file_max); + err = LFS_ERR_INVAL; + goto cleanup; + } + + lfs->file_max = superblock.file_max; + } + + if (superblock.attr_max) { + if (superblock.attr_max > lfs->attr_max) { + LFS_ERROR("Unsupported attr_max (%"PRIu32" > %"PRIu32")", + superblock.attr_max, lfs->attr_max); + err = LFS_ERR_INVAL; + goto cleanup; + } + + lfs->attr_max = superblock.attr_max; + + // we also need to update inline_max in case attr_max changed + lfs->inline_max = lfs_min(lfs->inline_max, lfs->attr_max); + } + + // this is where we get the block_count from disk if block_count=0 + if (lfs->cfg->block_count + && superblock.block_count != lfs->cfg->block_count) { + LFS_ERROR("Invalid block count (%"PRIu32" != %"PRIu32")", + superblock.block_count, lfs->cfg->block_count); + err = LFS_ERR_INVAL; + goto cleanup; + } + + lfs->block_count = superblock.block_count; + + if (superblock.block_size != lfs->cfg->block_size) { + LFS_ERROR("Invalid block size (%"PRIu32" != %"PRIu32")", + superblock.block_size, lfs->cfg->block_size); + err = LFS_ERR_INVAL; + goto cleanup; + } + } + + // has gstate? + err = lfs_dir_getgstate(lfs, &dir, &lfs->gstate); + if (err) { + goto cleanup; + } + } + + // update littlefs with gstate + if (!lfs_gstate_iszero(&lfs->gstate)) { + LFS_DEBUG("Found pending gstate 0x%08"PRIx32"%08"PRIx32"%08"PRIx32, + lfs->gstate.tag, + lfs->gstate.pair[0], + lfs->gstate.pair[1]); + } + lfs->gstate.tag += !lfs_tag_isvalid(lfs->gstate.tag); + lfs->gdisk = lfs->gstate; + + // setup free lookahead, to distribute allocations uniformly across + // boots, we start the allocator at a random location + lfs->lookahead.start = lfs->seed % lfs->block_count; + lfs_alloc_drop(lfs); + + return 0; + +cleanup: + lfs_unmount_(lfs); + return err; +} + +static int lfs_unmount_(lfs_t *lfs) { + return lfs_deinit(lfs); +} + + +/// Filesystem filesystem operations /// +static int lfs_fs_stat_(lfs_t *lfs, struct lfs_fsinfo *fsinfo) { + // if the superblock is up-to-date, we must be on the most recent + // minor version of littlefs + if (!lfs_gstate_needssuperblock(&lfs->gstate)) { + fsinfo->disk_version = lfs_fs_disk_version(lfs); + + // otherwise we need to read the minor version on disk + } else { + // fetch the superblock + lfs_mdir_t dir; + int err = lfs_dir_fetch(lfs, &dir, lfs->root); + if (err) { + return err; + } + + lfs_superblock_t superblock; + lfs_stag_t tag = lfs_dir_get(lfs, &dir, LFS_MKTAG(0x7ff, 0x3ff, 0), + LFS_MKTAG(LFS_TYPE_INLINESTRUCT, 0, sizeof(superblock)), + &superblock); + if (tag < 0) { + return tag; + } + lfs_superblock_fromle32(&superblock); + + // read the on-disk version + fsinfo->disk_version = superblock.version; + } + + // filesystem geometry + fsinfo->block_size = lfs->cfg->block_size; + fsinfo->block_count = lfs->block_count; + + // other on-disk configuration, we cache all of these for internal use + fsinfo->name_max = lfs->name_max; + fsinfo->file_max = lfs->file_max; + fsinfo->attr_max = lfs->attr_max; + + return 0; +} + +int lfs_fs_traverse_(lfs_t *lfs, + int (*cb)(void *data, lfs_block_t block), void *data, + bool includeorphans) { + // iterate over metadata pairs + lfs_mdir_t dir = {.tail = {0, 1}}; + +#ifdef LFS_MIGRATE + // also consider v1 blocks during migration + if (lfs->lfs1) { + int err = lfs1_traverse(lfs, cb, data); + if (err) { + return err; + } + + dir.tail[0] = lfs->root[0]; + dir.tail[1] = lfs->root[1]; + } +#endif + + struct lfs_tortoise_t tortoise = { + .pair = {LFS_BLOCK_NULL, LFS_BLOCK_NULL}, + .i = 1, + .period = 1, + }; + int err = LFS_ERR_OK; + while (!lfs_pair_isnull(dir.tail)) { + err = lfs_tortoise_detectcycles(&dir, &tortoise); + if (err < 0) { + return LFS_ERR_CORRUPT; + } + + for (int i = 0; i < 2; i++) { + int err = cb(data, dir.tail[i]); + if (err) { + return err; + } + } + + // iterate through ids in directory + int err = lfs_dir_fetch(lfs, &dir, dir.tail); + if (err) { + return err; + } + + for (uint16_t id = 0; id < dir.count; id++) { + struct lfs_ctz ctz; + lfs_stag_t tag = lfs_dir_get(lfs, &dir, LFS_MKTAG(0x700, 0x3ff, 0), + LFS_MKTAG(LFS_TYPE_STRUCT, id, sizeof(ctz)), &ctz); + if (tag < 0) { + if (tag == LFS_ERR_NOENT) { + continue; + } + return tag; + } + lfs_ctz_fromle32(&ctz); + + if (lfs_tag_type3(tag) == LFS_TYPE_CTZSTRUCT) { + err = lfs_ctz_traverse(lfs, NULL, &lfs->rcache, + ctz.head, ctz.size, cb, data); + if (err) { + return err; + } + } else if (includeorphans && + lfs_tag_type3(tag) == LFS_TYPE_DIRSTRUCT) { + for (int i = 0; i < 2; i++) { + err = cb(data, (&ctz.head)[i]); + if (err) { + return err; + } + } + } + } + } + +#ifndef LFS_READONLY + // iterate over any open files + for (lfs_file_t *f = (lfs_file_t*)lfs->mlist; f; f = f->next) { + if (f->type != LFS_TYPE_REG) { + continue; + } + + if (((f->flags & LFS_F_DIRTY) || (f->flags & LFS_F_DUSTY)) + && !(f->flags & LFS_F_INLINE)) { + int err = lfs_ctz_traverse(lfs, &f->cache, &lfs->rcache, + f->ctz.head, f->ctz.size, cb, data); + if (err) { + return err; + } + } + + if ((f->flags & LFS_F_WRITING) && !(f->flags & LFS_F_INLINE)) { + int err = lfs_ctz_traverse(lfs, &f->cache, &lfs->rcache, + f->block, f->pos, cb, data); + if (err) { + return err; + } + } + } +#endif + + return 0; +} + +#ifndef LFS_READONLY +static int lfs_fs_pred(lfs_t *lfs, + const lfs_block_t pair[2], lfs_mdir_t *pdir) { + // iterate over all directory directory entries + pdir->tail[0] = 0; + pdir->tail[1] = 1; + struct lfs_tortoise_t tortoise = { + .pair = {LFS_BLOCK_NULL, LFS_BLOCK_NULL}, + .i = 1, + .period = 1, + }; + int err = LFS_ERR_OK; + while (!lfs_pair_isnull(pdir->tail)) { + err = lfs_tortoise_detectcycles(pdir, &tortoise); + if (err < 0) { + return LFS_ERR_CORRUPT; + } + + if (lfs_pair_cmp(pdir->tail, pair) == 0) { + return 0; + } + + int err = lfs_dir_fetch(lfs, pdir, pdir->tail); + if (err) { + return err; + } + } + + return LFS_ERR_NOENT; +} +#endif + +#ifndef LFS_READONLY +struct lfs_fs_parent_match { + lfs_t *lfs; + const lfs_block_t pair[2]; +}; +#endif + +#ifndef LFS_READONLY +static int lfs_fs_parent_match(void *data, + lfs_tag_t tag, const void *buffer) { + struct lfs_fs_parent_match *find = data; + lfs_t *lfs = find->lfs; + const struct lfs_diskoff *disk = buffer; + (void)tag; + + lfs_block_t child[2]; + int err = lfs_bd_read(lfs, + &lfs->pcache, &lfs->rcache, lfs->cfg->block_size, + disk->block, disk->off, &child, sizeof(child)); + if (err) { + return err; + } + + lfs_pair_fromle32(child); + return (lfs_pair_cmp(child, find->pair) == 0) ? LFS_CMP_EQ : LFS_CMP_LT; +} +#endif + +#ifndef LFS_READONLY +static lfs_stag_t lfs_fs_parent(lfs_t *lfs, const lfs_block_t pair[2], + lfs_mdir_t *parent) { + // use fetchmatch with callback to find pairs + parent->tail[0] = 0; + parent->tail[1] = 1; + struct lfs_tortoise_t tortoise = { + .pair = {LFS_BLOCK_NULL, LFS_BLOCK_NULL}, + .i = 1, + .period = 1, + }; + int err = LFS_ERR_OK; + while (!lfs_pair_isnull(parent->tail)) { + err = lfs_tortoise_detectcycles(parent, &tortoise); + if (err < 0) { + return err; + } + + lfs_stag_t tag = lfs_dir_fetchmatch(lfs, parent, parent->tail, + LFS_MKTAG(0x7ff, 0, 0x3ff), + LFS_MKTAG(LFS_TYPE_DIRSTRUCT, 