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third_party_littlefs/lfs.c
Christopher Haster a3734eeb34 Added proper handling of orphans 
Unfortunately, threading all dir blocks in a linked-list did
not come without problems.

While it's possible to atomically add a dir to the linked list
(by adding the new dir into the linked-list position immediately
after it's parent, requiring only one atomic update to the parent
block), it is not easy to make sure the linked-list is in a state
that always allows atomic removal of dirs.

The simple solution is to allow this non-atomic removal, with an
additional step to remove any orphans that could have been created
by a power-loss. This deorphan step is only run if the normal
allocator has failed.
2017-04-18 01:44:01 -05:00

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/*
* The little filesystem
*
* Copyright (c) 2017 Christopher Haster
* Distributed under the MIT license
*/
#include "lfs.h"
#include "lfs_util.h"
#include <string.h>
#include <stdbool.h>
/// Block device operations ///
static int lfs_bd_info(lfs_t *lfs, struct lfs_bd_info *info) {
return lfs->bd_ops->info(lfs->bd, info);
}
static int lfs_bd_read(lfs_t *lfs, lfs_block_t block,
lfs_off_t off, lfs_size_t size, void *buffer) {
return lfs->bd_ops->read(lfs->bd, block, off, size, buffer);
}
static int lfs_bd_prog(lfs_t *lfs, lfs_block_t block,
lfs_off_t off, lfs_size_t size, const void *buffer) {
return lfs->bd_ops->prog(lfs->bd, block, off, size, buffer);
}
static int lfs_bd_erase(lfs_t *lfs, lfs_block_t block,
lfs_off_t off, lfs_size_t size) {
return lfs->bd_ops->erase(lfs->bd, block, off, size);
}
static int lfs_bd_sync(lfs_t *lfs) {
return lfs->bd_ops->sync(lfs->bd);
}
static int lfs_bd_cmp(lfs_t *lfs, lfs_block_t block,
lfs_off_t off, lfs_size_t size, const void *buffer) {
const uint8_t *data = buffer;
for (lfs_off_t i = 0; i < size; i++) {
uint8_t c;
int err = lfs_bd_read(lfs, block, off+i, 1, &c);
if (err) {
return err;
}
if (c != *data) {
return false;
}
data += 1;
}
return true;
}
static int lfs_bd_crc(lfs_t *lfs, lfs_block_t block,
lfs_off_t off, lfs_size_t size, uint32_t *crc) {
while (off < size) {
uint8_t c;
int err = lfs_bd_read(lfs, block, off, 1, &c);
if (err) {
return err;
}
*crc = lfs_crc(&c, 1, *crc);
off += 1;
}
return 0;
}
/// Block allocator ///
// predeclared filesystem traversal
static int lfs_traverse(lfs_t *lfs, int (*cb)(void*, lfs_block_t), void *data);
int lfs_deorphan(lfs_t *lfs);
static int lfs_alloc_lookahead(void *p, lfs_block_t block) {
lfs_t *lfs = p;
lfs_block_t off = block - lfs->free.begin;
if (off < LFS_CFG_LOOKAHEAD) {
lfs->lookahead[off / 32] |= 1U << (off % 32);
}
return 0;
}
static int lfs_alloc_stride(void *p, lfs_block_t block) {
lfs_t *lfs = p;
lfs_block_t noff = block - lfs->free.begin;
lfs_block_t off = lfs->free.end - lfs->free.begin;
if (noff < off) {
lfs->free.end = noff + lfs->free.begin;
}
return 0;
}
static int lfs_alloc_scan(lfs_t *lfs) {
lfs_block_t start = lfs->free.begin;
while (true) {
// mask out blocks in lookahead region
memset(lfs->lookahead, 0, sizeof(lfs->lookahead));
int err = lfs_traverse(lfs, lfs_alloc_lookahead, lfs);
if (err) {
return err;
}
// check if we've found a free block
for (uint32_t off = 0; off < LFS_CFG_LOOKAHEAD; off++) {
if (lfs->lookahead[off / 32] & (1U << (off % 32))) {
continue;
}
// found free block, now find stride of free blocks
