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littlefs: Fix issue with trailing dots in file paths #6774

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Merged
merged 1 commit into from
May 3, 2018
Merged

littlefs: Fix issue with trailing dots in file paths #6774

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100 changes: 30 additions & 70 deletions features/filesystem/littlefs/littlefs/lfs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -783,26 +783,19 @@ 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;
entry->d.type = LFS_TYPE_DIR;
entry->d.elen = sizeof(entry->d) - 4;
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Will sizeof(entry->d) be ever < 4? Will that be corner case considering elen is uint8_t?

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No, the prefix for the entry stored on disk is a 4 byte header. If entry->d is less than 4, than the struct is malformed.

Also GCC is actually smart enough to warn on underflow for constants like these.

entry->d.alen = 0;
entry->d.nlen = 0;
entry->d.u.dir[0] = lfs->root[0];
entry->d.u.dir[1] = lfs->root[1];

while (true) {
nextname:
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)) {
Expand Down Expand Up @@ -834,10 +827,25 @@ static int lfs_dir_find(lfs_t *lfs, lfs_dir_t *dir,
suffix += sufflen;
}

// found path
if (pathname[0] == '\0') {
return 0;
}

// update what we've found
*path = pathname;

// find path
// 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;
}

// find entry matching name
while (true) {
int err = lfs_dir_next(lfs, dir, entry);
if (err) {
Expand Down Expand Up @@ -873,21 +881,8 @@ static int lfs_dir_find(lfs_t *lfs, lfs_dir_t *dir,
entry->d.type &= ~0x80;
}

// to next name
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;
}
}
}

Expand All @@ -904,13 +899,8 @@ int lfs_mkdir(lfs_t *lfs, const char *path) {

// 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);
int err = lfs_dir_find(lfs, &cwd, &entry, &path);
if (err != LFS_ERR_NOENT || strchr(path, '/') != NULL) {
return err ? err : LFS_ERR_EXIST;
}
Expand Down Expand Up @@ -954,13 +944,8 @@ 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);
int err = lfs_dir_find(lfs, dir, &entry, &path);
if (err) {
return err;
} else if (entry.d.type != LFS_TYPE_DIR) {
Expand Down Expand Up @@ -1302,13 +1287,8 @@ int lfs_file_open(lfs_t *lfs, lfs_file_t *file,

// 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);
int err = lfs_dir_find(lfs, &cwd, &entry, &path);
if (err && (err != LFS_ERR_NOENT || strchr(path, '/') != NULL)) {
return err;
}
Expand Down Expand Up @@ -1814,13 +1794,8 @@ lfs_soff_t lfs_file_size(lfs_t *lfs, lfs_file_t *file) {
/// 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);
int err = lfs_dir_find(lfs, &cwd, &entry, &path);
if (err) {
return err;
}
Expand Down Expand Up @@ -1855,13 +1830,8 @@ int lfs_remove(lfs_t *lfs, const char *path) {
}

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);
int err = lfs_dir_find(lfs, &cwd, &entry, &path);
if (err) {
return err;
}
Expand Down Expand Up @@ -1916,24 +1886,14 @@ int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath) {

// 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);
int 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)) {
Expand Down
16 changes: 16 additions & 0 deletions features/filesystem/littlefs/littlefs/tests/test_paths.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -90,6 +90,22 @@ tests/test.py << TEST
lfs_unmount(&lfs) => 0;
TEST

echo "--- Trailing dot path tests ---"
tests/test.py << TEST
lfs_mount(&lfs, &cfg) => 0;
lfs_stat(&lfs, "tea/hottea/", &info) => 0;
strcmp(info.name, "hottea") => 0;
lfs_stat(&lfs, "tea/hottea/.", &info) => 0;
strcmp(info.name, "hottea") => 0;
lfs_stat(&lfs, "tea/hottea/./.", &info) => 0;
strcmp(info.name, "hottea") => 0;
lfs_stat(&lfs, "tea/hottea/..", &info) => 0;
strcmp(info.name, "tea") => 0;
lfs_stat(&lfs, "tea/hottea/../.", &info) => 0;
strcmp(info.name, "tea") => 0;
lfs_unmount(&lfs) => 0;
TEST

echo "--- Root dot dot path tests ---"
tests/test.py << TEST
lfs_mount(&lfs, &cfg) => 0;
Expand Down