0, 8), + NULL, + lfs_fs_parent_match, &(struct lfs_fs_parent_match){ + lfs, {pair[0], pair[1]}}); + if (tag && tag != LFS_ERR_NOENT) { + return tag; + } + } + + return LFS_ERR_NOENT; +} +#endif + +static void lfs_fs_prepsuperblock(lfs_t *lfs, bool needssuperblock) { + lfs->gstate.tag = (lfs->gstate.tag & ~LFS_MKTAG(0, 0, 0x200)) + | (uint32_t)needssuperblock << 9; +} + +#ifndef LFS_READONLY +static int lfs_fs_preporphans(lfs_t *lfs, int8_t orphans) { + LFS_ASSERT(lfs_tag_size(lfs->gstate.tag) > 0x000 || orphans >= 0); + LFS_ASSERT(lfs_tag_size(lfs->gstate.tag) < 0x1ff || orphans <= 0); + lfs->gstate.tag += orphans; + lfs->gstate.tag = ((lfs->gstate.tag & ~LFS_MKTAG(0x800, 0, 0)) | + ((uint32_t)lfs_gstate_hasorphans(&lfs->gstate) << 31)); + + return 0; +} +#endif + +#ifndef LFS_READONLY +static void lfs_fs_prepmove(lfs_t *lfs, + uint16_t id, const lfs_block_t pair[2]) { + lfs->gstate.tag = ((lfs->gstate.tag & ~LFS_MKTAG(0x7ff, 0x3ff, 0)) | + ((id != 0x3ff) ? LFS_MKTAG(LFS_TYPE_DELETE, id, 0) : 0)); + lfs->gstate.pair[0] = (id != 0x3ff) ? pair[0] : 0; + lfs->gstate.pair[1] = (id != 0x3ff) ? pair[1] : 0; +} +#endif + +#ifndef LFS_READONLY +static int lfs_fs_desuperblock(lfs_t *lfs) { + if (!lfs_gstate_needssuperblock(&lfs->gstate)) { + return 0; + } + + LFS_DEBUG("Rewriting superblock {0x%"PRIx32", 0x%"PRIx32"}", + lfs->root[0], + lfs->root[1]); + + lfs_mdir_t root; + int err = lfs_dir_fetch(lfs, &root, lfs->root); + if (err) { + return err; + } + + // write a new superblock + lfs_superblock_t superblock = { + .version = lfs_fs_disk_version(lfs), + .block_size = lfs->cfg->block_size, + .block_count = lfs->block_count, + .name_max = lfs->name_max, + .file_max = lfs->file_max, + .attr_max = lfs->attr_max, + }; + + lfs_superblock_tole32(&superblock); + err = lfs_dir_commit(lfs, &root, LFS_MKATTRS( + {LFS_MKTAG(LFS_TYPE_INLINESTRUCT, 0, sizeof(superblock)), + &superblock})); + if (err) { + return err; + } + + lfs_fs_prepsuperblock(lfs, false); + return 0; +} +#endif + +#ifndef LFS_READONLY +static int lfs_fs_demove(lfs_t *lfs) { + if (!lfs_gstate_hasmove(&lfs->gdisk)) { + return 0; + } + + // Fix bad moves + LFS_DEBUG("Fixing move {0x%"PRIx32", 0x%"PRIx32"} 0x%"PRIx16, + lfs->gdisk.pair[0], + lfs->gdisk.pair[1], + lfs_tag_id(lfs->gdisk.tag)); + + // no other gstate is supported at this time, so if we found something else + // something most likely went wrong in gstate calculation + LFS_ASSERT(lfs_tag_type3(lfs->gdisk.tag) == LFS_TYPE_DELETE); + + // fetch and delete the moved entry + lfs_mdir_t movedir; + int err = lfs_dir_fetch(lfs, &movedir, lfs->gdisk.pair); + if (err) { + return err; + } + + // prep gstate and delete move id + uint16_t moveid = lfs_tag_id(lfs->gdisk.tag); + lfs_fs_prepmove(lfs, 0x3ff, NULL); + err = lfs_dir_commit(lfs, &movedir, LFS_MKATTRS( + {LFS_MKTAG(LFS_TYPE_DELETE, moveid, 0), NULL})); + if (err) { + return err; + } + + return 0; +} +#endif + +#ifndef LFS_READONLY +static int lfs_fs_deorphan(lfs_t *lfs, bool powerloss) { + if (!lfs_gstate_hasorphans(&lfs->gstate)) { + return 0; + } + + // Check for orphans in two separate passes: + // - 1 for half-orphans (relocations) + // - 2 for full-orphans (removes/renames) + // + // Two separate passes are needed as half-orphans can contain outdated + // references to full-orphans, effectively hiding them from the deorphan + // search. + // + int pass = 0; + while (pass < 2) { + // Fix any orphans + lfs_mdir_t pdir = {.split = true, .tail = {0, 1}}; + lfs_mdir_t dir; + bool moreorphans = false; + + // iterate over all directory directory entries + while (!lfs_pair_isnull(pdir.tail)) { + int err = lfs_dir_fetch(lfs, &dir, pdir.tail); + if (err) { + return err; + } + + // check head blocks for orphans + if (!pdir.split) { + // check if we have a parent + lfs_mdir_t parent; + lfs_stag_t tag = lfs_fs_parent(lfs, pdir.tail, &parent); + if (tag < 0 && tag != LFS_ERR_NOENT) { + return tag; + } + + if (pass == 0 && tag != LFS_ERR_NOENT) { + lfs_block_t pair[2]; + lfs_stag_t state = lfs_dir_get(lfs, &parent, + LFS_MKTAG(0x7ff, 0x3ff, 0), tag, pair); + if (state < 0) { + return state; + } + lfs_pair_fromle32(pair); + + if (!lfs_pair_issync(pair, pdir.tail)) { + // we have desynced + LFS_DEBUG("Fixing half-orphan " + "{0x%"PRIx32", 0x%"PRIx32"} " + "-> {0x%"PRIx32", 0x%"PRIx32"}", + pdir.tail[0], pdir.tail[1], pair[0], pair[1]); + + // fix pending move in this pair? this looks like an + // optimization but is in fact _required_ since + // relocating may outdate the move. + uint16_t moveid = 0x3ff; + if (lfs_gstate_hasmovehere(&lfs->gstate, pdir.pair)) { + moveid = lfs_tag_id(lfs->gstate.tag); + LFS_DEBUG("Fixing move while fixing orphans " + "{0x%"PRIx32", 0x%"PRIx32"} 0x%"PRIx16"\n", + pdir.pair[0], pdir.pair[1], moveid); + lfs_fs_prepmove(lfs, 0x3ff, NULL); + } + + lfs_pair_tole32(pair); + state = lfs_dir_orphaningcommit(lfs, &pdir, LFS_MKATTRS( + {LFS_MKTAG_IF(moveid != 0x3ff, + LFS_TYPE_DELETE, moveid, 0), NULL}, + {LFS_MKTAG(LFS_TYPE_SOFTTAIL, 0x3ff, 8), + pair})); + lfs_pair_fromle32(pair); + if (state < 0) { + return state; + } + + // did our commit create more orphans? + if (state == LFS_OK_ORPHANED) { + moreorphans = true; + } + + // refetch tail + continue; + } + } + + // note we only check for full orphans if we may have had a + // power-loss, otherwise orphans are created intentionally + // during operations such as lfs_mkdir + if (pass == 1 && tag == LFS_ERR_NOENT && powerloss) { + // we are an orphan + LFS_DEBUG("Fixing orphan {0x%"PRIx32", 0x%"PRIx32"}", + pdir.tail[0], pdir.tail[1]); + + // steal state + err = lfs_dir_getgstate(lfs, &dir, &lfs->gdelta); + if (err) { + return err; + } + + // steal tail + lfs_pair_tole32(dir.tail); + int state = lfs_dir_orphaningcommit(lfs, &pdir, LFS_MKATTRS( + {LFS_MKTAG(LFS_TYPE_TAIL + dir.split, 0x3ff, 8), + dir.tail})); + lfs_pair_fromle32(dir.tail); + if (state < 0) { + return state; + } + + // did our commit create more orphans? + if (state == LFS_OK_ORPHANED) { + moreorphans = true; + } + + // refetch tail + continue; + } + } + + pdir = dir; + } + + pass = moreorphans ? 