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f3578e3250
third_party_littlefs/lfs.c
Christopher Haster f3578e3250 Removed clamping to block size in ctz linked-list 
Initially, I was concerned that the number of pointers in the ctz
linked-list could exceed the storage in a block. Long story short
this isn't really possible outside of extremely small block sizes.

Since clamping impacts the layout of files on disk, removing the
block size removed quite a bit of logic and corner cases. Replaced
with an assert on block size during initialization.

---

Long story long, the minimum block size needed to store all ctz
pointers in a filesystem can be found with this formula:

B = (w/8)*log2(2^w / (B - 2*(w/8)))

where:
B = block size in bytes
w = pointer width in bits

It's not a very pretty formula, but does give us some useful info
if we apply some math:

min block size:
32 bit ctz linked-list = 104 bytes
64 bit ctz linked-list = 448 bytes

For littlefs, 128 bytes is a perfectly reasonable minimum block size.
2017-10-12 20:31:33 -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"
#include <string.h>
#include <stdlib.h>
#include <assert.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;
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;
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
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 = (((lfs_soff_t)(block - lfs->free.begin)
% (lfs_soff_t)(lfs->cfg->block_count))
+ lfs->cfg->block_count) % lfs->cfg->block_count;
if (off < lfs->free.lookahead) {
lfs->free.buffer[off / 32] |= 1U << (off % 32);
}
return 0;
}
static int lfs_alloc(lfs_t *lfs, lfs_block_t *block) {
while (true) {
while (true) {
// check if we have looked at all blocks since last ack
if (lfs->free.begin + lfs->free.off == lfs->free.end) {
LFS_WARN("No more free space %d", lfs->free.end);
return LFS_ERR_NOSPC;
}
if (lfs->free.off >= lfs->free.lookahead) {
break;
}
lfs_block_t off = lfs->free.off;
lfs->free.off += 1;
if (!(lfs->free.buffer[off / 32] & (1U << (off % 32)))) {
// found a free block
*block = (lfs->free.begin + off) % lfs->cfg->block_count;
return 0;
}
}
lfs->free.begin += lfs->free.lookahead;
lfs->free.off = 0;
// find mask of free blocks from tree
memset(lfs->free.buffer, 0, lfs->free.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.end = lfs->free.begin + lfs->free.off + lfs->cfg->block_count;
}
/// 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);
if (err) {
return err;
}
// set defaults
dir->d.rev += 1;
dir->d.size = sizeof(dir->d)+4;
dir->d.tail[0] = -1;
dir->d.tail[1] = -1;
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));
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_crc(&crc, &test, sizeof(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) {
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_crc(&crc, &dir->d, sizeof(dir->d));
err = lfs_bd_prog(lfs, dir->pair[0], 0, &dir->d, sizeof(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);
int 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;
int 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;
}
}
err = lfs_bd_prog(lfs, dir->pair[0], newoff, &crc, 4);
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
crc = 0xffffffff;
err = lfs_bd_crc(lfs, dir->pair[0], 0, 0x7fffffff & dir->d.size, &crc);
if (err) {
return err;
}
if (crc == 0) {
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
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]);
return lfs_relocate(lfs, oldpair, dir->pair);
}
return 0;
}
static int lfs_dir_update(lfs_t *lfs, lfs_dir_t *dir,
const lfs_entry_t *entry, const void *data) {
return 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);
}
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;
return lfs_dir_commit(lfs, dir, (struct lfs_region[]){
{entry->off, 0, &entry->d, sizeof(entry->d)},
{entry->off, 0, data, entry->d.nlen}
}, 2);
}
// we need to allocate a new dir block
if (!(0x80000000 & dir->d.size)) {
lfs_dir_t newdir;
int err = lfs_dir_alloc(lfs, &newdir);
if (err) {
return err;
}
newdir.d.tail[0] = dir->d.tail[0];
newdir.d.tail[1] = dir->d.tail[1];
entry->off = newdir.d.size - 4;
err = lfs_dir_commit(lfs, &newdir, (struct lfs_region[]){
{entry->off, 0, &entry->d, sizeof(entry->d)},
{entry->off, 0, data, entry->d.nlen}
}, 2);
if (err) {
return err;
}
dir->d.size |= 0x80000000;
dir->d.tail[0] = newdir.pair[0];
dir->d.tail[1] = newdir.pair[1];
return lfs_dir_commit(lfs, dir, 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) {
// either shift out the one entry or remove the whole dir 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)) {
