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path-util: make path_extract_filename/directory() handle "." gracefully

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This makes the functions handle "xx/" and "xx/." as equivalent.
Moreover, now path_extract_directory() returns normalized path, that is
no redundant "/" or "/./" are contained.
This commit is contained in:
Yu Watanabe
2021-05-28 13:44:38 +09:00
parent 484cd43cae
commit 0195046449
4 changed files with 70 additions and 63 deletions
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src/basic/path-util.c
+38 -39
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@@ -1043,82 +1043,81 @@ const char *last_path_component(const char *path) {
return path + k;
}
int path_extract_filename(const char *p, char **ret) {
int path_extract_filename(const char *path, char **ret) {
_cleanup_free_ char *a = NULL;
const char *c;
size_t n;
const char *c, *next = NULL;
int r;
/* Extracts the filename part (i.e. right-most component) from a path, i.e. string that passes
* filename_is_valid(). A wrapper around last_path_component(), but eats up trailing
* slashes. Returns:
*
* -EINVAL → if the passed in path is not a valid path
* -EADDRNOTAVAIL → if only a directory was specified, but no filename, i.e. the root dir itself is specified
* -EINVAL → if the path is not valid
* -EADDRNOTAVAIL → if only a directory was specified, but no filename, i.e. the root dir
* itself or "." is specified
* -ENOMEM → no memory
*
* Returns >= 0 on success. If the input path has a trailing slash, returns O_DIRECTORY, to indicate
* the referenced file must be a directory.
* Returns >= 0 on success. If the input path has a trailing slash, returns O_DIRECTORY, to
* indicate the referenced file must be a directory.
*
* This function guarantees to return a fully valid filename, i.e. one that passes
* filename_is_valid() – this means "." and ".." are not accepted. */
if (!path_is_valid(p))
if (!path_is_valid(path))
return -EINVAL;
/* Special case the root dir, because in that case we simply have no filename, but
* last_path_component() won't complain */
if (path_equal(p, "/"))
r = path_find_last_component(path, false, &next, &c);
if (r < 0)
return r;
if (r == 0) /* root directory */
return -EADDRNOTAVAIL;
c = last_path_component(p);
n = strcspn(c, "/");
a = strndup(c, n);
a = strndup(c, r);
if (!a)
return -ENOMEM;
if (!filename_is_valid(a))
return -EINVAL;
*ret = TAKE_PTR(a);
return c[n] == '/' ? O_DIRECTORY : 0;
return strlen(c) > (size_t)r ? O_DIRECTORY : 0;
}
int path_extract_directory(const char *p, char **ret) {
int path_extract_directory(const char *path, char **ret) {
_cleanup_free_ char *a = NULL;
const char *c;
const char *c, *next = NULL;
int r;
/* The inverse of path_extract_filename(), i.e. returns the directory path prefix. Returns:
*
* -EINVAL → if the passed in path is not a valid path
* -EINVAL → if the path is not valid
* -EDESTADDRREQ → if no directory was specified in the passed in path, i.e. only a filename was passed
* -EADDRNOTAVAIL → if the passed in parameter had no filename but did have a directory, i.e. the root dir itself was specified
* -EADDRNOTAVAIL → if the passed in parameter had no filename but did have a directory, i.e.
* the root dir itself or "." was specified
* -ENOMEM → no memory (surprise!)
*
* This function guarantees to return a fully valid path, i.e. one that passes path_is_valid().
*/
if (!path_is_valid(p))
return -EINVAL;
r = path_find_last_component(path, false, &next, &c);
if (r < 0)
return r;
if (r == 0) /* empty or root */
return isempty(path) ? -EINVAL : -EADDRNOTAVAIL;
if (next == path) {
if (*path != '/') /* filename only */
return -EDESTADDRREQ;
/* Special case the root dir, because otherwise for an input of "///" last_path_component() returns
* the pointer to the last slash only, which might be seen as a valid path below. */
if (path_equal(p, "/"))
return -EADDRNOTAVAIL;
a = strdup("/");
if (!a)
return -ENOMEM;
*ret = TAKE_PTR(a);
return 0;
}
c = last_path_component(p);
/* Delete trailing slashes, but keep one */
while (c > p+1 && c[-1] == '/')
c--;
if (p == c) /* No path whatsoever? Then return a recognizable error */
return -EDESTADDRREQ;
a = strndup(p, c - p);
a = strndup(path, next - path);
if (!a)
return -ENOMEM;
path_simplify(a, true);
if (!path_is_valid(a))
return -EINVAL;