0 : pass+1; + } + + // mark orphans as fixed + return lfs_fs_preporphans(lfs, -lfs_gstate_getorphans(&lfs->gstate)); +} +#endif + +#ifndef LFS_READONLY +static int lfs_fs_forceconsistency(lfs_t *lfs) { + int err = lfs_fs_desuperblock(lfs); + if (err) { + return err; + } + + err = lfs_fs_demove(lfs); + if (err) { + return err; + } + + err = lfs_fs_deorphan(lfs, true); + if (err) { + return err; + } + + return 0; +} +#endif + +#ifndef LFS_READONLY +static int lfs_fs_mkconsistent_(lfs_t *lfs) { + // lfs_fs_forceconsistency does most of the work here + int err = lfs_fs_forceconsistency(lfs); + if (err) { + return err; + } + + // do we have any pending gstate? + lfs_gstate_t delta = {0}; + lfs_gstate_xor(&delta, &lfs->gdisk); + lfs_gstate_xor(&delta, &lfs->gstate); + if (!lfs_gstate_iszero(&delta)) { + // lfs_dir_commit will implicitly write out any pending gstate + lfs_mdir_t root; + err = lfs_dir_fetch(lfs, &root, lfs->root); + if (err) { + return err; + } + + err = lfs_dir_commit(lfs, &root, NULL, 0); + if (err) { + return err; + } + } + + return 0; +} +#endif + +static int lfs_fs_size_count(void *p, lfs_block_t block) { + (void)block; + lfs_size_t *size = p; + *size += 1; + return 0; +} + +static lfs_ssize_t lfs_fs_size_(lfs_t *lfs) { + lfs_size_t size = 0; + int err = lfs_fs_traverse_(lfs, lfs_fs_size_count, &size, false); + if (err) { + return err; + } + + return size; +} + +// explicit garbage collection +#ifndef LFS_READONLY +static int lfs_fs_gc_(lfs_t *lfs) { + // force consistency, even if we're not necessarily going to write, + // because this function is supposed to take care of janitorial work + // isn't it? + int err = lfs_fs_forceconsistency(lfs); + if (err) { + return err; + } + + // try to compact metadata pairs, note we can't really accomplish + // anything if compact_thresh doesn't at least leave a prog_size + // available + if (lfs->cfg->compact_thresh + < lfs->cfg->block_size - lfs->cfg->prog_size) { + // iterate over all mdirs + lfs_mdir_t mdir = {.tail = {0, 1}}; + while (!lfs_pair_isnull(mdir.tail)) { + err = lfs_dir_fetch(lfs, &mdir, mdir.tail); + if (err) { + return err; + } + + // not erased? exceeds our compaction threshold? + if (!mdir.erased || ((lfs->cfg->compact_thresh == 0) + ? mdir.off > lfs->cfg->block_size - lfs->cfg->block_size/8 + : mdir.off > lfs->cfg->compact_thresh)) { + // the easiest way to trigger a compaction is to mark + // the mdir as unerased and add an empty commit + mdir.erased = false; + err = lfs_dir_commit(lfs, &mdir, NULL, 0); + if (err) { + return err; + } + } + } + } + + // try to populate the lookahead buffer, unless it's already full + if (lfs->lookahead.size < lfs_min( + 8 * lfs->cfg->lookahead_size, + lfs->block_count)) { + err = lfs_alloc_scan(lfs); + if (err) { + return err; + } + } + + return 0; +} +#endif + +#ifndef LFS_READONLY +#ifdef LFS_SHRINKNONRELOCATING +static int lfs_shrink_checkblock(void *data, lfs_block_t block) { + lfs_size_t threshold = *((lfs_size_t*)data); + if (block >= threshold) { + return LFS_ERR_NOTEMPTY; + } + return 0; +} +#endif + +static int lfs_fs_grow_(lfs_t *lfs, lfs_size_t block_count) { + int err; + + if (block_count == lfs->block_count) { + return 0; + } + + +#ifndef LFS_SHRINKNONRELOCATING + // shrinking is not supported + LFS_ASSERT(block_count >= lfs->block_count); +#endif +#ifdef LFS_SHRINKNONRELOCATING + if (block_count < lfs->block_count) { + err = lfs_fs_traverse_(lfs, lfs_shrink_checkblock, &block_count, true); + if (err) { + return err; + } + } +#endif + + lfs->block_count = block_count; + + // fetch the root + lfs_mdir_t root; + err = lfs_dir_fetch(lfs, &root, lfs->root); + if (err) { + return err; + } + + // update the superblock + lfs_superblock_t superblock; + lfs_stag_t tag = lfs_dir_get(lfs, &root, LFS_MKTAG(0x7ff, 0x3ff, 0), + LFS_MKTAG(LFS_TYPE_INLINESTRUCT, 0, sizeof(superblock)), + &superblock); + if (tag < 0) { + return tag; + } + lfs_superblock_fromle32(&superblock); + + superblock.block_count = lfs->block_count; + + lfs_superblock_tole32(&superblock); + err = lfs_dir_commit(lfs, &root, LFS_MKATTRS( + {tag, &superblock})); + if (err) { + return err; + } + return 0; +} +#endif + +#ifdef LFS_MIGRATE +////// Migration from littelfs v1 below this ////// + +/// Version info /// + +// Software library version +// Major (top-nibble), incremented on backwards incompatible changes +// Minor (bottom-nibble), incremented on feature additions +#define LFS1_VERSION 0x00010007 +#define LFS1_VERSION_MAJOR (0xffff & (LFS1_VERSION >> 16)) +#define LFS1_VERSION_MINOR (0xffff & (LFS1_VERSION >> 0)) + +// Version of On-disk data structures +// Major (top-nibble), incremented on backwards incompatible changes +// Minor (bottom-nibble), incremented on feature additions +#define LFS1_DISK_VERSION 0x00010001 +#define LFS1_DISK_VERSION_MAJOR (0xffff & (LFS1_DISK_VERSION >> 16)) +#define LFS1_DISK_VERSION_MINOR (0xffff & (LFS1_DISK_VERSION >> 0)) + + +/// v1 Definitions /// + +// File types +enum lfs1_type { + LFS1_TYPE_REG = 0x11, + LFS1_TYPE_DIR = 0x22, + LFS1_TYPE_SUPERBLOCK = 0x2e, +}; + +typedef struct lfs1 { + lfs_block_t root[2]; +} lfs1_t; + +typedef struct lfs1_entry { + lfs_off_t off; + + struct lfs1_disk_entry { + uint8_t type; + uint8_t elen; + uint8_t alen; + uint8_t nlen; + union { + struct { + lfs_block_t head; + lfs_size_t size; + } file; + lfs_block_t dir[2]; + } u; + } d; +} lfs1_entry_t; + +typedef struct lfs1_dir { + struct lfs1_dir *next; + lfs_block_t pair[2]; + lfs_off_t off; + + lfs_block_t head[2]; + lfs_off_t pos; + + struct lfs1_disk_dir { + uint32_t rev; + lfs_size_t size; + lfs_block_t tail[2]; + } d; +} lfs1_dir_t; + +typedef struct lfs1_superblock { + lfs_off_t off; + + struct lfs1_disk_superblock { + uint8_t type; + uint8_t elen; + uint8_t alen; + uint8_t nlen; + lfs_block_t root[2]; + uint32_t block_size; + uint32_t block_count; + uint32_t version; + char magic[8]; + } d; +} lfs1_superblock_t; + + +/// Low-level wrappers v1->v2 /// +static void lfs1_crc(uint32_t *crc, const void *buffer, size_t size) { + *crc = lfs_crc(*crc, buffer, size); +} + +static int lfs1_bd_read(lfs_t *lfs, lfs_block_t block, + lfs_off_t off, void *buffer, lfs_size_t size) { + // if we ever do more than writes to alternating pairs, + // this may need to consider pcache + return lfs_bd_read(lfs, &lfs->pcache, &lfs->rcache, size, + block, off, buffer, size); +} + +static int lfs1_bd_crc(lfs_t *lfs, lfs_block_t block, + lfs_off_t off, lfs_size_t size, uint32_t *crc) { + for (lfs_off_t i = 0; i < size; i++) { + uint8_t c; + int err = lfs1_bd_read(lfs, block, off+i, &c, 1); + if (err) { + return err; + } + + lfs1_crc(crc, &c, 1); + } + + return 0; +} + + +/// Endian swapping functions /// +static void lfs1_dir_fromle32(struct lfs1_disk_dir *d) { + d->rev = lfs_fromle32(d->rev); + d->size = lfs_fromle32(d->size); + d->tail[0] = lfs_fromle32(d->tail[0]); + d->tail[1] = lfs_fromle32(d->tail[1]); +} + +static void lfs1_dir_tole32(struct lfs1_disk_dir *d) { + d->rev = lfs_tole32(d->rev); + d->size = lfs_tole32(d->size); + d->tail[0] = lfs_tole32(d->tail[0]); + d->tail[1] = lfs_tole32(d->tail[1]); +} + +static void lfs1_entry_fromle32(struct lfs1_disk_entry *d) { + d->u.dir[0] = lfs_fromle32(d->u.dir[0]); + d->u.dir[1] = lfs_fromle32(d->u.dir[1]); +} + +static void lfs1_entry_tole32(struct lfs1_disk_entry *d) { + d->u.dir[0] = lfs_tole32(d->u.dir[0]); + d->u.dir[1] = lfs_tole32(d->u.dir[1]); +} + +static void lfs1_superblock_fromle32(struct lfs1_disk_superblock *d) { + d->root[0] = lfs_fromle32(d->root[0]); + d->root[1] = lfs_fromle32(d->root[1]); + d->block_size = lfs_fromle32(d->block_size); + d->block_count = lfs_fromle32(d->block_count); + d->version = lfs_fromle32(d->version); +} + + +///// Metadata pair and directory operations /// +static inline lfs_size_t lfs1_entry_size(const lfs1_entry_t *entry) { + return 4 + entry->d.elen + entry->d.alen + entry->d.nlen; +} + +static int lfs1_dir_fetch(lfs_t *lfs, + lfs1_dir_t *dir, const lfs_block_t pair[2]) { + // copy out pair, otherwise may be aliasing dir + const lfs_block_t