return lfs_dir_commit(lfs, dir, (struct lfs_region[]){
{entry->off, lfs_entry_size(entry), NULL, 0},
}, 1);
} else {
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);
}
} else {
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 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);
}
}
}
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));
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, "/");
// 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;
}
}
return 0;
}
/// 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_EXISTS;
}
// 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;
}
// check for root, can only be something like '/././../.'
if (strspn(path, "/.") == strlen(path)) {
dir->head[0] = dir->pair[0];
dir->head[1] = dir->pair[1];
dir->pos = sizeof(dir->d) - 2;
dir->off = sizeof(dir->d);
return 0;
}
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);
return 0;
}
int lfs_dir_close(lfs_t *lfs, lfs_dir_t *dir) {
// do nothing, dir is always synchronized
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;
}
int 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) {
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_index(lfs_t *lfs, lfs_off_t *off) {
lfs_off_t i = 0;
while (*off >= lfs->cfg->block_size) {
i += 1;
*off -= lfs->cfg->block_size;
*off += 4*(lfs_ctz(i) + 1);
}
return i;
}
static int lfs_index_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 = -1;
*off = 0;
return 0;
}
lfs_off_t current = lfs_index(lfs, &(lfs_off_t){size-1});
lfs_off_t target = lfs_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);
if (err) {
return err;
}
assert(head >= 2 && head <= lfs->cfg->block_count);
current -= 1 << skip;
}
*block = head;
*off = pos;
return 0;
}
static int lfs_index_extend(lfs_t *lfs,
lfs_cache_t *rcache, lfs_cache_t *pcache,
lfs_block_t head, lfs_size_t size,
lfs_off_t *block, lfs_block_t *off) {
while (true) {
// go ahead and grab a block
int err = lfs_alloc(lfs, block);
if (err) {
return err;
}
assert(*block >= 2 && *block <= lfs->cfg->block_count);
err = lfs_bd_erase(lfs, *block);
if (err) {
if (err == LFS_ERR_CORRUPT) {
goto relocate;
}
return err;
}
if (size == 0) {
*off = 0;
return 0;
}
size -= 1;
lfs_off_t index = lfs_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;
int err = lfs_cache_read(lfs, rcache, NULL, head, i, &data, 1);
if (err) {
return err;
}
err = lfs_cache_prog(lfs, pcache, rcache, *block, i, &data, 1);
if (err) {
if (err == LFS_ERR_CORRUPT) {
goto relocate;
}
return err;
}
}
*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++) {
int err = lfs_cache_prog(lfs, pcache, rcache,
*block, 4*i, &head, 4);
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);
if (err) {
return err;
}
}
assert(head >= 2 && head <= lfs->cfg->block_count);
}
*off = 4*skips;
return 0;
relocate:
LFS_DEBUG("Bad block at %d", *block);
// just clear cache and try a new block
pcache->block = 0xffffffff;
}
}
static int lfs_index_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_index(lfs, &(lfs_off_t){size-1});
while (true) {
int err = cb(data, head);
if (err) {
return err;
}
if (index == 0) {
return 0;
}
err = lfs_cache_read(lfs, rcache, pcache, head, 0, &head, 4);
if (err) {
return err;
}
index -= 1;
}
return 0;
}
/// 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 = -1;
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_EXISTS;
}
// 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) {
file->head = -1;
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 = malloc(lfs->cfg->read_size);
if (!file->cache.buffer) {
return LFS_ERR_NOMEM;
}
} else {
file->cache.buffer = 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) {
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) && !lfs_pairisnull(file->pair)) {
// update dir entry
lfs_dir_t cwd;
int 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));
if (err) {
return err;
}
if (entry.d.type != LFS_TYPE_REG) {
// sanity check valid entry
return LFS_ERR_INVAL;
}
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_INVAL;
}
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_index_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_INVAL;
}
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_index_find(lfs, &file->cache, NULL,
file->head, file->size,
file->pos-1, &file->block, &file->off);
if (err) {
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_index_extend(lfs, &lfs->rcache, &file->cache,
file->block, file->pos,
&file->block, &file->off);
if (err) {
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;
}
return err;
}
break;
relocate:
err = lfs_file_relocate(lfs, file);
if (err) {
return err;
}