// since this is relatively cheap (stress on relatively)
lfs->free.begin += off;
lfs->free.end = lfs->block_count; // before superblock
// find maximum stride in tree
return lfs_traverse(lfs, lfs_alloc_stride, lfs);
}
// continue to next lookahead unless we've searched the whole device
if (start-1 - lfs->free.begin < LFS_CFG_LOOKAHEAD) {
return 0;
}
// continue to next lookahead region
lfs->free.begin += LFS_CFG_LOOKAHEAD;
}
}
static int lfs_alloc(lfs_t *lfs, lfs_block_t *block) {
// If we don't remember any free blocks we will need to start searching
if (lfs->free.begin == lfs->free.end) {
int err = lfs_alloc_scan(lfs);
if (err) {
return err;
}
if (lfs->free.begin == lfs->free.end) {
// Still can't allocate a block? check for orphans
int err = lfs_deorphan(lfs);
if (err) {
return err;
}
err = lfs_alloc_scan(lfs);
if (err) {
return err;
}
if (lfs->free.begin == lfs->free.end) {
// Ok, it's true, we're out of space
return LFS_ERROR_NO_SPACE;
}
}
}
// Take first available block
*block = lfs->free.begin;
lfs->free.begin += 1;
return 0;
}
static int lfs_alloc_erased(lfs_t *lfs, lfs_block_t *block) {
int err = lfs_alloc(lfs, block);
if (err) {
return err;
}
return lfs_bd_erase(lfs, *block, 0, lfs->block_size);
}
/// Index list operations ///
// Next index offset
static lfs_off_t lfs_indexnext(lfs_t *lfs, lfs_off_t ioff) {
ioff += 1;
while (ioff % lfs->words == 0) {
ioff += lfs_min(lfs_ctz(ioff/lfs->words + 1), lfs->words-1) + 1;
}
return ioff;
}
static lfs_off_t lfs_indexfrom(lfs_t *lfs, lfs_off_t off) {
lfs_off_t i = 0;
while (off > lfs->block_size) {
i = lfs_indexnext(lfs, i);
off -= lfs->block_size;
}
return i;
}
// Find index in index chain given its index offset
static int lfs_index_find(lfs_t *lfs, lfs_block_t head,
lfs_size_t icount, lfs_off_t ioff, lfs_block_t *block) {
lfs_off_t iitarget = ioff / lfs->words;
lfs_off_t iicurrent = (icount-1) / lfs->words;
while (iitarget != iicurrent) {
lfs_size_t skip = lfs_min(
lfs_min(lfs_ctz(iicurrent+1), lfs->words-1),
lfs_npw2((iitarget ^ iicurrent)+1)-1);
int err = lfs_bd_read(lfs, head, 4*skip, 4, &head);
if (err) {
return err;
}
iicurrent -= 1 << skip;
}
return lfs_bd_read(lfs, head, 4*(ioff % lfs->words), 4, block);
}
// Append index to index chain, updates head and icount
static int lfs_index_append(lfs_t *lfs, lfs_block_t *headp,
lfs_size_t *icountp, lfs_block_t block) {
lfs_block_t head = *headp;
lfs_size_t ioff = *icountp - 1;
ioff += 1;
while (ioff % lfs->words == 0) {
lfs_block_t nhead;
int err = lfs_alloc_erased(lfs, &nhead);
if (err) {
return err;
}
lfs_off_t skips = lfs_min(
lfs_ctz(ioff/lfs->words + 1), lfs->words-2) + 1;
for (lfs_off_t i = 0; i < skips; i++) {
err = lfs_bd_prog(lfs, nhead, 4*i, 4, &head);
if (err) {
return err;
}
if (head && i != skips-1) {
err = lfs_bd_read(lfs, head, 4*i, 4, &head);
if (err) {
return err;
}
}
}
ioff += skips;
head = nhead;
}
int err = lfs_bd_prog(lfs, head, 4*(ioff % lfs->words), 4, &block);
if (err) {
return err;
}
*headp = head;
*icountp = ioff + 1;
return 0;
}
static int lfs_index_traverse(lfs_t *lfs, lfs_block_t head,
lfs_size_t icount, int (*cb)(void*, lfs_block_t), void *data) {
lfs_off_t iicurrent = (icount-1) / lfs->words;
while (iicurrent > 0) {
int err = cb(data, head);
if (err) {
return err;
}
lfs_size_t skip = lfs_min(lfs_ctz(iicurrent+1), lfs->words-1);
for (lfs_off_t i = skip; i < lfs->words; i++) {
lfs_block_t block;