tpair[2] = {pair[0], pair[1]}; + bool valid = false; + + // check both blocks for the most recent revision + for (int i = 0; i < 2; i++) { + struct lfs1_disk_dir test; + int err = lfs1_bd_read(lfs, tpair[i], 0, &test, sizeof(test)); + lfs1_dir_fromle32(&test); + if (err) { + if (err == LFS_ERR_CORRUPT) { + continue; + } + return err; + } + + if (valid && lfs_scmp(test.rev, dir->d.rev) < 0) { + continue; + } + + if ((0x7fffffff & test.size) < sizeof(test)+4 || + (0x7fffffff & test.size) > lfs->cfg->block_size) { + continue; + } + + uint32_t crc = 0xffffffff; + lfs1_dir_tole32(&test); + lfs1_crc(&crc, &test, sizeof(test)); + lfs1_dir_fromle32(&test); + err = lfs1_bd_crc(lfs, tpair[i], sizeof(test), + (0x7fffffff & test.size) - sizeof(test), &crc); + if (err) { + if (err == LFS_ERR_CORRUPT) { + continue; + } + return err; + } + + if (crc != 0) { + continue; + } + + valid = true; + + // setup dir in case it's valid + dir->pair[0] = tpair[(i+0) % 2]; + dir->pair[1] = tpair[(i+1) % 2]; + dir->off = sizeof(dir->d); + dir->d = test; + } + + if (!valid) { + LFS_ERROR("Corrupted dir pair at {0x%"PRIx32", 0x%"PRIx32"}", + tpair[0], tpair[1]); + return LFS_ERR_CORRUPT; + } + + return 0; +} + +static int lfs1_dir_next(lfs_t *lfs, lfs1_dir_t *dir, lfs1_entry_t *entry) { + while (dir->off + sizeof(entry->d) > (0x7fffffff & dir->d.size)-4) { + if (!(0x80000000 & dir->d.size)) { + entry->off = dir->off; + return LFS_ERR_NOENT; + } + + int err = lfs1_dir_fetch(lfs, dir, dir->d.tail); + if (err) { + return err; + } + + dir->off = sizeof(dir->d); + dir->pos += sizeof(dir->d) + 4; + } + + int err = lfs1_bd_read(lfs, dir->pair[0], dir->off, + &entry->d, sizeof(entry->d)); + lfs1_entry_fromle32(&entry->d); + if (err) { + return err; + } + + entry->off = dir->off; + dir->off += lfs1_entry_size(entry); + dir->pos += lfs1_entry_size(entry); + return 0; +} + +/// littlefs v1 specific operations /// +int lfs1_traverse(lfs_t *lfs, int (*cb)(void*, lfs_block_t), void *data) { + if (lfs_pair_isnull(lfs->lfs1->root)) { + return 0; + } + + // iterate over metadata pairs + lfs1_dir_t dir; + lfs1_entry_t entry; + lfs_block_t cwd[2] = {0, 1}; + + while (true) { + for (int i = 0; i < 2; i++) { + int err = cb(data, cwd[i]); + if (err) { + return err; + } + } + + int err = lfs1_dir_fetch(lfs, &dir, cwd); + if (err) { + return err; + } + + // iterate over contents + while (dir.off + sizeof(entry.d) <= (0x7fffffff & dir.d.size)-4) { + err = lfs1_bd_read(lfs, dir.pair[0], dir.off, + &entry.d, sizeof(entry.d)); + lfs1_entry_fromle32(&entry.d); + if (err) { + return err; + } + + dir.off += lfs1_entry_size(&entry); + if ((0x70 & entry.d.type) == (0x70 & LFS1_TYPE_REG)) { + err = lfs_ctz_traverse(lfs, NULL, &lfs->rcache, + entry.d.u.file.head, entry.d.u.file.size, cb, data); + if (err) { + return err; + } + } + } + + // we also need to check if we contain a threaded v2 directory + lfs_mdir_t dir2 = {.split=true, .tail={cwd[0], cwd[1]}}; + while (dir2.split) { + err = lfs_dir_fetch(lfs, &dir2, dir2.tail); + if (err) { + break; + } + + for (int i = 0; i < 2; i++) { + err = cb(data, dir2.pair[i]); + if (err) { + return err; + } + } + } + + cwd[0] = dir.d.tail[0]; + cwd[1] = dir.d.tail[1]; + + if (lfs_pair_isnull(cwd)) { + break; + } + } + + return 0; +} + +static int lfs1_moved(lfs_t *lfs, const void *e) { + if (lfs_pair_isnull(lfs->lfs1->root)) { + return 0; + } + + // skip superblock + lfs1_dir_t cwd; + int err = lfs1_dir_fetch(lfs, &cwd, (const lfs_block_t[2]){0, 1}); + if (err) { + return err; + } + + // iterate over all directory directory entries + lfs1_entry_t entry; + while (!lfs_pair_isnull(cwd.d.tail)) { + err = lfs1_dir_fetch(lfs, &cwd, cwd.d.tail); + if (err) { + return err; + } + + while (true) { + err = lfs1_dir_next(lfs, &cwd, &entry); + if (err && err != LFS_ERR_NOENT) { + return err; + } + + if (err == LFS_ERR_NOENT) { + break; + } + + if (!(0x80 & entry.d.type) && + memcmp(&entry.d.u, e, sizeof(entry.d.u)) == 0) { + return true; + } + } + } + + return false; +} + +/// Filesystem operations /// +static int lfs1_mount(lfs_t *lfs, struct lfs1 *lfs1, + const struct lfs_config *cfg) { + int err = 0; + { + err = lfs_init(lfs, cfg); + if (err) { + return err; + } + + lfs->lfs1 = lfs1; + lfs->lfs1->root[0] = LFS_BLOCK_NULL; + lfs->lfs1->root[1] = LFS_BLOCK_NULL; + + // setup free lookahead + lfs->lookahead.start = 0; + lfs->lookahead.size = 0; + lfs->lookahead.next = 0; + lfs_alloc_ckpoint(lfs); + + // load superblock + lfs1_dir_t dir; + lfs1_superblock_t superblock; + err = lfs1_dir_fetch(lfs, &dir, (const lfs_block_t[2]){0, 1}); + if (err && err != LFS_ERR_CORRUPT) { + goto cleanup; + } + + if (!err) { + err = lfs1_bd_read(lfs, dir.pair[0], sizeof(dir.d), + &superblock.d, sizeof(superblock.d)); + lfs1_superblock_fromle32(&superblock.d); + if (err) { + goto cleanup; + } + + lfs->lfs1->root[0] = superblock.d.root[0]; + lfs->lfs1->root[1] = superblock.d.root[1]; + } + + if (err || memcmp(superblock.d.magic, "littlefs", 8) != 0) { + LFS_ERROR("Invalid superblock at {0x%"PRIx32", 0x%"PRIx32"}", + 0, 1); + err = LFS_ERR_CORRUPT; + goto cleanup; + } + + uint16_t major_version = (0xffff & (superblock.d.version >> 16)); + uint16_t minor_version = (0xffff & (superblock.d.version >> 0)); + if ((major_version != LFS1_DISK_VERSION_MAJOR || + minor_version > LFS1_DISK_VERSION_MINOR)) { + LFS_ERROR("Invalid version v%d.%d", major_version, minor_version); + err = LFS_ERR_INVAL; + goto cleanup; + } + + return 0; + } + +cleanup: + lfs_deinit(lfs); + return err; +} + +static int lfs1_unmount(lfs_t *lfs) { + return lfs_deinit(lfs); +} + +/// v1 migration /// +static int lfs_migrate_(lfs_t *lfs, const struct lfs_config *cfg) { + struct lfs1 lfs1; + + // Indeterminate filesystem size not allowed for migration. + LFS_ASSERT(cfg->block_count != 0); + + int err = lfs1_mount(lfs, &lfs1, cfg); + if (err) { + return err; + } + + { + // iterate through each directory, copying over entries + // into new directory + lfs1_dir_t dir1; + lfs_mdir_t dir2; + dir1.d.tail[0] = lfs->lfs1->root[0]; + dir1.d.tail[1] = lfs->lfs1->root[1]; + while (!lfs_pair_isnull(dir1.d.tail)) { + // iterate old dir + err = lfs1_dir_fetch(lfs, &dir1, dir1.d.tail); + if (err) { + goto cleanup; + } + + // create new dir and bind as temporary pretend root + err = lfs_dir_alloc(lfs, &dir2); + if (err) { + goto cleanup; + } + + dir2.rev = dir1.d.rev; + dir1.head[0] = dir1.pair[0]; + dir1.head[1] = dir1.pair[1]; + lfs->root[0] = dir2.pair[0]; + lfs->root[1] = dir2.pair[1]; + + err = lfs_dir_commit(lfs, &dir2, NULL, 0); + if (err) { + goto cleanup; + } + + while (true) { + lfs1_entry_t entry1; + err = lfs1_dir_next(lfs, &dir1, &entry1); + if (err && err != LFS_ERR_NOENT) { + goto cleanup; + } + + if (err == LFS_ERR_NOENT) { + break; + } + + // check that entry has not been moved + if (entry1.d.type & 0x80) { + int moved = lfs1_moved(lfs, &entry1.d.u); + if (moved < 0) { + err = moved; + goto cleanup; + } + + if (moved) { + continue; + } + + entry1.d.type &= ~0x80; + } + + // also fetch name + char name[LFS_NAME_MAX+1]; + memset(name, 0, sizeof(name)); + err = lfs1_bd_read(lfs, dir1.pair[0], + entry1.off + 4+entry1.d.elen+entry1.d.alen, + name, entry1.d.nlen); + if (err) { + goto cleanup; + } + + bool isdir = (entry1.d.type == LFS1_TYPE_DIR); + + // create entry in new dir + err = lfs_dir_fetch(lfs, &dir2, lfs->root); + if (err) { + goto cleanup; + } + + uint16_t id; + err = lfs_dir_find(lfs, &dir2, &(const char*){name}, &id); + if (!