/*
 * The little filesystem
 *
 * Copyright (c) 2017, Arm Limited. All rights reserved.
 * SPDX-License-Identifier: BSD-3-Clause
 */
#ifndef LFS2_H
#define LFS2_H

#include <stdint.h>
#include <stdbool.h>
#include "lfs2_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 LFS2_VERSION 0x00020003
#define LFS2_VERSION_MAJOR (0xffff & (LFS2_VERSION >> 16))
#define LFS2_VERSION_MINOR (0xffff & (LFS2_VERSION >> 0))

// Version of On-disk data structures
// Major (top-nibble), incremented on backwards incompatible changes
// Minor (bottom-nibble), incremented on feature additions
#define LFS2_DISK_VERSION 0x00020000
#define LFS2_DISK_VERSION_MAJOR (0xffff & (LFS2_DISK_VERSION >> 16))
#define LFS2_DISK_VERSION_MINOR (0xffff & (LFS2_DISK_VERSION >> 0))


/// Definitions ///

// Type definitions
typedef uint32_t lfs2_size_t;
typedef uint32_t lfs2_off_t;

typedef int32_t lfs2_ssize_t;
typedef int32_t lfs2_soff_t;

typedef uint32_t lfs2_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 LFS2_NAME_MAX
#define LFS2_NAME_MAX 255
#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 lfs2_file_seek, lfs2_file_size, and lfs2_file_tell will return
// incorrect values due to using signed integers. Stored in superblock and
// must be respected by other littlefs drivers.
#ifndef LFS2_FILE_MAX
#define LFS2_FILE_MAX 2147483647
#endif

// Maximum size of custom attributes in bytes, may be redefined, but there is
// no real benefit to using a smaller LFS2_ATTR_MAX. Limited to <= 1022.
#ifndef LFS2_ATTR_MAX
#define LFS2_ATTR_MAX 1022
#endif

// Possible error codes, these are negative to allow
// valid positive return values
enum lfs2_error {
 LFS2_ERR_OK = 0, // No error
 LFS2_ERR_IO = -5, // Error during device operation
 LFS2_ERR_CORRUPT = -84, // Corrupted
 LFS2_ERR_NOENT = -2, // No directory entry
 LFS2_ERR_EXIST = -17, // Entry already exists
 LFS2_ERR_NOTDIR = -20, // Entry is not a dir
 LFS2_ERR_ISDIR = -21, // Entry is a dir
 LFS2_ERR_NOTEMPTY = -39, // Dir is not empty
 LFS2_ERR_BADF = -9, // Bad file number
 LFS2_ERR_FBIG = -27, // File too large
 LFS2_ERR_INVAL = -22, // Invalid parameter
 LFS2_ERR_NOSPC = -28, // No space left on device
 LFS2_ERR_NOMEM = -12, // No more memory available
 LFS2_ERR_NOATTR = -61, // No data/attr available
 LFS2_ERR_NAMETOOLONG = -36, // File name too long
};

// File types
enum lfs2_type {
 // file types
 LFS2_TYPE_REG = 0x001,
 LFS2_TYPE_DIR = 0x002,

 // internally used types
 LFS2_TYPE_SPLICE = 0x400,
 LFS2_TYPE_NAME = 0x000,
 LFS2_TYPE_STRUCT = 0x200,
 LFS2_TYPE_USERATTR = 0x300,
 LFS2_TYPE_FROM = 0x100,
 LFS2_TYPE_TAIL = 0x600,
 LFS2_TYPE_GLOBALS = 0x700,
 LFS2_TYPE_CRC = 0x500,

 // internally used type specializations
 LFS2_TYPE_CREATE = 0x401,
 LFS2_TYPE_DELETE = 0x4ff,
 LFS2_TYPE_SUPERBLOCK = 0x0ff,
 LFS2_TYPE_DIRSTRUCT = 0x200,
 LFS2_TYPE_CTZSTRUCT = 0x202,
 LFS2_TYPE_INLINESTRUCT = 0x201,
 LFS2_TYPE_SOFTTAIL = 0x600,
 LFS2_TYPE_HARDTAIL = 0x601,
 LFS2_TYPE_MOVESTATE = 0x7ff,

 // internal chip sources
 LFS2_FROM_NOOP = 0x000,
 LFS2_FROM_MOVE = 0x101,
 LFS2_FROM_USERATTRS = 0x102,
};