int err = lfs_bd_read(lfs, head, 4*i, 4, &block);
if (err) {
return err;
}
err = cb(data, block);
if (err) {
return err;
}
}
err = lfs_bd_read(lfs, head, 0, 4, &head);
if (err) {
return err;
}
iicurrent -= 1;
}
int err = cb(data, head);
if (err) {
return err;
}
for (lfs_off_t i = 0; i < lfs->words; i++) {
lfs_block_t block;
int err = lfs_bd_read(lfs, head, 4*i, 4, &block);
if (err) {
return err;
}
err = cb(data, block);
if (err) {
return err;
}
}
return 0;
}
/// Metadata pair 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 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]));
}
struct lfs_fetch_region {
lfs_off_t off;
lfs_size_t size;
void *data;
};
static int lfs_pair_fetch(lfs_t *lfs, lfs_block_t pair[2],
int count, const struct lfs_fetch_region *regions) {
int checked = 0;
int rev = 0;
for (int i = 0; i < 2; i++) {
uint32_t nrev;
int err = lfs_bd_read(lfs, pair[1], 0, 4, &nrev);
if (err) {
return err;
}
if (checked > 0 && lfs_scmp(nrev, rev) < 0) {
continue;
}
uint32_t crc = 0xffffffff;
err = lfs_bd_crc(lfs, pair[1], 0, lfs->block_size, &crc);
if (err) {
return err;
}
if (crc != 0) {
lfs_pairswap(pair);
}
checked += 1;
rev = nrev;
lfs_pairswap(pair);
}
if (checked == 0) {
LFS_ERROR("Corrupted metadata pair at %d %d", pair[0], pair[1]);
return LFS_ERROR_CORRUPT;
}
for (int i = 0; i < count; i++) {
int err = lfs_bd_read(lfs, pair[0],
regions[i].off, regions[i].size, regions[i].data);
if (err) {
return err;
}
}
return 0;
}
struct lfs_commit_region {
lfs_off_t off;
lfs_size_t size;
const void *data;
};
static int lfs_pair_commit(lfs_t *lfs, lfs_block_t pair[2],
int count, const struct lfs_commit_region *regions) {
uint32_t crc = 0xffffffff;
int err = lfs_bd_erase(lfs, pair[1], 0, lfs->block_size);
if (err) {
return err;
}
lfs_off_t off = 0;
while (off < lfs->block_size - 4) {
if (count > 0 && regions[0].off == off) {
crc = lfs_crc(regions[0].data, regions[0].size, crc);
int err = lfs_bd_prog(lfs, pair[1],
off, regions[0].size, regions[0].data);
if (err) {
return err;
}
off += regions[0].size;
count -= 1;
regions += 1;
} else {
// TODO faster strides?
// TODO should we start crcing what's already
// programmed after dir size?
uint8_t data;
int err = lfs_bd_read(lfs, pair[0], off, 1, &data);
if (err) {
return err;
}
crc = lfs_crc((void*)&data, 1, crc);
err = lfs_bd_prog(lfs, pair[1], off, 1, &data);
if (err) {
return err;
}
off += 1;
}
}
err = lfs_bd_prog(lfs, pair[1], lfs->block_size-4, 4, &crc);
if (err) {
return err;
}
err = lfs_bd_sync(lfs);
if (err) {
return err;
}
lfs_pairswap(pair);
return 0;
}
// TODO maybe there is a better abstraction for this?
static int lfs_pair_shift(lfs_t *lfs, lfs_block_t pair[2],
int count, const struct lfs_commit_region *regions,
lfs_off_t blank_start, lfs_size_t blank_size) {
uint32_t crc = 0xffffffff;
int err = lfs_bd_erase(lfs, pair[1], 0, lfs->block_size);
if (err) {
return err;
}
lfs_off_t woff = 0;
lfs_off_t roff = 0;
while (woff < lfs->block_size - 4) {
if (count > 0 && regions[0].off == woff) {
crc = lfs_crc(regions[0].data, regions[0].size, crc);
int err = lfs_bd_prog(lfs, pair[1],
woff, regions[0].size, regions[0].data);
if (err) {
return err;
}
woff += regions[0].size;
roff += regions[0].size;
count -= 1;
regions += 1;
} else if (roff == blank_start) {
roff += blank_size;
} else if (roff < lfs->block_size - 4) {
// TODO faster strides?
// TODO should we start crcing what's already
// programmed after dir size?
