2 This file is part of systemd.
4 Copyright 2010 Lennart Poettering
6 systemd is free software; you can redistribute it and/or modify it
7 under the terms of the GNU Lesser General Public License as published by
8 the Free Software Foundation; either version 2.1 of the License, or
9 (at your option) any later version.
11 systemd is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public License
17 along with systemd; If not, see <http://www.gnu.org/licenses/>.
26 #include <linux/magic.h>
30 #include "alloc-util.h"
31 #include "dirent-util.h"
37 //#include "missing.h"
39 #include "parse-util.h"
40 #include "path-util.h"
41 #include "process-util.h"
42 #include "stat-util.h"
43 #include "stdio-util.h"
44 #include "string-util.h"
46 //#include "time-util.h"
47 #include "user-util.h"
50 int unlink_noerrno(const char *path) {
61 #if 0 /// UNNEEDED by elogind
62 int rmdir_parents(const char *path, const char *stop) {
71 /* Skip trailing slashes */
72 while (l > 0 && path[l-1] == '/')
78 /* Skip last component */
79 while (l > 0 && path[l-1] != '/')
82 /* Skip trailing slashes */
83 while (l > 0 && path[l-1] == '/')
93 if (path_startswith(stop, t)) {
110 int rename_noreplace(int olddirfd, const char *oldpath, int newdirfd, const char *newpath) {
114 ret = renameat2(olddirfd, oldpath, newdirfd, newpath, RENAME_NOREPLACE);
118 /* renameat2() exists since Linux 3.15, btrfs added support for it later.
119 * If it is not implemented, fallback to another method. */
120 if (!IN_SET(errno, EINVAL, ENOSYS))
123 /* The link()/unlink() fallback does not work on directories. But
124 * renameat() without RENAME_NOREPLACE gives the same semantics on
125 * directories, except when newpath is an *empty* directory. This is
127 ret = fstatat(olddirfd, oldpath, &buf, AT_SYMLINK_NOFOLLOW);
128 if (ret >= 0 && S_ISDIR(buf.st_mode)) {
129 ret = renameat(olddirfd, oldpath, newdirfd, newpath);
130 return ret >= 0 ? 0 : -errno;
133 /* If it is not a directory, use the link()/unlink() fallback. */
134 ret = linkat(olddirfd, oldpath, newdirfd, newpath, 0);
138 ret = unlinkat(olddirfd, oldpath, 0);
140 /* backup errno before the following unlinkat() alters it */
142 (void) unlinkat(newdirfd, newpath, 0);
151 int readlinkat_malloc(int fd, const char *p, char **ret) {
166 n = readlinkat(fd, p, c, l-1);
173 if ((size_t) n < l-1) {
184 int readlink_malloc(const char *p, char **ret) {
185 return readlinkat_malloc(AT_FDCWD, p, ret);
188 #if 0 /// UNNEEDED by elogind
189 int readlink_value(const char *p, char **ret) {
190 _cleanup_free_ char *link = NULL;
194 r = readlink_malloc(p, &link);
198 value = basename(link);
202 value = strdup(value);
212 int readlink_and_make_absolute(const char *p, char **r) {
213 _cleanup_free_ char *target = NULL;
220 j = readlink_malloc(p, &target);
224 k = file_in_same_dir(p, target);
232 #if 0 /// UNNEEDED by elogind
233 int readlink_and_canonicalize(const char *p, const char *root, char **ret) {
240 r = readlink_and_make_absolute(p, &t);
244 r = chase_symlinks(t, root, 0, &s);
246 /* If we can't follow up, then let's return the original string, slightly cleaned up. */
247 *ret = path_kill_slashes(t);
256 int readlink_and_make_absolute_root(const char *root, const char *path, char **ret) {
257 _cleanup_free_ char *target = NULL, *t = NULL;
261 full = prefix_roota(root, path);
