Mbed OS Reference | lfs.h Source File

 /*
  * The little filesystem
  *
  * Copyright (c) 2017, Arm Limited. All rights reserved.
  * SPDX-License-Identifier: BSD-3-Clause
  */
 #ifndef LFS_H
 #define LFS_H
 
 #include <stdint.h>
 #include <stdbool.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 0x00010006
 #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 0x00010001
 #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;
 
 // Max name size in bytes
 #ifndef LFS_NAME_MAX
 #define LFS_NAME_MAX 255
 #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  = -52,  // 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_INVAL    = -22,  // Invalid parameter
     LFS_ERR_NOSPC    = -28,  // No space left on device
     LFS_ERR_NOMEM    = -12,  // No more memory available
 };
 
 // File types
 enum lfs_type {
     LFS_TYPE_REG        = 0x11,
     LFS_TYPE_DIR        = 0x22,
     LFS_TYPE_SUPERBLOCK = 0x2e,
 };
 
 // File open flags
 enum lfs_open_flags {
     // open flags
     LFS_O_RDONLY = 1,        // Open a file as read only
     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
 
     // internally used flags
     LFS_F_DIRTY   = 0x10000, // File does not match storage
     LFS_F_WRITING = 0x20000, // File has been written since last flush
     LFS_F_READING = 0x40000, // File has been read since last flush
     LFS_F_ERRED   = 0x80000, // An error occurred during write
 };
 
 // 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 propogated
     // 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 propogated 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 propogated 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 propogated to the user.
     int (*sync)(const struct lfs_config *c);
 
     // Minimum size of a block read. This determines the size of read buffers.
     // This may be larger than the physical read size to improve performance
     // by caching more of the block device.
     lfs_size_t read_size;
 
     // Minimum size of a block program. This determines the size of program
     // buffers. This may be larger than the physical program size to improve
     // performance by caching more of the block device.
     // Must be a multiple of the read size.
     lfs_size_t prog_size;
 
     // Size of an erasable block. This does not impact ram consumption and
     // may be larger than the physical erase size. However, this should be
     // kept small as each file currently takes up an entire block.
     // Must be a multiple of the program size.
     lfs_size_t block_size;
 
     // Number of erasable blocks on the device.
     lfs_size_t block_count;
 
     // Number of blocks to lookahead during block allocation. A larger
     // lookahead reduces the number of passes required to allocate a block.
     // The lookahead buffer requires only 1 bit per block so it can be quite
     // large with little ram impact. Should be a multiple of 32.
     lfs_size_t lookahead;
 
     // Optional, statically allocated read buffer. Must be read sized.
     void *read_buffer;
 
     // Optional, statically allocated program buffer. Must be program sized.
     void *prog_buffer;
 
     // Optional, statically allocated lookahead buffer. Must be 1 bit per
     // lookahead block.
     void *lookahead_buffer;
 
     // Optional, statically allocated buffer for files. Must be program sized.
     // If enabled, only one file may be opened at a time.
     void *file_buffer;
 };
 
 // Optional configuration provided during lfs_file_opencfg
 struct lfs_file_config {
     // Optional, statically allocated buffer for files. Must be program sized.
     // If NULL, malloc will be used by default.
     void *buffer;
 };
 
 // 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
     lfs_size_t size;
 
     // Name of the file stored as a null-terminated string
     char name[LFS_NAME_MAX+1];
 };
 
 
 /// littlefs data structures ///
 typedef struct lfs_entry {
     lfs_off_t off;
 
     struct lfs_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;
 } lfs_entry_t;
 
 typedef struct lfs_cache {
     lfs_block_t block;
     lfs_off_t off;
     uint8_t *buffer;
 } lfs_cache_t;
 
 typedef struct lfs_file {
     struct lfs_file *next;
     lfs_block_t pair[2];
     lfs_off_t poff;
 
     lfs_block_t head;
     lfs_size_t size;
 
     const struct lfs_file_config *cfg;
     uint32_t flags;
     lfs_off_t pos;
     lfs_block_t block;
     lfs_off_t off;
     lfs_cache_t cache;
 } lfs_file_t;
 
 typedef struct lfs_dir {
     struct lfs_dir *next;
     lfs_block_t pair[2];
     lfs_off_t off;
 
     lfs_block_t head[2];
     lfs_off_t pos;
 
     struct lfs_disk_dir {
         uint32_t rev;
         lfs_size_t size;
         lfs_block_t tail[2];
     } d;
 } lfs_dir_t;
 
 typedef struct lfs_superblock {
     lfs_off_t off;
 
     struct lfs_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;
 } lfs_superblock_t;
 
 typedef struct lfs_free {
     lfs_block_t off;
     lfs_block_t size;
     lfs_block_t i;
     lfs_block_t ack;
     uint32_t *buffer;
 } lfs_free_t;
 
 // The littlefs type
 typedef struct lfs {
     const struct lfs_config *cfg;
 
     lfs_block_t root[2];
     lfs_file_t *files;
     lfs_dir_t *dirs;
 
     lfs_cache_t rcache;
     lfs_cache_t pcache;
 
     lfs_free_t free;
     bool deorphaned;
 } lfs_t;
 
 
 /// Filesystem functions ///
 
 // 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);
 
 // 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 ///
 
 // 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);
 
 // 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);
 
 // 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);
 
 
 /// File operations ///
 
 // 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);
 
 // 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 be 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);
 
 // 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);
 
 // Change the position of the file
 //
 // The change in position is determined by the offset and whence flag.
 // Returns the old 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);
 
 // 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);
 
 // 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_CUR)
 // 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 ///
 
 // Create a directory
 //
 // Returns a negative error code on failure.
 int lfs_mkdir(lfs_t *lfs, const char *path);
 
 // 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 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);
 
 
 /// Miscellaneous littlefs specific operations ///
 
 // 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_traverse(lfs_t *lfs, int (*cb)(void*, lfs_block_t), void *data);
 
 // Prunes any recoverable errors that may have occurred in the filesystem
 //
 // Not needed to be called by user unless an operation is interrupted
 // but the filesystem is still mounted. This is already called on first
 // allocation.
 //
 // Returns a negative error code on failure.
 int lfs_deorphan(lfs_t *lfs);
 
 
 #ifdef __cplusplus
 } /* extern "C" */
 #endif
 
 #endif
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