From b864dc9ef4aa00191dfa81accbe93f9ed0382261 Mon Sep 17 00:00:00 2001
From: Michal Sekletar <msekleta@redhat.com>
Date: Tue, 9 Mar 2021 17:22:32 +0100
Subject: [PATCH] install: refactor find_symlinks() and don't search for
symlinks recursively
After all we are only interested in symlinks either in top-level config
directory or in .wants and .requires sub-directories.
As a bonus this should speed up ListUnitFiles() roughly 3-4x on systems
with a lot of units that use drop-ins (e.g. SSH jump hosts with a lot of
user session scopes).
(cherry picked from commit 43b4e3058c106e663bbd5413e7bd106e55d6fd79)
Resolves: #1828758
---
src/shared/install.c | 207 ++++++++++++++++++++-----------------------
1 file changed, 96 insertions(+), 111 deletions(-)
diff --git a/src/shared/install.c b/src/shared/install.c
index f2f968e329..761bf8074e 100644
--- a/src/shared/install.c
+++ b/src/shared/install.c
@@ -503,137 +503,88 @@ static int remove_marked_symlinks(
return r;
}
-static int find_symlinks_fd(
+static int find_symlinks_in_directory(
+ DIR *dir,
+ const char *dir_path,
const char *root_dir,
const char *name,
- int fd,
- const char *path,
const char *config_path,
bool *same_name_link) {
+ struct dirent *de;
int r = 0;
- _cleanup_closedir_ DIR *d = NULL;
- assert(name);
- assert(fd >= 0);
- assert(path);
- assert(config_path);
- assert(same_name_link);
-
- d = fdopendir(fd);
- if (!d) {
- safe_close(fd);
- return -errno;
- }
-
- for (;;) {
- struct dirent *de;
-
- errno = 0;
- de = readdir(d);
- if (!de && errno != 0)
- return -errno;
+ FOREACH_DIRENT(de, dir, return -errno) {
+ _cleanup_free_ char *p = NULL, *dest = NULL;
+ bool found_path = false, found_dest, b = false;
+ int q;
- if (!de)
- return r;
+ dirent_ensure_type(dir, de);
- if (hidden_file(de->d_name))
+ if (de->d_type != DT_LNK)
continue;
- dirent_ensure_type(d, de);
-
- if (de->d_type == DT_DIR) {
- int nfd, q;
- _cleanup_free_ char *p = NULL;
-
- nfd = openat(fd, de->d_name, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW);
- if (nfd < 0) {
- if (errno == ENOENT)
- continue;
-
- if (r == 0)
- r = -errno;
- continue;
- }
-
- p = path_make_absolute(de->d_name, path);
- if (!p) {
- safe_close(nfd);
- return -ENOMEM;
- }
+ /* Acquire symlink name */
+ p = path_make_absolute(de->d_name, dir_path);
+ if (!p)
+ return -ENOMEM;
- /* This will close nfd, regardless whether it succeeds or not */
- q = find_symlinks_fd(root_dir, name, nfd, p, config_path, same_name_link);
- if (q > 0)
- return 1;
+ /* Acquire symlink destination */
+ q = readlinkat_malloc(dirfd(dir), de->d_name, &dest);
+ if (q == -ENOENT)
+ continue;
+ if (q < 0) {
if (r == 0)
r = q;
+ continue;
+ }
- } else if (de->d_type == DT_LNK) {
- _cleanup_free_ char *p = NULL, *dest = NULL;
- bool found_path, found_dest, b = false;
- int q;
+ /* Make absolute */
+ if (!path_is_absolute(dest)) {
+ char *x;
- /* Acquire symlink name */
- p = path_make_absolute(de->d_name, path);
- if (!p)
+ x = path_join(dir_path, dest, NULL);
+ if (!x)
return -ENOMEM;
- /* Acquire symlink destination */
- q = readlink_malloc(p, &dest);
- if (q < 0) {
- if (q == -ENOENT)
- continue;
+ free(dest);
+ dest = x;
- if (r == 0)
- r = q;
- continue;
- }
-
- /* Make absolute */
- if (!path_is_absolute(dest)) {
- char *x;
-
- x = prefix_root(root_dir, dest);
- if (!x)
- return -ENOMEM;
-
- free(dest);
- dest = x;
- }
+ }
- /* Check if the symlink itself matches what we
- * are looking for */
- if (path_is_absolute(name))
- found_path = path_equal(p, name);
- else
- found_path = streq(de->d_name, name);
+ /* Check if the symlink itself matches what we
+ * are looking for */
+ if (path_is_absolute(name))
+ found_path = path_equal(p, name);
+ else
+ found_path = streq(de->d_name, name);
- /* Check if what the symlink points to
- * matches what we are looking for */
- if (path_is_absolute(name))
- found_dest = path_equal(dest, name);
- else
- found_dest = streq(basename(dest), name);
+ /* Check if what the symlink points to
+ * matches what we are looking for */
+ if (path_is_absolute(name))
+ found_dest = path_equal(dest, name);
+ else
+ found_dest = streq(basename(dest), name);
- if (found_path && found_dest) {
- _cleanup_free_ char *t = NULL;
+ if (found_path && found_dest) {
+ _cleanup_free_ char *t = NULL;
- /* Filter out same name links in the main
- * config path */
- t = path_make_absolute(name, config_path);
- if (!t)
- return -ENOMEM;
-
- b = path_equal(t, p);
- }
+ /* Filter out same name links in the main
+ * config path */
+ t = path_make_absolute(name, config_path);
+ if (!t)
+ return -ENOMEM;
- if (b)
- *same_name_link = true;
- else if (found_path || found_dest)
- return 1;
+ b = path_equal(p, t);
}
+
+ if (b)
+ *same_name_link = true;
+ else if (found_path || found_dest)
+ return 1;
}
+
+ return r;
}
static int find_symlinks(
@@ -642,21 +593,55 @@ static int find_symlinks(
const char *config_path,
bool *same_name_link) {
- int fd;
+ _cleanup_closedir_ DIR *config_dir = NULL;
+ struct dirent *de;
+ int r = 0;
assert(name);
assert(config_path);
assert(same_name_link);
- fd = open(config_path, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW);
- if (fd < 0) {
- if (errno == ENOENT)
+ config_dir = opendir(config_path);
+ if (!config_dir) {
+ if (IN_SET(errno, ENOENT, ENOTDIR, EACCES))
return 0;
return -errno;
}
- /* This takes possession of fd and closes it */
- return find_symlinks_fd(root_dir, name, fd, config_path, config_path, same_name_link);
+ FOREACH_DIRENT(de, config_dir, return -errno) {
+ const char *suffix;
+ _cleanup_free_ const char *path = NULL;
+ _cleanup_closedir_ DIR *d = NULL;
+
+ dirent_ensure_type(config_dir, de);
+
+ if (de->d_type != DT_DIR)
+ continue;
+
+ suffix = strrchr(de->d_name, '.');
+ if (!streq(suffix, ".wants") && !streq(suffix, ".requires"))
+ continue;
+
+ path = path_join(config_path, de->d_name, NULL);
+ if (!path)
+ return -ENOMEM;
+
+ d = opendir(path);
+ if (!d) {
+ log_error_errno(errno, "Failed to open directory '%s' while scanning for symlinks, ignoring: %m", path);
+ continue;
+ }
+
+ r = find_symlinks_in_directory(d, path, root_dir, name, config_path, same_name_link);
+ if (r > 0)
+ return 1;
+ else if (r < 0)
+ log_debug_errno(r, "Failed to lookup for symlinks in '%s': %m", path);
+ }
+
+ /* We didn't find any suitable symlinks in .wants or .requires directories, let's look for linked unit files in this directory. */
+ rewinddir(config_dir);
+ return find_symlinks_in_directory(config_dir, config_path, root_dir, name, config_path, same_name_link);
}
static int find_symlinks_in_scope(