uint8_t data;
int err = lfs_bd_read(lfs, pair[0], roff, 1, &data);
if (err) {
return err;
}
crc = lfs_crc((void*)&data, 1, crc);
err = lfs_bd_prog(lfs, pair[1], woff, 1, &data);
if (err) {
return err;
}
woff += 1;
roff += 1;
} else {
uint8_t data = 0;
crc = lfs_crc((void*)&data, 1, crc);
err = lfs_bd_prog(lfs, pair[1], woff, 1, &data);
if (err) {
return err;
}
woff += 1;
}
}
err = lfs_bd_prog(lfs, pair[1], lfs->block_size-4, 4, &crc);
if (err) {
return err;
}
err = lfs_bd_sync(lfs);
if (err) {
return err;
}
lfs_pairswap(pair);
return 0;
}
/// Directory operations ///
static int lfs_dir_alloc(lfs_t *lfs, lfs_dir_t *dir,
lfs_block_t parent[2], lfs_block_t tail[2]) {
// 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, 4, &dir->d.rev);
if (err) {
return err;
}
dir->d.rev += 1;
// Calculate total size
dir->d.size = sizeof(dir->d);
dir->off = sizeof(dir->d);
// Other defaults
dir->d.tail[0] = tail[0];
dir->d.tail[1] = tail[1];
// Write out to memory
if (!parent) {
return lfs_pair_commit(lfs, dir->pair,
1, (struct lfs_commit_region[]){
{0, sizeof(dir->d), &dir->d}
});
} else {
dir->d.size += 2*sizeof(struct lfs_disk_entry) + 3;
return lfs_pair_commit(lfs, dir->pair,
5, (struct lfs_commit_region[]){
{0, sizeof(dir->d), &dir->d},
{sizeof(dir->d), sizeof(struct lfs_disk_entry),
&(struct lfs_disk_entry){
.type = LFS_TYPE_DIR,
.len = sizeof(struct lfs_disk_entry)+1,
.u.dir[0] = dir->pair[0],
.u.dir[1] = dir->pair[1],
}},
{sizeof(dir->d)+sizeof(struct lfs_disk_entry), 1, "."},
{sizeof(dir->d)+sizeof(struct lfs_disk_entry)+1,
sizeof(struct lfs_disk_entry),
&(struct lfs_disk_entry){
.type = LFS_TYPE_DIR,
.len = sizeof(struct lfs_disk_entry)+2,
.u.dir[0] = parent[0] ? parent[0] : dir->pair[0],
.u.dir[1] = parent[1] ? parent[1] : dir->pair[1],
}},
{sizeof(dir->d)+2*sizeof(struct lfs_disk_entry)+1, 2, ".."},
});
}
}
static int lfs_dir_fetch(lfs_t *lfs, lfs_dir_t *dir, lfs_block_t pair[2]) {
dir->pair[0] = pair[0];
dir->pair[1] = pair[1];
dir->off = sizeof(dir->d);
return lfs_pair_fetch(lfs, dir->pair,
1, (struct lfs_fetch_region[1]) {
{0, sizeof(dir->d), &dir->d}
});
}
static int lfs_dir_next(lfs_t *lfs, lfs_dir_t *dir, lfs_entry_t *entry) {
while (true) {
if ((0x7fffffff & dir->d.size) - dir->off < sizeof(entry->d)) {
if (!(dir->d.size >> 31)) {
entry->dir[0] = dir->pair[0];
entry->dir[1] = dir->pair[1];
entry->off = dir->off;
return LFS_ERROR_NO_ENTRY;
}
int err = lfs_dir_fetch(lfs, dir, dir->d.tail);
if (err) {
return err;
}
dir->off = sizeof(dir->d);
}
int err = lfs_bd_read(lfs, dir->pair[0], dir->off,
sizeof(entry->d), &entry->d);
if (err) {
return err;
}
dir->off += entry->d.len;
if (entry->d.type == LFS_TYPE_REG || entry->d.type == LFS_TYPE_DIR) {
entry->dir[0] = dir->pair[0];
entry->dir[1] = dir->pair[1];
entry->off = dir->off - entry->d.len;
return 0;
}
}
}
static int lfs_dir_find(lfs_t *lfs, lfs_dir_t *dir,
const char **path, lfs_entry_t *entry) {
while (true) {
const char *pathname = *path;
lfs_size_t pathlen = strcspn(pathname, "/");
while (true) {
int err = lfs_dir_next(lfs, dir, entry);
if (err) {
return err;
}
if (entry->d.len - sizeof(entry->d) != pathlen) {
continue;
}
int ret = lfs_bd_cmp(lfs, entry->dir[0],
entry->off + sizeof(entry->d), pathlen, pathname);
if (ret < 0) {
return ret;
}
// Found match
if (ret == true) {
break;
}
}
pathname += pathlen;
pathname += strspn(pathname, "/");
if (pathname[0] == '\0') {
return 0;
}
if (entry->d.type != LFS_TYPE_DIR) {
return LFS_ERROR_NOT_DIR;
}
int err = lfs_dir_fetch(lfs, dir, entry->d.u.dir);
if (err) {
return err;
}
*path = pathname;
}
return 0;
}
static int lfs_dir_append(lfs_t *lfs, lfs_dir_t *dir,
const char **path, lfs_entry_t *entry) {
int err = lfs_dir_find(lfs, dir, path, entry);
if (err != LFS_ERROR_NO_ENTRY) {
return err ? err : LFS_ERROR_EXISTS;
}
