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lfs.c
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lfs.c
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/*
* The little filesystem
*
* Copyright (c) 2022, The littlefs authors.
* Copyright (c) 2017, Arm Limited. All rights reserved.
* SPDX-License-Identifier: BSD-3-Clause
*/
#include "lfs.h"
#include "lfs_util.h"
// some constants used throughout the code
#define LFS_BLOCK_NULL ((lfs_block_t)-1)
#define LFS_BLOCK_INLINE ((lfs_block_t)-2)
enum {
LFS_OK_RELOCATED = 1,
LFS_OK_DROPPED = 2,
LFS_OK_ORPHANED = 3,
};
enum {
LFS_CMP_EQ = 0,
LFS_CMP_LT = 1,
LFS_CMP_GT = 2,
};
/// Caching block device operations ///
static inline void lfs_cache_drop(lfs_t *lfs, lfs_cache_t *rcache) {
// do not zero, cheaper if cache is readonly or only going to be
// written with identical data (during relocates)
(void)lfs;
rcache->block = LFS_BLOCK_NULL;
}
static inline void lfs_cache_zero(lfs_t *lfs, lfs_cache_t *pcache) {
// zero to avoid information leak
memset(pcache->buffer, 0xff, lfs->cfg->cache_size);
pcache->block = LFS_BLOCK_NULL;
}
static int lfs_bd_read(lfs_t *lfs,
const lfs_cache_t *pcache, lfs_cache_t *rcache, lfs_size_t hint,
lfs_block_t block, lfs_off_t off,
void *buffer, lfs_size_t size) {
uint8_t *data = buffer;
if (off+size > lfs->cfg->block_size
|| (lfs->block_count && block >= lfs->block_count)) {
return LFS_ERR_CORRUPT;
}
while (size > 0) {
lfs_size_t diff = size;
if (pcache && block == pcache->block &&
off < pcache->off + pcache->size) {
if (off >= pcache->off) {
// is already in pcache?
diff = lfs_min(diff, pcache->size - (off-pcache->off));
memcpy(data, &pcache->buffer[off-pcache->off], diff);
data += diff;
off += diff;
size -= diff;
continue;
}
// pcache takes priority
diff = lfs_min(diff, pcache->off-off);
}
if (block == rcache->block &&
off < rcache->off + rcache->size) {
if (off >= rcache->off) {
// is already in rcache?
diff = lfs_min(diff, rcache->size - (off-rcache->off));
memcpy(data, &rcache->buffer[off-rcache->off], diff);
data += diff;
off += diff;
size -= diff;
continue;
}
// rcache takes priority
diff = lfs_min(diff, rcache->off-off);
}
if (size >= hint && off % lfs->cfg->read_size == 0 &&
size >= lfs->cfg->read_size) {
// bypass cache?
diff = lfs_aligndown(diff, lfs->cfg->read_size);
int err = lfs->cfg->read(lfs->cfg, block, off, data, diff);
if (err) {
return err;
}
data += diff;
off += diff;
size -= diff;
continue;
}
// load to cache, first condition can no longer fail
LFS_ASSERT(!lfs->block_count || block < lfs->block_count);
rcache->block = block;
rcache->off = lfs_aligndown(off, lfs->cfg->read_size);
rcache->size = lfs_min(
lfs_min(
lfs_alignup(off+hint, lfs->cfg->read_size),