// File open flags
enum lfs2_open_flags {
 // open flags
 LFS2_O_RDONLY = 1, // Open a file as read only
#ifndef LFS2_READONLY
 LFS2_O_WRONLY = 2, // Open a file as write only
 LFS2_O_RDWR = 3, // Open a file as read and write
 LFS2_O_CREAT = 0x0100, // Create a file if it does not exist
 LFS2_O_EXCL = 0x0200, // Fail if a file already exists
 LFS2_O_TRUNC = 0x0400, // Truncate the existing file to zero size
 LFS2_O_APPEND = 0x0800, // Move to end of file on every write
#endif

 // internally used flags
#ifndef LFS2_READONLY
 LFS2_F_DIRTY = 0x010000, // File does not match storage
 LFS2_F_WRITING = 0x020000, // File has been written since last flush
#endif
 LFS2_F_READING = 0x040000, // File has been read since last flush
#ifndef LFS2_READONLY
 LFS2_F_ERRED = 0x080000, // An error occurred during write
#endif
 LFS2_F_INLINE = 0x100000, // Currently inlined in directory entry
};

// File seek flags
enum lfs2_whence_flags {
 LFS2_SEEK_SET = 0, // Seek relative to an absolute position
 LFS2_SEEK_CUR = 1, // Seek relative to the current file position
 LFS2_SEEK_END = 2, // Seek relative to the end of the file
};


// Configuration provided during initialization of the littlefs
struct lfs2_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 lfs2_config *c, lfs2_block_t block,
 lfs2_off_t off, void *buffer, lfs2_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 LFS2_ERR_CORRUPT if the block should be considered bad.
 int (*prog)(const struct lfs2_config *c, lfs2_block_t block,
 lfs2_off_t off, const void *buffer, lfs2_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 LFS2_ERR_CORRUPT if the block should be considered bad.
 int (*erase)(const struct lfs2_config *c, lfs2_block_t block);

 // Sync the state of the underlying block device. Negative error codes
 // are propogated to the user.
 int (*sync)(const struct lfs2_config *c);

#ifdef LFS2_THREADSAFE
 // Lock the underlying block device. Negative error codes
 // are propogated to the user.
 int (*lock)(const struct lfs2_config *c);

 // Unlock the underlying block device. Negative error codes
 // are propogated to the user.
 int (*unlock)(const struct lfs2_config *c);
#endif

 // Minimum size of a block read. All read operations will be a
 // multiple of this value.
 lfs2_size_t read_size;

 // Minimum size of a block program. All program operations will be a
 // multiple of this value.
 lfs2_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, non-inlined files
 // take up at minimum one block. Must be a multiple of the read
 // and program sizes.
 lfs2_size_t block_size;

 // Number of erasable blocks on the device.
 lfs2_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. 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.
 lfs2_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. Must be a multiple of 8.
 lfs2_size_t lookahead_size;

 // Optional statically allocated read buffer. Must be cache_size.
 // By default lfs2_malloc is used to allocate this buffer.
 void *read_buffer;

 // Optional statically allocated program buffer. Must be cache_size.
 // By default lfs2_malloc is used to allocate this buffer.
 void *prog_buffer;

 // Optional statically allocated lookahead buffer. Must be lookahead_size
 // and aligned to a 32-bit boundary. By default lfs2_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 LFS2_NAME_MAX define. Defaults to LFS2_NAME_MAX when zero. Stored in
 // superblock and must be respected by other littlefs drivers.
 lfs2_size_t name_max;

 // Optional upper limit on files in bytes. No downside for larger files
 // but must be <= LFS2_FILE_MAX. Defaults to LFS2_FILE_MAX when zero. Stored
 // in superblock and must be respected by other littlefs drivers.
 lfs2_size_t file_max;

 // Optional upper limit on custom attributes in bytes. No downside for
 // larger attributes size but must be <= LFS2_ATTR_MAX. Defaults to
 // LFS2_ATTR_MAX when zero.
 lfs2_size_t attr_max;
};

// File info structure
struct lfs2_info {
 // Type of the file, either LFS2_TYPE_REG or LFS2_TYPE_DIR
 uint8_t type;

 // Size of the file, only valid for REG files. Limited to 32-bits.
 lfs2_size_t size;

 // Name of the file stored as a null-terminated string. Limited to
 // LFS2_NAME_MAX+1, which can be changed by redefining LFS2_NAME_MAX to
 // reduce RAM. LFS2_NAME_MAX is stored in superblock and must be
 // respected by other littlefs drivers.
 char name[LFS2_NAME_MAX+1];
};