// Check if we fit
if ((0x7fffffff & dir->d.size) + sizeof(entry->d) + strlen(*path)
> lfs->block_size - 4) {
lfs_dir_t olddir;
memcpy(&olddir, dir, sizeof(olddir));
int err = lfs_dir_alloc(lfs, dir, 0, olddir.d.tail);
if (err) {
return err;
}
entry->dir[0] = dir->pair[0];
entry->dir[1] = dir->pair[1];
entry->off = dir->off;
olddir.d.rev += 1;
olddir.d.size |= 1 << 31;
olddir.d.tail[0] = dir->pair[0];
olddir.d.tail[1] = dir->pair[1];
return lfs_pair_commit(lfs, olddir.pair,
1, (struct lfs_commit_region[]){
{0, sizeof(olddir.d), &olddir.d}
});
}
return 0;
}
int lfs_mkdir(lfs_t *lfs, const char *path) {
// Allocate entry for directory
lfs_dir_t cwd;
int err = lfs_dir_fetch(lfs, &cwd, lfs->cwd);
if (err) {
return err;
}
lfs_entry_t entry;
err = lfs_dir_append(lfs, &cwd, &path, &entry);
if (err) {
return err;
}
// Build up new directory
lfs_dir_t dir;
err = lfs_dir_alloc(lfs, &dir, cwd.pair, cwd.d.tail);
if (err) {
return err;
}
entry.d.type = LFS_TYPE_DIR;
entry.d.len = sizeof(entry.d) + strlen(path);
entry.d.u.dir[0] = dir.pair[0];
entry.d.u.dir[1] = dir.pair[1];
cwd.d.rev += 1;
cwd.d.size += entry.d.len;
cwd.d.tail[0] = dir.pair[0];
cwd.d.tail[1] = dir.pair[1];
return lfs_pair_commit(lfs, entry.dir,
3, (struct lfs_commit_region[3]) {
{0, sizeof(cwd.d), &cwd.d},
{entry.off, sizeof(entry.d), &entry.d},
{entry.off+sizeof(entry.d), entry.d.len - sizeof(entry.d), path}
});
}
int lfs_dir_open(lfs_t *lfs, lfs_dir_t *dir, const char *path) {
if (path[0] == '/') {
dir->pair[0] = lfs->root[0];
dir->pair[1] = lfs->root[1];
} else {
dir->pair[0] = lfs->cwd[0];
dir->pair[1] = lfs->cwd[1];
}
int err = lfs_dir_fetch(lfs, dir, dir->pair);
if (err) {
return err;
} else if (strcmp(path, "/") == 0) {
return 0;
}
lfs_entry_t entry;
err = lfs_dir_find(lfs, dir, &path, &entry);
if (err) {
return err;
} else if (entry.d.type != LFS_TYPE_DIR) {
return LFS_ERROR_NOT_DIR;
}
return lfs_dir_fetch(lfs, dir, entry.d.u.dir);
}
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));
lfs_entry_t entry;
int err = lfs_dir_next(lfs, dir, &entry);
if (err) {
return (err == LFS_ERROR_NO_ENTRY) ? 0 : err;
}
info->type = entry.d.type & 0xff;
if (info->type == LFS_TYPE_REG) {
info->size = entry.d.u.file.size;
}
err = lfs_bd_read(lfs, entry.dir[0], entry.off + sizeof(entry.d),
entry.d.len - sizeof(entry.d), info->name);
if (err) {
return err;
}
return 1;
}
/// File operations ///
int lfs_file_open(lfs_t *lfs, lfs_file_t *file,
const char *path, int flags) {
// Allocate entry for file if it doesn't exist
// TODO check open files
lfs_dir_t cwd;
int err = lfs_dir_fetch(lfs, &cwd, lfs->cwd);
if (err) {
return err;
}
if (flags & LFS_O_CREAT) {
err = lfs_dir_append(lfs, &cwd, &path, &file->entry);
if (err && err != LFS_ERROR_EXISTS) {
return err;
}
} else {
err = lfs_dir_find(lfs, &cwd, &path, &file->entry);
if (err) {
return err;
}
}
if ((flags & LFS_O_CREAT) && err != LFS_ERROR_EXISTS) {
// Store file
file->head = 0;
file->size = 0;
file->wblock = 0;
file->windex = 0;
file->rblock = 0;
file->rindex = 0;
file->roff = 0;
file->entry.d.type = 1;
file->entry.d.len = sizeof(file->entry.d) + strlen(path);
file->entry.d.u.file.head = file->head;
file->entry.d.u.file.size = file->size;
cwd.d.rev += 1;
cwd.d.size += file->entry.d.len;
return lfs_pair_commit(lfs, file->entry.dir,
3, (struct lfs_commit_region[3]) {
{0, sizeof(cwd.d), &cwd.d},
{file->entry.off,
sizeof(file->entry.d),
&file->entry.d},
{file->entry.off+sizeof(file->entry.d),
file->entry.d.len-sizeof(file->entry.d),
path}
});
} else if (file->entry.d.type == LFS_TYPE_DIR) {
return LFS_ERROR_IS_DIR;
} else {
file->head = file->entry.d.u.file.head;
file->size = file->entry.d.u.file.size;
file->windex = lfs_indexfrom(lfs, file->size);
file->rblock = 0;
file->rindex = 0;
file->roff = 0;
// TODO do this lazily in write?
