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path-util: introduce path_find_last_component()

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This commit is contained in:
Yu Watanabe
2021-05-03 23:47:57 +09:00
parent 15bac3e8fd
commit 484cd43cae
3 changed files with 184 additions and 0 deletions
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103
src/basic/path-util.c
View File

@@ -897,6 +897,109 @@ int path_find_first_component(const char **p, bool accept_dot_dot, const char **
return len;
}
static const char *skip_slash_or_dot_backward(const char *path, const char *q) {
assert(path);
for (; q >= path; q--) {
if (*q == '/')
continue;
if (q > path && strneq(q - 1, "/.", 2))
continue;
break;
}
return q;
}
int path_find_last_component(const char *path, bool accept_dot_dot, const char **next, const char **ret) {
const char *q, *last_end, *last_begin;
size_t len;
/* Similar to path_find_first_component(), but search components from the end.
*
* Examples
* Input: path: "//.//aaa///bbbbb/cc//././"
* next: NULL
* Output: next: "/cc//././"
* ret: "cc//././"
* return value: 2 (== strlen("cc"))
*
* Input: path: "//.//aaa///bbbbb/cc//././"
* next: "/cc//././"
* Output: next: "///bbbbb/cc//././"
* ret: "bbbbb/cc//././"
* return value: 5 (== strlen("bbbbb"))
*
* Input: path: "/", ".", "", or NULL
* Output: next: equivalent to path
* ret: NULL
* return value: 0
*
* Input: path: "(too long component)"
* Output: return value: -EINVAL
*
* (when accept_dot_dot is false)
* Input: path: "//..//aaa///bbbbb/cc/..//"
* Output: return value: -EINVAL
*/
if (isempty(path)) {
if (next)
*next = path;
if (ret)
*ret = NULL;
return 0;
}
if (next && *next) {
if (*next < path || *next > path + strlen(path))
return -EINVAL;
if (*next == path) {
if (ret)
*ret = NULL;
return 0;
}
if (!IN_SET(**next, '\0', '/'))
return -EINVAL;
q = *next - 1;
} else
q = path + strlen(path) - 1;
q = skip_slash_or_dot_backward(path, q);
if ((q < path) || /* the root directory */
(q == path && *q == '.')) { /* path is "." or "./" */
if (next)
*next = path;
if (ret)
*ret = NULL;
return 0;
}
last_end = q + 1;
while (q >= path && *q != '/')
q--;
last_begin = q + 1;
len = last_end - last_begin;
if (len > NAME_MAX)
return -EINVAL;
if (!accept_dot_dot && len == 2 && strneq(last_begin, "..", 2))
return -EINVAL;
if (next) {
q = skip_slash_or_dot_backward(path, q);
if (q < path)
*next = path;
else
*next = q + 1;
}
if (ret)
*ret = last_begin;
return len;
}
const char *last_path_component(const char *path) {
/* Finds the last component of the path, preserving the optional trailing slash that signifies a directory.

1
src/basic/path-util.h
View File

@@ -153,6 +153,7 @@ int fsck_exists(const char *fstype);
char* dirname_malloc(const char *path);
int path_find_first_component(const char **p, bool accept_dot_dot, const char **ret);
int path_find_last_component(const char *path, bool accept_dot_dot, const char **next, const char **ret);
const char *last_path_component(const char *path);
int path_extract_filename(const char *p, char **ret);
int path_extract_directory(const char *p, char **ret);

