/*
 * The little filesystem
 *
 * 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 0x00020002
#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 0x00020000
#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
#if defined(LFS_NAME_LIMIT) && \
        LFS_NAME_LIMIT > 0 && LFS_NAME_MAX <= 1022
#define LFS_NAME_MAX LFS_NAME_LIMIT
#else
#define LFS_NAME_MAX 255
#endif
#endif

// Maximum size of a file in bytes, may be redefined to limit to support other
// drivers. Limited on disk to <= 4294967296. However, above 2147483647 the
// functions lfs_file_seek, lfs_file_size, and lfs_file_tell will return
// incorrect values due to using signed integers. Stored in superblock and
// must be respected by other littlefs drivers.
#ifndef LFS_FILE_MAX
#if defined(LFS_FILE_LIMIT) && \
        LFS_FILE_LIMIT > 0 && LFS_FILE_LIMIT <= 4294967296
#define LFS_FILE_MAX LFS_FILE_LIMIT
#else
#define LFS_FILE_MAX 2147483647
#endif
#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.
#ifndef LFS_ATTR_MAX
#if defined(LFS_ATTR_LIMIT) && \
        LFS_ATTR_LIMIT > 0 && LFS_ATTR_LIMIT <= 1022
#define LFS_ATTR_MAX LFS_FILE_LIMIT
#else
#define LFS_ATTR_MAX 1022
#endif
#endif

// 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,

    // 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
    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   = 0x010000, // File does not match storage
    LFS_F_WRITING = 0x020000, // File has been written since last flush
    LFS_F_READING = 0x040000, // File has been read since last flush
    LFS_F_ERRED   = 0x080000, // An error occured during write
    LFS_F_INLINE  = 0x100000, // Currently inlined in directory entry
    LFS_F_OPENED  = 0x200000, // File has been opened
};

// 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

// If every config option is provided at compile time, littlefs switches
// to "LFS_STATICCFG" mode. The dynamic lfs_cfg struct is not included in
// the lfs_t struct, and *cfg functions are no longer available.
#if defined(LFS_BD_READ) && \
        defined(LFS_BD_PROG) && \
        defined(LFS_BD_ERASE) && \
        defined(LFS_BD_SYNC) && \
        defined(LFS_READ_SIZE) && \
        defined(LFS_PROG_SIZE) && \
        defined(LFS_BLOCK_SIZE) && \
        defined(LFS_BLOCK_COUNT) && \
        defined(LFS_BLOCK_CYCLES) && \
        defined(LFS_BUFFER_SIZE) && \
        defined(LFS_LOOKAHEAD_SIZE) && \
        defined(LFS_READ_BUFFER) && \
        defined(LFS_PROG_BUFFER) && \
        defined(LFS_LOOKAHEAD_BUFFER) && \
        defined(LFS_NAME_LIMIT) && \
        defined(LFS_FILE_LIMIT) && \
        defined(LFS_ATTR_LIMIT)
#define LFS_STATICCFG
#endif

// Dynamic config struct
#ifndef LFS_STATICCFG
struct lfs_cfg {
#endif
    // Opaque user provided context that can be used to pass
    // information to the block device operations
    #if !(defined(LFS_BD_READ) && \
            defined(LFS_BD_PROG) && \
            defined(LFS_BD_ERASE) && \
            defined(LFS_BD_SYNC))
    void *bd_ctx;
    #endif

    // Read a region in a block. Negative error codes are propogated
    // to the user.
    #ifndef LFS_BD_READ
    int (*bd_read)(void *ctx, lfs_block_t block,
            lfs_off_t off, void *buffer, lfs_size_t size);
    #define LFS_CFG_BD_READ(cfg, block, off, buffer, size) \
            (cfg)->bd_read((cfg)->bd_ctx, block, off, buffer, size)
    #else
    #define LFS_CFG_BD_READ(cfg, block, off, buffer, size) \
            lfs_bd_read(block, off, buffer, size)
    #endif

    // 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.
    #ifndef LFS_BD_PROG
    int (*bd_prog)(void *ctx, lfs_block_t block,
            lfs_off_t off, const void *buffer, lfs_size_t size);
    #define LFS_CFG_BD_PROG(cfg, block, off, buffer, size) \
            (cfg)->bd_prog((cfg)->bd_ctx, block, off, buffer, size)
    #else
    #define LFS_CFG_BD_PROG(cfg, block, off, buffer, size) \
            lfs_bd_prog(block, off, buffer, size)
    #endif

    // 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.
    #ifndef LFS_BD_ERASE
    int (*bd_erase)(void *ctx, lfs_block_t block);
    #define LFS_CFG_BD_ERASE(cfg, block) \
            (cfg)->bd_erase((cfg)->bd_ctx, block)
    #else
    #define LFS_CFG_BD_ERASE(cfg, block) \
            lfs_bd_erase(block)
    #endif

    // Sync the state of the underlying block device. Negative error codes
    // are propogated to the user.
    #ifndef LFS_BD_SYNC
    int (*bd_sync)(void *ctx);
    #define LFS_CFG_BD_SYNC(cfg) \
            (cfg)->bd_sync((cfg)->bd_ctx)
    #else
    #define LFS_CFG_BD_SYNC(cfg) \
            lfs_bd_sync()
    #endif

    // Minimum size of a block read. All read operations will be a
    // multiple of this value.
    #ifndef LFS_READ_SIZE
    lfs_size_t read_size;
    #define LFS_CFG_READ_SIZE(cfg) (cfg)->read_size
    #else
    #define LFS_CFG_READ_SIZE(cfg) LFS_READ_SIZE
    #endif

    // Minimum size of a block program. All program operations will be a
    // multiple of this value.
    #ifndef LFS_PROG_SIZE
    lfs_size_t prog_size;
    #define LFS_CFG_PROG_SIZE(cfg) (cfg)->prog_size
    #else
    #define LFS_CFG_PROG_SIZE(cfg) LFS_PROG_SIZE
    #endif

    // Size of an erasable block. 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.
    #ifndef LFS_BLOCK_SIZE
    lfs_size_t block_size;
    #define LFS_CFG_BLOCK_SIZE(cfg) (cfg)->block_size
    #else
    #define LFS_CFG_BLOCK_SIZE(cfg) LFS_BLOCK_SIZE
    #endif

    // Number of erasable blocks on the device.
    #ifndef LFS_BLOCK_COUNT
    lfs_size_t block_count;
    #define LFS_CFG_BLOCK_COUNT(cfg) (cfg)->block_count
    #else
    #define LFS_CFG_BLOCK_COUNT(cfg) LFS_BLOCK_COUNT
    #endif

    // 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.
    #ifndef LFS_BLOCK_CYCLES
    int32_t block_cycles;
    #define LFS_CFG_BLOCK_CYCLES(cfg) (cfg)->block_cycles
    #else
    #define LFS_CFG_BLOCK_CYCLES(cfg) LFS_BLOCK_CYCLES
    #endif

    // Size of internal buffers used to cache slices of blocks in RAM.
    // The littlefs needs a read buffer, a program buffer, and one additional
    // buffer per file. Larger buffers 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.
    #ifndef LFS_BUFFER_SIZE
    lfs_size_t buffer_size;
    #define LFS_CFG_BUFFER_SIZE(cfg) (cfg)->buffer_size
    #else
    #define LFS_CFG_BUFFER_SIZE(cfg) LFS_BUFFER_SIZE
    #endif

    // 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. Must be a multiple of 8.
    #ifndef LFS_LOOKAHEAD_SIZE
    lfs_size_t lookahead_size;
    #define LFS_CFG_LOOKAHEAD_SIZE(cfg) (cfg)->lookahead_size
    #else
    #define LFS_CFG_LOOKAHEAD_SIZE(cfg) LFS_LOOKAHEAD_SIZE
    #endif

