lfs.h 24 KB

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  1. /*
  2. * The little filesystem
  3. *
  4. * Copyright (c) 2022, The littlefs authors.
  5. * Copyright (c) 2017, Arm Limited. All rights reserved.
  6. * SPDX-License-Identifier: BSD-3-Clause
  7. */
  8. #ifndef LFS_H
  9. #define LFS_H
  10. #include "lfs_util.h"
  11. #ifdef __cplusplus
  12. extern "C"
  13. {
  14. #endif
  15. /// Version info ///
  16. // Software library version
  17. // Major (top-nibble), incremented on backwards incompatible changes
  18. // Minor (bottom-nibble), incremented on feature additions
  19. #define LFS_VERSION 0x00020007
  20. #define LFS_VERSION_MAJOR (0xffff & (LFS_VERSION >> 16))
  21. #define LFS_VERSION_MINOR (0xffff & (LFS_VERSION >> 0))
  22. // Version of On-disk data structures
  23. // Major (top-nibble), incremented on backwards incompatible changes
  24. // Minor (bottom-nibble), incremented on feature additions
  25. #define LFS_DISK_VERSION 0x00020001
  26. #define LFS_DISK_VERSION_MAJOR (0xffff & (LFS_DISK_VERSION >> 16))
  27. #define LFS_DISK_VERSION_MINOR (0xffff & (LFS_DISK_VERSION >> 0))
  28. /// Definitions ///
  29. // Type definitions
  30. typedef uint32_t lfs_size_t;
  31. typedef uint32_t lfs_off_t;
  32. typedef int32_t lfs_ssize_t;
  33. typedef int32_t lfs_soff_t;
  34. typedef uint32_t lfs_block_t;
  35. // Maximum name size in bytes, may be redefined to reduce the size of the
  36. // info struct. Limited to <= 1022. Stored in superblock and must be
  37. // respected by other littlefs drivers.
  38. #ifndef LFS_NAME_MAX
  39. #define LFS_NAME_MAX 255
  40. #endif
  41. // Maximum size of a file in bytes, may be redefined to limit to support other
  42. // drivers. Limited on disk to <= 4294967296. However, above 2147483647 the
  43. // functions lfs_file_seek, lfs_file_size, and lfs_file_tell will return
  44. // incorrect values due to using signed integers. Stored in superblock and
  45. // must be respected by other littlefs drivers.
  46. #ifndef LFS_FILE_MAX
  47. #define LFS_FILE_MAX 2147483647
  48. #endif
  49. // Maximum size of custom attributes in bytes, may be redefined, but there is
  50. // no real benefit to using a smaller LFS_ATTR_MAX. Limited to <= 1022.
  51. #ifndef LFS_ATTR_MAX
  52. #define LFS_ATTR_MAX 1022
  53. #endif
  54. // Possible error codes, these are negative to allow
  55. // valid positive return values
  56. enum lfs_error {
  57. LFS_ERR_OK = 0, // No error
  58. LFS_ERR_IO = -5, // Error during device operation
  59. LFS_ERR_CORRUPT = -84, // Corrupted
  60. LFS_ERR_NOENT = -2, // No directory entry
  61. LFS_ERR_EXIST = -17, // Entry already exists
  62. LFS_ERR_NOTDIR = -20, // Entry is not a dir
  63. LFS_ERR_ISDIR = -21, // Entry is a dir
  64. LFS_ERR_NOTEMPTY = -39, // Dir is not empty
  65. LFS_ERR_BADF = -9, // Bad file number
  66. LFS_ERR_FBIG = -27, // File too large
  67. LFS_ERR_INVAL = -22, // Invalid parameter
  68. LFS_ERR_NOSPC = -28, // No space left on device
  69. LFS_ERR_NOMEM = -12, // No more memory available
  70. LFS_ERR_NOATTR = -61, // No data/attr available
  71. LFS_ERR_NAMETOOLONG = -36, // File name too long
  72. };
  73. // File types
  74. enum lfs_type {
  75. // file types
  76. LFS_TYPE_REG = 0x001,
  77. LFS_TYPE_DIR = 0x002,
  78. // internally used types
  79. LFS_TYPE_SPLICE = 0x400,
  80. LFS_TYPE_NAME = 0x000,
  81. LFS_TYPE_STRUCT = 0x200,
  82. LFS_TYPE_USERATTR = 0x300,
  83. LFS_TYPE_FROM = 0x100,
  84. LFS_TYPE_TAIL = 0x600,
  85. LFS_TYPE_GLOBALS = 0x700,
  86. LFS_TYPE_CRC = 0x500,
  87. // internally used type specializations
  88. LFS_TYPE_CREATE = 0x401,
  89. LFS_TYPE_DELETE = 0x4ff,
  90. LFS_TYPE_SUPERBLOCK = 0x0ff,
  91. LFS_TYPE_DIRSTRUCT = 0x200,
  92. LFS_TYPE_CTZSTRUCT = 0x202,
  93. LFS_TYPE_INLINESTRUCT = 0x201,
  94. LFS_TYPE_SOFTTAIL = 0x600,
  95. LFS_TYPE_HARDTAIL = 0x601,
  96. LFS_TYPE_MOVESTATE = 0x7ff,
  97. LFS_TYPE_CCRC = 0x500,
  98. LFS_TYPE_FCRC = 0x5ff,
  99. // internal chip sources
  100. LFS_FROM_NOOP = 0x000,
  101. LFS_FROM_MOVE = 0x101,
  102. LFS_FROM_USERATTRS = 0x102,
  103. };
  104. // File open flags
  105. enum lfs_open_flags {
  106. // open flags
  107. LFS_O_RDONLY = 1, // Open a file as read only
  108. #ifndef LFS_READONLY
  109. LFS_O_WRONLY = 2, // Open a file as write only
  110. LFS_O_RDWR = 3, // Open a file as read and write
  111. LFS_O_CREAT = 0x0100, // Create a file if it does not exist
  112. LFS_O_EXCL = 0x0200, // Fail if a file already exists
  113. LFS_O_TRUNC = 0x0400, // Truncate the existing file to zero size
  114. LFS_O_APPEND = 0x0800, // Move to end of file on every write
  115. #endif
  116. // internally used flags
  117. #ifndef LFS_READONLY
  118. LFS_F_DIRTY = 0x010000, // File does not match storage
  119. LFS_F_WRITING = 0x020000, // File has been written since last flush
  120. #endif
  121. LFS_F_READING = 0x040000, // File has been read since last flush
  122. #ifndef LFS_READONLY
  123. LFS_F_ERRED = 0x080000, // An error occurred during write
  124. #endif
  125. LFS_F_INLINE = 0x100000, // Currently inlined in directory entry
  126. };
  127. // File seek flags
  128. enum lfs_whence_flags {
  129. LFS_SEEK_SET = 0, // Seek relative to an absolute position
  130. LFS_SEEK_CUR = 1, // Seek relative to the current file position
  131. LFS_SEEK_END = 2, // Seek relative to the end of the file
  132. };
  133. // Configuration provided during initialization of the littlefs
  134. struct lfs_config {
  135. // Opaque user provided context that can be used to pass
  136. // information to the block device operations
  137. void *context;
  138. // Read a region in a block. Negative error codes are propagated
  139. // to the user.
  140. int (*read)(const struct lfs_config *c, lfs_block_t block,
  141. lfs_off_t off, void *buffer, lfs_size_t size);
  142. // Program a region in a block. The block must have previously
  143. // been erased. Negative error codes are propagated to the user.
  144. // May return LFS_ERR_CORRUPT if the block should be considered bad.
  145. int (*prog)(const struct lfs_config *c, lfs_block_t block,
  146. lfs_off_t off, const void *buffer, lfs_size_t size);
  147. // Erase a block. A block must be erased before being programmed.
  148. // The state of an erased block is undefined. Negative error codes
  149. // are propagated to the user.
  150. // May return LFS_ERR_CORRUPT if the block should be considered bad.
  151. int (*erase)(const struct lfs_config *c, lfs_block_t block);
  152. // Sync the state of the underlying block device. Negative error codes
  153. // are propagated to the user.
  154. int (*sync)(const struct lfs_config *c);
  155. #ifdef LFS_THREADSAFE
  156. // Lock the underlying block device. Negative error codes
  157. // are propagated to the user.
  158. int (*lock)(const struct lfs_config *c);
  159. // Unlock the underlying block device. Negative error codes
  160. // are propagated to the user.
  161. int (*unlock)(const struct lfs_config *c);
  162. #endif
  163. // Minimum size of a block read in bytes. All read operations will be a
  164. // multiple of this value.
  165. lfs_size_t read_size;
  166. // Minimum size of a block program in bytes. All program operations will be
  167. // a multiple of this value.
  168. lfs_size_t prog_size;
  169. // Size of an erasable block in bytes. This does not impact ram consumption
  170. // and may be larger than the physical erase size. However, non-inlined
  171. // files take up at minimum one block. Must be a multiple of the read and
  172. // program sizes.
  173. lfs_size_t block_size;
  174. // Number of erasable blocks on the device.
  175. lfs_size_t block_count;
  176. // Number of erase cycles before littlefs evicts metadata logs and moves
  177. // the metadata to another block. Suggested values are in the
  178. // range 100-1000, with large values having better performance at the cost
  179. // of less consistent wear distribution.
  180. //
  181. // Set to -1 to disable block-level wear-leveling.
  182. int32_t block_cycles;
  183. // Size of block caches in bytes. Each cache buffers a portion of a block in
  184. // RAM. The littlefs needs a read cache, a program cache, and one additional
  185. // cache per file. Larger caches can improve performance by storing more
  186. // data and reducing the number of disk accesses. Must be a multiple of the
  187. // read and program sizes, and a factor of the block size.
  188. lfs_size_t cache_size;
  189. // Size of the lookahead buffer in bytes. A larger lookahead buffer
  190. // increases the number of blocks found during an allocation pass. The
  191. // lookahead buffer is stored as a compact bitmap, so each byte of RAM
  192. // can track 8 blocks. Must be a multiple of 8.
  193. lfs_size_t lookahead_size;
  194. // Optional statically allocated read buffer. Must be cache_size.
  195. // By default lfs_malloc is used to allocate this buffer.
  196. void *read_buffer;
  197. // Optional statically allocated program buffer. Must be cache_size.
  198. // By default lfs_malloc is used to allocate this buffer.
  199. void *prog_buffer;
  200. // Optional statically allocated lookahead buffer. Must be lookahead_size
  201. // and aligned to a 32-bit boundary. By default lfs_malloc is used to
  202. // allocate this buffer.
  203. void *lookahead_buffer;
  204. // Optional upper limit on length of file names in bytes. No downside for
  205. // larger names except the size of the info struct which is controlled by
  206. // the LFS_NAME_MAX define. Defaults to LFS_NAME_MAX when zero. Stored in
  207. // superblock and must be respected by other littlefs drivers.
  208. lfs_size_t name_max;
  209. // Optional upper limit on files in bytes. No downside for larger files
  210. // but must be <= LFS_FILE_MAX. Defaults to LFS_FILE_MAX when zero. Stored
  211. // in superblock and must be respected by other littlefs drivers.
  212. lfs_size_t file_max;
  213. // Optional upper limit on custom attributes in bytes. No downside for
  214. // larger attributes size but must be <= LFS_ATTR_MAX. Defaults to
  215. // LFS_ATTR_MAX when zero.
  216. lfs_size_t attr_max;
  217. // Optional upper limit on total space given to metadata pairs in bytes. On
  218. // devices with large blocks (e.g. 128kB) setting this to a low size (2-8kB)
  219. // can help bound the metadata compaction time. Must be <= block_size.
  220. // Defaults to block_size when zero.
  221. lfs_size_t metadata_max;
  222. #ifdef LFS_MULTIVERSION
  223. // On-disk version to use when writing in the form of 16-bit major version
  224. // + 16-bit minor version. This limiting metadata to what is supported by
  225. // older minor versions. Note that some features will be lost. Defaults to
  226. // to the most recent minor version when zero.
  227. uint32_t disk_version;
  228. #endif
  229. };
  230. // File info structure
  231. struct lfs_info {
  232. // Type of the file, either LFS_TYPE_REG or LFS_TYPE_DIR
  233. uint8_t type;
  234. // Size of the file, only valid for REG files. Limited to 32-bits.
  235. lfs_size_t size;
  236. // Name of the file stored as a null-terminated string. Limited to
  237. // LFS_NAME_MAX+1, which can be changed by redefining LFS_NAME_MAX to
  238. // reduce RAM. LFS_NAME_MAX is stored in superblock and must be
  239. // respected by other littlefs drivers.
  240. char name[LFS_NAME_MAX+1];
  241. };
  242. // Filesystem info structure
  243. struct lfs_fsinfo {
  244. // On-disk version.
  245. uint32_t disk_version;
  246. // Upper limit on the length of file names in bytes.
  247. lfs_size_t name_max;
  248. // Upper limit on the size of files in bytes.
  249. lfs_size_t file_max;
  250. // Upper limit on the size of custom attributes in bytes.
  251. lfs_size_t attr_max;
  252. };
  253. // Custom attribute structure, used to describe custom attributes
  254. // committed atomically during file writes.
  255. struct lfs_attr {
  256. // 8-bit type of attribute, provided by user and used to
  257. // identify the attribute
  258. uint8_t type;
  259. // Pointer to buffer containing the attribute
  260. void *buffer;
  261. // Size of attribute in bytes, limited to LFS_ATTR_MAX
  262. lfs_size_t size;
  263. };
  264. // Optional configuration provided during lfs_file_opencfg
  265. struct lfs_file_config {
  266. // Optional statically allocated file buffer. Must be cache_size.
  267. // By default lfs_malloc is used to allocate this buffer.
  268. void *buffer;
  269. // Optional list of custom attributes related to the file. If the file
  270. // is opened with read access, these attributes will be read from disk
  271. // during the open call. If the file is opened with write access, the
  272. // attributes will be written to disk every file sync or close. This
  273. // write occurs atomically with update to the file's contents.
  274. //
  275. // Custom attributes are uniquely identified by an 8-bit type and limited
  276. // to LFS_ATTR_MAX bytes. When read, if the stored attribute is smaller
  277. // than the buffer, it will be padded with zeros. If the stored attribute
  278. // is larger, then it will be silently truncated. If the attribute is not
  279. // found, it will be created implicitly.
  280. struct lfs_attr *attrs;
  281. // Number of custom attributes in the list
  282. lfs_size_t attr_count;
  283. };
  284. /// internal littlefs data structures ///
  285. typedef struct lfs_cache {
  286. lfs_block_t block;
  287. lfs_off_t off;
  288. lfs_size_t size;
  289. uint8_t *buffer;
  290. } lfs_cache_t;
  291. typedef struct lfs_mdir {
  292. lfs_block_t pair[2];
  293. uint32_t rev;
  294. lfs_off_t off;
  295. uint32_t etag;
  296. uint16_t count;
  297. bool erased;
  298. bool split;
  299. lfs_block_t tail[2];
  300. } lfs_mdir_t;
  301. // littlefs directory type
  302. typedef struct lfs_dir {
  303. struct lfs_dir *next;
  304. uint16_t id;
  305. uint8_t type;
  306. lfs_mdir_t m;
  307. lfs_off_t pos;
  308. lfs_block_t head[2];
  309. } lfs_dir_t;
  310. // littlefs file type
  311. typedef struct lfs_file {
  312. struct lfs_file *next;
  313. uint16_t id;
  314. uint8_t type;
  315. lfs_mdir_t m;
  316. struct lfs_ctz {
  317. lfs_block_t head;
  318. lfs_size_t size;
  319. } ctz;
  320. uint32_t flags;
  321. lfs_off_t pos;
  322. lfs_block_t block;
  323. lfs_off_t off;
  324. lfs_cache_t cache;
  325. const struct lfs_file_config *cfg;
  326. } lfs_file_t;
  327. typedef struct lfs_superblock {
  328. uint32_t version;
  329. lfs_size_t block_size;
  330. lfs_size_t block_count;
  331. lfs_size_t name_max;
  332. lfs_size_t file_max;
  333. lfs_size_t attr_max;
  334. } lfs_superblock_t;
  335. typedef struct lfs_gstate {
  336. uint32_t tag;
  337. lfs_block_t pair[2];
  338. } lfs_gstate_t;
  339. // The littlefs filesystem type
  340. typedef struct lfs {
  341. lfs_cache_t rcache;
  342. lfs_cache_t pcache;
  343. lfs_block_t root[2];
  344. struct lfs_mlist {
  345. struct lfs_mlist *next;
  346. uint16_t id;
  347. uint8_t type;
  348. lfs_mdir_t m;
  349. } *mlist;
  350. uint32_t seed;
  351. lfs_gstate_t gstate;
  352. lfs_gstate_t gdisk;
  353. lfs_gstate_t gdelta;
  354. struct lfs_free {
  355. lfs_block_t off;
  356. lfs_block_t size;
  357. lfs_block_t i;
  358. lfs_block_t ack;
  359. uint32_t *buffer;
  360. } free;
  361. const struct lfs_config *cfg;
  362. lfs_size_t name_max;
  363. lfs_size_t file_max;
  364. lfs_size_t attr_max;
  365. lfs_size_t block_count;
  366. #ifdef LFS_MIGRATE
  367. struct lfs1 *lfs1;
  368. #endif
  369. } lfs_t;
  370. /// Filesystem functions ///
  371. #ifndef LFS_READONLY
  372. // Format a block device with the littlefs
  373. //
  374. // Requires a littlefs object and config struct. This clobbers the littlefs
  375. // object, and does not leave the filesystem mounted. The config struct must
  376. // be zeroed for defaults and backwards compatibility.
  377. //
  378. // Returns a negative error code on failure.
  379. int lfs_format(lfs_t *lfs, const struct lfs_config *config);
  380. #endif
  381. // Mounts a littlefs
  382. //
  383. // Requires a littlefs object and config struct. Multiple filesystems
  384. // may be mounted simultaneously with multiple littlefs objects. Both
  385. // lfs and config must be allocated while mounted. The config struct must
  386. // be zeroed for defaults and backwards compatibility.
  387. //
  388. // Returns a negative error code on failure.
  389. int lfs_mount(lfs_t *lfs, const struct lfs_config *config);
  390. // Unmounts a littlefs
  391. //
  392. // Does nothing besides releasing any allocated resources.
  393. // Returns a negative error code on failure.
  394. int lfs_unmount(lfs_t *lfs);
  395. /// General operations ///
  396. #ifndef LFS_READONLY
  397. // Removes a file or directory
  398. //
  399. // If removing a directory, the directory must be empty.
  400. // Returns a negative error code on failure.
  401. int lfs_remove(lfs_t *lfs, const char *path);
  402. #endif
  403. #ifndef LFS_READONLY
  404. // Rename or move a file or directory
  405. //
  406. // If the destination exists, it must match the source in type.
  407. // If the destination is a directory, the directory must be empty.
  408. //
  409. // Returns a negative error code on failure.
  410. int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath);
  411. #endif
  412. // Find info about a file or directory
  413. //
  414. // Fills out the info structure, based on the specified file or directory.
  415. // Returns a negative error code on failure.
  416. int lfs_stat(lfs_t *lfs, const char *path, struct lfs_info *info);
  417. // Get a custom attribute
  418. //
  419. // Custom attributes are uniquely identified by an 8-bit type and limited
  420. // to LFS_ATTR_MAX bytes. When read, if the stored attribute is smaller than
  421. // the buffer, it will be padded with zeros. If the stored attribute is larger,
  422. // then it will be silently truncated. If no attribute is found, the error
  423. // LFS_ERR_NOATTR is returned and the buffer is filled with zeros.
  424. //
  425. // Returns the size of the attribute, or a negative error code on failure.
  426. // Note, the returned size is the size of the attribute on disk, irrespective
  427. // of the size of the buffer. This can be used to dynamically allocate a buffer
  428. // or check for existence.
  429. lfs_ssize_t lfs_getattr(lfs_t *lfs, const char *path,
  430. uint8_t type, void *buffer, lfs_size_t size);
  431. #ifndef LFS_READONLY
  432. // Set custom attributes
  433. //
  434. // Custom attributes are uniquely identified by an 8-bit type and limited
  435. // to LFS_ATTR_MAX bytes. If an attribute is not found, it will be
  436. // implicitly created.
  437. //
  438. // Returns a negative error code on failure.
  439. int lfs_setattr(lfs_t *lfs, const char *path,
  440. uint8_t type, const void *buffer, lfs_size_t size);
  441. #endif
  442. #ifndef LFS_READONLY
  443. // Removes a custom attribute
  444. //
  445. // If an attribute is not found, nothing happens.
  446. //
  447. // Returns a negative error code on failure.
  448. int lfs_removeattr(lfs_t *lfs, const char *path, uint8_t type);
  449. #endif
  450. /// File operations ///
  451. #ifndef LFS_NO_MALLOC
  452. // Open a file
  453. //
  454. // The mode that the file is opened in is determined by the flags, which
  455. // are values from the enum lfs_open_flags that are bitwise-ored together.
  456. //
  457. // Returns a negative error code on failure.
  458. int lfs_file_open(lfs_t *lfs, lfs_file_t *file,
  459. const char *path, int flags);
  460. // if LFS_NO_MALLOC is defined, lfs_file_open() will fail with LFS_ERR_NOMEM
  461. // thus use lfs_file_opencfg() with config.buffer set.
  462. #endif
  463. // Open a file with extra configuration
  464. //
  465. // The mode that the file is opened in is determined by the flags, which
  466. // are values from the enum lfs_open_flags that are bitwise-ored together.
  467. //
  468. // The config struct provides additional config options per file as described
  469. // above. The config struct must remain allocated while the file is open, and
  470. // the config struct must be zeroed for defaults and backwards compatibility.
  471. //
  472. // Returns a negative error code on failure.
  473. int lfs_file_opencfg(lfs_t *lfs, lfs_file_t *file,
  474. const char *path, int flags,
  475. const struct lfs_file_config *config);
  476. // Close a file
  477. //
  478. // Any pending writes are written out to storage as though
  479. // sync had been called and releases any allocated resources.
  480. //
  481. // Returns a negative error code on failure.
  482. int lfs_file_close(lfs_t *lfs, lfs_file_t *file);
  483. // Synchronize a file on storage
  484. //
  485. // Any pending writes are written out to storage.
  486. // Returns a negative error code on failure.
  487. int lfs_file_sync(lfs_t *lfs, lfs_file_t *file);
  488. // Read data from file
  489. //
  490. // Takes a buffer and size indicating where to store the read data.
  491. // Returns the number of bytes read, or a negative error code on failure.
  492. lfs_ssize_t lfs_file_read(lfs_t *lfs, lfs_file_t *file,
  493. void *buffer, lfs_size_t size);
  494. #ifndef LFS_READONLY
  495. // Write data to file
  496. //
  497. // Takes a buffer and size indicating the data to write. The file will not
  498. // actually be updated on the storage until either sync or close is called.
  499. //
  500. // Returns the number of bytes written, or a negative error code on failure.
  501. lfs_ssize_t lfs_file_write(lfs_t *lfs, lfs_file_t *file,
  502. const void *buffer, lfs_size_t size);
  503. #endif
  504. // Change the position of the file
  505. //
  506. // The change in position is determined by the offset and whence flag.
  507. // Returns the new position of the file, or a negative error code on failure.
  508. lfs_soff_t lfs_file_seek(lfs_t *lfs, lfs_file_t *file,
  509. lfs_soff_t off, int whence);
  510. #ifndef LFS_READONLY
  511. // Truncates the size of the file to the specified size
  512. //
  513. // Returns a negative error code on failure.
  514. int lfs_file_truncate(lfs_t *lfs, lfs_file_t *file, lfs_off_t size);
  515. #endif
  516. // Return the position of the file
  517. //
  518. // Equivalent to lfs_file_seek(lfs, file, 0, LFS_SEEK_CUR)
  519. // Returns the position of the file, or a negative error code on failure.
  520. lfs_soff_t lfs_file_tell(lfs_t *lfs, lfs_file_t *file);
  521. // Change the position of the file to the beginning of the file
  522. //
  523. // Equivalent to lfs_file_seek(lfs, file, 0, LFS_SEEK_SET)
  524. // Returns a negative error code on failure.
  525. int lfs_file_rewind(lfs_t *lfs, lfs_file_t *file);
  526. // Return the size of the file
  527. //
  528. // Similar to lfs_file_seek(lfs, file, 0, LFS_SEEK_END)
  529. // Returns the size of the file, or a negative error code on failure.
  530. lfs_soff_t lfs_file_size(lfs_t *lfs, lfs_file_t *file);
  531. /// Directory operations ///
  532. #ifndef LFS_READONLY
  533. // Create a directory
  534. //
  535. // Returns a negative error code on failure.
  536. int lfs_mkdir(lfs_t *lfs, const char *path);
  537. #endif
  538. // Open a directory
  539. //
  540. // Once open a directory can be used with read to iterate over files.
  541. // Returns a negative error code on failure.
  542. int lfs_dir_open(lfs_t *lfs, lfs_dir_t *dir, const char *path);
  543. // Close a directory
  544. //
  545. // Releases any allocated resources.
  546. // Returns a negative error code on failure.
  547. int lfs_dir_close(lfs_t *lfs, lfs_dir_t *dir);
  548. // Read an entry in the directory
  549. //
  550. // Fills out the info structure, based on the specified file or directory.
  551. // Returns a positive value on success, 0 at the end of directory,
  552. // or a negative error code on failure.
  553. int lfs_dir_read(lfs_t *lfs, lfs_dir_t *dir, struct lfs_info *info);
  554. // Change the position of the directory
  555. //
  556. // The new off must be a value previous returned from tell and specifies
  557. // an absolute offset in the directory seek.
  558. //
  559. // Returns a negative error code on failure.
  560. int lfs_dir_seek(lfs_t *lfs, lfs_dir_t *dir, lfs_off_t off);
  561. // Return the position of the directory
  562. //
  563. // The returned offset is only meant to be consumed by seek and may not make
  564. // sense, but does indicate the current position in the directory iteration.
  565. //
  566. // Returns the position of the directory, or a negative error code on failure.
  567. lfs_soff_t lfs_dir_tell(lfs_t *lfs, lfs_dir_t *dir);
  568. // Change the position of the directory to the beginning of the directory
  569. //
  570. // Returns a negative error code on failure.
  571. int lfs_dir_rewind(lfs_t *lfs, lfs_dir_t *dir);
  572. /// Filesystem-level filesystem operations
  573. // Find on-disk info about the filesystem
  574. //
  575. // Fills out the fsinfo structure based on the filesystem found on-disk.
  576. // Returns a negative error code on failure.
  577. int lfs_fs_stat(lfs_t *lfs, struct lfs_fsinfo *fsinfo);
  578. // Finds the current size of the filesystem
  579. //
  580. // Note: Result is best effort. If files share COW structures, the returned
  581. // size may be larger than the filesystem actually is.
  582. //
  583. // Returns the number of allocated blocks, or a negative error code on failure.
  584. lfs_ssize_t lfs_fs_size(lfs_t *lfs);
  585. // Traverse through all blocks in use by the filesystem
  586. //
  587. // The provided callback will be called with each block address that is
  588. // currently in use by the filesystem. This can be used to determine which
  589. // blocks are in use or how much of the storage is available.
  590. //
  591. // Returns a negative error code on failure.
  592. int lfs_fs_traverse(lfs_t *lfs, int (*cb)(void*, lfs_block_t), void *data);
  593. #ifndef LFS_READONLY
  594. // Attempt to make the filesystem consistent and ready for writing
  595. //
  596. // Calling this function is not required, consistency will be implicitly
  597. // enforced on the first operation that writes to the filesystem, but this
  598. // function allows the work to be performed earlier and without other
  599. // filesystem changes.
  600. //
  601. // Returns a negative error code on failure.
  602. int lfs_fs_mkconsistent(lfs_t *lfs);
  603. #endif
  604. #ifndef LFS_READONLY
  605. #ifdef LFS_MIGRATE
  606. // Attempts to migrate a previous version of littlefs
  607. //
  608. // Behaves similarly to the lfs_format function. Attempts to mount
  609. // the previous version of littlefs and update the filesystem so it can be
  610. // mounted with the current version of littlefs.
  611. //
  612. // Requires a littlefs object and config struct. This clobbers the littlefs
  613. // object, and does not leave the filesystem mounted. The config struct must
  614. // be zeroed for defaults and backwards compatibility.
  615. //
  616. // Returns a negative error code on failure.
  617. int lfs_migrate(lfs_t *lfs, const struct lfs_config *cfg);
  618. #endif
  619. #endif
  620. #ifdef __cplusplus
  621. } /* extern "C" */
  622. #endif
  623. #endif