// TODO cow the head i/d block
if (file->size < lfs->block_size) {
file->wblock = file->head;
} else {
int err = lfs_index_find(lfs, file->head, file->windex,
file->windex, &file->wblock);
if (err) {
return err;
}
}
return 0;
}
}
int lfs_file_close(lfs_t *lfs, lfs_file_t *file) {
// Store file
lfs_dir_t cwd;
int err = lfs_dir_fetch(lfs, &cwd, file->entry.dir);
if (err) {
return err;
}
file->entry.d.u.file.head = file->head;
file->entry.d.u.file.size = file->size;
cwd.d.rev += 1;
return lfs_pair_commit(lfs, file->entry.dir,
3, (struct lfs_commit_region[3]) {
{0, sizeof(cwd.d), &cwd.d},
{file->entry.off, sizeof(file->entry.d), &file->entry.d},
});
}
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;
while (nsize > 0) {
lfs_off_t woff = file->size % lfs->block_size;
if (file->size == 0) {
int err = lfs_alloc_erased(lfs, &file->wblock);
if (err) {
return err;
}
file->head = file->wblock;
file->windex = 0;
} else if (woff == 0) {
int err = lfs_alloc_erased(lfs, &file->wblock);
if (err) {
return err;
}
err = lfs_index_append(lfs, &file->head,
&file->windex, file->wblock);
if (err) {
return err;
}
}
lfs_size_t diff = lfs_min(nsize, lfs->block_size - woff);
int err = lfs_bd_prog(lfs, file->wblock, woff, diff, data);
if (err) {
return err;
}
file->size += diff;
data += diff;
nsize -= diff;
}
return size;
}
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;
while (nsize > 0 && file->roff < file->size) {
lfs_off_t roff = file->roff % lfs->block_size;
// TODO cache index blocks
if (file->size < lfs->block_size) {
file->rblock = file->head;
} else if (roff == 0) {
int err = lfs_index_find(lfs, file->head, file->windex,
file->rindex, &file->rblock);
if (err) {
return err;
}
file->rindex = lfs_indexnext(lfs, file->rindex);
}
lfs_size_t diff = lfs_min(
lfs_min(nsize, file->size-file->roff),
lfs->block_size - roff);
int err = lfs_bd_read(lfs, file->rblock, roff, diff, data);
if (err) {
return err;
}
file->roff += diff;
data += diff;
nsize -= diff;
}
return size - nsize;
}
/// Generic filesystem operations ///
static int lfs_configure(lfs_t *lfs, const struct lfs_config *config) {
lfs->bd = config->bd;
lfs->bd_ops = config->bd_ops;
struct lfs_bd_info info;
int err = lfs_bd_info(lfs, &info);
if (err) {
return err;
}
if (config->read_size) {
if (config->read_size < info.read_size ||
config->read_size % info.read_size != 0) {
LFS_ERROR("Invalid read size %u, device has %u\n",
config->read_size, info.read_size);
return LFS_ERROR_INVALID;
}
lfs->read_size = config->read_size;
} else {
lfs->read_size = info.read_size;
}
if (config->prog_size) {
if (config->prog_size < info.prog_size ||
config->prog_size % info.prog_size != 0) {
LFS_ERROR("Invalid prog size %u, device has %u\n",
config->prog_size, info.prog_size);
return LFS_ERROR_INVALID;
}
lfs->prog_size = config->prog_size;
} else {
lfs->prog_size = info.prog_size;
}
if (config->block_size) {
if (config->block_size < info.erase_size ||
config->block_size % info.erase_size != 0) {
LFS_ERROR("Invalid block size %u, device has %u\n",
config->prog_size, info.prog_size);
return LFS_ERROR_INVALID;
}
lfs->block_size = config->block_size;
} else {
lfs->block_size = lfs_min(512, info.erase_size);
}
if (config->block_count) {
if (config->block_count > info.total_size/info.erase_size) {
LFS_ERROR("Invalid block size %u, device has %u\n",
config->block_size,
(uint32_t)(info.total_size/info.erase_size));
return LFS_ERROR_INVALID;