    // Optional statically allocated read buffer. Must be cache_size.
    // By default lfs_malloc is used to allocate this buffer.
    #ifndef LFS_READ_BUFFER
    void *read_buffer;
    #define LFS_CFG_READ_BUFFER(cfg) (cfg)->read_buffer
    #else
    #define LFS_CFG_READ_BUFFER(cfg) LFS_READ_BUFFER
    #endif

    // Optional statically allocated program buffer. Must be cache_size.
    // By default lfs_malloc is used to allocate this buffer.
    #ifndef LFS_PROG_BUFFER
    void *prog_buffer;
    #define LFS_CFG_PROG_BUFFER(cfg) (cfg)->prog_buffer
    #else
    #define LFS_CFG_PROG_BUFFER(cfg) LFS_PROG_BUFFER
    #endif

    // Optional statically allocated lookahead buffer. Must be lookahead_size
    // and aligned to a 32-bit boundary. By default lfs_malloc is used to
    // allocate this buffer.
    #ifndef LFS_LOOKAHEAD_BUFFER
    void *lookahead_buffer;
    #define LFS_CFG_LOOKAHEAD_BUFFER(cfg) (cfg)->lookahead_buffer
    #else
    #define LFS_CFG_LOOKAHEAD_BUFFER(cfg) LFS_LOOKAHEAD_BUFFER
    #endif

    // 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 when zero. Stored in
    // superblock and must be respected by other littlefs drivers.
    #ifndef LFS_NAME_LIMIT
    lfs_size_t name_limit;
    #define LFS_CFG_NAME_LIMIT(cfg) (cfg)->name_limit
    #else
    #define LFS_CFG_NAME_LIMIT(cfg) LFS_NAME_LIMIT
    #endif

    // Optional upper limit on files in bytes. No downside for larger files
    // but must be <= LFS_FILE_MAX. Defaults to LFS_FILE_MAX when zero. Stored
    // in superblock and must be respected by other littlefs drivers.
    #ifndef LFS_FILE_LIMIT
    lfs_size_t file_limit;
    #define LFS_CFG_FILE_LIMIT(cfg) (cfg)->file_limit
    #else
    #define LFS_CFG_FILE_LIMIT(cfg) LFS_FILE_LIMIT
    #endif

    // 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 when zero.
    #ifndef LFS_ATTR_LIMIT
    lfs_size_t attr_limit;
    #define LFS_CFG_ATTR_LIMIT(cfg) (cfg)->attr_limit
    #else
    #define LFS_CFG_ATTR_LIMIT(cfg) LFS_ATTR_LIMIT
    #endif
#ifndef LFS_STATICCFG
};
#endif

// Configurable callbacks are a bit special, when LFS_BD_* is defined,
// LFS_CFG_* instead expands into a call to an extern lfs_bd_*, which
// must be defined by the user. This preserves type-safety of the
// callbacks.
#ifdef LFS_BD_READ
extern int lfs_bd_read(lfs_block_t block,
        lfs_off_t off, void *buffer, lfs_size_t size);
#endif
#ifdef LFS_BD_PROG
extern int lfs_bd_prog(lfs_block_t block,
        lfs_off_t off, const void *buffer, lfs_size_t size);
#endif
#ifdef LFS_BD_ERASE
extern int lfs_bd_erase(lfs_block_t block);
#endif
#ifdef LFS_BD_SYNC
extern int lfs_bd_sync(void);
#endif

// If every config option is provided at compile time, littlefs switches
// to "LFS_FILE_STATICCFG" mode. The dynamic lfs_file_cfg struct is not
// included in the lfs_file_t struct, and *cfg functions are no longer
// available.
#if defined(LFS_FILE_BUFFER) && \
        defined(LFS_FILE_ATTRS) && \
        defined(LFS_FILE_ATTR_COUNT)
#define LFS_STATICCFG
#endif

#ifndef LFS_FILE_STATICCFG
// Optional configuration provided during lfs_file_opencfg
struct lfs_file_cfg {
#endif
    // Optional statically allocated file buffer. Must be cache_size.
    // By default lfs_malloc is used to allocate this buffer.
    #ifndef LFS_FILE_BUFFER
    void *buffer;
    #define LFS_FILE_CFG_BUFFER(cfg) (cfg)->buffer
    #else
    #define LFS_FILE_CFG_BUFFER(cfg) LFS_FILE_BUFFER
    #endif

    // 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.
    #ifndef LFS_FILE_ATTRS
    struct lfs_attr *attrs;
    #define LFS_FILE_CFG_ATTRS(cfg) (cfg)->attrs
    #else
    #define LFS_FILE_CFG_ATTRS(cfg) LFS_FILE_ATTRS
    #endif

    // Number of custom attributes in the list
    #ifndef LFS_FILE_ATTR_COUNT
    lfs_size_t attr_count;
    #define LFS_FILE_CFG_ATTR_COUNT(cfg) (cfg)->attr_count
    #else
    #define LFS_FILE_CFG_ATTR_COUNT(cfg) LFS_FILE_ATTR_COUNT
    #endif
#ifndef LFS_FILE_STATICCFG
};
#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];
};

// 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;
};


/// 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;

#ifndef LFS_FILE_STATICCFG
    const struct lfs_file_cfg *cfg;
#endif
} lfs_file_t;

typedef struct lfs_superblock {
    uint32_t version;
    lfs_size_t block_size;
    lfs_size_t block_count;
    lfs_size_t name_limit;
    lfs_size_t file_limit;
    lfs_size_t attr_limit;
} 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_free {
        lfs_block_t off;
        lfs_block_t size;
        lfs_block_t i;
        lfs_block_t ack;
        uint32_t *buffer;
    } free;

#ifndef LFS_STATICCFG
    const struct lfs_cfg *cfg;
#endif
    lfs_size_t name_limit;
    lfs_size_t file_limit;
    lfs_size_t attr_limit;

#ifdef LFS_MIGRATE
    struct lfs1 *lfs1;
#endif
} lfs_t;


/// Filesystem functions ///

#if defined(LFS_STATICCFG)
// Format a block device with littlefs
//
// Requires a littlefs object. This clobbers the littlefs object, and does
// not leave the filesystem mounted.
//
// Returns a negative error code on failure.
int lfs_format(lfs_t *lfs);
#endif

#if !defined(LFS_STATICCFG)
// Format a block device with littlefs with per-filesystem configuration
//
// 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_formatcfg(lfs_t *lfs, const struct lfs_cfg *config);
#endif

#if defined(LFS_STATICCFG)
// Mounts littlefs
//
// Requires a littlefs object and static configuration.
//
// Returns a negative error code on failure.
int lfs_mount(lfs_t *lfs);
#endif

#if !defined(LFS_STATICCFG)
// Mounts a littlefs with per-filesystem configuration
//
// 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_mountcfg(lfs_t *lfs, const struct lfs_cfg *config);
#endif

// 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);

// 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 existance.
lfs_ssize_t lfs_getattr(lfs_t *lfs, const char *path,
        uint8_t type, void *buffer, lfs_size_t size);

// 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);

// 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);


/// 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);

#if !defined(LFS_FILE_STATICCFG)
// Open a file with per-file 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_cfg *config);
#endif

// 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 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);

// 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_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 ///

// 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 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

// 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);

#if defined(LFS_MIGRATE) && defined(LFS_STATICCFG)
// 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. This clobbers the littlefs object, and does
// not leave the filesystem mounted.
//
// Returns a negative error code on failure.
int lfs_migrate(lfs_t *lfs, const struct lfs_cfg *cfg);
#endif

#if defined(LFS_MIGRATE) && !defined(LFS_STATICCFG)
// Attempts to migrate a previous version of littlefs with per-filesystem
// configuration
//
// 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_migratecfg(lfs_t *lfs, const struct lfs_cfg *cfg);
#endif


#ifdef __cplusplus
}
#endif

#endif