lib/littlefs: Add littlefs v2.1.3 source.

1 files changed, 651 insertions, 0 deletions

diff --git a/lib/littlefs/lfs2.h b/lib/littlefs/lfs2.h
new file mode 100644
index 000000000..fdbe007cc
--- /dev/null
+++ b/lib/littlefs/lfs2.h
@@ -0,0 +1,651 @@
+/*
+ * 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>
+
+#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 0x00020001
+#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
+    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
+
+    // internally used flags
+    LFS2_F_DIRTY   = 0x010000, // File does not match storage
+    LFS2_F_WRITING = 0x020000, // File has been written since last flush
+    LFS2_F_READING = 0x040000, // File has been read since last flush
+    LFS2_F_ERRED   = 0x080000, // An error occured during write
+    LFS2_F_INLINE  = 0x100000, // Currently inlined in directory entry
+    LFS2_F_OPENED  = 0x200000, // File has been opened
+};
+
+// 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);
+
+    // 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;
+
+// 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;
+
+    struct lfs2_gstate {
+        uint32_t tag;
+        lfs2_block_t pair[2];
+    } gstate, gpending, 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 ///
+
+// 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);
+
+// 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 ///
+
+// 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);
+
+// 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);
+
+// 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);
+
+// 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);
+
+// 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);
+
+
+/// 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);
+
+// 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);
+
+// 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);
+
+// 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);
+
+// 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 ///
+
+// Create a directory
+//
+// Returns a negative error code on failure.
+int lfs2_mkdir(lfs2_t *lfs2, 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 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);
+
+#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
+
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif