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9637b96069
third_party_littlefs/lfs.c
Christopher Haster 9637b96069 Fixed lookahead overflow and removed unbounded lookahead pointers 
As pointed out by davidefer, the lookahead pointer modular arithmetic
does not work around integer overflow when the pointer size is not a
multiple of the block count.

To avoid overflow problems, the easy solution is to stop trying to
work around integer overflows and keep the lookahead offset inside the
block device. To make this work, the ack was modified into a resetable
counter that is decremented every block allocation.

As a plus, quite a bit of the allocation logic ended up simplified.
2018-04-11 14:38:25 -05:00

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/*
* The little filesystem
*
* Copyright (c) 2017 ARM Limited
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "lfs.h"
#include "lfs_util.h"
/// Caching block device operations ///
static int lfs_cache_read(lfs_t *lfs, lfs_cache_t *rcache,
const lfs_cache_t *pcache, lfs_block_t block,
lfs_off_t off, void *buffer, lfs_size_t size) {
uint8_t *data = buffer;
LFS_ASSERT(block < lfs->cfg->block_count);
while (size > 0) {
if (pcache && block == pcache->block && off >= pcache->off &&
off < pcache->off + lfs->cfg->prog_size) {
// is already in pcache?
lfs_size_t diff = lfs_min(size,
lfs->cfg->prog_size - (off-pcache->off));
memcpy(data, &pcache->buffer[off-pcache->off], diff);
data += diff;
off += diff;
size -= diff;
continue;
}
if (block == rcache->block && off >= rcache->off &&
off < rcache->off + lfs->cfg->read_size) {
// is already in rcache?
lfs_size_t diff = lfs_min(size,
lfs->cfg->read_size - (off-rcache->off));
memcpy(data, &rcache->buffer[off-rcache->off], diff);
data += diff;
off += diff;
size -= diff;
continue;
}
if (off % lfs->cfg->read_size == 0 && size >= lfs->cfg->read_size) {
// bypass cache?
lfs_size_t diff = size - (size % 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
rcache->block = block;
rcache->off = off - (off % lfs->cfg->read_size);
int err = lfs->cfg->read(lfs->cfg, rcache->block,
rcache->off, rcache->buffer, lfs->cfg->read_size);
if (err) {
return err;
}
}
return 0;
}
static int lfs_cache_cmp(lfs_t *lfs, lfs_cache_t *rcache,
const lfs_cache_t *pcache, lfs_block_t block,
lfs_off_t off, const void *buffer, lfs_size_t size) {
const uint8_t *data = buffer;
for (lfs_off_t i = 0; i < size; i++) {
uint8_t c;
int err = lfs_cache_read(lfs, rcache, pcache,
block, off+i, &c, 1);
if (err) {
return err;
}
if (c != data[i]) {
return false;
}
}
return true;
}
static int lfs_cache_crc(lfs_t *lfs, lfs_cache_t *rcache,
const lfs_cache_t *pcache, lfs_block_t block,
lfs_off_t off, lfs_size_t size, uint32_t *crc) {
for (lfs_off_t i = 0; i < size; i++) {
uint8_t c;
int err = lfs_cache_read(lfs, rcache, pcache,
block, off+i, &c, 1);
if (err) {
return err;
}
lfs_crc(crc, &c, 1);
}
return 0;
}
static int lfs_cache_flush(lfs_t *lfs,
lfs_cache_t *pcache, lfs_cache_t *rcache) {
if (pcache->block != 0xffffffff) {
int err = lfs->cfg->prog(lfs->cfg, pcache->block,
pcache->off, pcache->buffer, lfs->cfg->prog_size);
if (err) {
return err;
}
if (rcache) {
int res = lfs_cache_cmp(lfs, rcache, NULL, pcache->block,
pcache->off, pcache->buffer, lfs->cfg->prog_size);
if (res < 0) {
return res;
}
if (!res) {
return LFS_ERR_CORRUPT;
}
}
pcache->block = 0xffffffff;
}
return 0;
}
static int lfs_cache_prog(lfs_t *lfs, lfs_cache_t *pcache,
lfs_cache_t *rcache, lfs_block_t block,
lfs_off_t off, const void *buffer, lfs_size_t size) {
const uint8_t *data = buffer;
LFS_ASSERT(block < lfs->cfg->block_count);
while (size > 0) {
if (block == pcache->block && off >= pcache->off &&
off < pcache->off + lfs->cfg->prog_size) {
// is already in pcache?
lfs_size_t diff = lfs_min(size,
lfs->cfg->prog_size - (off-pcache->off));
memcpy(&pcache->buffer[off-pcache->off], data, diff);
data += diff;
off += diff;
size -= diff;
if (off % lfs->cfg->prog_size == 0) {
// eagerly flush out pcache if we fill up
int err = lfs_cache_flush(lfs, pcache, rcache);
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 == 0xffffffff);
if (off % lfs->cfg->prog_size == 0 &&
size >= lfs->cfg->prog_size) {
// bypass pcache?
lfs_size_t diff = size - (size % lfs->cfg->prog_size);
int err = lfs->cfg->prog(lfs->cfg, block, off, data, diff);
if (err) {
return err;
}
if (rcache) {
int res = lfs_cache_cmp(lfs, rcache, NULL,
block, off, data, diff);
if (res < 0) {
return res;
}
if (!res) {
return LFS_ERR_CORRUPT;
}
}
data += diff;
off += diff;
size -= diff;
continue;
}
// prepare pcache, first condition can no longer fail
pcache->block = block;
pcache->off = off - (off % lfs->cfg->prog_size);
}
return 0;
}
/// General lfs block device operations ///
static int lfs_bd_read(lfs_t *lfs, lfs_block_t block,
lfs_off_t off, void *buffer, lfs_size_t size) {
// if we ever do more than writes to alternating pairs,
// this may need to consider pcache
return lfs_cache_read(lfs, &lfs->rcache, NULL,
block, off, buffer, size);
}
static int lfs_bd_prog(lfs_t *lfs, lfs_block_t block,
lfs_off_t off, const void *buffer, lfs_size_t size) {
return lfs_cache_prog(lfs, &lfs->pcache, NULL,
block, off, buffer, size);
}
static int lfs_bd_cmp(lfs_t *lfs, lfs_block_t block,
lfs_off_t off, const void *buffer, lfs_size_t size) {
return lfs_cache_cmp(lfs, &lfs->rcache, NULL, block, off, buffer, size);
}
static int lfs_bd_crc(lfs_t *lfs, lfs_block_t block,
lfs_off_t off, lfs_size_t size, uint32_t *crc) {
return lfs_cache_crc(lfs, &lfs->rcache, NULL, block, off, size, crc);
}
static int lfs_bd_erase(lfs_t *lfs, lfs_block_t block) {
return lfs->cfg->erase(lfs->cfg, block);
}
static int lfs_bd_sync(lfs_t *lfs) {
lfs->rcache.block = 0xffffffff;
int err = lfs_cache_flush(lfs, &lfs->pcache, NULL);
if (err) {
return err;
}
return lfs->cfg->sync(lfs->cfg);
}
/// Internal operations predeclared here ///
int lfs_traverse(lfs_t *lfs, int (*cb)(void*, lfs_block_t), void *data);
static int lfs_pred(lfs_t *lfs, const lfs_block_t dir[2], lfs_dir_t *pdir);
static int lfs_parent(lfs_t *lfs, const lfs_block_t dir[2],
lfs_dir_t *parent, lfs_entry_t *entry);
static int lfs_moved(lfs_t *lfs, const void *e);
static int lfs_relocate(lfs_t *lfs,
const lfs_block_t oldpair[2], const lfs_block_t newpair[2]);
int lfs_deorphan(lfs_t *lfs);
/// Block allocator ///
static int lfs_alloc_lookahead(void *p, lfs_block_t block) {
lfs_t *lfs = p;
lfs_block_t off = ((block - lfs->free.off)
+ lfs->cfg->block_count) % lfs->cfg->block_count;
if (off < lfs->free.size) {
lfs->free.buffer[off / 32] |= 1U << (off % 32);
}
return 0;
}
static int lfs_alloc(lfs_t *lfs, lfs_block_t *block) {
while (true) {
while (lfs->free.i != lfs->free.size) {
lfs_block_t off = lfs->free.i;
lfs->free.i += 1;
lfs->free.ack -= 1;
if (!(lfs->free.buffer[off / 32] & (1U << (off % 32)))) {
// found a free block
*block = (lfs->free.off + off) % lfs->cfg->block_count;
// eagerly find next off so an alloc ack can
// discredit old lookahead blocks
while (lfs->free.i != lfs->free.size &&
(lfs->free.buffer[lfs->free.i / 32]
& (1U << (lfs->free.i % 32)))) {
lfs->free.i += 1;
lfs->free.ack -= 1;
}
return 0;
}
}
// check if we have looked at all blocks since last ack
if (lfs->free.ack == 0) {
LFS_WARN("No more free space %d", lfs->free.i + lfs->free.off);
return LFS_ERR_NOSPC;
}
lfs->free.off = (lfs->free.off + lfs->free.size)
% lfs->cfg->block_count;
lfs->free.size = lfs_min(lfs->cfg->lookahead, lfs->free.ack);
lfs->free.i = 0;
// find mask of free blocks from tree
memset(lfs->free.buffer, 0, lfs->cfg->lookahead/8);
int err = lfs_traverse(lfs, lfs_alloc_lookahead, lfs);
if (err) {
return err;
}
}
}
static void lfs_alloc_ack(lfs_t *lfs) {
lfs->free.ack = lfs->cfg->block_count;
}
/// Endian swapping functions ///
static void lfs_dir_fromle32(struct lfs_disk_dir *d) {
d->rev = lfs_fromle32(d->rev);
d->size = lfs_fromle32(d->size);
d->tail[0] = lfs_fromle32(d->tail[0]);
d->tail[1] = lfs_fromle32(d->tail[1]);
}
static void lfs_dir_tole32(struct lfs_disk_dir *d) {
d->rev = lfs_tole32(d->rev);
d->size = lfs_tole32(d->size);
d->tail[0] = lfs_tole32(d->tail[0]);
d->tail[1] = lfs_tole32(d->tail[1]);
}
static void lfs_entry_fromle32(struct lfs_disk_entry *d) {
d->u.dir[0] = lfs_fromle32(d->u.dir[0]);
d->u.dir[1] = lfs_fromle32(d->u.dir[1]);
}
static void lfs_entry_tole32(struct lfs_disk_entry *d) {
d->u.dir[0] = lfs_tole32(d->u.dir[0]);
d->u.dir[1] = lfs_tole32(d->u.dir[1]);
}
static void lfs_superblock_fromle32(struct lfs_disk_superblock *d) {
d->root[0] = lfs_fromle32(d->root[0]);
d->root[1] = lfs_fromle32(d->root[1]);
d->block_size = lfs_fromle32(d->block_size);
d->block_count = lfs_fromle32(d->block_count);
d->version = lfs_fromle32(d->version);
}
static void lfs_superblock_tole32(struct lfs_disk_superblock *d) {
d->root[0] = lfs_tole32(d->root[0]);
d->root[1] = lfs_tole32(d->root[1]);
d->block_size = lfs_tole32(d->block_size);
d->block_count = lfs_tole32(d->block_count);
d->version = lfs_tole32(d->version);
}
/// Metadata pair and directory operations ///
static inline void lfs_pairswap(lfs_block_t pair[2]) {
lfs_block_t t = pair[0];
pair[0] = pair[1];
pair[1] = t;
}
static inline bool lfs_pairisnull(const lfs_block_t pair[2]) {
return pair[0] == 0xffffffff || pair[1] == 0xffffffff;
}
static inline int lfs_paircmp(
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_pairsync(
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 lfs_size_t lfs_entry_size(const lfs_entry_t *entry) {
return 4 + entry->d.elen + entry->d.alen + entry->d.nlen;
}
static int lfs_dir_alloc(lfs_t *lfs, lfs_dir_t *dir) {
// allocate pair of dir blocks
for (int i = 0; i < 2; i++) {
int err = lfs_alloc(lfs, &dir->pair[i]);
if (err) {
return err;
}
}
// rather than clobbering one of the blocks we just pretend
// the revision may be valid
int err = lfs_bd_read(lfs, dir->pair[0], 0, &dir->d.rev, 4);
dir->d.rev = lfs_fromle32(dir->d.rev);
if (err) {
return err;
}
// set defaults
dir->d.rev += 1;
dir->d.size = sizeof(dir->d)+4;
dir->d.tail[0] = 0xffffffff;
dir->d.tail[1] = 0xffffffff;
dir->off = sizeof(dir->d);
// don't write out yet, let caller take care of that
return 0;
}
static int lfs_dir_fetch(lfs_t *lfs,
lfs_dir_t *dir, const lfs_block_t pair[2]) {
// copy out pair, otherwise may be aliasing dir
const lfs_block_t tpair[2] = {pair[0], pair[1]};
bool valid = false;
// check both blocks for the most recent revision
for (int i = 0; i < 2; i++) {
struct lfs_disk_dir test;
int err = lfs_bd_read(lfs, tpair[i], 0, &test, sizeof(test));
lfs_dir_fromle32(&test);
if (err) {
return err;
}
if (valid && lfs_scmp(test.rev, dir->d.rev) < 0) {
continue;
}
if ((0x7fffffff & test.size) < sizeof(test)+4 ||
(0x7fffffff & test.size) > lfs->cfg->block_size) {
continue;
}
uint32_t crc = 0xffffffff;
lfs_dir_tole32(&test);
lfs_crc(&crc, &test, sizeof(test));
lfs_dir_fromle32(&test);
err = lfs_bd_crc(lfs, tpair[i], sizeof(test),
(0x7fffffff & test.size) - sizeof(test), &crc);
if (err) {
return err;
}
if (crc != 0) {
continue;
}
valid = true;
// setup dir in case it's valid
dir->pair[0] = tpair[(i+0) % 2];
dir->pair[1] = tpair[(i+1) % 2];
dir->off = sizeof(dir->d);
dir->d = test;
}
if (!valid) {
LFS_ERROR("Corrupted dir pair at %d %d", tpair[0], tpair[1]);
return LFS_ERR_CORRUPT;
}
return 0;
}
struct lfs_region {
lfs_off_t oldoff;
lfs_size_t oldlen;
const void *newdata;
lfs_size_t newlen;
};
static int lfs_dir_commit(lfs_t *lfs, lfs_dir_t *dir,
const struct lfs_region *regions, int count) {
// increment revision count
dir->d.rev += 1;
// keep pairs in order such that pair[0] is most recent
lfs_pairswap(dir->pair);
for (int i = 0; i < count; i++) {
dir->d.size += regions[i].newlen - regions[i].oldlen;
}
const lfs_block_t oldpair[2] = {dir->pair[0], dir->pair[1]};
bool relocated = false;
while (true) {
if (true) {
int err = lfs_bd_erase(lfs, dir->pair[0]);
if (err) {
if (err == LFS_ERR_CORRUPT) {
goto relocate;
}
return err;
}
uint32_t crc = 0xffffffff;
lfs_dir_tole32(&dir->d);
lfs_crc(&crc, &dir->d, sizeof(dir->d));
err = lfs_bd_prog(lfs, dir->pair[0], 0, &dir->d, sizeof(dir->d));
lfs_dir_fromle32(&dir->d);
if (err) {
if (err == LFS_ERR_CORRUPT) {
goto relocate;
}
return err;
}
int i = 0;
lfs_off_t oldoff = sizeof(dir->d);
lfs_off_t newoff = sizeof(dir->d);
while (newoff < (0x7fffffff & dir->d.size)-4) {
if (i < count && regions[i].oldoff == oldoff) {
lfs_crc(&crc, regions[i].newdata, regions[i].newlen);
err = lfs_bd_prog(lfs, dir->pair[0],
newoff, regions[i].newdata, regions[i].newlen);
if (err) {
if (err == LFS_ERR_CORRUPT) {
goto relocate;
}
return err;
}
oldoff += regions[i].oldlen;
newoff += regions[i].newlen;
i += 1;
} else {
uint8_t data;
err = lfs_bd_read(lfs, oldpair[1], oldoff, &data, 1);
if (err) {
return err;
}
lfs_crc(&crc, &data, 1);
err = lfs_bd_prog(lfs, dir->pair[0], newoff, &data, 1);
if (err) {
if (err == LFS_ERR_CORRUPT) {
goto relocate;
}
return err;
}
oldoff += 1;
newoff += 1;
}
}
crc = lfs_tole32(crc);
err = lfs_bd_prog(lfs, dir->pair[0], newoff, &crc, 4);
crc = lfs_fromle32(crc);
if (err) {
if (err == LFS_ERR_CORRUPT) {
goto relocate;
}
return err;
}
err = lfs_bd_sync(lfs);
if (err) {
if (err == LFS_ERR_CORRUPT) {
goto relocate;
}
return err;
}
// successful commit, check checksum to make sure
uint32_t ncrc = 0xffffffff;
err = lfs_bd_crc(lfs, dir->pair[0], 0,
(0x7fffffff & dir->d.size)-4, &ncrc);
if (err) {
return err;
}
if (ncrc != crc) {
goto relocate;
}
}
break;
relocate:
//commit was corrupted
LFS_DEBUG("Bad block at %d", dir->pair[0]);
// drop caches and prepare to relocate block
relocated = true;
lfs->pcache.block = 0xffffffff;
// can't relocate superblock, filesystem is now frozen
if (lfs_paircmp(oldpair, (const lfs_block_t[2]){0, 1}) == 0) {
LFS_WARN("Superblock %d has become unwritable", oldpair[0]);
return LFS_ERR_CORRUPT;
}
// relocate half of pair
int err = lfs_alloc(lfs, &dir->pair[0]);
if (err) {
return err;
}
}
if (relocated) {
// update references if we relocated
LFS_DEBUG("Relocating %d %d to %d %d",
oldpair[0], oldpair[1], dir->pair[0], dir->pair[1]);
int err = lfs_relocate(lfs, oldpair, dir->pair);
if (err) {
return err;
}
}
// shift over any directories that are affected
for (lfs_dir_t *d = lfs->dirs; d; d = d->next) {
if (lfs_paircmp(d->pair, dir->pair) == 0) {
d->pair[0] = dir->pair[0];
d->pair[1] = dir->pair[1];
}
}
return 0;
}
static int lfs_dir_update(lfs_t *lfs, lfs_dir_t *dir,
lfs_entry_t *entry, const void *data) {
lfs_entry_tole32(&entry->d);
int err = lfs_dir_commit(lfs, dir, (struct lfs_region[]){
{entry->off, sizeof(entry->d), &entry->d, sizeof(entry->d)},
{entry->off+sizeof(entry->d), entry->d.nlen, data, entry->d.nlen}
}, data ? 2 : 1);
lfs_entry_fromle32(&entry->d);
return err;
}
static int lfs_dir_append(lfs_t *lfs, lfs_dir_t *dir,
lfs_entry_t *entry, const void *data) {
// check if we fit, if top bit is set we do not and move on
while (true) {
if (dir->d.size + lfs_entry_size(entry) <= lfs->cfg->block_size) {
entry->off = dir->d.size - 4;
lfs_entry_tole32(&entry->d);
int err = lfs_dir_commit(lfs, dir, (struct lfs_region[]){
{entry->off, 0, &entry->d, sizeof(entry->d)},
{entry->off, 0, data, entry->d.nlen}
}, 2);
lfs_entry_fromle32(&entry->d);
return err;
}
// we need to allocate a new dir block
if (!(0x80000000 & dir->d.size)) {
lfs_dir_t olddir = *dir;
int err = lfs_dir_alloc(lfs, dir);
if (err) {
return err;
}
dir->d.tail[0] = olddir.d.tail[0];
dir->d.tail[1] = olddir.d.tail[1];
entry->off = dir->d.size - 4;
lfs_entry_tole32(&entry->d);
err = lfs_dir_commit(lfs, dir, (struct lfs_region[]){
{entry->off, 0, &entry->d, sizeof(entry->d)},
{entry->off, 0, data, entry->d.nlen}
}, 2);
lfs_entry_fromle32(&entry->d);
if (err) {
return err;
}
olddir.d.size |= 0x80000000;
olddir.d.tail[0] = dir->pair[0];
olddir.d.tail[1] = dir->pair[1];
return lfs_dir_commit(lfs, &olddir, NULL, 0);
}
int err = lfs_dir_fetch(lfs, dir, dir->d.tail);
if (err) {
return err;
}
}
}
static int lfs_dir_remove(lfs_t *lfs, lfs_dir_t *dir, lfs_entry_t *entry) {
// check if we should just drop the directory block
if ((dir->d.size & 0x7fffffff) == sizeof(dir->d)+4
+ lfs_entry_size(entry)) {
lfs_dir_t pdir;
int res = lfs_pred(lfs, dir->pair, &pdir);
if (res < 0) {
return res;
}
if (pdir.d.size & 0x80000000) {
pdir.d.size &= dir->d.size | 0x7fffffff;
pdir.d.tail[0] = dir->d.tail[0];
pdir.d.tail[1] = dir->d.tail[1];
return lfs_dir_commit(lfs, &pdir, NULL, 0);
}
}
// shift out the entry
int err = lfs_dir_commit(lfs, dir, (struct lfs_region[]){
{entry->off, lfs_entry_size(entry), NULL, 0},
}, 1);
if (err) {
return err;
}
// shift over any files/directories that are affected
for (lfs_file_t *f = lfs->files; f; f = f->next) {
if (lfs_paircmp(f->pair, dir->pair) == 0) {
if (f->poff == entry->off) {
f->pair[0] = 0xffffffff;
f->pair[1] = 0xffffffff;
} else if (f->poff > entry->off) {
f->poff -= lfs_entry_size(entry);
}
}
}
for (lfs_dir_t *d = lfs->dirs; d; d = d->next) {
if (lfs_paircmp(d->pair, dir->pair) == 0) {
if (d->off > entry->off) {
d->off -= lfs_entry_size(entry);
d->pos -= lfs_entry_size(entry);
}
}
}
return 0;
}
static int lfs_dir_next(lfs_t *lfs, lfs_dir_t *dir, lfs_entry_t *entry) {
while (dir->off + sizeof(entry->d) > (0x7fffffff & dir->d.size)-4) {
if (!(0x80000000 & dir->d.size)) {
entry->off = dir->off;
return LFS_ERR_NOENT;
}
int err = lfs_dir_fetch(lfs, dir, dir->d.tail);
if (err) {
return err;
}
dir->off = sizeof(dir->d);
dir->pos += sizeof(dir->d) + 4;
}
int err = lfs_bd_read(lfs, dir->pair[0], dir->off,
&entry->d, sizeof(entry->d));
lfs_entry_fromle32(&entry->d);
if (err) {
return err;
}
entry->off = dir->off;
dir->off += lfs_entry_size(entry);
dir->pos += lfs_entry_size(entry);
return 0;
}
static int lfs_dir_find(lfs_t *lfs, lfs_dir_t *dir,
lfs_entry_t *entry, const char **path) {
const char *pathname = *path;
size_t pathlen;
while (true) {
nextname:
// skip slashes
pathname += strspn(pathname, "/");
pathlen = strcspn(pathname, "/");
// special case for root dir
if (pathname[0] == '\0') {
*entry = (lfs_entry_t){
.d.type = LFS_TYPE_DIR,
.d.elen = sizeof(entry->d) - 4,
.d.alen = 0,
.d.nlen = 0,
.d.u.dir[0] = lfs->root[0],
.d.u.dir[1] = lfs->root[1],
};
return 0;
}
// skip '.' and root '..'
if ((pathlen == 1 && memcmp(pathname, ".", 1) == 0) ||
(pathlen == 2 && memcmp(pathname, "..", 2) == 0)) {
pathname += pathlen;
goto nextname;
}
// skip if matched by '..' in name
const char *suffix = pathname + pathlen;
size_t sufflen;
int depth = 1;
while (true) {
suffix += strspn(suffix, "/");
sufflen = strcspn(suffix, "/");
if (sufflen == 0) {
break;
}
if (sufflen == 2 && memcmp(suffix, "..", 2) == 0) {
depth -= 1;
if (depth == 0) {
pathname = suffix + sufflen;
goto nextname;
}
} else {
depth += 1;
}
suffix += sufflen;
}
// update what we've found
*path = pathname;
// find path
while (true) {
int err = lfs_dir_next(lfs, dir, entry);
if (err) {
return err;
}
if (((0x7f & entry->d.type) != LFS_TYPE_REG &&
(0x7f & entry->d.type) != LFS_TYPE_DIR) ||
entry->d.nlen != pathlen) {
continue;
}
int res = lfs_bd_cmp(lfs, dir->pair[0],
entry->off + 4+entry->d.elen+entry->d.alen,
pathname, pathlen);
if (res < 0) {
return res;
}
// found match
if (res) {
break;
}
}
// check that entry has not been moved
if (entry->d.type & 0x80) {
int moved = lfs_moved(lfs, &entry->d.u);
if (moved < 0 || moved) {
return (moved < 0) ? moved : LFS_ERR_NOENT;
}
entry->d.type &= ~0x80;
}
pathname += pathlen;
pathname += strspn(pathname, "/");
if (pathname[0] == '\0') {
return 0;
}
// continue on if we hit a directory
if (entry->d.type != LFS_TYPE_DIR) {
return LFS_ERR_NOTDIR;
}
int err = lfs_dir_fetch(lfs, dir, entry->d.u.dir);
if (err) {
return err;
}
}
}
/// Top level directory operations ///
int lfs_mkdir(lfs_t *lfs, const char *path) {
// deorphan if we haven't yet, needed at most once after poweron
if (!lfs->deorphaned) {
int err = lfs_deorphan(lfs);
if (err) {
return err;
}
}
// fetch parent directory
lfs_dir_t cwd;
int err = lfs_dir_fetch(lfs, &cwd, lfs->root);
if (err) {
return err;
}
lfs_entry_t entry;
err = lfs_dir_find(lfs, &cwd, &entry, &path);
if (err != LFS_ERR_NOENT || strchr(path, '/') != NULL) {
return err ? err : LFS_ERR_EXIST;
}
// build up new directory
lfs_alloc_ack(lfs);
lfs_dir_t dir;
err = lfs_dir_alloc(lfs, &dir);
if (err) {
return err;
}
dir.d.tail[0] = cwd.d.tail[0];
dir.d.tail[1] = cwd.d.tail[1];
err = lfs_dir_commit(lfs, &dir, NULL, 0);
if (err) {
return err;
}
entry.d.type = LFS_TYPE_DIR;
entry.d.elen = sizeof(entry.d) - 4;
entry.d.alen = 0;
entry.d.nlen = strlen(path);
entry.d.u.dir[0] = dir.pair[0];
entry.d.u.dir[1] = dir.pair[1];
cwd.d.tail[0] = dir.pair[0];
cwd.d.tail[1] = dir.pair[1];
err = lfs_dir_append(lfs, &cwd, &entry, path);
if (err) {
return err;
}
lfs_alloc_ack(lfs);
return 0;
}
int lfs_dir_open(lfs_t *lfs, lfs_dir_t *dir, const char *path) {
dir->pair[0] = lfs->root[0];
dir->pair[1] = lfs->root[1];
int err = lfs_dir_fetch(lfs, dir, dir->pair);
if (err) {
return err;
}
lfs_entry_t entry;
err = lfs_dir_find(lfs, dir, &entry, &path);
if (err) {
return err;
} else if (entry.d.type != LFS_TYPE_DIR) {
return LFS_ERR_NOTDIR;
}
err = lfs_dir_fetch(lfs, dir, entry.d.u.dir);
if (err) {
return err;
}
// setup head dir
// special offset for '.' and '..'
dir->head[0] = dir->pair[0];
dir->head[1] = dir->pair[1];
dir->pos = sizeof(dir->d) - 2;
dir->off = sizeof(dir->d);
// add to list of directories
dir->next = lfs->dirs;
lfs->dirs = dir;
return 0;
}
int lfs_dir_close(lfs_t *lfs, lfs_dir_t *dir) {
// remove from list of directories
for (lfs_dir_t **p = &lfs->dirs; *p; p = &(*p)->next) {
if (*p == dir) {
*p = dir->next;
break;
}
}
return 0;
}
int lfs_dir_read(lfs_t *lfs, lfs_dir_t *dir, struct lfs_info *info) {
memset(info, 0, sizeof(*info));
// special offset for '.' and '..'
if (dir->pos == sizeof(dir->d) - 2) {
info->type = LFS_TYPE_DIR;
strcpy(info->name, ".");
dir->pos += 1;
return 1;
} else if (dir->pos == sizeof(dir->d) - 1) {
info->type = LFS_TYPE_DIR;
strcpy(info->name, "..");
dir->pos += 1;
return 1;
}
lfs_entry_t entry;
while (true) {
int err = lfs_dir_next(lfs, dir, &entry);
if (err) {
return (err == LFS_ERR_NOENT) ? 0 : err;
}
if ((0x7f & entry.d.type) != LFS_TYPE_REG &&
(0x7f & entry.d.type) != LFS_TYPE_DIR) {
continue;
}
// check that entry has not been moved
if (entry.d.type & 0x80) {
int moved = lfs_moved(lfs, &entry.d.u);
if (moved < 0) {
return moved;
}
if (moved) {
continue;
}
entry.d.type &= ~0x80;
}
break;
}
info->type = entry.d.type;
if (info->type == LFS_TYPE_REG) {
info->size = entry.d.u.file.size;
}
int err = lfs_bd_read(lfs, dir->pair[0],
entry.off + 4+entry.d.elen+entry.d.alen,
info->name, entry.d.nlen);
if (err) {
return err;
}
return 1;
}
int lfs_dir_seek(lfs_t *lfs, lfs_dir_t *dir, lfs_off_t off) {
// simply walk from head dir
int err = lfs_dir_rewind(lfs, dir);
if (err) {
return err;
}
dir->pos = off;
while (off > (0x7fffffff & dir->d.size)) {
off -= 0x7fffffff & dir->d.size;
if (!(0x80000000 & dir->d.size)) {
return LFS_ERR_INVAL;
}
err = lfs_dir_fetch(lfs, dir, dir->d.tail);
if (err) {
return err;
}
}
dir->off = off;
return 0;
}
lfs_soff_t lfs_dir_tell(lfs_t *lfs, lfs_dir_t *dir) {
(void)lfs;
return dir->pos;
}
int lfs_dir_rewind(lfs_t *lfs, lfs_dir_t *dir) {
// reload the head dir
int err = lfs_dir_fetch(lfs, dir, dir->head);
if (err) {
return err;
}
dir->pair[0] = dir->head[0];
dir->pair[1] = dir->head[1];
dir->pos = sizeof(dir->d) - 2;
dir->off = sizeof(dir->d);
return 0;
}
/// File index list operations ///
static int lfs_ctz_index(lfs_t *lfs, lfs_off_t *off) {
lfs_off_t size = *off;
lfs_off_t b = lfs->cfg->block_size - 2*4;
lfs_off_t i = size / b;
if (i == 0) {
return 0;
}
i = (size - 4*(lfs_popc(i-1)+2)) / b;
*off = size - b*i - 4*lfs_popc(i);
return i;
}
static int lfs_ctz_find(lfs_t *lfs,
lfs_cache_t *rcache, const lfs_cache_t *pcache,
lfs_block_t head, lfs_size_t size,
lfs_size_t pos, lfs_block_t *block, lfs_off_t *off) {
if (size == 0) {
*block = 0xffffffff;
*off = 0;
return 0;
}
lfs_off_t current = lfs_ctz_index(lfs, &(lfs_off_t){size-1});
lfs_off_t target = lfs_ctz_index(lfs, &pos);
while (current > target) {
lfs_size_t skip = lfs_min(
lfs_npw2(current-target+1) - 1,
lfs_ctz(current));
int err = lfs_cache_read(lfs, rcache, pcache, head, 4*skip, &head, 4);
head = lfs_fromle32(head);
if (err) {
return err;
}
LFS_ASSERT(head >= 2 && head <= lfs->cfg->block_count);
current -= 1 << skip;
}
*block = head;
*off = pos;
return 0;
}
static int lfs_ctz_extend(lfs_t *lfs,
lfs_cache_t *rcache, lfs_cache_t *pcache,
lfs_block_t head, lfs_size_t size,
lfs_block_t *block, lfs_off_t *off) {
while (true) {
// go ahead and grab a block
lfs_block_t nblock;
int err = lfs_alloc(lfs, &nblock);
if (err) {
return err;
}
LFS_ASSERT(nblock >= 2 && nblock <= lfs->cfg->block_count);
if (true) {
err = lfs_bd_erase(lfs, nblock);
if (err) {
if (err == LFS_ERR_CORRUPT) {
goto relocate;
}
return err;
}
if (size == 0) {
*block = nblock;
*off = 0;
return 0;
}
size -= 1;
lfs_off_t index = lfs_ctz_index(lfs, &size);
size += 1;
// just copy out the last block if it is incomplete
if (size != lfs->cfg->block_size) {
for (lfs_off_t i = 0; i < size; i++) {
uint8_t data;
err = lfs_cache_read(lfs, rcache, NULL,
head, i, &data, 1);
if (err) {
return err;
}
err = lfs_cache_prog(lfs, pcache, rcache,
nblock, i, &data, 1);
if (err) {
if (err == LFS_ERR_CORRUPT) {
goto relocate;
}
return err;
}
}
*block = nblock;
*off = size;
return 0;
}
// append block
index += 1;
lfs_size_t skips = lfs_ctz(index) + 1;
for (lfs_off_t i = 0; i < skips; i++) {
head = lfs_tole32(head);
err = lfs_cache_prog(lfs, pcache, rcache,
nblock, 4*i, &head, 4);
head = lfs_fromle32(head);
if (err) {
if (err == LFS_ERR_CORRUPT) {
goto relocate;
}
return err;
}
if (i != skips-1) {
err = lfs_cache_read(lfs, rcache, NULL,
head, 4*i, &head, 4);
head = lfs_fromle32(head);
if (err) {
return err;
}
}
LFS_ASSERT(head >= 2 && head <= lfs->cfg->block_count);
}
*block = nblock;
*off = 4*skips;
return 0;
}
relocate:
LFS_DEBUG("Bad block at %d", nblock);
// just clear cache and try a new block
pcache->block = 0xffffffff;
}
}
static int lfs_ctz_traverse(lfs_t *lfs,
lfs_cache_t *rcache, const lfs_cache_t *pcache,
lfs_block_t head, lfs_size_t size,
int (*cb)(void*, lfs_block_t), void *data) {
if (size == 0) {
return 0;
}
lfs_off_t index = lfs_ctz_index(lfs, &(lfs_off_t){size-1});
while (true) {
int err = cb(data, head);
if (err) {
return err;
}
if (index == 0) {
return 0;
}
lfs_block_t heads[2];
int count = 2 - (index & 1);
err = lfs_cache_read(lfs, rcache, pcache, head, 0, &heads, count*4);
heads[0] = lfs_fromle32(heads[0]);
heads[1] = lfs_fromle32(heads[1]);
if (err) {
return err;
}
for (int i = 0; i < count-1; i++) {
err = cb(data, heads[i]);
if (err) {
return err;
}
}
head = heads[count-1];
index -= count;
}
}
/// Top level file operations ///
int lfs_file_open(lfs_t *lfs, lfs_file_t *file,
const char *path, int flags) {
// deorphan if we haven't yet, needed at most once after poweron
if ((flags & 3) != LFS_O_RDONLY && !lfs->deorphaned) {
int err = lfs_deorphan(lfs);
if (err) {
return err;
}
}
// allocate entry for file if it doesn't exist
lfs_dir_t cwd;
int err = lfs_dir_fetch(lfs, &cwd, lfs->root);
if (err) {
return err;
}
lfs_entry_t entry;
err = lfs_dir_find(lfs, &cwd, &entry, &path);
if (err && (err != LFS_ERR_NOENT || strchr(path, '/') != NULL)) {
return err;
}
if (err == LFS_ERR_NOENT) {
if (!(flags & LFS_O_CREAT)) {
return LFS_ERR_NOENT;
}
// create entry to remember name
entry.d.type = LFS_TYPE_REG;
entry.d.elen = sizeof(entry.d) - 4;
entry.d.alen = 0;
entry.d.nlen = strlen(path);
entry.d.u.file.head = 0xffffffff;
entry.d.u.file.size = 0;
err = lfs_dir_append(lfs, &cwd, &entry, path);
if (err) {
return err;
}
} else if (entry.d.type == LFS_TYPE_DIR) {
return LFS_ERR_ISDIR;
} else if (flags & LFS_O_EXCL) {
return LFS_ERR_EXIST;
}
// setup file struct
file->pair[0] = cwd.pair[0];
file->pair[1] = cwd.pair[1];
file->poff = entry.off;
file->head = entry.d.u.file.head;
file->size = entry.d.u.file.size;
file->flags = flags;
file->pos = 0;
if (flags & LFS_O_TRUNC) {
if (file->size != 0) {
file->flags |= LFS_F_DIRTY;
}
file->head = 0xffffffff;
file->size = 0;
}
// allocate buffer if needed
file->cache.block = 0xffffffff;
if (lfs->cfg->file_buffer) {
file->cache.buffer = lfs->cfg->file_buffer;
} else if ((file->flags & 3) == LFS_O_RDONLY) {
file->cache.buffer = lfs_malloc(lfs->cfg->read_size);
if (!file->cache.buffer) {
return LFS_ERR_NOMEM;
}
} else {
file->cache.buffer = lfs_malloc(lfs->cfg->prog_size);
if (!file->cache.buffer) {
return LFS_ERR_NOMEM;
}
}
// add to list of files
file->next = lfs->files;
lfs->files = file;
return 0;
}
int lfs_file_close(lfs_t *lfs, lfs_file_t *file) {
int err = lfs_file_sync(lfs, file);
// remove from list of files
for (lfs_file_t **p = &lfs->files; *p; p = &(*p)->next) {
if (*p == file) {
*p = file->next;
break;
}
}
// clean up memory
if (!lfs->cfg->file_buffer) {
lfs_free(file->cache.buffer);
}
return err;
}
static int lfs_file_relocate(lfs_t *lfs, lfs_file_t *file) {
relocate:
LFS_DEBUG("Bad block at %d", file->block);
// just relocate what exists into new block
lfs_block_t nblock;
int err = lfs_alloc(lfs, &nblock);
if (err) {
return err;
}
err = lfs_bd_erase(lfs, nblock);
if (err) {
if (err == LFS_ERR_CORRUPT) {
goto relocate;
}
return err;
}
// either read from dirty cache or disk
for (lfs_off_t i = 0; i < file->off; i++) {
uint8_t data;
err = lfs_cache_read(lfs, &lfs->rcache, &file->cache,
file->block, i, &data, 1);
if (err) {
return err;
}
err = lfs_cache_prog(lfs, &lfs->pcache, &lfs->rcache,
nblock, i, &data, 1);
if (err) {
if (err == LFS_ERR_CORRUPT) {
goto relocate;
}
return err;
}
}
// copy over new state of file
memcpy(file->cache.buffer, lfs->pcache.buffer, lfs->cfg->prog_size);
file->cache.block = lfs->pcache.block;
file->cache.off = lfs->pcache.off;
lfs->pcache.block = 0xffffffff;
file->block = nblock;
return 0;
}
static int lfs_file_flush(lfs_t *lfs, lfs_file_t *file) {
if (file->flags & LFS_F_READING) {
// just drop read cache
file->cache.block = 0xffffffff;
file->flags &= ~LFS_F_READING;
}
if (file->flags & LFS_F_WRITING) {
lfs_off_t pos = file->pos;
// copy over anything after current branch
lfs_file_t orig = {
.head = file->head,
.size = file->size,
.flags = LFS_O_RDONLY,
.pos = file->pos,
.cache = lfs->rcache,
};
lfs->rcache.block = 0xffffffff;
while (file->pos < file->size) {
// copy over a byte at a time, leave it up to caching
// to make this efficient
uint8_t data;
lfs_ssize_t res = lfs_file_read(lfs, &orig, &data, 1);
if (res < 0) {
return res;
}
res = lfs_file_write(lfs, file, &data, 1);
if (res < 0) {
return res;
}
// keep our reference to the rcache in sync
if (lfs->rcache.block != 0xffffffff) {
orig.cache.block = 0xffffffff;
lfs->rcache.block = 0xffffffff;
}
}
// write out what we have
while (true) {
int err = lfs_cache_flush(lfs, &file->cache, &lfs->rcache);
if (err) {
if (err == LFS_ERR_CORRUPT) {
goto relocate;
}
return err;
}
break;
relocate:
err = lfs_file_relocate(lfs, file);
if (err) {
return err;
}
}
// actual file updates
file->head = file->block;
file->size = file->pos;
file->flags &= ~LFS_F_WRITING;
file->flags |= LFS_F_DIRTY;
file->pos = pos;
}
return 0;
}
int lfs_file_sync(lfs_t *lfs, lfs_file_t *file) {
int err = lfs_file_flush(lfs, file);
if (err) {
return err;
}
if ((file->flags & LFS_F_DIRTY) &&
!(file->flags & LFS_F_ERRED) &&
!lfs_pairisnull(file->pair)) {
// update dir entry
lfs_dir_t cwd;
err = lfs_dir_fetch(lfs, &cwd, file->pair);
if (err) {
return err;
}
lfs_entry_t entry = {.off = file->poff};
err = lfs_bd_read(lfs, cwd.pair[0], entry.off,
&entry.d, sizeof(entry.d));
lfs_entry_fromle32(&entry.d);
if (err) {
return err;
}
LFS_ASSERT(entry.d.type == LFS_TYPE_REG);
entry.d.u.file.head = file->head;
entry.d.u.file.size = file->size;
err = lfs_dir_update(lfs, &cwd, &entry, NULL);
if (err) {
return err;
}
file->flags &= ~LFS_F_DIRTY;
}
return 0;
}
lfs_ssize_t lfs_file_read(lfs_t *lfs, lfs_file_t *file,
void *buffer, lfs_size_t size) {
uint8_t *data = buffer;
lfs_size_t nsize = size;
if ((file->flags & 3) == LFS_O_WRONLY) {
return LFS_ERR_BADF;
}
if (file->flags & LFS_F_WRITING) {
// flush out any writes
int err = lfs_file_flush(lfs, file);
if (err) {
return err;
}
}
if (file->pos >= file->size) {
// eof if past end
return 0;
}
size = lfs_min(size, file->size - file->pos);
nsize = size;
while (nsize > 0) {
// check if we need a new block
if (!(file->flags & LFS_F_READING) ||
file->off == lfs->cfg->block_size) {
int err = lfs_ctz_find(lfs, &file->cache, NULL,
file->head, file->size,
file->pos, &file->block, &file->off);
if (err) {
return err;
}
file->flags |= LFS_F_READING;
}
// read as much as we can in current block
lfs_size_t diff = lfs_min(nsize, lfs->cfg->block_size - file->off);
int err = lfs_cache_read(lfs, &file->cache, NULL,
file->block, file->off, data, diff);
if (err) {
return err;
}
file->pos += diff;
file->off += diff;
data += diff;
nsize -= diff;
}
return size;
}
lfs_ssize_t lfs_file_write(lfs_t *lfs, lfs_file_t *file,
const void *buffer, lfs_size_t size) {
const uint8_t *data = buffer;
lfs_size_t nsize = size;
if ((file->flags & 3) == LFS_O_RDONLY) {
return LFS_ERR_BADF;
}
if (file->flags & LFS_F_READING) {
// drop any reads
int err = lfs_file_flush(lfs, file);
if (err) {
return err;
}
}
if ((file->flags & LFS_O_APPEND) && file->pos < file->size) {
file->pos = file->size;
}
if (!(file->flags & LFS_F_WRITING) && file->pos > file->size) {
// fill with zeros
lfs_off_t pos = file->pos;
file->pos = file->size;
while (file->pos < pos) {
lfs_ssize_t res = lfs_file_write(lfs, file, &(uint8_t){0}, 1);
if (res < 0) {
return res;
}
}
}
while (nsize > 0) {
// check if we need a new block
if (!(file->flags & LFS_F_WRITING) ||
file->off == lfs->cfg->block_size) {
if (!(file->flags & LFS_F_WRITING) && file->pos > 0) {
// find out which block we're extending from
int err = lfs_ctz_find(lfs, &file->cache, NULL,
file->head, file->size,
file->pos-1, &file->block, &file->off);
if (err) {
file->flags |= LFS_F_ERRED;
return err;
}
// mark cache as dirty since we may have read data into it
file->cache.block = 0xffffffff;
}
// extend file with new blocks
lfs_alloc_ack(lfs);
int err = lfs_ctz_extend(lfs, &lfs->rcache, &file->cache,
file->block, file->pos,
&file->block, &file->off);
if (err) {
file->flags |= LFS_F_ERRED;
return err;
}
file->flags |= LFS_F_WRITING;
}
// program as much as we can in current block
lfs_size_t diff = lfs_min(nsize, lfs->cfg->block_size - file->off);
while (true) {
int err = lfs_cache_prog(lfs, &file->cache, &lfs->rcache,
file->block, file->off, data, diff);
if (err) {
if (err == LFS_ERR_CORRUPT) {
goto relocate;
}
file->flags |= LFS_F_ERRED;
return err;
}
break;
relocate:
err = lfs_file_relocate(lfs, file);
if (err) {
file->flags |= LFS_F_ERRED;
return err;
}
}
file->pos += diff;
file->off += diff;
data += diff;
nsize -= diff;
lfs_alloc_ack(lfs);
}
file->flags &= ~LFS_F_ERRED;
return size;
}
lfs_soff_t lfs_file_seek(lfs_t *lfs, lfs_file_t *file,
lfs_soff_t off, int whence) {
// write out everything beforehand, may be noop if rdonly
int err = lfs_file_flush(lfs, file);
if (err) {
return err;
}
// update pos
if (whence == LFS_SEEK_SET) {
file->pos = off;
} else if (whence == LFS_SEEK_CUR) {
if (off < 0 && (lfs_off_t)-off > file->pos) {
return LFS_ERR_INVAL;
}
file->pos = file->pos + off;
} else if (whence == LFS_SEEK_END) {
if (off < 0 && (lfs_off_t)-off > file->size) {
return LFS_ERR_INVAL;
}
file->pos = file->size + off;
}
return file->pos;
}
int lfs_file_truncate(lfs_t *lfs, lfs_file_t *file, lfs_off_t size) {
if ((file->flags & 3) == LFS_O_RDONLY) {
return LFS_ERR_BADF;
}
lfs_off_t oldsize = lfs_file_size(lfs, file);
if (size < oldsize) {
// need to flush since directly changing metadata
int err = lfs_file_flush(lfs, file);
if (err) {
return err;
}
// lookup new head in ctz skip list
err = lfs_ctz_find(lfs, &file->cache, NULL,
file->head, file->size,
size, &file->head, &(lfs_off_t){0});
if (err) {
return err;
}
file->size = size;
file->flags |= LFS_F_DIRTY;
} else if (size > oldsize) {
lfs_off_t pos = file->pos;
// flush+seek if not already at end
if (file->pos != oldsize) {
int err = lfs_file_seek(lfs, file, 0, LFS_SEEK_END);
if (err < 0) {
return err;
}
}
// fill with zeros
while (file->pos < size) {
lfs_ssize_t res = lfs_file_write(lfs, file, &(uint8_t){0}, 1);
if (res < 0) {
return res;
}
}
// restore pos
int err = lfs_file_seek(lfs, file, pos, LFS_SEEK_SET);
if (err < 0) {
return err;
}
}
return 0;
}
lfs_soff_t lfs_file_tell(lfs_t *lfs, lfs_file_t *file) {
(void)lfs;
return file->pos;
}
int lfs_file_rewind(lfs_t *lfs, lfs_file_t *file) {
lfs_soff_t res = lfs_file_seek(lfs, file, 0, LFS_SEEK_SET);
if (res < 0) {
return res;
}
return 0;
}
lfs_soff_t lfs_file_size(lfs_t *lfs, lfs_file_t *file) {
(void)lfs;
if (file->flags & LFS_F_WRITING) {
return lfs_max(file->pos, file->size);
} else {
return file->size;
}
}
/// General fs operations ///
int lfs_stat(lfs_t *lfs, const char *path, struct lfs_info *info) {
lfs_dir_t cwd;
int err = lfs_dir_fetch(lfs, &cwd, lfs->root);
if (err) {
return err;
}
lfs_entry_t entry;
err = lfs_dir_find(lfs, &cwd, &entry, &path);
if (err) {
return err;
}
memset(info, 0, sizeof(*info));
info->type = entry.d.type;
if (info->type == LFS_TYPE_REG) {
info->size = entry.d.u.file.size;
}
if (lfs_paircmp(entry.d.u.dir, lfs->root) == 0) {
strcpy(info->name, "/");
} else {
err = lfs_bd_read(lfs, cwd.pair[0],
entry.off + 4+entry.d.elen+entry.d.alen,
info->name, entry.d.nlen);
if (err) {
return err;
}
}
return 0;
}
int lfs_remove(lfs_t *lfs, const char *path) {
// deorphan if we haven't yet, needed at most once after poweron
if (!lfs->deorphaned) {
int err = lfs_deorphan(lfs);
if (err) {
return err;
}
}
lfs_dir_t cwd;
int err = lfs_dir_fetch(lfs, &cwd, lfs->root);
if (err) {
return err;
}
lfs_entry_t entry;
err = lfs_dir_find(lfs, &cwd, &entry, &path);
if (err) {
return err;
}
lfs_dir_t dir;
if (entry.d.type == LFS_TYPE_DIR) {
// must be empty before removal, checking size
// without masking top bit checks for any case where
// dir is not empty
err = lfs_dir_fetch(lfs, &dir, entry.d.u.dir);
if (err) {
return err;
} else if (dir.d.size != sizeof(dir.d)+4) {
return LFS_ERR_NOTEMPTY;
}
}
// remove the entry
err = lfs_dir_remove(lfs, &cwd, &entry);
if (err) {
return err;
}
// if we were a directory, find pred, replace tail
if (entry.d.type == LFS_TYPE_DIR) {
int res = lfs_pred(lfs, dir.pair, &cwd);
if (res < 0) {
return res;
}
LFS_ASSERT(res); // must have pred
cwd.d.tail[0] = dir.d.tail[0];
cwd.d.tail[1] = dir.d.tail[1];
err = lfs_dir_commit(lfs, &cwd, NULL, 0);
if (err) {
return err;
}
}
return 0;
}
int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath) {
// deorphan if we haven't yet, needed at most once after poweron
if (!lfs->deorphaned) {
int err = lfs_deorphan(lfs);
if (err) {
return err;
}
}
// find old entry
lfs_dir_t oldcwd;
int err = lfs_dir_fetch(lfs, &oldcwd, lfs->root);
if (err) {
return err;
}
lfs_entry_t oldentry;
err = lfs_dir_find(lfs, &oldcwd, &oldentry, &oldpath);
if (err) {
return err;
}
// allocate new entry
lfs_dir_t newcwd;
err = lfs_dir_fetch(lfs, &newcwd, lfs->root);
if (err) {
return err;
}
lfs_entry_t preventry;
err = lfs_dir_find(lfs, &newcwd, &preventry, &newpath);
if (err && (err != LFS_ERR_NOENT || strchr(newpath, '/') != NULL)) {
return err;
}
bool prevexists = (err != LFS_ERR_NOENT);
bool samepair = (lfs_paircmp(oldcwd.pair, newcwd.pair) == 0);
// must have same type
if (prevexists && preventry.d.type != oldentry.d.type) {
return LFS_ERR_ISDIR;
}
lfs_dir_t dir;
if (prevexists && preventry.d.type == LFS_TYPE_DIR) {
// must be empty before removal, checking size
// without masking top bit checks for any case where
// dir is not empty
err = lfs_dir_fetch(lfs, &dir, preventry.d.u.dir);
if (err) {
return err;
} else if (dir.d.size != sizeof(dir.d)+4) {
return LFS_ERR_NOTEMPTY;
}
}
// mark as moving
oldentry.d.type |= 0x80;
err = lfs_dir_update(lfs, &oldcwd, &oldentry, NULL);
if (err) {
return err;
}
// update pair if newcwd == oldcwd
if (samepair) {
newcwd = oldcwd;
}
// move to new location
lfs_entry_t newentry = preventry;
newentry.d = oldentry.d;
newentry.d.type &= ~0x80;
newentry.d.nlen = strlen(newpath);
if (prevexists) {
err = lfs_dir_update(lfs, &newcwd, &newentry, newpath);
if (err) {
return err;
}
} else {
err = lfs_dir_append(lfs, &newcwd, &newentry, newpath);
if (err) {
return err;
}
}
// update pair if newcwd == oldcwd
if (samepair) {
oldcwd = newcwd;
}
// remove old entry
err = lfs_dir_remove(lfs, &oldcwd, &oldentry);
if (err) {
return err;
}
// if we were a directory, find pred, replace tail
if (prevexists && preventry.d.type == LFS_TYPE_DIR) {
int res = lfs_pred(lfs, dir.pair, &newcwd);
if (res < 0) {
return res;
}
LFS_ASSERT(res); // must have pred
newcwd.d.tail[0] = dir.d.tail[0];
newcwd.d.tail[1] = dir.d.tail[1];
err = lfs_dir_commit(lfs, &newcwd, NULL, 0);
if (err) {
return err;
}
}
return 0;
}
/// Filesystem operations ///
static int lfs_init(lfs_t *lfs, const struct lfs_config *cfg) {
lfs->cfg = cfg;
// setup read cache
lfs->rcache.block = 0xffffffff;
if (lfs->cfg->read_buffer) {
lfs->rcache.buffer = lfs->cfg->read_buffer;
} else {
lfs->rcache.buffer = lfs_malloc(lfs->cfg->read_size);
if (!lfs->rcache.buffer) {
return LFS_ERR_NOMEM;
}
}
// setup program cache
lfs->pcache.block = 0xffffffff;
if (lfs->cfg->prog_buffer) {
lfs->pcache.buffer = lfs->cfg->prog_buffer;
} else {
lfs->pcache.buffer = lfs_malloc(lfs->cfg->prog_size);
if (!lfs->pcache.buffer) {
return LFS_ERR_NOMEM;
}
}
// setup lookahead, round down to nearest 32-bits
LFS_ASSERT(lfs->cfg->lookahead % 32 == 0);
LFS_ASSERT(lfs->cfg->lookahead > 0);
if (lfs->cfg->lookahead_buffer) {
lfs->free.buffer = lfs->cfg->lookahead_buffer;
} else {
lfs->free.buffer = lfs_malloc(lfs->cfg->lookahead/8);
if (!lfs->free.buffer) {
return LFS_ERR_NOMEM;
}
}
// check that program and read sizes are multiples of the block size
LFS_ASSERT(lfs->cfg->prog_size % lfs->cfg->read_size == 0);
LFS_ASSERT(lfs->cfg->block_size % lfs->cfg->prog_size == 0);
// check that the block size is large enough to fit ctz pointers
LFS_ASSERT(4*lfs_npw2(0xffffffff / (lfs->cfg->block_size-2*4))
<= lfs->cfg->block_size);
// setup default state
lfs->root[0] = 0xffffffff;
lfs->root[1] = 0xffffffff;
lfs->files = NULL;
lfs->dirs = NULL;
lfs->deorphaned = false;
return 0;
}
static int lfs_deinit(lfs_t *lfs) {
// free allocated memory
if (!lfs->cfg->read_buffer) {
lfs_free(lfs->rcache.buffer);
}
if (!lfs->cfg->prog_buffer) {
lfs_free(lfs->pcache.buffer);
}
if (!lfs->cfg->lookahead_buffer) {
lfs_free(lfs->free.buffer);
}
return 0;
}
int lfs_format(lfs_t *lfs, const struct lfs_config *cfg) {
int err = lfs_init(lfs, cfg);
if (err) {
return err;
}
// create free lookahead
memset(lfs->free.buffer, 0, lfs->cfg->lookahead/8);
lfs->free.off = 0;
lfs->free.size = lfs_min(lfs->cfg->lookahead, lfs->cfg->block_count);
lfs->free.i = 0;
lfs_alloc_ack(lfs);
// create superblock dir
lfs_dir_t superdir;
err = lfs_dir_alloc(lfs, &superdir);
if (err) {
return err;
}
// write root directory
lfs_dir_t root;
err = lfs_dir_alloc(lfs, &root);
if (err) {
return err;
}
err = lfs_dir_commit(lfs, &root, NULL, 0);
if (err) {
return err;
}
lfs->root[0] = root.pair[0];
lfs->root[1] = root.pair[1];
// write superblocks
lfs_superblock_t superblock = {
.off = sizeof(superdir.d),
.d.type = LFS_TYPE_SUPERBLOCK,
.d.elen = sizeof(superblock.d) - sizeof(superblock.d.magic) - 4,
.d.nlen = sizeof(superblock.d.magic),
.d.version = LFS_DISK_VERSION,
.d.magic = {"littlefs"},
.d.block_size = lfs->cfg->block_size,
.d.block_count = lfs->cfg->block_count,
.d.root = {lfs->root[0], lfs->root[1]},
};
superdir.d.tail[0] = root.pair[0];
superdir.d.tail[1] = root.pair[1];
superdir.d.size = sizeof(superdir.d) + sizeof(superblock.d) + 4;
// write both pairs to be safe
lfs_superblock_tole32(&superblock.d);
bool valid = false;
for (int i = 0; i < 2; i++) {
err = lfs_dir_commit(lfs, &superdir, (struct lfs_region[]){
{sizeof(superdir.d), sizeof(superblock.d),
&superblock.d, sizeof(superblock.d)}
}, 1);
if (err && err != LFS_ERR_CORRUPT) {
return err;
}
valid = valid || !err;
}
if (!valid) {
return LFS_ERR_CORRUPT;
}
// sanity check that fetch works
err = lfs_dir_fetch(lfs, &superdir, (const lfs_block_t[2]){0, 1});
if (err) {
return err;
}
lfs_alloc_ack(lfs);
return lfs_deinit(lfs);
}
int lfs_mount(lfs_t *lfs, const struct lfs_config *cfg) {
int err = lfs_init(lfs, cfg);
if (err) {
return err;
}
// setup free lookahead
lfs->free.off = 0;
lfs->free.size = 0;
lfs->free.i = 0;
lfs_alloc_ack(lfs);
// load superblock
lfs_dir_t dir;
lfs_superblock_t superblock;
err = lfs_dir_fetch(lfs, &dir, (const lfs_block_t[2]){0, 1});
if (err && err != LFS_ERR_CORRUPT) {
return err;
}
if (!err) {
err = lfs_bd_read(lfs, dir.pair[0], sizeof(dir.d),
&superblock.d, sizeof(superblock.d));
lfs_superblock_fromle32(&superblock.d);
if (err) {
return err;
}
lfs->root[0] = superblock.d.root[0];
lfs->root[1] = superblock.d.root[1];
}
if (err || memcmp(superblock.d.magic, "littlefs", 8) != 0) {
LFS_ERROR("Invalid superblock at %d %d", 0, 1);
return LFS_ERR_CORRUPT;
}
uint16_t major_version = (0xffff & (superblock.d.version >> 16));
uint16_t minor_version = (0xffff & (superblock.d.version >> 0));
if ((major_version != LFS_DISK_VERSION_MAJOR ||
minor_version > LFS_DISK_VERSION_MINOR)) {
LFS_ERROR("Invalid version %d.%d", major_version, minor_version);
return LFS_ERR_INVAL;
}
return 0;
}
int lfs_unmount(lfs_t *lfs) {
return lfs_deinit(lfs);
}
/// Littlefs specific operations ///
int lfs_traverse(lfs_t *lfs, int (*cb)(void*, lfs_block_t), void *data) {
if (lfs_pairisnull(lfs->root)) {
return 0;
}
// iterate over metadata pairs
lfs_dir_t dir;
lfs_entry_t entry;
lfs_block_t cwd[2] = {0, 1};
while (true) {
for (int i = 0; i < 2; i++) {
int err = cb(data, cwd[i]);
if (err) {
return err;
}
}
int err = lfs_dir_fetch(lfs, &dir, cwd);
if (err) {
return err;
}
// iterate over contents
while (dir.off + sizeof(entry.d) <= (0x7fffffff & dir.d.size)-4) {
err = lfs_bd_read(lfs, dir.pair[0], dir.off,
&entry.d, sizeof(entry.d));
lfs_entry_fromle32(&entry.d);
if (err) {
return err;
}
dir.off += lfs_entry_size(&entry);
if ((0x70 & entry.d.type) == (0x70 & LFS_TYPE_REG)) {
err = lfs_ctz_traverse(lfs, &lfs->rcache, NULL,
entry.d.u.file.head, entry.d.u.file.size, cb, data);
if (err) {
return err;
}
}
}
cwd[0] = dir.d.tail[0];
cwd[1] = dir.d.tail[1];
if (lfs_pairisnull(cwd)) {
break;
}
}
// iterate over any open files
for (lfs_file_t *f = lfs->files; f; f = f->next) {
if (f->flags & LFS_F_DIRTY) {
int err = lfs_ctz_traverse(lfs, &lfs->rcache, &f->cache,
f->head, f->size, cb, data);
if (err) {
return err;
}
}
if (f->flags & LFS_F_WRITING) {
int err = lfs_ctz_traverse(lfs, &lfs->rcache, &f->cache,
f->block, f->pos, cb, data);
if (err) {
return err;
}
}
}
return 0;
}
static int lfs_pred(lfs_t *lfs, const lfs_block_t dir[2], lfs_dir_t *pdir) {
if (lfs_pairisnull(lfs->root)) {
return 0;
}
// iterate over all directory directory entries
int err = lfs_dir_fetch(lfs, pdir, (const lfs_block_t[2]){0, 1});
if (err) {
return err;
}
while (!lfs_pairisnull(pdir->d.tail)) {
if (lfs_paircmp(pdir->d.tail, dir) == 0) {
return true;
}
err = lfs_dir_fetch(lfs, pdir, pdir->d.tail);
if (err) {
return err;
}
}
return false;
}
static int lfs_parent(lfs_t *lfs, const lfs_block_t dir[2],
lfs_dir_t *parent, lfs_entry_t *entry) {
if (lfs_pairisnull(lfs->root)) {
return 0;
}
parent->d.tail[0] = 0;
parent->d.tail[1] = 1;
// iterate over all directory directory entries
while (!lfs_pairisnull(parent->d.tail)) {
int err = lfs_dir_fetch(lfs, parent, parent->d.tail);
if (err) {
return err;
}
while (true) {
err = lfs_dir_next(lfs, parent, entry);
if (err && err != LFS_ERR_NOENT) {
return err;
}
if (err == LFS_ERR_NOENT) {
break;
}
if (((0x70 & entry->d.type) == (0x70 & LFS_TYPE_DIR)) &&
lfs_paircmp(entry->d.u.dir, dir) == 0) {
return true;
}
}
}
return false;
}
static int lfs_moved(lfs_t *lfs, const void *e) {
if (lfs_pairisnull(lfs->root)) {
return 0;
}
// skip superblock
lfs_dir_t cwd;
int err = lfs_dir_fetch(lfs, &cwd, (const lfs_block_t[2]){0, 1});
if (err) {
return err;
}
// iterate over all directory directory entries
lfs_entry_t entry;
while (!lfs_pairisnull(cwd.d.tail)) {
err = lfs_dir_fetch(lfs, &cwd, cwd.d.tail);
if (err) {
return err;
}
while (true) {
err = lfs_dir_next(lfs, &cwd, &entry);
if (err && err != LFS_ERR_NOENT) {
return err;
}
if (err == LFS_ERR_NOENT) {
break;
}
if (!(0x80 & entry.d.type) &&
memcmp(&entry.d.u, e, sizeof(entry.d.u)) == 0) {
return true;
}
}
}
return false;
}
static int lfs_relocate(lfs_t *lfs,
const lfs_block_t oldpair[2], const lfs_block_t newpair[2]) {
// find parent
lfs_dir_t parent;
lfs_entry_t entry;
int res = lfs_parent(lfs, oldpair, &parent, &entry);
if (res < 0) {
return res;
}
if (res) {
// update disk, this creates a desync
entry.d.u.dir[0] = newpair[0];
entry.d.u.dir[1] = newpair[1];
int err = lfs_dir_update(lfs, &parent, &entry, NULL);
if (err) {
return err;
}
// update internal root
if (lfs_paircmp(oldpair, lfs->root) == 0) {
LFS_DEBUG("Relocating root %d %d", newpair[0], newpair[1]);
lfs->root[0] = newpair[0];
lfs->root[1] = newpair[1];
}
// clean up bad block, which should now be a desync
return lfs_deorphan(lfs);
}
// find pred
res = lfs_pred(lfs, oldpair, &parent);
if (res < 0) {
return res;
}
if (res) {
// just replace bad pair, no desync can occur
parent.d.tail[0] = newpair[0];
parent.d.tail[1] = newpair[1];
return lfs_dir_commit(lfs, &parent, NULL, 0);
}
// couldn't find dir, must be new
return 0;
}
int lfs_deorphan(lfs_t *lfs) {
lfs->deorphaned = true;
if (lfs_pairisnull(lfs->root)) {
return 0;
}
lfs_dir_t pdir = {.d.size = 0x80000000};
lfs_dir_t cwd = {.d.tail[0] = 0, .d.tail[1] = 1};
// iterate over all directory directory entries
while (!lfs_pairisnull(cwd.d.tail)) {
int err = lfs_dir_fetch(lfs, &cwd, cwd.d.tail);
if (err) {
return err;
}
// check head blocks for orphans
if (!(0x80000000 & pdir.d.size)) {
// check if we have a parent
lfs_dir_t parent;
lfs_entry_t entry;
int res = lfs_parent(lfs, pdir.d.tail, &parent, &entry);
if (res < 0) {
return res;
}
if (!res) {
// we are an orphan
LFS_DEBUG("Found orphan %d %d",
pdir.d.tail[0], pdir.d.tail[1]);
pdir.d.tail[0] = cwd.d.tail[0];
pdir.d.tail[1] = cwd.d.tail[1];
err = lfs_dir_commit(lfs, &pdir, NULL, 0);
if (err) {
return err;
}
break;
}
if (!lfs_pairsync(entry.d.u.dir, pdir.d.tail)) {
// we have desynced
LFS_DEBUG("Found desync %d %d",
entry.d.u.dir[0], entry.d.u.dir[1]);
pdir.d.tail[0] = entry.d.u.dir[0];
pdir.d.tail[1] = entry.d.u.dir[1];
err = lfs_dir_commit(lfs, &pdir, NULL, 0);
if (err) {
return err;
}
break;
}
}
// check entries for moves
lfs_entry_t entry;
while (true) {
err = lfs_dir_next(lfs, &cwd, &entry);
if (err && err != LFS_ERR_NOENT) {
return err;
}
if (err == LFS_ERR_NOENT) {
break;
}
// found moved entry
if (entry.d.type & 0x80) {
int moved = lfs_moved(lfs, &entry.d.u);
if (moved < 0) {
return moved;
}
if (moved) {
LFS_DEBUG("Found move %d %d",
entry.d.u.dir[0], entry.d.u.dir[1]);
err = lfs_dir_remove(lfs, &cwd, &entry);
if (err) {
return err;
}
} else {
LFS_DEBUG("Found partial move %d %d",
entry.d.u.dir[0], entry.d.u.dir[1]);
entry.d.type &= ~0x80;
err = lfs_dir_update(lfs, &cwd, &entry, NULL);
if (err) {
return err;
}
}
}
}
memcpy(&pdir, &cwd, sizeof(pdir));
}
return 0;
}
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