// Custom attribute structure, used to describe custom attributes
// committed atomically during file writes.
struct lfs2_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 LFS2_ATTR_MAX
 lfs2_size_t size;
};

// Optional configuration provided during lfs2_file_opencfg
struct lfs2_file_config {
 // Optional statically allocated file buffer. Must be cache_size.
 // By default lfs2_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 LFS2_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 lfs2_attr *attrs;

 // Number of custom attributes in the list
 lfs2_size_t attr_count;
};


/// internal littlefs data structures ///
typedef struct lfs2_cache {
 lfs2_block_t block;
 lfs2_off_t off;
 lfs2_size_t size;
 uint8_t *buffer;
} lfs2_cache_t;

typedef struct lfs2_mdir {
 lfs2_block_t pair[2];
 uint32_t rev;
 lfs2_off_t off;
 uint32_t etag;
 uint16_t count;
 bool erased;
 bool split;
 lfs2_block_t tail[2];
} lfs2_mdir_t;

// littlefs directory type
typedef struct lfs2_dir {
 struct lfs2_dir *next;
 uint16_t id;
 uint8_t type;
 lfs2_mdir_t m;

 lfs2_off_t pos;
 lfs2_block_t head[2];
} lfs2_dir_t;

// littlefs file type
typedef struct lfs2_file {
 struct lfs2_file *next;
 uint16_t id;
 uint8_t type;
 lfs2_mdir_t m;

 struct lfs2_ctz {
 lfs2_block_t head;
 lfs2_size_t size;
 } ctz;

 uint32_t flags;
 lfs2_off_t pos;
 lfs2_block_t block;
 lfs2_off_t off;
 lfs2_cache_t cache;

 const struct lfs2_file_config *cfg;
} lfs2_file_t;

typedef struct lfs2_superblock {
 uint32_t version;
 lfs2_size_t block_size;
 lfs2_size_t block_count;
 lfs2_size_t name_max;
 lfs2_size_t file_max;
 lfs2_size_t attr_max;
} lfs2_superblock_t;

typedef struct lfs2_gstate {
 uint32_t tag;
 lfs2_block_t pair[2];
} lfs2_gstate_t;

// The littlefs filesystem type
typedef struct lfs2 {
 lfs2_cache_t rcache;
 lfs2_cache_t pcache;

 lfs2_block_t root[2];
 struct lfs2_mlist {
 struct lfs2_mlist *next;
 uint16_t id;
 uint8_t type;
 lfs2_mdir_t m;
 } *mlist;
 uint32_t seed;

 lfs2_gstate_t gstate;
 lfs2_gstate_t gdisk;
 lfs2_gstate_t gdelta;

 struct lfs2_free {
 lfs2_block_t off;
 lfs2_block_t size;
 lfs2_block_t i;
 lfs2_block_t ack;
 uint32_t *buffer;
 } free;

 const struct lfs2_config *cfg;
 lfs2_size_t name_max;
 lfs2_size_t file_max;
 lfs2_size_t attr_max;

#ifdef LFS2_MIGRATE
 struct lfs21 *lfs21;
#endif
} lfs2_t;


/// Filesystem functions ///

#ifndef LFS2_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 lfs2_format(lfs2_t *lfs2, const struct lfs2_config *config);
#endif

// Mounts a littlefs
//
// Requires a littlefs object and config struct. Multiple filesystems
// may be mounted simultaneously with multiple littlefs objects. Both
// lfs2 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 lfs2_mount(lfs2_t *lfs2, const struct lfs2_config *config);

// Unmounts a littlefs
//
// Does nothing besides releasing any allocated resources.
// Returns a negative error code on failure.
int lfs2_unmount(lfs2_t *lfs2);

/// General operations ///

#ifndef LFS2_READONLY
// Removes a file or directory
//
// If removing a directory, the directory must be empty.
// Returns a negative error code on failure.
int lfs2_remove(lfs2_t *lfs2, const char *path);
#endif

#ifndef LFS2_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 lfs2_rename(lfs2_t *lfs2, 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 lfs2_stat(lfs2_t *lfs2, const char *path, struct lfs2_info *info);

// Get a custom attribute
//
// Custom attributes are uniquely identified by an 8-bit type and limited
// to LFS2_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
// LFS2_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.
lfs2_ssize_t lfs2_getattr(lfs2_t *lfs2, const char *path,
 uint8_t type, void *buffer, lfs2_size_t size);