}
file->pos += diff;
file->off += diff;
data += diff;
nsize -= diff;
lfs_alloc_ack(lfs);
}
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 > file->pos) {
return LFS_ERR_INVAL;
}
file->pos = file->pos + off;
} else if (whence == LFS_SEEK_END) {
if (-off > file->size) {
return LFS_ERR_INVAL;
}
file->pos = file->size + off;
}
return file->pos;
}
lfs_soff_t lfs_file_tell(lfs_t *lfs, lfs_file_t *file) {
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) {
return lfs_max(file->pos, file->size);
}
/// General fs oprations ///
int lfs_stat(lfs_t *lfs, const char *path, struct lfs_info *info) {
// check for root, can only be something like '/././../.'
if (strspn(path, "/.") == strlen(path)) {
memset(info, 0, sizeof(*info));
info->type = LFS_TYPE_DIR;
strcpy(info->name, "/");
return 0;
}
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;
}
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
int 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_INVAL;
}
}
// 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;
}
assert(res); // must have pred
cwd.d.tail[0] = dir.d.tail[0];
cwd.d.tail[1] = dir.d.tail[1];
int 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_INVAL;
}
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
int 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_INVAL;
}
}
// 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) {
int err = lfs_dir_update(lfs, &newcwd, &newentry, newpath);
if (err) {
return err;
}
} else {
int 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;
}
assert(res); // must have pred
newcwd.d.tail[0] = dir.d.tail[0];
newcwd.d.tail[1] = dir.d.tail[1];
int 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 = 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 = malloc(lfs->cfg->prog_size);
if (!lfs->pcache.buffer) {
return LFS_ERR_NOMEM;
}
}
// setup lookahead, round down to nearest 32-bits
lfs->free.lookahead = lfs_min(lfs->cfg->lookahead, lfs->cfg->block_count);
lfs->free.lookahead = 32 * (lfs->free.lookahead / 32);
assert(lfs->free.lookahead > 0);
if (lfs->cfg->lookahead_buffer) {
lfs->free.buffer = lfs->cfg->lookahead_buffer;
} else {
lfs->free.buffer = malloc(lfs->free.lookahead/8);
if (!lfs->free.buffer) {
return LFS_ERR_NOMEM;
}
}
// check that the block size is large enough to fit ctz pointers
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->deorphaned = false;
return 0;
}
static int lfs_deinit(lfs_t *lfs) {
// free allocated memory
if (!lfs->cfg->read_buffer) {
free(lfs->rcache.buffer);
}
if (!lfs->cfg->prog_buffer) {
free(lfs->pcache.buffer);
}
if (!lfs->cfg->lookahead_buffer) {
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->free.lookahead/8);
lfs->free.begin = 0;
lfs->free.off = 0;
lfs->free.end = lfs->free.begin + lfs->cfg->block_count;
// create superblock dir
lfs_alloc_ack(lfs);
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 = 0x00010001,
.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
bool valid = false;
for (int i = 0; i < 2; i++) {
int 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.begin = -lfs->free.lookahead;
lfs->free.off = lfs->free.lookahead;
lfs->free.end = lfs->free.begin + lfs->cfg->block_count;
// 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) {
int err = lfs_bd_read(lfs, dir.pair[0], sizeof(dir.d),
&superblock.d, sizeof(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", dir.pair[0], dir.pair[1]);
return LFS_ERR_CORRUPT;
}
if (superblock.d.version > (0x00010001 | 0x0000ffff)) {
LFS_ERROR("Invalid version %d.%d\n",
0xffff & (superblock.d.version >> 16),
0xffff & (superblock.d.version >> 0));
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) {
int err = lfs_bd_read(lfs, dir.pair[0], dir.off,
&entry.d, sizeof(entry.d));
if (err) {
return err;
}
dir.off += lfs_entry_size(&entry);
if ((0x70 & entry.d.type) == (0x70 & LFS_TYPE_REG)) {
int err = lfs_index_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_index_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_index_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;
}
int 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) {
int 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)) {
int err = lfs_dir_fetch(lfs, &cwd, cwd.d.tail);
if (err) {
return err;
}
while (true) {
int 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) {
int 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]);
int 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;
int err = lfs_dir_update(lfs, &cwd, &entry, NULL);
if (err) {
return err;
}
}
}
}
memcpy(&pdir, &cwd, sizeof(pdir));
}
return 0;
}
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