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Fixed handling of root as target for create operations

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Before this patch, when calling lfs_mkdir or lfs_file_open with root
as the target, littlefs wouldn't find the path properly and happily
run into undefined behaviour.

The fix is to populate a directory entry for root in the lfs_dir_find
function. As an added plus, this allowed several special cases around
root to be completely dropped.
This commit is contained in:
Christopher Haster
2018-02-22 15:24:17 -06:00
parent 1476181bd1
commit d9c36371e7
2 changed files with 26 additions and 22 deletions
Download Patch File Download Diff File Expand all files Collapse all files

34
lfs.c
View File

@@ -780,6 +780,19 @@ static int lfs_dir_find(lfs_t *lfs, lfs_dir_t *dir,
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)) {
@@ -936,15 +949,6 @@ int lfs_dir_open(lfs_t *lfs, lfs_dir_t *dir, const char *path) {
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) {
@@ -1799,14 +1803,6 @@ 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) {
// 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) {
@@ -1825,12 +1821,16 @@ int lfs_stat(lfs_t *lfs, const char *path, struct lfs_info *info) {
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;
}

4
tests/test_paths.sh
View File

@@ -108,6 +108,10 @@ tests/test.py << TEST
lfs_stat(&lfs, "/", &info) => 0;
info.type => LFS_TYPE_DIR;
strcmp(info.name, "/") => 0;
lfs_mkdir(&lfs, "/") => LFS_ERR_EXIST;
lfs_file_open(&lfs, &file[0], "/", LFS_O_WRONLY | LFS_O_CREAT)
=> LFS_ERR_ISDIR;
lfs_unmount(&lfs) => 0;
TEST