lfs->cfg->block_size)
- rcache->off,
lfs->cfg->cache_size);
int err = lfs->cfg->read(lfs->cfg, rcache->block,
rcache->off, rcache->buffer, rcache->size);
LFS_ASSERT(err <= 0);
if (err) {
return err;
}
}
return 0;
}
static int lfs_bd_cmp(lfs_t *lfs,
const lfs_cache_t *pcache, lfs_cache_t *rcache, lfs_size_t hint,
lfs_block_t block, lfs_off_t off,
const void *buffer, lfs_size_t size) {
const uint8_t *data = buffer;
lfs_size_t diff = 0;
for (lfs_off_t i = 0; i < size; i += diff) {
uint8_t dat[8];
diff = lfs_min(size-i, sizeof(dat));
int err = lfs_bd_read(lfs,
pcache, rcache, hint-i,
block, off+i, &dat, diff);
if (err) {
return err;
}
int res = memcmp(dat, data + i, diff);
if (res) {
return res < 0 ? LFS_CMP_LT : LFS_CMP_GT;
}
}
return LFS_CMP_EQ;
}
static int lfs_bd_crc(lfs_t *lfs,
const lfs_cache_t *pcache, lfs_cache_t *rcache, lfs_size_t hint,
lfs_block_t block, lfs_off_t off, lfs_size_t size, uint32_t *crc) {
lfs_size_t diff = 0;
for (lfs_off_t i = 0; i < size; i += diff) {
uint8_t dat[8];
diff = lfs_min(size-i, sizeof(dat));
int err = lfs_bd_read(lfs,
pcache, rcache, hint-i,
block, off+i, &dat, diff);
if (err) {
return err;
}
*crc = lfs_crc(*crc, &dat, diff);
}
return 0;
}
#ifndef LFS_READONLY
static int lfs_bd_flush(lfs_t *lfs,
lfs_cache_t *pcache, lfs_cache_t *rcache, bool validate) {
if (pcache->block != LFS_BLOCK_NULL && pcache->block != LFS_BLOCK_INLINE) {
LFS_ASSERT(pcache->block < lfs->block_count);
lfs_size_t diff = lfs_alignup(pcache->size, lfs->cfg->prog_size);
int err = lfs->cfg->prog(lfs->cfg, pcache->block,
pcache->off, pcache->buffer, diff);
LFS_ASSERT(err <= 0);
if (err) {
return err;
}
if (validate) {
// check data on disk
lfs_cache_drop(lfs, rcache);
int res = lfs_bd_cmp(lfs,
NULL, rcache, diff,
pcache->block, pcache->off, pcache->buffer, diff);
if (res < 0) {
return res;
}
if (res != LFS_CMP_EQ) {
return LFS_ERR_CORRUPT;
}
}
lfs_cache_zero(lfs, pcache);
}
return 0;
}
#endif
#ifndef LFS_READONLY
static int lfs_bd_sync(lfs_t *lfs,
lfs_cache_t *pcache, lfs_cache_t *rcache, bool validate) {
lfs_cache_drop(lfs, rcache);
int err = lfs_bd_flush(lfs, pcache, rcache, validate);
if (err) {
return err;
}
err = lfs->cfg->sync(lfs->cfg);
LFS_ASSERT(err <= 0);
return err;
}
#endif
#ifndef LFS_READONLY
static int lfs_bd_prog(lfs_t *lfs,
lfs_cache_t *pcache, lfs_cache_t *rcache, bool validate,
lfs_block_t block, lfs_off_t off,
const void *buffer, lfs_size_t size) {
const uint8_t *data = buffer;
LFS_ASSERT(block == LFS_BLOCK_INLINE || block < lfs->block_count);
LFS_ASSERT(off + size <= lfs->cfg->block_size);
while (size > 0) {
if (block == pcache->block &&
off >= pcache->off &&
off < pcache->off + lfs->cfg->cache_size) {
// already fits in pcache?
lfs_size_t diff = lfs_min(size,
lfs->cfg->cache_size - (off-pcache->off));
memcpy(&pcache->buffer[off-pcache->off], data, diff);
data += diff;
off += diff;
size -= diff;
pcache->size = lfs_max(pcache->size, off - pcache->off);
if (pcache->size == lfs->cfg->cache_size) {
// eagerly flush out pcache if we fill up
int err = lfs_bd_flush(lfs, pcache, rcache, validate);
if (err) {
return err;
}
}
continue;
}
// pcache must have been flushed, either by programming and
// entire block or manually flushing the pcache
LFS_ASSERT(pcache->block == LFS_BLOCK_NULL);
// prepare pcache, first condition can no longer fail
pcache->block = block;
pcache->off = lfs_aligndown(off, lfs->cfg->prog_size);
pcache->size = 0;
}
return 0;
}
#endif
#ifndef LFS_READONLY
static int lfs_bd_erase(lfs_t *lfs, lfs_block_t block) {
LFS_ASSERT(block < lfs->block_count);
int err = lfs->cfg->erase(lfs->cfg, block);
LFS_ASSERT(err <= 0);
return err;
}
#endif
/// Small type-level utilities ///
// operations on block pairs
static inline void lfs_pair_swap(lfs_block_t pair[2]) {
lfs_block_t t = pair[0];
pair[0] = pair[1];
pair[1] = t;
}
static inline bool lfs_pair_isnull(const lfs_block_t pair[2]) {
return pair[0] == LFS_BLOCK_NULL || pair[1] == LFS_BLOCK_NULL;
}
static inline int lfs_pair_cmp(
const lfs_block_t paira[2],
const lfs_block_t pairb[2]) {
return !(paira[0] == pairb[0] || paira[1] == pairb[1] ||
paira[0] == pairb[1] || paira[1] == pairb[0]);
}
static inline bool lfs_pair_issync(
const lfs_block_t paira[2],
const lfs_block_t pairb[2]) {
return (paira[0] == pairb[0] && paira[1] == pairb[1]) ||
(paira[0] == pairb[1] && paira[1] == pairb[0]);
}
static inline void lfs_pair_fromle32(lfs_block_t pair[2]) {
pair[0] = lfs_fromle32(pair[0]);
pair[1] = lfs_fromle32(pair[1]);
}
#ifndef LFS_READONLY
static inline void lfs_pair_tole32(lfs_block_t pair[2]) {
pair[0] = lfs_tole32(pair[0]);
pair[1] = lfs_tole32(pair[1]);
}
#endif
// operations on 32-bit entry tags
typedef uint32_t lfs_tag_t;
typedef int32_t lfs_stag_t;
#define LFS_MKTAG(type, id, size) \
(((lfs_tag_t)(type) << 20) | ((lfs_tag_t)(id) << 10) | (lfs_tag_t)(size))
#define LFS_MKTAG_IF(cond, type, id, size) \
((cond) ? LFS_MKTAG(type, id, size) : LFS_MKTAG(LFS_FROM_NOOP, 0, 0))
#define LFS_MKTAG_IF_ELSE(cond, type1, id1, size1, type2, id2, size2) \
((cond) ? LFS_MKTAG(type1, id1, size1) : LFS_MKTAG(type2, id2, size2))
static inline bool lfs_tag_isvalid(lfs_tag_t tag) {
return !(tag & 0x80000000);
}
static inline bool lfs_tag_isdelete(lfs_tag_t tag) {
return ((int32_t)(tag << 22) >> 22) == -1;
}
static inline uint16_t lfs_tag_type1(lfs_tag_t tag) {
return (tag & 0x70000000) >> 20;
}
static inline uint16_t lfs_tag_type2(lfs_tag_t tag) {
return (tag & 0x78000000) >> 20;
}
static inline uint16_t lfs_tag_type3(lfs_tag_t tag) {
return (tag & 0x7ff00000) >> 20;
}
static inline uint8_t lfs_tag_chunk(lfs_tag_t tag) {
return (tag & 0x0ff00000) >> 20;
}
static inline int8_t lfs_tag_splice(lfs_tag_t tag) {
return (int8_t)lfs_tag_chunk(tag);
}
static inline uint16_t lfs_tag_id(lfs_tag_t tag) {
return (tag & 0x000ffc00) >> 10;
}
static inline lfs_size_t lfs_tag_size(lfs_tag_t tag) {
return tag & 0x000003ff;
}
static inline lfs_size_t lfs_tag_dsize(lfs_tag_t tag) {
return sizeof(tag) + lfs_tag_size(tag + lfs_tag_isdelete(tag));
}
// operations on attributes in attribute lists
struct lfs_mattr {
lfs_tag_t tag;
const void *buffer;
};
struct lfs_diskoff {
lfs_block_t block;
lfs_off_t off;
};
#define LFS_MKATTRS(...) \
(struct lfs_mattr[]){__VA_ARGS__}, \
sizeof((struct lfs_mattr[]){__VA_ARGS__}) / sizeof(struct lfs_mattr)
// operations on global state
static inline void lfs_gstate_xor(lfs_gstate_t *a, const lfs_gstate_t *b) {
for (int i = 0; i < 3; i++) {
((uint32_t*)a)[i] ^= ((const uint32_t*)b)[i];
}
}
static inline bool lfs_gstate_iszero(const lfs_gstate_t *a) {
for (int i = 0; i < 3; i++) {
if (((uint32_t*)a)[i] != 0) {
return false;
}
}
return true;
}
#ifndef LFS_READONLY
static inline bool lfs_gstate_hasorphans(const lfs_gstate_t *a) {
return lfs_tag_size(a->tag);
}
static inline uint8_t lfs_gstate_getorphans(const lfs_gstate_t *a) {
return lfs_tag_size(a->tag) & 0x1ff;
}
static inline bool lfs_gstate_hasmove(const lfs_gstate_t *a) {
return lfs_tag_type1(a->tag);
}
#endif
static inline bool lfs_gstate_needssuperblock(const lfs_gstate_t *a) {
return lfs_tag_size(a->tag) >> 9;
}
static inline bool lfs_gstate_hasmovehere(const lfs_gstate_t *a,
const lfs_block_t *pair) {
return lfs_tag_type1(a->tag) && lfs_pair_cmp(a->pair, pair) == 0;
}
static inline void lfs_gstate_fromle32(lfs_gstate_t *a) {
a->tag = lfs_fromle32(a->tag);
a->pair[0] = lfs_fromle32(a->pair[0]);
a->pair[1] = lfs_fromle32(a->pair[1]);
}
#ifndef LFS_READONLY
static inline void lfs_gstate_tole32(lfs_gstate_t *a) {
a->tag = lfs_tole32(a->tag);
a->pair[0] = lfs_tole32(a->pair[0]);
a->pair[1] = lfs_tole32(a->pair[1]);
}
#endif
// operations on forward-CRCs used to track erased state
struct lfs_fcrc {
lfs_size_t size;
uint32_t crc;
};
static void lfs_fcrc_fromle32(struct lfs_fcrc *fcrc) {
fcrc->size = lfs_fromle32(fcrc->size);
fcrc->crc = lfs_fromle32(fcrc->crc);
}
#ifndef LFS_READONLY
static void lfs_fcrc_tole32(struct lfs_fcrc *fcrc) {
fcrc->size = lfs_tole32(fcrc->size);
fcrc->crc = lfs_tole32(fcrc->crc);
}
#endif
// other endianness operations
static void lfs_ctz_fromle32(struct lfs_ctz *ctz) {
ctz->head = lfs_fromle32(ctz->head);
ctz->size = lfs_fromle32(ctz->size);
}
#ifndef LFS_READONLY
static void lfs_ctz_tole32(struct lfs_ctz *ctz) {
ctz->head = lfs_tole32(ctz->head);
ctz->size = lfs_tole32(ctz->size);
}
#endif
static inline void lfs_superblock_fromle32(lfs_superblock_t *superblock) {
superblock->version = lfs_fromle32(superblock->version);
superblock->block_size = lfs_fromle32(superblock->block_size);
superblock->block_count = lfs_fromle32(superblock->block_count);
superblock->name_max = lfs_fromle32(superblock->name_max);
superblock->file_max = lfs_fromle32(superblock->file_max);
superblock->attr_max = lfs_fromle32(superblock->attr_max);
}
#ifndef LFS_READONLY
static inline void lfs_superblock_tole32(lfs_superblock_t *superblock) {
superblock->version = lfs_tole32(superblock->version);
superblock->block_size = lfs_tole32(superblock->block_size);
superblock->block_count = lfs_tole32(superblock->block_count);
superblock->name_max = lfs_tole32(superblock->name_max);
superblock->file_max = lfs_tole32(superblock->file_max);
superblock->attr_max = lfs_tole32(superblock->attr_max);
}
#endif
#ifndef LFS_NO_ASSERT
static bool lfs_mlist_isopen(struct lfs_mlist *head,
struct lfs_mlist *node) {
for (struct lfs_mlist **p = &head; *p; p = &(*p)->next) {
if (*p == (struct lfs_mlist*)node) {
return true;
}
}
return false;
}
#endif
static void lfs_mlist_remove(lfs_t *lfs, struct lfs_mlist *mlist) {
for (struct lfs_mlist **p = &lfs->mlist; *p; p = &(*p)->next) {
if (*p == mlist) {
*p = (*p)->next;
break;
}
}
}
static void lfs_mlist_append(lfs_t *lfs, struct lfs_mlist *mlist) {
mlist->next = lfs->mlist;
lfs->mlist = mlist;
}
// some other filesystem operations
static uint32_t lfs_fs_disk_version(lfs_t *lfs) {
(void)lfs;
#ifdef LFS_MULTIVERSION
if (lfs->cfg->disk_version) {
return lfs->cfg->disk_version;
} else
#endif
{
return LFS_DISK_VERSION;
}
}
static uint16_t lfs_fs_disk_version_major(lfs_t *lfs) {
return 0xffff & (lfs_fs_disk_version(lfs) >> 16);
}
static uint16_t lfs_fs_disk_version_minor(lfs_t *lfs) {
return 0xffff & (lfs_fs_disk_version(lfs) >> 0);
}
/// Internal operations predeclared here ///
#ifndef LFS_READONLY
static int lfs_dir_commit(lfs_t *lfs, lfs_mdir_t *dir,
const struct lfs_mattr *attrs, int attrcount);
static int lfs_dir_compact(lfs_t *lfs,
lfs_mdir_t *dir, const struct lfs_mattr *attrs, int attrcount,
lfs_mdir_t *source, uint16_t begin, uint16_t end);
static lfs_ssize_t lfs_file_flushedwrite(lfs_t *lfs, lfs_file_t *file,
const void *buffer, lfs_size_t size);
static lfs_ssize_t lfs_file_write_(lfs_t *lfs, lfs_file_t *file,
const void *buffer, lfs_size_t size);
static int lfs_file_sync_(lfs_t *lfs, lfs_file_t *file);
static int lfs_file_outline(lfs_t *lfs, lfs_file_t *file);
static int lfs_file_flush(lfs_t *lfs, lfs_file_t *file);
static int lfs_fs_deorphan(lfs_t *lfs, bool powerloss);
static int lfs_fs_preporphans(lfs_t *lfs, int8_t orphans);
static void lfs_fs_prepmove(lfs_t *lfs,
uint16_t id, const lfs_block_t pair[2]);
static int lfs_fs_pred(lfs_t *lfs, const lfs_block_t dir[2],
lfs_mdir_t *pdir);
static lfs_stag_t lfs_fs_parent(lfs_t *lfs, const lfs_block_t dir[2],
lfs_mdir_t *parent);
static int lfs_fs_forceconsistency(lfs_t *lfs);
#endif
static void lfs_fs_prepsuperblock(lfs_t *lfs, bool needssuperblock);
#ifdef LFS_MIGRATE
static int lfs1_traverse(lfs_t *lfs,
int (*cb)(void*, lfs_block_t), void *data);
#endif
static int lfs_dir_rewind_(lfs_t *lfs, lfs_dir_t *dir);
static lfs_ssize_t lfs_file_flushedread(lfs_t *lfs, lfs_file_t *file,
void *buffer, lfs_size_t size);
static lfs_ssize_t lfs_file_read_(lfs_t *lfs, lfs_file_t *file,
void *buffer, lfs_size_t size);
static int lfs_file_close_(lfs_t *lfs, lfs_file_t *file);
static lfs_soff_t lfs_file_size_(lfs_t *lfs, lfs_file_t *file);
static lfs_ssize_t lfs_fs_size_(lfs_t *lfs);
static int lfs_fs_traverse_(lfs_t *lfs,
int (*cb)(void *data, lfs_block_t block), void *data,
bool includeorphans);
static int lfs_deinit(lfs_t *lfs);
static int lfs_unmount_(lfs_t *lfs);
/// Block allocator ///
// allocations should call this when all allocated blocks are committed to
// the filesystem
//
// after a checkpoint, the block allocator may realloc any untracked blocks
static void lfs_alloc_ckpoint(lfs_t *lfs) {
lfs->lookahead.ckpoint = lfs->block_count;
}
// drop the lookahead buffer, this is done during mounting and failed
// traversals in order to avoid invalid lookahead state
static void lfs_alloc_drop(lfs_t *lfs) {
lfs->lookahead.size = 0;
lfs->lookahead.next = 0;
lfs_alloc_ckpoint(lfs);
}
#ifndef LFS_READONLY
static int lfs_alloc_lookahead(void *p, lfs_block_t block) {
lfs_t *lfs = (lfs_t*)p;
lfs_block_t off = ((block - lfs->lookahead.start)
+ lfs->block_count) % lfs->block_count;
if (off < lfs->lookahead.size) {
lfs->lookahead.buffer[off / 8] |= 1U << (off % 8);
}
return 0;
}
#endif
#ifndef LFS_READONLY
static int lfs_alloc_scan(lfs_t *lfs) {
// move lookahead buffer to the first unused block
//
// note we limit the lookahead buffer to at most the amount of blocks
// checkpointed, this prevents the math in lfs_alloc from underflowing
lfs->lookahead.start = (lfs->lookahead.start + lfs->lookahead.next)
% lfs->block_count;
lfs->lookahead.next = 0;
lfs->lookahead.size = lfs_min(
8*lfs->cfg->lookahead_size,
lfs->lookahead.ckpoint);
// find mask of free blocks from tree
memset(lfs->lookahead.buffer, 0, lfs->cfg->lookahead_size);
int err = lfs_fs_traverse_(lfs, lfs_alloc_lookahead, lfs, true);
if (err) {
lfs_alloc_drop(lfs);
return err;
}
return 0;
}
#endif
#ifndef LFS_READONLY
static int lfs_alloc(lfs_t *lfs, lfs_block_t *block) {
while (true) {
// scan our lookahead buffer for free blocks
while (lfs->lookahead.next < lfs->lookahead.size) {
if (!(lfs->lookahead.buffer[lfs->lookahead.next / 8]
& (1U << (lfs->lookahead.next % 8)))) {
// found a free block
*block = (lfs->lookahead.start + lfs->lookahead.next)
% lfs->block_count;
// eagerly find next free block to maximize how many blocks
// lfs_alloc_ckpoint makes available for scanning
while (true) {
lfs->lookahead.next += 1;
lfs->lookahead.ckpoint -= 1;
if (lfs->lookahead.next >= lfs->lookahead.size
|| !(lfs->lookahead.buffer[lfs->lookahead.next / 8]
& (1U << (lfs->lookahead.next % 8)))) {
return 0;
}
}
}
lfs->lookahead.next += 1;
lfs->lookahead.ckpoint -= 1;
}
// In order to keep our block allocator from spinning forever when our
// filesystem is full, we mark points where there are no in-flight
// allocations with a checkpoint before starting a set of allocations.
//
// If we've looked at all blocks since the last checkpoint, we report
// the filesystem as out of storage.
//
if (lfs->lookahead.ckpoint <= 0) {
LFS_ERROR("No more free space 0x%"PRIx32,
(lfs->lookahead.start + lfs->lookahead.next)
% lfs->block_count);
return LFS_ERR_NOSPC;
}
// No blocks in our lookahead buffer, we need to scan the filesystem for
// unused blocks in the next lookahead window.
int err = lfs_alloc_scan(lfs);
if(err) {
return err;
}
}
}
#endif
/// Metadata pair and directory operations ///
static lfs_stag_t lfs_dir_getslice(lfs_t *lfs, const lfs_mdir_t *dir,
lfs_tag_t gmask, lfs_tag_t gtag,
lfs_off_t goff, void *gbuffer, lfs_size_t gsize) {
lfs_off_t off = dir->off;
lfs_tag_t ntag = dir->etag;
lfs_stag_t gdiff = 0;
// synthetic moves
if (lfs_gstate_hasmovehere(&lfs->gdisk, dir->pair) &&
lfs_tag_id(gmask) != 0) {
if (lfs_tag_id(lfs->gdisk.tag) == lfs_tag_id(gtag)) {
return LFS_ERR_NOENT;
} else if (lfs_tag_id(lfs->gdisk.tag) < lfs_tag_id(gtag)) {
gdiff -= LFS_MKTAG(0, 1, 0);
}
}
// iterate over dir block backwards (for faster lookups)
while (off >= sizeof(lfs_tag_t) + lfs_tag_dsize(ntag)) {
off -= lfs_tag_dsize(ntag);
lfs_tag_t tag = ntag;
int err = lfs_bd_read(lfs,
NULL, &lfs->rcache, sizeof(ntag),
dir->pair[0], off, &ntag, sizeof(ntag));
if (err) {
return err;
}
ntag = (lfs_frombe32(ntag) ^ tag) & 0x7fffffff;
if (lfs_tag_id(gmask) != 0 &&
lfs_tag_type1(tag) == LFS_TYPE_SPLICE &&
lfs_tag_id(tag) <= lfs_tag_id(gtag - gdiff)) {
if (tag == (LFS_MKTAG(LFS_TYPE_CREATE, 0, 0) |
(LFS_MKTAG(0, 0x3ff, 0) & (gtag - gdiff)))) {
// found where we were created
return LFS_ERR_NOENT;
}
// move around splices
gdiff += LFS_MKTAG(0, lfs_tag_splice(tag), 0);
}
if ((gmask & tag) == (gmask & (gtag - gdiff))) {
if (lfs_tag_isdelete(tag)) {
return LFS_ERR_NOENT;
}
lfs_size_t diff = lfs_min(lfs_tag_size(tag), gsize);
err = lfs_bd_read(lfs,
NULL, &lfs->rcache, diff,
dir->pair[0], off+sizeof(tag)+goff, gbuffer, diff);
if (err) {
return err;
}
memset((uint8_t*)gbuffer + diff, 0, gsize - diff);
return tag + gdiff;
}
}
return LFS_ERR_NOENT;
}
static lfs_stag_t lfs_dir_get(lfs_t *lfs, const lfs_mdir_t *dir,
lfs_tag_t gmask, lfs_tag_t gtag, void *buffer) {
return lfs_dir_getslice(lfs, dir,
gmask, gtag,
0, buffer, lfs_tag_size(gtag));
}
static int lfs_dir_getread(lfs_t *lfs, const lfs_mdir_t *dir,
const lfs_cache_t *pcache, lfs_cache_t *rcache, lfs_size_t hint,
lfs_tag_t gmask, lfs_tag_t gtag,
lfs_off_t off, void *buffer, lfs_size_t size) {
uint8_t *data = buffer;
if (off+size > lfs->cfg->block_size) {
return LFS_ERR_CORRUPT;
}
while (size > 0) {
lfs_size_t diff = size;
if (pcache && pcache->block == LFS_BLOCK_INLINE &&
off < pcache->off + pcache->size) {
if (off >= pcache->off) {
// is already in pcache?
diff = lfs_min(diff, pcache->size - (off-pcache->off));
memcpy(data, &pcache->buffer[off-pcache->off], diff);
data += diff;
off += diff;
size -= diff;
continue;
}
// pcache takes priority
diff = lfs_min(diff, pcache->off-off);
}
if (rcache->block == LFS_BLOCK_INLINE &&
off < rcache->off + rcache->size) {
if (off >= rcache->off) {
// is already in rcache?
diff = lfs_min(diff, rcache->size - (off-rcache->off));
memcpy(data, &rcache->buffer[off-rcache->off], diff);
data += diff;
off += diff;
size -= diff;
continue;
}
// rcache takes priority
diff = lfs_min(diff, rcache->off-off);
}
// load to cache, first condition can no longer fail
rcache->block = LFS_BLOCK_INLINE;
rcache->off = lfs_aligndown(off, lfs->cfg->read_size);
rcache->size = lfs_min(lfs_alignup(off+hint, lfs->cfg->read_size),
lfs->cfg->cache_size);
int err = lfs_dir_getslice(lfs, dir, gmask, gtag,
rcache->off, rcache->buffer, rcache->size);
if (err < 0) {
return err;
}
}
return 0;
}
#ifndef LFS_READONLY
static int lfs_dir_traverse_filter(void *p,
lfs_tag_t tag, const void *buffer) {
lfs_tag_t *filtertag = p;
(void)buffer;
// which mask depends on unique bit in tag structure
uint32_t mask = (tag & LFS_MKTAG(0x100, 0, 0))
? LFS_MKTAG(0x7ff, 0x3ff, 0)
: LFS_MKTAG(0x700, 0x3ff, 0);
// check for redundancy
if ((mask & tag) == (mask & *filtertag) ||
lfs_tag_isdelete(*filtertag) ||
(LFS_MKTAG(0x7ff, 0x3ff, 0) & tag) == (
LFS_MKTAG(LFS_TYPE_DELETE, 0, 0) |
(LFS_MKTAG(0, 0x3ff, 0) & *filtertag))) {
*filtertag = LFS_MKTAG(LFS_FROM_NOOP, 0, 0);
return true;
}
// check if we need to adjust for created/deleted tags
if (lfs_tag_type1(tag) == LFS_TYPE_SPLICE &&
lfs_tag_id(tag) <= lfs_tag_id(*filtertag)) {
*filtertag += LFS_MKTAG(0, lfs_tag_splice(tag), 0);
}
return false;
}
#endif
#ifndef LFS_READONLY
// maximum recursive depth of lfs_dir_traverse, the deepest call:
//
// traverse with commit
// '-> traverse with move
// '-> traverse with filter
//
#define LFS_DIR_TRAVERSE_DEPTH 3
struct lfs_dir_traverse {
const lfs_mdir_t *dir;
lfs_off_t off;
lfs_tag_t ptag;
const struct lfs_mattr *attrs;
int attrcount;
lfs_tag_t tmask;
lfs_tag_t ttag;
uint16_t begin;
uint16_t end;
int16_t diff;
int (*cb)(void *data, lfs_tag_t tag, const void *buffer);
void *data;
lfs_tag_t tag;
const void *buffer;
struct lfs_diskoff disk;
};
static int lfs_dir_traverse(lfs_t *lfs,
const lfs_mdir_t *dir, lfs_off_t off, lfs_tag_t ptag,
const struct lfs_mattr *attrs, int attrcount,
lfs_tag_t tmask, lfs_tag_t ttag,
uint16_t begin, uint16_t end, int16_t diff,
int (*cb)(void *data, lfs_tag_t tag, const void *buffer), void *data) {
// This function in inherently recursive, but bounded. To allow tool-based
// analysis without unnecessary code-cost we use an explicit stack
struct lfs_dir_traverse stack[LFS_DIR_TRAVERSE_DEPTH-1];
unsigned sp = 0;
int res;
// iterate over directory and attrs
lfs_tag_t tag;
const void *buffer;
struct lfs_diskoff disk = {0};
while (true) {
{
if (off+lfs_tag_dsize(ptag) < dir->off) {
off += lfs_tag_dsize(ptag);
int err = lfs_bd_read(lfs,
NULL, &lfs->rcache, sizeof(tag),
dir->pair[0], off, &tag, sizeof(tag));
if (err) {
return err;
}
tag = (lfs_frombe32(tag) ^ ptag) | 0x80000000;
disk.block = dir->pair[0];
disk.off = off+sizeof(lfs_tag_t);
buffer = &disk;
ptag = tag;
} else if (attrcount > 0) {
tag = attrs[0].tag;
buffer = attrs[0].buffer;
attrs += 1;
attrcount -= 1;
} else {
// finished traversal, pop from stack?
res = 0;
break;
}
// do we need to filter?
lfs_tag_t mask = LFS_MKTAG(0x7ff, 0, 0);
if ((mask & tmask & tag) != (mask & tmask & ttag)) {
continue;
}
if (lfs_tag_id(tmask) != 0) {
LFS_ASSERT(sp < LFS_DIR_TRAVERSE_DEPTH);
// recurse, scan for duplicates, and update tag based on
// creates/deletes
stack[sp] = (struct lfs_dir_traverse){
.dir = dir,
.off = off,
.ptag = ptag,
.attrs = attrs,
.attrcount = attrcount,
.tmask = tmask,
.ttag = ttag,
.begin = begin,
.end = end,
.diff = diff,
.cb = cb,
.data = data,
.tag = tag,
.buffer = buffer,
.disk = disk,
};
sp += 1;
tmask = 0;
ttag = 0;
begin = 0;
end = 0;
diff = 0;
cb = lfs_dir_traverse_filter;
data = &stack[sp-1].tag;
continue;
}
}
popped:
// in filter range?
if (lfs_tag_id(tmask) != 0 &&
!(lfs_tag_id(tag) >= begin && lfs_tag_id(tag) < end)) {
continue;
}
// handle special cases for mcu-side operations
if (lfs_tag_type3(tag) == LFS_FROM_NOOP) {
// do nothing
} else if (lfs_tag_type3(tag) == LFS_FROM_MOVE) {
// Without this condition, lfs_dir_traverse can exhibit an
// extremely expensive O(n^3) of nested loops when renaming.
// This happens because lfs_dir_traverse tries to filter tags by
// the tags in the source directory, triggering a second
// lfs_dir_traverse with its own filter operation.
//
// traverse with commit