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util-lib: introduce new empty_or_root() helper (#8746) 

We check the same condition at various places. Let's add a trivial,
common helper for this, and use it everywhere.

It's not going to make things much faster or much shorter, but I think a
lot more readable
This commit is contained in:
Lennart Poettering 2018-04-18 14:20:49 +02:00 committed by Zbigniew Jędrzejewski-Szmek
parent 12777909c9
commit 57ea45e11a
11 changed files with 50 additions and 18 deletions
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10
coccinelle/empty-or-root.cocci Normal file
View File

@ -0,0 +1,10 @@
@@
expression s;
@@
- (isempty(s) || path_equal(s, "/"))
+ empty_or_root(s)
@@
expression s;
@@
- (!isempty(s) && !path_equal(s, "/"))
+ !empty_or_root(s)

4
src/basic/cgroup-util.c
View File

@ -421,7 +421,7 @@ int cg_migrate(
* exist in the root cgroup, we only check for
* them there. */
if (cfrom &&
(isempty(pfrom) || path_equal(pfrom, "/")) &&
empty_or_root(pfrom) &&
is_kernel_thread(pid) > 0)
continue;
@ -1185,7 +1185,7 @@ int cg_is_empty_recursive(const char *controller, const char *path) {
assert(path);
/* The root cgroup is always populated */
if (controller && (isempty(path) || path_equal(path, "/")))
if (controller && empty_or_root(path))
return false;
r = cg_unified_controller(controller);

12
src/basic/fs-util.c
View File

@ -564,10 +564,6 @@ int inotify_add_watch_fd(int fd, int what, uint32_t mask) {
return r;
}
static bool noop_root(const char *root) {
return isempty(root) || path_equal(root, "/");
}
static bool safe_transition(const struct stat *a, const struct stat *b) {
/* Returns true if the transition from a to b is safe, i.e. that we never transition from unprivileged to
* privileged files or directories. Why bother? So that unprivileged code can't symlink to privileged files
@ -618,7 +614,7 @@ int chase_symlinks(const char *path, const char *original_root, unsigned flags,
* specified path. */
/* A root directory of "/" or "" is identical to none */
if (noop_root(original_root))
if (empty_or_root(original_root))
original_root = NULL;
if (!original_root && !ret && (flags & (CHASE_NONEXISTENT|CHASE_NO_AUTOFS|CHASE_SAFE|CHASE_OPEN)) == CHASE_OPEN) {
@ -703,7 +699,7 @@ int chase_symlinks(const char *path, const char *original_root, unsigned flags,
/* If we already are at the top, then going up will not change anything. This is in-line with
* how the kernel handles this. */
if (isempty(done) || path_equal(done, "/"))
if (empty_or_root(done))
continue;
parent = dirname_malloc(done);
@ -889,7 +885,7 @@ int chase_symlinks_and_open(
if (chase_flags & CHASE_NONEXISTENT)
return -EINVAL;
if (noop_root(root) && !ret_path && (chase_flags & (CHASE_NO_AUTOFS|CHASE_SAFE)) == 0) {
if (empty_or_root(root) && !ret_path && (chase_flags & (CHASE_NO_AUTOFS|CHASE_SAFE)) == 0) {
/* Shortcut this call if none of the special features of this call are requested */
r = open(path, open_flags);
if (r < 0)
@ -929,7 +925,7 @@ int chase_symlinks_and_opendir(
if (chase_flags & CHASE_NONEXISTENT)
return -EINVAL;
if (noop_root(root) && !ret_path && (chase_flags & (CHASE_NO_AUTOFS|CHASE_SAFE)) == 0) {
if (empty_or_root(root) && !ret_path && (chase_flags & (CHASE_NO_AUTOFS|CHASE_SAFE)) == 0) {
/* Shortcut this call if none of the special features of this call are requested */
d = opendir(path);
if (!d)