(err == LFS_ERR_NOENT && id != 0x3ff)) { + err = (err < 0) ? err : LFS_ERR_EXIST; + goto cleanup; + } + + lfs1_entry_tole32(&entry1.d); + err = lfs_dir_commit(lfs, &dir2, LFS_MKATTRS( + {LFS_MKTAG(LFS_TYPE_CREATE, id, 0), NULL}, + {LFS_MKTAG_IF_ELSE(isdir, + LFS_TYPE_DIR, id, entry1.d.nlen, + LFS_TYPE_REG, id, entry1.d.nlen), + name}, + {LFS_MKTAG_IF_ELSE(isdir, + LFS_TYPE_DIRSTRUCT, id, sizeof(entry1.d.u), + LFS_TYPE_CTZSTRUCT, id, sizeof(entry1.d.u)), + &entry1.d.u})); + lfs1_entry_fromle32(&entry1.d); + if (err) { + goto cleanup; + } + } + + if (!lfs_pair_isnull(dir1.d.tail)) { + // find last block and update tail to thread into fs + err = lfs_dir_fetch(lfs, &dir2, lfs->root); + if (err) { + goto cleanup; + } + + while (dir2.split) { + err = lfs_dir_fetch(lfs, &dir2, dir2.tail); + if (err) { + goto cleanup; + } + } + + lfs_pair_tole32(dir2.pair); + err = lfs_dir_commit(lfs, &dir2, LFS_MKATTRS( + {LFS_MKTAG(LFS_TYPE_SOFTTAIL, 0x3ff, 8), dir1.d.tail})); + lfs_pair_fromle32(dir2.pair); + if (err) { + goto cleanup; + } + } + + // Copy over first block to thread into fs. Unfortunately + // if this fails there is not much we can do. + LFS_DEBUG("Migrating {0x%"PRIx32", 0x%"PRIx32"} " + "-> {0x%"PRIx32", 0x%"PRIx32"}", + lfs->root[0], lfs->root[1], dir1.head[0], dir1.head[1]); + + err = lfs_bd_erase(lfs, dir1.head[1]); + if (err) { + goto cleanup; + } + + err = lfs_dir_fetch(lfs, &dir2, lfs->root); + if (err) { + goto cleanup; + } + + for (lfs_off_t i = 0; i < dir2.off; i++) { + uint8_t dat; + err = lfs_bd_read(lfs, + NULL, &lfs->rcache, dir2.off, + dir2.pair[0], i, &dat, 1); + if (err) { + goto cleanup; + } + + err = lfs_bd_prog(lfs, + &lfs->pcache, &lfs->rcache, true, + dir1.head[1], i, &dat, 1); + if (err) { + goto cleanup; + } + } + + err = lfs_bd_flush(lfs, &lfs->pcache, &lfs->rcache, true); + if (err) { + goto cleanup; + } + } + + // Create new superblock. This marks a successful migration! + err = lfs1_dir_fetch(lfs, &dir1, (const lfs_block_t[2]){0, 1}); + if (err) { + goto cleanup; + } + + dir2.pair[0] = dir1.pair[0]; + dir2.pair[1] = dir1.pair[1]; + dir2.rev = dir1.d.rev; + dir2.off = sizeof(dir2.rev); + dir2.etag = 0xffffffff; + dir2.count = 0; + dir2.tail[0] = lfs->lfs1->root[0]; + dir2.tail[1] = lfs->lfs1->root[1]; + dir2.erased = false; + dir2.split = true; + + lfs_superblock_t superblock = { + .version = LFS_DISK_VERSION, + .block_size = lfs->cfg->block_size, + .block_count = lfs->cfg->block_count, + .name_max = lfs->name_max, + .file_max = lfs->file_max, + .attr_max = lfs->attr_max, + }; + + lfs_superblock_tole32(&superblock); + err = lfs_dir_commit(lfs, &dir2, LFS_MKATTRS( + {LFS_MKTAG(LFS_TYPE_CREATE, 0, 0), NULL}, + {LFS_MKTAG(LFS_TYPE_SUPERBLOCK, 0, 8), "littlefs"}, + {LFS_MKTAG(LFS_TYPE_INLINESTRUCT, 0, sizeof(superblock)), + &superblock})); + if (err) { + goto cleanup; + } + + // sanity check that fetch works + err = lfs_dir_fetch(lfs, &dir2, (const lfs_block_t[2]){0, 1}); + if (err) { + goto cleanup; + } + + // force compaction to prevent accidentally mounting v1 + dir2.erased = false; + err = lfs_dir_commit(lfs, &dir2, NULL, 0); + if (err) { + goto cleanup; + } + } + +cleanup: + lfs1_unmount(lfs); + return err; +} + +#endif + + +/// Public API wrappers /// + +// Here we can add tracing/thread safety easily + +// Thread-safe wrappers if enabled +#ifdef LFS_THREADSAFE +#define LFS_LOCK(cfg) cfg->lock(cfg) +#define LFS_UNLOCK(cfg) cfg->unlock(cfg) +#else +#define LFS_LOCK(cfg) ((void)cfg, 0) +#define LFS_UNLOCK(cfg) ((void)cfg) +#endif + +// Public API +#ifndef LFS_READONLY +int lfs_format(lfs_t *lfs, const struct lfs_config *cfg) { + int err = LFS_LOCK(cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_format(%p, %p {.context=%p, " + ".read=%p, .prog=%p, .erase=%p, .sync=%p, " + ".read_size=%"PRIu32", .prog_size=%"PRIu32", " + ".block_size=%"PRIu32", .block_count=%"PRIu32", " + ".block_cycles=%"PRId32", .cache_size=%"PRIu32", " + ".lookahead_size=%"PRIu32", .read_buffer=%p, " + ".prog_buffer=%p, .lookahead_buffer=%p, " + ".name_max=%"PRIu32", .file_max=%"PRIu32", " + ".attr_max=%"PRIu32"})", + (void*)lfs, (void*)cfg, cfg->context, + (void*)(uintptr_t)cfg->read, (void*)(uintptr_t)cfg->prog, + (void*)(uintptr_t)cfg->erase, (void*)(uintptr_t)cfg->sync, + cfg->read_size, cfg->prog_size, cfg->block_size, cfg->block_count, + cfg->block_cycles, cfg->cache_size, cfg->lookahead_size, + cfg->read_buffer, cfg->prog_buffer, cfg->lookahead_buffer, + cfg->name_max, cfg->file_max, cfg->attr_max); + + err = lfs_format_(lfs, cfg); + + LFS_TRACE("lfs_format -> %d", err); + LFS_UNLOCK(cfg); + return err; +} +#endif + +int lfs_mount(lfs_t *lfs, const struct lfs_config *cfg) { + int err = LFS_LOCK(cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_mount(%p, %p {.context=%p, " + ".read=%p, .prog=%p, .erase=%p, .sync=%p, " + ".read_size=%"PRIu32", .prog_size=%"PRIu32", " + ".block_size=%"PRIu32", .block_count=%"PRIu32", " + ".block_cycles=%"PRId32", .cache_size=%"PRIu32", " + ".lookahead_size=%"PRIu32", .read_buffer=%p, " + ".prog_buffer=%p, .lookahead_buffer=%p, " + ".name_max=%"PRIu32", .file_max=%"PRIu32", " + ".attr_max=%"PRIu32"})", + (void*)lfs, (void*)cfg, cfg->context, + (void*)(uintptr_t)cfg->read, (void*)(uintptr_t)cfg->prog, + (void*)(uintptr_t)cfg->erase, (void*)(uintptr_t)cfg->sync, + cfg->read_size, cfg->prog_size, cfg->block_size, cfg->block_count, + cfg->block_cycles, cfg->cache_size, cfg->lookahead_size, + cfg->read_buffer, cfg->prog_buffer, cfg->lookahead_buffer, + cfg->name_max, cfg->file_max, cfg->attr_max); + + err = lfs_mount_(lfs, cfg); + + LFS_TRACE("lfs_mount -> %d", err); + LFS_UNLOCK(cfg); + return err; +} + +int lfs_unmount(lfs_t *lfs) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_unmount(%p)", (void*)lfs); + + err = lfs_unmount_(lfs); + + LFS_TRACE("lfs_unmount -> %d", err); + LFS_UNLOCK(lfs->cfg); + return err; +} + +#ifndef LFS_READONLY +int lfs_remove(lfs_t *lfs, const char *path) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_remove(%p, \"%s\")", (void*)lfs, path); + + err = lfs_remove_(lfs, path); + + LFS_TRACE("lfs_remove -> %d", err); + LFS_UNLOCK(lfs->cfg); + return err; +} +#endif + +#ifndef LFS_READONLY +int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_rename(%p, \"%s\", \"%s\")", (void*)lfs, oldpath, newpath); + + err = lfs_rename_(lfs, oldpath, newpath); + + LFS_TRACE("lfs_rename -> %d", err); + LFS_UNLOCK(lfs->cfg); + return err; +} +#endif + +int lfs_stat(lfs_t *lfs, const char *path, struct lfs_info *info) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_stat(%p, \"%s\", %p)", (void*)lfs, path, (void*)info); + + err = lfs_stat_(lfs, path, info); + + LFS_TRACE("lfs_stat -> %d", err); + LFS_UNLOCK(lfs->cfg); + return err; +} + +lfs_ssize_t lfs_getattr(lfs_t *lfs, const char *path, + uint8_t type, void *buffer, lfs_size_t size) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_getattr(%p, \"%s\", %"PRIu8", %p, %"PRIu32")", + (void*)lfs, path, type, buffer, size); + + lfs_ssize_t res = lfs_getattr_(lfs, path, type, buffer, size); + + LFS_TRACE("lfs_getattr -> %"PRId32, res); + LFS_UNLOCK(lfs->cfg); + return res; +} + +#ifndef LFS_READONLY +int lfs_setattr(lfs_t *lfs, const char *path, + uint8_t type, const void *buffer, lfs_size_t size) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_setattr(%p, \"%s\", %"PRIu8", %p, %"PRIu32")", + (void*)lfs, path, type, buffer, size); + + err = lfs_setattr_(lfs, path, type, buffer, size); + + LFS_TRACE("lfs_setattr -> %d", err); + LFS_UNLOCK(lfs->cfg); + return err; +} +#endif + +#ifndef LFS_READONLY +int lfs_removeattr(lfs_t *lfs, const char *path, uint8_t type) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_removeattr(%p, \"%s\", %"PRIu8")", (void*)lfs, path, type); + + err = lfs_removeattr_(lfs, path, type); + + LFS_TRACE("lfs_removeattr -> %d", err); + LFS_UNLOCK(lfs->cfg); + return err; +} +#endif + +#ifndef LFS_NO_MALLOC +int lfs_file_open(lfs_t *lfs, lfs_file_t *file, const char *path, int flags) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_file_open(%p, %p, \"%s\", %x)", + (void*)lfs, (void*)file, path, (unsigned)flags); + LFS_ASSERT(!lfs_mlist_isopen(lfs->mlist, (struct lfs_mlist*)file)); + + err = lfs_file_open_(lfs, file, path, flags); + + LFS_TRACE("lfs_file_open -> %d", err); + LFS_UNLOCK(lfs->cfg); + return err; +} +#endif + +int lfs_file_opencfg(lfs_t *lfs, lfs_file_t *file, + const char *path, int flags, + const struct lfs_file_config *cfg) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_file_opencfg(%p, %p, \"%s\", %x, %p {" + ".buffer=%p, .attrs=%p, .attr_count=%"PRIu32"})", + (void*)lfs, (void*)file, path, (unsigned)flags, + (void*)cfg, cfg->buffer, (void*)cfg->attrs, cfg->attr_count); + LFS_ASSERT(!lfs_mlist_isopen(lfs->mlist, (struct lfs_mlist*)file)); + + err = lfs_file_opencfg_(lfs, file, path, flags, cfg); + + LFS_TRACE("lfs_file_opencfg -> %d", err); + LFS_UNLOCK(lfs->cfg); + return err; +} + +int lfs_file_close(lfs_t *lfs, lfs_file_t *file) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_file_close(%p, %p)", (void*)lfs, (void*)file); + LFS_ASSERT(lfs_mlist_isopen(lfs->mlist, (struct lfs_mlist*)file)); + + err = lfs_file_close_(lfs, file); + + LFS_TRACE("lfs_file_close -> %d", err); + LFS_UNLOCK(lfs->cfg); + return err; +} + +#ifndef LFS_READONLY +int lfs_file_sync(lfs_t *lfs, lfs_file_t *file) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_file_sync(%p, %p)", (void*)lfs, (void*)file); + LFS_ASSERT(lfs_mlist_isopen(lfs->mlist, (struct lfs_mlist*)file)); + + err = lfs_file_sync_(lfs, file); + + LFS_TRACE("lfs_file_sync -> %d", err); + LFS_UNLOCK(lfs->cfg); + return err; +} +#endif + +lfs_ssize_t lfs_file_read(lfs_t *lfs, lfs_file_t *file, + void *buffer, lfs_size_t size) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_file_read(%p, %p, %p, %"PRIu32")", + (void*)lfs, (void*)file, buffer, size); + LFS_ASSERT(lfs_mlist_isopen(lfs->mlist, (struct lfs_mlist*)file)); + + lfs_ssize_t res = lfs_file_read_(lfs, file, buffer, size); + + LFS_TRACE("lfs_file_read -> %"PRId32, res); + LFS_UNLOCK(lfs->cfg); + return res; +} + +#ifndef LFS_READONLY +lfs_ssize_t lfs_file_write(lfs_t *lfs, lfs_file_t *file, + const void *buffer, lfs_size_t size) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_file_write(%p, %p, %p, %"PRIu32")", + (void*)lfs, (void*)file, buffer, size); + LFS_ASSERT(lfs_mlist_isopen(lfs->mlist, (struct lfs_mlist*)file)); + + lfs_ssize_t res = lfs_file_write_(lfs, file, buffer, size); + + LFS_TRACE("lfs_file_write -> %"PRId32, res); + LFS_UNLOCK(lfs->cfg); + return res; +} +#endif + +lfs_soff_t lfs_file_seek(lfs_t *lfs, lfs_file_t *file, + lfs_soff_t off, int whence) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_file_seek(%p, %p, %"PRId32", %d)", + (void*)lfs, (void*)file, off, whence); + LFS_ASSERT(lfs_mlist_isopen(lfs->mlist, (struct lfs_mlist*)file)); + + lfs_soff_t res = lfs_file_seek_(lfs, file, off, whence); + + LFS_TRACE("lfs_file_seek -> %"PRId32, res); + LFS_UNLOCK(lfs->cfg); + return res; +} + +#ifndef LFS_READONLY +int lfs_file_truncate(lfs_t *lfs, lfs_file_t *file, lfs_off_t size) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_file_truncate(%p, %p, %"PRIu32")", + (void*)lfs, (void*)file, size); + LFS_ASSERT(lfs_mlist_isopen(lfs->mlist, (struct lfs_mlist*)file)); + + err = lfs_file_truncate_(lfs, file, size); + + LFS_TRACE("lfs_file_truncate -> %d", err); + LFS_UNLOCK(lfs->cfg); + return err; +} +#endif + +lfs_soff_t lfs_file_tell(lfs_t *lfs, lfs_file_t *file) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_file_tell(%p, %p)", (void*)lfs, (void*)file); + LFS_ASSERT(lfs_mlist_isopen(lfs->mlist, (struct lfs_mlist*)file)); + + lfs_soff_t res = lfs_file_tell_(lfs, file); + + LFS_TRACE("lfs_file_tell -> %"PRId32, res); + LFS_UNLOCK(lfs->cfg); + return res; +} + +int lfs_file_rewind(lfs_t *lfs, lfs_file_t *file) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_file_rewind(%p, %p)", (void*)lfs, (void*)file); + + err = lfs_file_rewind_(lfs, file); + + LFS_TRACE("lfs_file_rewind -> %d", err); + LFS_UNLOCK(lfs->cfg); + return err; +} + +lfs_soff_t lfs_file_size(lfs_t *lfs, lfs_file_t *file) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_file_size(%p, %p)", (void*)lfs, (void*)file); + LFS_ASSERT(lfs_mlist_isopen(lfs->mlist, (struct lfs_mlist*)file)); + + lfs_soff_t res = lfs_file_size_(lfs, file); + + LFS_TRACE("lfs_file_size -> %"PRIu32, res); + LFS_UNLOCK(lfs->cfg); + return res; +} + +#ifndef LFS_READONLY +int lfs_mkdir(lfs_t *lfs, const char *path) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_mkdir(%p, \"%s\")", (void*)lfs, path); + + err = lfs_mkdir_(lfs, path); + + LFS_TRACE("lfs_mkdir -> %d", err); + LFS_UNLOCK(lfs->cfg); + return err; +} +#endif + +int lfs_dir_open(lfs_t *lfs, lfs_dir_t *dir, const char *path) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_dir_open(%p, %p, \"%s\")", (void*)lfs, (void*)dir, path); + LFS_ASSERT(!lfs_mlist_isopen(lfs->mlist, (struct lfs_mlist*)dir)); + + err = lfs_dir_open_(lfs, dir, path); + + LFS_TRACE("lfs_dir_open -> %d", err); + LFS_UNLOCK(lfs->cfg); + return err; +} + +int lfs_dir_close(lfs_t *lfs, lfs_dir_t *dir) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_dir_close(%p, %p)", (void*)lfs, (void*)dir); + + err = lfs_dir_close_(lfs, dir); + + LFS_TRACE("lfs_dir_close -> %d", err); + LFS_UNLOCK(lfs->cfg); + return err; +} + +int lfs_dir_read(lfs_t *lfs, lfs_dir_t *dir, struct lfs_info *info) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_dir_read(%p, %p, %p)", + (void*)lfs, (void*)dir, (void*)info); + + err = lfs_dir_read_(lfs, dir, info); + + LFS_TRACE("lfs_dir_read -> %d", err); + LFS_UNLOCK(lfs->cfg); + return err; +} + +int lfs_dir_seek(lfs_t *lfs, lfs_dir_t *dir, lfs_off_t off) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_dir_seek(%p, %p, %"PRIu32")", + (void*)lfs, (void*)dir, off); + + err = lfs_dir_seek_(lfs, dir, off); + + LFS_TRACE("lfs_dir_seek -> %d", err); + LFS_UNLOCK(lfs->cfg); + return err; +} + +lfs_soff_t lfs_dir_tell(lfs_t *lfs, lfs_dir_t *dir) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_dir_tell(%p, %p)", (void*)lfs, (void*)dir); + + lfs_soff_t res = lfs_dir_tell_(lfs, dir); + + LFS_TRACE("lfs_dir_tell -> %"PRId32, res); + LFS_UNLOCK(lfs->cfg); + return res; +} + +int lfs_dir_rewind(lfs_t *lfs, lfs_dir_t *dir) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_dir_rewind(%p, %p)", (void*)lfs, (void*)dir); + + err = lfs_dir_rewind_(lfs, dir); + + LFS_TRACE("lfs_dir_rewind -> %d", err); + LFS_UNLOCK(lfs->cfg); + return err; +} + +int lfs_fs_stat(lfs_t *lfs, struct lfs_fsinfo *fsinfo) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_fs_stat(%p, %p)", (void*)lfs, (void*)fsinfo); + + err = lfs_fs_stat_(lfs, fsinfo); + + LFS_TRACE("lfs_fs_stat -> %d", err); + LFS_UNLOCK(lfs->cfg); + return err; +} + +lfs_ssize_t lfs_fs_size(lfs_t *lfs) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_fs_size(%p)", (void*)lfs); + + lfs_ssize_t res = lfs_fs_size_(lfs); + + LFS_TRACE("lfs_fs_size -> %"PRId32, res); + LFS_UNLOCK(lfs->cfg); + return res; +} + +int lfs_fs_traverse(lfs_t *lfs, int (*cb)(void *, lfs_block_t), void *data) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_fs_traverse(%p, %p, %p)", + (void*)lfs, (void*)(uintptr_t)cb, data); + + err = lfs_fs_traverse_(lfs, cb, data, true); + + LFS_TRACE("lfs_fs_traverse -> %d", err); + LFS_UNLOCK(lfs->cfg); + return err; +} + +#ifndef LFS_READONLY +int lfs_fs_mkconsistent(lfs_t *lfs) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_fs_mkconsistent(%p)", (void*)lfs); + + err = lfs_fs_mkconsistent_(lfs); + + LFS_TRACE("lfs_fs_mkconsistent -> %d", err); + LFS_UNLOCK(lfs->cfg); + return err; +} +#endif + +#ifndef LFS_READONLY +int lfs_fs_gc(lfs_t *lfs) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_fs_gc(%p)", (void*)lfs); + + err = lfs_fs_gc_(lfs); + + LFS_TRACE("lfs_fs_gc -> %d", err); + LFS_UNLOCK(lfs->cfg); + return err; +} +#endif + +#ifndef LFS_READONLY +int lfs_fs_grow(lfs_t *lfs, lfs_size_t block_count) { + int err = LFS_LOCK(lfs->cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_fs_grow(%p, %"PRIu32")", (void*)lfs, block_count); + + err = lfs_fs_grow_(lfs, block_count); + + LFS_TRACE("lfs_fs_grow -> %d", err); + LFS_UNLOCK(lfs->cfg); + return err; +} +#endif + +#ifdef LFS_MIGRATE +int lfs_migrate(lfs_t *lfs, const struct lfs_config *cfg) { + int err = LFS_LOCK(cfg); + if (err) { + return err; + } + LFS_TRACE("lfs_migrate(%p, %p {.context=%p, " + ".read=%p, .prog=%p, .erase=%p, .sync=%p, " + ".read_size=%"PRIu32", .prog_size=%"PRIu32", " + ".block_size=%"PRIu32", .block_count=%"PRIu32", " + ".block_cycles=%"PRId32", .cache_size=%"PRIu32", " + ".lookahead_size=%"PRIu32", .read_buffer=%p, " + ".prog_buffer=%p, .lookahead_buffer=%p, " + ".name_max=%"PRIu32", .file_max=%"PRIu32", " + ".attr_max=%"PRIu32"})", + (void*)lfs, (void*)cfg, cfg->context, + (void*)(uintptr_t)cfg->read, (void*)(uintptr_t)cfg->prog, + (void*)(uintptr_t)cfg->erase, (void*)(uintptr_t)cfg->sync, + cfg->read_size, cfg->prog_size, cfg->block_size, cfg->block_count, + cfg->block_cycles, cfg->cache_size, cfg->lookahead_size, + cfg->read_buffer, cfg->prog_buffer, cfg->lookahead_buffer, + cfg->name_max, cfg->file_max, cfg->attr_max); + + err = lfs_migrate_(lfs, cfg); + + LFS_TRACE("lfs_migrate -> %d", err); + LFS_UNLOCK(cfg); + return err; +} +#endif + diff --git a/library/littlefs/lfs_crc.c b/library/littlefs/lfs_crc.c new file mode 100644 index 0000000..e205aea --- /dev/null +++ b/library/littlefs/lfs_crc.c @@ -0,0 +1,20 @@ +#include "lfs_util.h" + +// Software CRC implementation with small lookup table +uint32_t lfs_crc(uint32_t crc, const void *buffer, size_t size) { + static const uint32_t rtable[16] = { + 0x00000000, 0x1db71064, 0x3b6e20c8, 0x26d930ac, + 0x76dc4190, 0x6b6b51f4, 0x4db26158, 0x5005713c, + 0xedb88320, 0xf00f9344, 0xd6d6a3e8, 0xcb61b38c, + 0x9b64c2b0, 0x86d3d2d4, 0xa00ae278, 0xbdbdf21c, + }; + + const uint8_t *data = buffer; + + for (size_t i = 0; i < size; i++) { + crc = (crc >> 4) ^ rtable[(crc ^ (data[i] >> 0)) & 0xf]; + crc = (crc >> 4) ^ rtable[(crc ^ (data[i] >> 4)) & 0xf]; + } + + return crc; +} diff --git a/library/littlefs/lfs_filebd.c b/library/littlefs/lfs_filebd.c new file mode 100644 index 0000000..d1614b9 --- /dev/null +++ b/library/littlefs/lfs_filebd.c @@ -0,0 +1,168 @@ +/* + * Block device emulated in a file + * + * Copyright (c) 2022, The littlefs authors. + * Copyright (c) 2017, Arm Limited. All rights reserved. + * SPDX-License-Identifier: BSD-3-Clause + */ +#include "lfs_filebd.h" + +#include +#include +#include + +#ifdef _WIN32 +#include +#endif + +int lfs_filebd_create(const struct lfs_config *cfg, const char *path, + const struct lfs_filebd_config *bdcfg) { + LFS_FILEBD_TRACE("lfs_filebd_create(%p {.context=%p, " + ".read=%p, .prog=%p, .erase=%p, .sync=%p}, " + "\"%s\", " + "%p {.read_size=%"PRIu32", .prog_size=%"PRIu32", " + ".erase_size=%"PRIu32", .erase_count=%"PRIu32"})", + (void*)cfg, cfg->context, + (void*)(uintptr_t)cfg->read, (void*)(uintptr_t)cfg->prog, + (void*)(uintptr_t)cfg->erase, (void*)(uintptr_t)cfg->sync, + path, + (void*)bdcfg, + bdcfg->read_size, bdcfg->prog_size, bdcfg->erase_size, + bdcfg->erase_count); + lfs_filebd_t *bd = cfg->context; + bd->cfg = bdcfg; + + // open file + #ifdef _WIN32 + bd->fd = open(path, O_RDWR | O_CREAT | O_BINARY, 0666); + #else + bd->fd = open(path, O_RDWR | O_CREAT, 0666); + #endif + + if (bd->fd < 0) { + int err = -errno; + LFS_FILEBD_TRACE("lfs_filebd_create -> %d", err); + return err; + } + + LFS_FILEBD_TRACE("lfs_filebd_create -> %d", 0); + return 0; +} + +int lfs_filebd_destroy(const struct lfs_config *cfg) { + LFS_FILEBD_TRACE("lfs_filebd_destroy(%p)", (void*)cfg); + lfs_filebd_t *bd = cfg->context; + int err = close(bd->fd); + if (err < 0) { + err = -errno; + LFS_FILEBD_TRACE("lfs_filebd_destroy -> %d", err); + return err; + } + LFS_FILEBD_TRACE("lfs_filebd_destroy -> %d", 0); + return 0; +} + +int lfs_filebd_read(const struct lfs_config *cfg, lfs_block_t block, + lfs_off_t off, void *buffer, lfs_size_t size) { + LFS_FILEBD_TRACE("lfs_filebd_read(%p, " + "0x%"PRIx32", %"PRIu32", %p, %"PRIu32")", + (void*)cfg, block, off, buffer, size); + lfs_filebd_t *bd = cfg->context; + + // check if read is valid + LFS_ASSERT(block < bd->cfg->erase_count); + LFS_ASSERT(off % bd->cfg->read_size == 0); + LFS_ASSERT(size % bd->cfg->read_size == 0); + LFS_ASSERT(off+size <= bd->cfg->erase_size); + + // zero for reproducibility (in case file is truncated) + memset(buffer, 0, size); + + // read + off_t res1 = lseek(bd->fd, + (off_t)block*bd->cfg->erase_size + (off_t)off, SEEK_SET); + if (res1 < 0) { + int err = -errno; + LFS_FILEBD_TRACE("lfs_filebd_read -> %d", err); + return err; + } + + ssize_t res2 = read(bd->fd, buffer, size); + if (res2 < 0) { + int err = -errno; + LFS_FILEBD_TRACE("lfs_filebd_read -> %d", err); + return