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Extended entry tag to support attributes

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Zero attributes are actually supported at the moment, but this change
will allow entry attribute to be added in a backwards compatible manner.

Each dir entry is now prefixed with a 32 bit tag:
4b - entry type
4b - data structure
8b - entry len
8b - attribute len
8b - name len

A full entry on disk looks a bit like this:
[-  8 -|-  8 -|-  8 -|-  8 -|-- elen --|-- alen --|-- nlen --]
[ type | elen | alen | nlen |  entry   |  attrs   |   name   ]

The actually contents of the attributes section is a bit handwavey
until the first attributes are implemented, but to put plans in place:
Each attribute will be prefixed with only a byte that indicates the type
of attribute. Attributes should be sorted based on portability, since
unknown attributes will force attribute parsing to stop.
This commit is contained in:
Christopher Haster
2017-07-18 02:09:35 -05:00
parent 8795f0e0b7
commit c2283a2753
2 changed files with 41 additions and 33 deletions
Download Patch File Download Diff File Expand all files Collapse all files

64
lfs.c
View File

@@ -560,8 +560,7 @@ 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.len-sizeof(entry->d),
data, entry->d.len-sizeof(entry->d)}
{entry->off+sizeof(entry->d), entry->d.nlen, data, entry->d.nlen}
}, data ? 2 : 1);
}
@@ -569,11 +568,12 @@ 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 + entry->d.len <= lfs->cfg->block_size) {
if (dir->d.size + 4+entry->d.elen+entry->d.alen+entry->d.nlen
<= 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.len - sizeof(entry->d)}
{entry->off, 0, data, entry->d.nlen}
}, 2);
}
@@ -590,7 +590,7 @@ static int lfs_dir_append(lfs_t *lfs, lfs_dir_t *dir,
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.len - sizeof(entry->d)}
{entry->off, 0, data, entry->d.nlen}
}, 2);
if (err) {
return err;
@@ -620,7 +620,8 @@ static int lfs_dir_remove(lfs_t *lfs, lfs_dir_t *dir, lfs_entry_t *entry) {
if (!(pdir.d.size & 0x80000000)) {
return lfs_dir_commit(lfs, dir, (struct lfs_region[]){
{entry->off, entry->d.len, NULL, 0},
{entry->off, 4+entry->d.elen+entry->d.alen+entry->d.nlen,
NULL, 0},
}, 1);
} else {
pdir.d.tail[0] = dir->d.tail[0];
@@ -629,7 +630,8 @@ static int lfs_dir_remove(lfs_t *lfs, lfs_dir_t *dir, lfs_entry_t *entry) {
}
} else {
return lfs_dir_commit(lfs, dir, (struct lfs_region[]){
{entry->off, entry->d.len, NULL, 0},
{entry->off, 4+entry->d.elen+entry->d.alen+entry->d.nlen,
NULL, 0},
}, 1);
}
}
@@ -656,9 +658,9 @@ static int lfs_dir_next(lfs_t *lfs, lfs_dir_t *dir, lfs_entry_t *entry) {
return err;
}
dir->off += entry->d.len;
dir->pos += entry->d.len;
entry->off = dir->off - entry->d.len;
entry->off = dir->off;
dir->off += 4+entry->d.elen+entry->d.alen+entry->d.nlen;
dir->pos += 4+entry->d.elen+entry->d.alen+entry->d.nlen;
return 0;
}
@@ -713,12 +715,13 @@ static int lfs_dir_find(lfs_t *lfs, lfs_dir_t *dir,
if ((entry->d.type != LFS_TYPE_REG &&
entry->d.type != LFS_TYPE_DIR) ||
entry->d.name != pathlen) {
entry->d.nlen != pathlen) {
continue;
}
int res = lfs_bd_cmp(lfs, dir->pair[0],
entry->off + sizeof(entry->d), pathname, pathlen);
entry->off + 4+entry->d.elen+entry->d.alen,
pathname, pathlen);
if (res < 0) {
return res;
}
@@ -784,8 +787,9 @@ int lfs_mkdir(lfs_t *lfs, const char *path) {
}