#ifndef LFS2_READONLY
// Set custom attributes
//
// Custom attributes are uniquely identified by an 8-bit type and limited
// to LFS2_ATTR_MAX bytes. If an attribute is not found, it will be
// implicitly created.
//
// Returns a negative error code on failure.
int lfs2_setattr(lfs2_t *lfs2, const char *path,
 uint8_t type, const void *buffer, lfs2_size_t size);
#endif

#ifndef LFS2_READONLY
// Removes a custom attribute
//
// If an attribute is not found, nothing happens.
//
// Returns a negative error code on failure.
int lfs2_removeattr(lfs2_t *lfs2, const char *path, uint8_t type);
#endif


/// File operations ///

// Open a file
//
// The mode that the file is opened in is determined by the flags, which
// are values from the enum lfs2_open_flags that are bitwise-ored together.
//
// Returns a negative error code on failure.
int lfs2_file_open(lfs2_t *lfs2, lfs2_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 lfs2_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 lfs2_file_opencfg(lfs2_t *lfs2, lfs2_file_t *file,
 const char *path, int flags,
 const struct lfs2_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 lfs2_file_close(lfs2_t *lfs2, lfs2_file_t *file);

// Synchronize a file on storage
//
// Any pending writes are written out to storage.
// Returns a negative error code on failure.
int lfs2_file_sync(lfs2_t *lfs2, lfs2_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.
lfs2_ssize_t lfs2_file_read(lfs2_t *lfs2, lfs2_file_t *file,
 void *buffer, lfs2_size_t size);

#ifndef LFS2_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.
lfs2_ssize_t lfs2_file_write(lfs2_t *lfs2, lfs2_file_t *file,
 const void *buffer, lfs2_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.
lfs2_soff_t lfs2_file_seek(lfs2_t *lfs2, lfs2_file_t *file,
 lfs2_soff_t off, int whence);

#ifndef LFS2_READONLY
// Truncates the size of the file to the specified size
//
// Returns a negative error code on failure.
int lfs2_file_truncate(lfs2_t *lfs2, lfs2_file_t *file, lfs2_off_t size);
#endif

// Return the position of the file
//
// Equivalent to lfs2_file_seek(lfs2, file, 0, LFS2_SEEK_CUR)
// Returns the position of the file, or a negative error code on failure.
lfs2_soff_t lfs2_file_tell(lfs2_t *lfs2, lfs2_file_t *file);

// Change the position of the file to the beginning of the file
//
// Equivalent to lfs2_file_seek(lfs2, file, 0, LFS2_SEEK_SET)
// Returns a negative error code on failure.
int lfs2_file_rewind(lfs2_t *lfs2, lfs2_file_t *file);

// Return the size of the file
//
// Similar to lfs2_file_seek(lfs2, file, 0, LFS2_SEEK_END)
// Returns the size of the file, or a negative error code on failure.
lfs2_soff_t lfs2_file_size(lfs2_t *lfs2, lfs2_file_t *file);


/// Directory operations ///

#ifndef LFS2_READONLY
// Create a directory
//
// Returns a negative error code on failure.
int lfs2_mkdir(lfs2_t *lfs2, 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 lfs2_dir_open(lfs2_t *lfs2, lfs2_dir_t *dir, const char *path);

// Close a directory
//
// Releases any allocated resources.
// Returns a negative error code on failure.
int lfs2_dir_close(lfs2_t *lfs2, lfs2_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 lfs2_dir_read(lfs2_t *lfs2, lfs2_dir_t *dir, struct lfs2_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 lfs2_dir_seek(lfs2_t *lfs2, lfs2_dir_t *dir, lfs2_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.
lfs2_soff_t lfs2_dir_tell(lfs2_t *lfs2, lfs2_dir_t *dir);

// Change the position of the directory to the beginning of the directory
//
// Returns a negative error code on failure.
int lfs2_dir_rewind(lfs2_t *lfs2, lfs2_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.
lfs2_ssize_t lfs2_fs_size(lfs2_t *lfs2);

// 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 lfs2_fs_traverse(lfs2_t *lfs2, int (*cb)(void*, lfs2_block_t), void *data);

#ifndef LFS2_READONLY
#ifdef LFS2_MIGRATE
// Attempts to migrate a previous version of littlefs
//
// Behaves similarly to the lfs2_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 lfs2_migrate(lfs2_t *lfs2, const struct lfs2_config *cfg);
#endif
#endif


#ifdef __cplusplus
} /* extern "C" */
#endif

#endif