err; + } + + LFS_FILEBD_TRACE("lfs_filebd_read -> %d", 0); + return 0; +} + +int lfs_filebd_prog(const struct lfs_config *cfg, lfs_block_t block, + lfs_off_t off, const void *buffer, lfs_size_t size) { + LFS_FILEBD_TRACE("lfs_filebd_prog(%p, " + "0x%"PRIx32", %"PRIu32", %p, %"PRIu32")", + (void*)cfg, block, off, buffer, size); + lfs_filebd_t *bd = cfg->context; + + // check if write is valid + LFS_ASSERT(block < bd->cfg->erase_count); + LFS_ASSERT(off % bd->cfg->prog_size == 0); + LFS_ASSERT(size % bd->cfg->prog_size == 0); + LFS_ASSERT(off+size <= bd->cfg->erase_size); + + // program data + off_t res1 = lseek(bd->fd, + (off_t)block*bd->cfg->erase_size + (off_t)off, SEEK_SET); + if (res1 < 0) { + int err = -errno; + LFS_FILEBD_TRACE("lfs_filebd_prog -> %d", err); + return err; + } + + ssize_t res2 = write(bd->fd, buffer, size); + if (res2 < 0) { + int err = -errno; + LFS_FILEBD_TRACE("lfs_filebd_prog -> %d", err); + return err; + } + + LFS_FILEBD_TRACE("lfs_filebd_prog -> %d", 0); + return 0; +} + +int lfs_filebd_erase(const struct lfs_config *cfg, lfs_block_t block) { + LFS_FILEBD_TRACE("lfs_filebd_erase(%p, 0x%"PRIx32" (%"PRIu32"))", + (void*)cfg, block, ((lfs_filebd_t*)cfg->context)->cfg->erase_size); + lfs_filebd_t *bd = cfg->context; + + // check if erase is valid + LFS_ASSERT(block < bd->cfg->erase_count); + + // erase is a noop + (void)block; + (void)bd; + + LFS_FILEBD_TRACE("lfs_filebd_erase -> %d", 0); + return 0; +} + +int lfs_filebd_sync(const struct lfs_config *cfg) { + LFS_FILEBD_TRACE("lfs_filebd_sync(%p)", (void*)cfg); + + // file sync + lfs_filebd_t *bd = cfg->context; + #ifdef _WIN32 + int err = FlushFileBuffers((HANDLE) _get_osfhandle(bd->fd)) ? 0 : -1; + #else + int err = fsync(bd->fd); + #endif + if (err) { + err = -errno; + LFS_FILEBD_TRACE("lfs_filebd_sync -> %d", 0); + return err; + } + + LFS_FILEBD_TRACE("lfs_filebd_sync -> %d", 0); + return 0; +} diff --git a/library/littlefs/lfs_flashbd.c b/library/littlefs/lfs_flashbd.c new file mode 100644 index 0000000..3846727 --- /dev/null +++ b/library/littlefs/lfs_flashbd.c @@ -0,0 +1,149 @@ +/* + * LittleFS block device adapter for W25QXX SPI Flash + * + * Maps littlefs read/prog/erase/sync callbacks to the W25QXX driver: + * read -> W25QXX_Read + * prog -> W25QXX_Write_NoCheck (littleFS guarantees erase-before-prog) + * erase -> W25QXX_Erase_Sector (4 KiB sector) + * sync -> W25QXX_Wait_Busy + */ +#include "lfs_flashbd.h" +#include "../../bspMCU/include/w25qxx.h" +#include + +int lfs_flashbd_create(const struct lfs_config *cfg, + const struct lfs_flashbd_config *bdcfg) { + lfs_flashbd_t *bd = (lfs_flashbd_t *)cfg->context; + + /* 参数校验 */ + if (bdcfg->base_addr % LFS_FLASHBD_SECTOR_SIZE != 0) { + return LFS_ERR_INVAL; + } + if (bdcfg->block_count == 0) { + return LFS_ERR_INVAL; + } + + bd->cfg = bdcfg; + + /* 初始化 W25QXX Flash */ + W25QXX_Init(); + + return LFS_ERR_OK; +} + +int lfs_flashbd_destroy(const struct lfs_config *cfg) { + (void)cfg; + return LFS_ERR_OK; +} + +int lfs_flashbd_read(const struct lfs_config *cfg, lfs_block_t block, + lfs_off_t off, void *buffer, lfs_size_t size) { + lfs_flashbd_t *bd = (lfs_flashbd_t *)cfg->context; + + LFS_ASSERT(block < bd->cfg->block_count); + LFS_ASSERT(off + size <= cfg->block_size); + + uint32_t addr = bd->cfg->base_addr + + (uint32_t)block * cfg->block_size + + (uint32_t)off; + + W25QXX_Read((uint8_t *)buffer, addr, (uint16_t)size); + + return LFS_ERR_OK; +} + +int lfs_flashbd_prog(const struct lfs_config *cfg, lfs_block_t block, + lfs_off_t off, const void *buffer, lfs_size_t size) { + lfs_flashbd_t *bd = (lfs_flashbd_t *)cfg->context; + + LFS_ASSERT(block < bd->cfg->block_count); + LFS_ASSERT(off + size <= cfg->block_size); + + uint32_t addr = bd->cfg->base_addr + + (uint32_t)block * cfg->block_size + + (uint32_t)off; + + /* + * W25QXX_Write_NoCheck 的第一个参数是 uint8_t*（非 const）， + * 但该函数只读取 buffer 内容，不会修改，故安全地去除 const。 + * littleFS 保证写入前块已擦除，因此无需带擦除的 W25QXX_Write。 + */ + W25QXX_Write_NoCheck((uint8_t *)(uintptr_t)buffer, addr, (uint16_t)size); + + return LFS_ERR_OK; +} + +int lfs_flashbd_erase(const struct lfs_config *cfg, lfs_block_t block) { + lfs_flashbd_t *bd = (lfs_flashbd_t *)cfg->context; + + LFS_ASSERT(block < bd->cfg->block_count); + + uint32_t addr = bd->cfg->base_addr + + (uint32_t)block * cfg->block_size; + + /* + * W25QXX_Erase_Sector 的参数是扇区号（内部会乘以 4096）， + * 所以传入字节地址除以扇区大小。 + */ + W25QXX_Erase_Sector(addr / LFS_FLASHBD_SECTOR_SIZE); + + return LFS_ERR_OK; +} + +int lfs_flashbd_sync(const struct lfs_config *cfg) { + (void)cfg; + W25QXX_Wait_Busy(); + return LFS_ERR_OK; +} + +void lfs_flashbd_default_config( + struct lfs_config *cfg, + lfs_flashbd_t *bd, + struct lfs_flashbd_config *bdcfg, + uint32_t base_addr, + uint32_t block_count, + void *read_buffer, + void *prog_buffer, + void *lookahead_buffer) { + memset(cfg, 0, sizeof(*cfg)); + + /* flashbd 配置 */ + bdcfg->base_addr = base_addr; + bdcfg->block_count = block_count; + + bd->cfg = bdcfg; + + /* 回调函数 */ + cfg->context = bd; + cfg->read = lfs_flashbd_read; + cfg->prog = lfs_flashbd_prog; + cfg->erase = lfs_flashbd_erase; + cfg->sync = lfs_flashbd_sync; + + /* 块设备参数 */ + cfg->read_size = 256; /* W25QXX 页大小，读取可任意长度 */ + cfg->prog_size = 256; /* W25QXX 页编程大小 */ + cfg->block_size = LFS_FLASHBD_SECTOR_SIZE; /* 4096 字节扇区 */ + cfg->block_count = block_count; + cfg->block_cycles = 500; /* 磨损均衡建议值 */ + cfg->cache_size = 256; /* 缓存大小 = prog_size */ + + /* + * lookahead 缓存是一个位图，每字节跟踪 8 个块。按块数自动计算， + * 保证一次分配扫描即可覆盖全部块（块数向上取整到字节）。 + * RAM 消耗 = ceil(block_count / 8) 字节，例如 3072 块 -> 384 字节。 + * 注意：若调用者提供静态 lookahead_buffer，其大小必须 >= 该值。 + */ + cfg->lookahead_size = (block_count + 7) / 8; + cfg->compact_thresh = 0; /* 使用默认值 */ + + /* 静态缓冲区，NULL 则由 littleFS 动态分配 */ + cfg->read_buffer = read_buffer; + cfg->prog_buffer = prog_buffer; + cfg->lookahead_buffer = lookahead_buffer; + + /* 使用默认值 */ + cfg->name_max = 0; + cfg->file_max = 0; + cfg->attr_max = 0; +} diff --git a/library/littlefs/lfs_util.c b/library/littlefs/lfs_util.c new file mode 100644 index 0000000..dac72ab --- /dev/null +++ b/library/littlefs/lfs_util.c @@ -0,0 +1,37 @@ +/* + * lfs util functions + * + * Copyright (c) 2022, The littlefs authors. + * Copyright (c) 2017, Arm Limited. All rights reserved. + * SPDX-License-Identifier: BSD-3-Clause + */ +#include "lfs_util.h" + +// Only compile if user does not provide custom config +#ifndef LFS_CONFIG + + +// If user provides their own CRC impl we don't need this +#ifndef LFS_CRC +// Software CRC implementation with small lookup table +uint32_t lfs_crc(uint32_t crc, const void *buffer, size_t size) { + static const uint32_t rtable[16] = { + 0x00000000, 0x1db71064, 0x3b6e20c8, 0x26d930ac, + 0x76dc4190, 0x6b6b51f4, 0x4db26158, 0x5005713c, + 0xedb88320, 0xf00f9344, 0xd6d6a3e8, 0xcb61b38c, + 0x9b64c2b0, 0x86d3d2d4, 0xa00ae278, 0xbdbdf21c, + }; + + const uint8_t *data = buffer; + + for (size_t i = 0; i < size; i++) { + crc = (crc >> 4) ^ rtable[(crc ^ (data[i] >> 0)) & 0xf]; + crc = (crc >> 4) ^ rtable[(crc ^ (data[i] >> 4)) & 0xf]; + } + + return crc; +} +#endif + + +#endif