80
src/test/test-path-util.c
View File

@@ -665,6 +665,85 @@ static void test_path_find_first_component(void) {
test_path_find_first_component_one(hoge, true, STRV_MAKE("a", "b", "c"), -EINVAL);
}
static void test_path_find_last_component_one(
const char *path,
bool accept_dot_dot,
char **expected,
int ret) {
log_debug("/* %s(\"%s\", accept_dot_dot=%s) */", __func__, strnull(path), yes_no(accept_dot_dot));
for (const char *next = NULL;;) {
const char *e;
int r;
r = path_find_last_component(path, accept_dot_dot, &next, &e);
if (r <= 0) {
if (r == 0) {
assert_se(next == path);
assert_se(!e);
}
assert_se(r == ret);
assert_se(strv_isempty(expected));
return;
}
assert_se(e);
assert_se(strcspn(e, "/") == (size_t) r);
assert_se(strlen_ptr(*expected) == (size_t) r);
assert_se(strneq(e, *expected++, r));
}
}
static void test_path_find_last_component(void) {
_cleanup_free_ char *hoge = NULL;
char foo[NAME_MAX * 2];
log_info("/* %s */", __func__);
test_path_find_last_component_one(NULL, false, NULL, 0);
test_path_find_last_component_one("", false, NULL, 0);
test_path_find_last_component_one("/", false, NULL, 0);
test_path_find_last_component_one(".", false, NULL, 0);
test_path_find_last_component_one("./", false, NULL, 0);
test_path_find_last_component_one("./.", false, NULL, 0);
test_path_find_last_component_one("..", false, NULL, -EINVAL);
test_path_find_last_component_one("/..", false, NULL, -EINVAL);
test_path_find_last_component_one("./..", false, NULL, -EINVAL);
test_path_find_last_component_one("////./././//.", false, NULL, 0);
test_path_find_last_component_one("a/b/c", false, STRV_MAKE("c", "b", "a"), 0);
test_path_find_last_component_one("././//.///aa./.bbb//./ccc/././/", false, STRV_MAKE("ccc", ".bbb", "aa."), 0);
test_path_find_last_component_one("././//.///aa/../.../bbb//./ccc/.", false, STRV_MAKE("ccc", "bbb", "..."), -EINVAL);
test_path_find_last_component_one("//./aaa///.//./.bbb/..///c.//d.dd///..eeee/.", false, STRV_MAKE("..eeee", "d.dd", "c."), -EINVAL);
test_path_find_last_component_one(NULL, true, NULL, 0);
test_path_find_last_component_one("", true, NULL, 0);
test_path_find_last_component_one("/", true, NULL, 0);
test_path_find_last_component_one(".", true, NULL, 0);
test_path_find_last_component_one("./", true, NULL, 0);
test_path_find_last_component_one("./.", true, NULL, 0);
test_path_find_last_component_one("..", true, STRV_MAKE(".."), 0);
test_path_find_last_component_one("/..", true, STRV_MAKE(".."), 0);
test_path_find_last_component_one("./..", true, STRV_MAKE(".."), 0);
test_path_find_last_component_one("////./././//.", true, NULL, 0);
test_path_find_last_component_one("a/b/c", true, STRV_MAKE("c", "b", "a"), 0);
test_path_find_last_component_one("././//.///aa./.bbb//./ccc/././/", true, STRV_MAKE("ccc", ".bbb", "aa."), 0);
test_path_find_last_component_one("././//.///aa/../.../bbb//./ccc/.", true, STRV_MAKE("ccc", "bbb", "...", "..", "aa"), 0);
test_path_find_last_component_one("//./aaa///.//./.bbb/..///c.//d.dd///..eeee/.", true, STRV_MAKE("..eeee", "d.dd", "c.", "..", ".bbb", "aaa"), 0);
memset(foo, 'a', sizeof(foo) -1);
char_array_0(foo);
test_path_find_last_component_one(foo, false, NULL, -EINVAL);
test_path_find_last_component_one(foo, true, NULL, -EINVAL);
hoge = strjoin(foo, "/a/b/c/");
assert_se(hoge);
test_path_find_last_component_one(hoge, false, STRV_MAKE("c", "b", "a"), -EINVAL);
test_path_find_last_component_one(hoge, true, STRV_MAKE("c", "b", "a"), -EINVAL);
}
static void test_last_path_component(void) {
assert_se(last_path_component(NULL) == NULL);
assert_se(streq(last_path_component("a/b/c"), "c"));
@@ -996,6 +1075,7 @@ int main(int argc, char **argv) {
test_prefix_root();
test_file_in_same_dir();
test_path_find_first_component();
test_path_find_last_component();
test_last_path_component();
test_path_extract_filename();
test_path_extract_directory();