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Added dir navigation without needing parent entries

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This should be the last step to removing the need for
parent entries.

Parent entries cause all sort of problems with atomic
directory updates, especially related to moving/deleting
directories.

I couldn't figure out a parser for '..' entries without,
O(n^2) runtime, a stack, or modifying the path itself.
Since the goal is constant memory consumption, I went
with the O(n^2) runtime solution, but this may need to
be optimized later.
This commit is contained in:
Christopher Haster
2017-04-14 18:27:06 -05:00
parent c25c893219
commit 1f13006e36
2 changed files with 42 additions and 3 deletions
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2
Makefile
View File

@@ -31,7 +31,7 @@ size: $(OBJ)
$(SIZE) -t $^
.SUFFIXES:
test: test_format test_dirs test_files test_alloc test_orphan
test: test_format test_dirs test_files test_alloc test_orphan test_paths
test_%: tests/test_%.sh
./$<

43
lfs.c
View File

@@ -627,9 +627,47 @@ static int lfs_dir_next(lfs_t *lfs, lfs_dir_t *dir, lfs_entry_t *entry) {
static int lfs_dir_find(lfs_t *lfs, lfs_dir_t *dir,
const char **path, lfs_entry_t *entry) {
const char *pathname = *path;
size_t pathlen;
while (true) {
const char *pathname = *path;
lfs_size_t pathlen = strcspn(pathname, "/");
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;
}
// find path
while (true) {
int err = lfs_dir_next(lfs, dir, entry);
if (err) {
@@ -658,6 +696,7 @@ static int lfs_dir_find(lfs_t *lfs, lfs_dir_t *dir,
return 0;
}
// continue on if we hit a directory
if (entry->d.type != LFS_TYPE_DIR) {
return LFS_ERROR_NOT_DIR;
}