entry.d.type = LFS_TYPE_DIR;
entry.d.name = strlen(path);
entry.d.len = sizeof(entry.d) + entry.d.name;
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];
@@ -880,8 +884,9 @@ int lfs_dir_read(lfs_t *lfs, lfs_dir_t *dir, struct lfs_info *info) {
info->size = entry.d.u.file.size;
}
int err = lfs_bd_read(lfs, dir->pair[0], entry.off + sizeof(entry.d),
info->name, entry.d.name);
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;
}
@@ -1117,8 +1122,9 @@ int lfs_file_open(lfs_t *lfs, lfs_file_t *file,
// create entry to remember name
entry.d.type = LFS_TYPE_REG;
entry.d.name = strlen(path);
entry.d.len = sizeof(entry.d) + entry.d.name;
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);
@@ -1537,8 +1543,9 @@ int lfs_stat(lfs_t *lfs, const char *path, struct lfs_info *info) {
info->size = entry.d.u.file.size;
}
err = lfs_bd_read(lfs, cwd.pair[0], entry.off + sizeof(entry.d),
info->name, entry.d.name);
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;
}
@@ -1585,7 +1592,7 @@ int lfs_remove(lfs_t *lfs, const char *path) {
f->pair[0] = 0xffffffff;
f->pair[1] = 0xffffffff;
} else if (f->poff > entry.off) {
f->poff -= entry.d.len;
f->poff -= 4 + entry.d.elen + entry.d.alen + entry.d.nlen;
}
}
}
@@ -1651,8 +1658,7 @@ int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath) {
// move to new location
lfs_entry_t newentry = preventry;
newentry.d = oldentry.d;
newentry.d.name = strlen(newpath);
newentry.d.len = sizeof(newentry.d) + newentry.d.name;
newentry.d.nlen = strlen(newpath);
if (prevexists) {
int err = lfs_dir_update(lfs, &newcwd, &newentry, newpath);
@@ -1690,7 +1696,7 @@ int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath) {
f->pair[0] = 0xffffffff;
f->pair[1] = 0xffffffff;
} else if (f->poff > oldentry.off) {
f->poff -= oldentry.d.len;
f->poff -= 4+oldentry.d.elen+oldentry.d.alen+oldentry.d.nlen;
}
}
}
@@ -1809,8 +1815,8 @@ int lfs_format(lfs_t *lfs, const struct lfs_config *cfg) {
lfs_superblock_t superblock = {
.off = sizeof(superdir.d),
.d.type = LFS_TYPE_SUPERBLOCK,
.d.name = sizeof(superblock.d.magic),
.d.len = sizeof(superblock.d),
.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,
@@ -1865,8 +1871,8 @@ int lfs_mount(lfs_t *lfs, const struct lfs_config *cfg) {
lfs_superblock_t superblock;
err = lfs_dir_fetch(lfs, &dir, (const lfs_block_t[2]){0, 1});
if (!err) {
err = lfs_bd_read(lfs, dir.pair[0],
sizeof(dir.d), &superblock.d, sizeof(superblock.d));
err = lfs_bd_read(lfs, dir.pair[0], sizeof(dir.d),
&superblock.d, sizeof(superblock.d));
lfs->root[0] = superblock.d.root[0];
lfs->root[1] = superblock.d.root[1];
@@ -1925,7 +1931,7 @@ int lfs_traverse(lfs_t *lfs, int (*cb)(void*, lfs_block_t), void *data) {
return err;
}
dir.off += entry.d.len;
dir.off += 4+entry.d.elen+entry.d.alen+entry.d.nlen;
if ((0xf & entry.d.type) == (0xf & LFS_TYPE_REG)) {
int err = lfs_index_traverse(lfs, &lfs->rcache, NULL,
entry.d.u.file.head, entry.d.u.file.size, cb, data);

10
lfs.h
View File

@@ -160,8 +160,9 @@ typedef struct lfs_entry {
struct lfs_disk_entry {
uint8_t type;
uint8_t name;
uint16_t len;
uint8_t elen;
uint8_t alen;
uint8_t nlen;
union {
struct {
lfs_block_t head;
@@ -212,8 +213,9 @@ typedef struct lfs_superblock {
struct lfs_disk_superblock {
uint8_t type;
uint8_t name;
uint16_t len;
uint8_t elen;
uint8_t alen;
uint8_t nlen;
lfs_block_t root[2];
uint32_t block_size;
uint32_t block_count;