}
lfs->block_count = config->block_count;
} else {
lfs->block_count = info.total_size / info.erase_size;
}
lfs->words = lfs->block_size / sizeof(uint32_t);
return 0;
}
int lfs_format(lfs_t *lfs, const struct lfs_config *config) {
int err = lfs_configure(lfs, config);
if (err) {
return err;
}
// Create free list
lfs->free.begin = 2;
lfs->free.end = lfs->block_count-1;
// Write root directory
lfs_dir_t root;
err = lfs_dir_alloc(lfs, &root,
(lfs_block_t[2]){0, 0}, (lfs_block_t[2]){0, 0});
if (err) {
return err;
}
lfs->root[0] = root.pair[0];
lfs->root[1] = root.pair[1];
lfs->cwd[0] = root.pair[0];
lfs->cwd[1] = root.pair[1];
// Write superblocks
lfs_superblock_t superblock = {
.pair = {0, 1},
.d.rev = 1,
.d.size = sizeof(superblock),
.d.root = {lfs->cwd[0], lfs->cwd[1]},
.d.magic = {"littlefs"},
.d.block_size = lfs->block_size,
.d.block_count = lfs->block_count,
};
for (int i = 0; i < 2; i++) {
int err = lfs_pair_commit(lfs, superblock.pair,
1, (struct lfs_commit_region[]){
{0, sizeof(superblock.d), &superblock.d}
});
if (err) {
LFS_ERROR("Failed to write superblock at %d", superblock.pair[1]);
return err;
}
uint32_t crc = 0xffffffff;
err = lfs_bd_crc(lfs, superblock.pair[0], 0, lfs->block_size, &crc);
if (err || crc != 0) {
LFS_ERROR("Failed to write superblock at %d", superblock.pair[0]);
return err ? err : LFS_ERROR_CORRUPT;
}
}
return 0;
}
int lfs_mount(lfs_t *lfs, const struct lfs_config *config) {
int err = lfs_configure(lfs, config);
if (err) {
return err;
}
lfs_superblock_t superblock = {
.pair = {0, 1},
};
err = lfs_pair_fetch(lfs, superblock.pair,
1, (struct lfs_fetch_region[]){
{0, sizeof(superblock.d), &superblock.d}
});
if ((err == LFS_ERROR_CORRUPT ||
memcmp(superblock.d.magic, "littlefs", 8) != 0)) {
LFS_ERROR("Invalid superblock at %d %d",
superblock.pair[0], superblock.pair[1]);
return LFS_ERROR_CORRUPT;
}
lfs->root[0] = superblock.d.root[0];
lfs->root[1] = superblock.d.root[1];
lfs->cwd[0] = superblock.d.root[0];
lfs->cwd[1] = superblock.d.root[1];
return err;
}
int lfs_unmount(lfs_t *lfs) {
// Do nothing for now
return 0;
}
static int lfs_traverse(lfs_t *lfs, int (*cb)(void*, lfs_block_t), void *data) {
// iterate over metadata pairs
lfs_dir_t dir;
lfs_file_t file;
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;
}
// skip '.' and '..'
dir.off += 2*sizeof(struct lfs_disk_entry) + 3;
// iterate over contents
while ((0x7fffffff & dir.d.size) >= dir.off + sizeof(file.entry.d)) {
int err = lfs_bd_read(lfs, dir.pair[0], dir.off,
sizeof(file.entry.d), &file.entry.d);
if (err) {
return err;
}
dir.off += file.entry.d.len;
if ((0xf & file.entry.d.type) == LFS_TYPE_REG) {
if (file.entry.d.u.file.size < lfs->block_size) {
int err = cb(data, file.entry.d.u.file.head);
if (err) {
return err;
}
} else {
int err = lfs_index_traverse(lfs,
file.entry.d.u.file.head,
lfs_indexfrom(lfs, file.entry.d.u.file.size),
cb, data);
if (err) {
return err;
}
}
}
}
cwd[0] = dir.d.tail[0];
cwd[1] = dir.d.tail[1];
if (!cwd[0]) {
return 0;
}
}
}
int lfs_deorphan(lfs_t *lfs) {
// iterate over all directories
lfs_block_t pred[2] = {0, 1};
lfs_block_t cwd[2] = {lfs->root[0], lfs->root[1]};
while (true) {
lfs_dir_t child;
int err = lfs_dir_fetch(lfs, &child, cwd);
if (err) {
return err;
}
// orphans can only be empty dirs
// there still might be a dir block with this size that isn't
// the head of a directory, so we still have to check for '..'