13
src/basic/path-util.c
View File

@ -640,7 +640,7 @@ char *prefix_root(const char *root, const char *path) {
while (path[0] == '/' && path[1] == '/')
path++;
if (isempty(root) || path_equal(root, "/"))
if (empty_or_root(root))
return strdup(path);
l = strlen(root) + 1 + strlen(path) + 1;
@ -965,3 +965,14 @@ bool dot_or_dot_dot(const char *path) {
return path[2] == 0;
}
bool empty_or_root(const char *root) {
/* For operations relative to some root directory, returns true if the specified root directory is redundant,
* i.e. either / or NULL or the empty string or any equivalent. */
if (!root)
return true;
return root[strspn(root, "/")] == 0;
}

4
src/basic/path-util.h
View File

@ -111,7 +111,7 @@ char *prefix_root(const char *root, const char *path);
size_t _l; \
while (_path[0] == '/' && _path[1] == '/') \
_path ++; \
if (isempty(_root) || path_equal(_root, "/")) \
if (empty_or_root(_root)) \
_ret = _path; \
else { \
_l = strlen(_root) + 1 + strlen(_path) + 1; \
@ -155,3 +155,5 @@ static inline const char *skip_dev_prefix(const char *p) {
return e ?: p;
}
bool empty_or_root(const char *root);

2
src/basic/unit-name.c
View File

@ -385,7 +385,7 @@ int unit_name_path_escape(const char *f, char **ret) {
path_kill_slashes(p);
if (STR_IN_SET(p, "/", ""))
if (empty_or_root(p))
s = strdup("-");
else {
if (!path_is_normalized(p))

3
src/basic/user-util.c
View File

@ -221,8 +221,7 @@ int get_user_creds_clean(
(isempty(*shell) || is_nologin_shell(*shell)))
*shell = NULL;
if (home &&
(isempty(*home) || path_equal(*home, "/")))
if (home && empty_or_root(*home))
*home = NULL;
return 0;

2
src/cgtop/cgtop.c
View File

@ -134,7 +134,7 @@ static bool is_root_cgroup(const char *path) {
if (detect_container() > 0)
return false;
return isempty(path) || path_equal(path, "/");
return empty_or_root(path);
}
static int process(

2
src/core/cgroup.c
View File

@ -40,7 +40,7 @@ bool manager_owns_root_cgroup(Manager *m) {
if (detect_container() > 0)
return false;
return isempty(m->cgroup_root) || path_equal(m->cgroup_root, "/");
return empty_or_root(m->cgroup_root);
}
bool unit_has_root_cgroup(Unit *u) {

2
src/shared/path-lookup.c
View File

@ -484,7 +484,7 @@ int lookup_paths_init(
assert(scope >= 0);
assert(scope < _UNIT_FILE_SCOPE_MAX);
if (!isempty(root_dir) && !path_equal(root_dir, "/")) {
if (!empty_or_root(root_dir)) {
if (scope == UNIT_FILE_USER)
return -EINVAL;

14
src/test/test-path-util.c
View File

@ -474,6 +474,19 @@ static void test_skip_dev_prefix(void) {
assert_se(streq(skip_dev_prefix("foo"), "foo"));
}
static void test_empty_or_root(void) {
assert_se(empty_or_root(NULL));
assert_se(empty_or_root(""));
assert_se(empty_or_root("/"));
assert_se(empty_or_root("//"));
assert_se(empty_or_root("///"));
assert_se(empty_or_root("/////////////////"));
assert_se(!empty_or_root("xxx"));
assert_se(!empty_or_root("/xxx"));
assert_se(!empty_or_root("/xxx/"));
assert_se(!empty_or_root("//yy//"));
}
int main(int argc, char **argv) {
log_set_max_level(LOG_DEBUG);
log_parse_environment();
@ -494,6 +507,7 @@ int main(int argc, char **argv) {
test_filename_is_valid();
test_hidden_or_backup_file();
test_skip_dev_prefix();
test_empty_or_root();
test_systemd_installation_has_version(argv[1]); /* NULL is OK */