if (child.d.size == sizeof(child.d) +
2*sizeof(struct lfs_disk_entry) + 3) {
lfs_entry_t entry;
err = lfs_dir_find(lfs, &child, &(const char*){".."}, &entry);
if (err && err != LFS_ERROR_NO_ENTRY) {
return err;
}
// only the head of directories can be orphans
if (err != LFS_ERROR_NO_ENTRY) {
lfs_dir_t dir;
int err = lfs_dir_fetch(lfs, &dir, entry.d.u.dir);
if (err) {
return err;
}
// check if we are any of our parents children
while (true) {
int err = lfs_dir_next(lfs, &dir, &entry);
if (err && err != LFS_ERROR_NO_ENTRY) {
return err;
}
if (err == LFS_ERROR_NO_ENTRY) {
// we are an orphan
LFS_INFO("Found orphan %d %d", cwd[0], cwd[1]);
int err = lfs_dir_fetch(lfs, &dir, pred);
if (err) {
return err;
}
dir.d.tail[0] = child.d.tail[0];
dir.d.tail[1] = child.d.tail[1];
dir.d.rev += 1;
err = lfs_pair_commit(lfs, dir.pair,
1, (struct lfs_commit_region[]) {
{0, sizeof(dir.d), &dir.d},
});
if (err) {
return err;
}
break;
} else if (lfs_paircmp(entry.d.u.dir, cwd) == 0) {
// has parent
break;
}
}
}
}
// to next directory
pred[0] = cwd[0];
pred[1] = cwd[1];
cwd[0] = child.d.tail[0];
cwd[1] = child.d.tail[1];
if (!cwd[0]) {
return 0;
}
}
}
int lfs_remove(lfs_t *lfs, const char *path) {
lfs_dir_t cwd;
int err = lfs_dir_fetch(lfs, &cwd, lfs->cwd);
if (err) {
return err;
}
lfs_entry_t entry;
err = lfs_dir_find(lfs, &cwd, &path, &entry);
if (err) {
return err;
}
lfs_dir_t dir;
if (entry.d.type == LFS_TYPE_DIR) {
// must be empty before removal
int err = lfs_dir_fetch(lfs, &dir, entry.d.u.dir);
if (err) {
return err;
} else if (dir.d.size != sizeof(dir.d) +
2*sizeof(struct lfs_disk_entry) + 3) {
return LFS_ERROR_INVALID;
}
}
cwd.d.rev += 1;
cwd.d.size -= entry.d.len;
// either shift out the one entry or remove the whole dir block
if (cwd.d.size == sizeof(dir.d)) {
lfs_dir_t pdir;
int err = lfs_dir_fetch(lfs, &pdir, lfs->cwd);
if (err) {
return err;
}
while (lfs_paircmp(pdir.d.tail, cwd.pair) != 0) {
int err = lfs_dir_fetch(lfs, &pdir, pdir.d.tail);
if (err) {
return err;
}
}
pdir.d.tail[0] = cwd.d.tail[0];
pdir.d.tail[1] = cwd.d.tail[1];
pdir.d.rev += 1;
err = lfs_pair_commit(lfs, pdir.pair,
1, (struct lfs_commit_region[]) {
{0, sizeof(pdir.d), &pdir.d},
});
if (err) {
return err;
}
} else {
int err = lfs_pair_shift(lfs, entry.dir,
1, (struct lfs_commit_region[]) {
{0, sizeof(cwd.d), &cwd.d},
},
entry.off, entry.d.len);
if (err) {
return err;
}
}
if (entry.d.type == LFS_TYPE_DIR) {
// remove ourselves from the dir list
// this may create an orphan, which must be deorphaned
lfs_dir_t pdir;
memcpy(&pdir, &cwd, sizeof(pdir));
while (pdir.d.tail[0]) {
if (lfs_paircmp(pdir.d.tail, entry.d.u.dir) == 0) {
pdir.d.tail[0] = dir.d.tail[0];
pdir.d.tail[1] = dir.d.tail[1];
pdir.d.rev += 1;
int err = lfs_pair_commit(lfs, pdir.pair,
1, (struct lfs_commit_region[]) {
{0, sizeof(pdir.d), &pdir.d},
});
if (err) {
return err;
}
break;
}
int err = lfs_dir_fetch(lfs, &pdir, pdir.d.tail);
if (err) {
return err;
}
}
}
return 0;
}
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