262 r = readlink_malloc(full, &target);
266 t = file_in_same_dir(path, target);
277 int chmod_and_chown(const char *path, mode_t mode, uid_t uid, gid_t gid) {
280 /* Under the assumption that we are running privileged we
281 * first change the access mode and only then hand out
282 * ownership to avoid a window where access is too open. */
284 if (mode != MODE_INVALID)
285 if (chmod(path, mode) < 0)
288 if (uid != UID_INVALID || gid != GID_INVALID)
289 if (chown(path, uid, gid) < 0)
295 int fchmod_umask(int fd, mode_t m) {
300 r = fchmod(fd, m & (~u)) < 0 ? -errno : 0;
306 int fd_warn_permissions(const char *path, int fd) {
309 if (fstat(fd, &st) < 0)
312 if (st.st_mode & 0111)
313 log_warning("Configuration file %s is marked executable. Please remove executable permission bits. Proceeding anyway.", path);
315 if (st.st_mode & 0002)
316 log_warning("Configuration file %s is marked world-writable. Please remove world writability permission bits. Proceeding anyway.", path);
318 if (getpid_cached() == 1 && (st.st_mode & 0044) != 0044)
319 log_warning("Configuration file %s is marked world-inaccessible. This has no effect as configuration data is accessible via APIs without restrictions. Proceeding anyway.", path);
324 int touch_file(const char *path, bool parents, usec_t stamp, uid_t uid, gid_t gid, mode_t mode) {
325 _cleanup_close_ int fd;
331 mkdir_parents(path, 0755);
333 fd = open(path, O_WRONLY|O_CREAT|O_CLOEXEC|O_NOCTTY,
334 (mode == 0 || mode == MODE_INVALID) ? 0644 : mode);
338 if (mode != MODE_INVALID) {
339 r = fchmod(fd, mode);
344 if (uid != UID_INVALID || gid != GID_INVALID) {
345 r = fchown(fd, uid, gid);
350 if (stamp != USEC_INFINITY) {
351 struct timespec ts[2];
353 timespec_store(&ts[0], stamp);
355 r = futimens(fd, ts);
357 r = futimens(fd, NULL);
364 int touch(const char *path) {
365 return touch_file(path, false, USEC_INFINITY, UID_INVALID, GID_INVALID, MODE_INVALID);
368 #if 0 /// UNNEEDED by elogind
369 int symlink_idempotent(const char *from, const char *to) {
370 _cleanup_free_ char *p = NULL;
376 if (symlink(from, to) < 0) {
380 r = readlink_malloc(to, &p);
391 int symlink_atomic(const char *from, const char *to) {
392 _cleanup_free_ char *t = NULL;
398 r = tempfn_random(to, NULL, &t);
402 if (symlink(from, t) < 0)
405 if (rename(t, to) < 0) {
413 int mknod_atomic(const char *path, mode_t mode, dev_t dev) {
414 _cleanup_free_ char *t = NULL;
419 r = tempfn_random(path, NULL, &t);
423 if (mknod(t, mode, dev) < 0)
426 if (rename(t, path) < 0) {
434 int mkfifo_atomic(const char *path, mode_t mode) {
435 _cleanup_free_ char *t = NULL;
440 r = tempfn_random(path, NULL, &t);
444 if (mkfifo(t, mode) < 0)
447 if (rename(t, path) < 0) {
456 int get_files_in_directory(const char *path, char ***list) {
457 _cleanup_closedir_ DIR *d = NULL;
459 size_t bufsize = 0, n = 0;
460 _cleanup_strv_free_ char **l = NULL;
464 /* Returns all files in a directory in *list, and the number
465 * of files as return value. If list is NULL returns only the
472 FOREACH_DIRENT_ALL(de, d, return -errno) {
473 dirent_ensure_type(d, de);
475 if (!dirent_is_file(de))
479 /* one extra slot is needed for the terminating NULL */
480 if (!GREEDY_REALLOC(l, bufsize, n + 2))
483 l[n] = strdup(de->d_name);
494 l = NULL; /* avoid freeing */
500 static int getenv_tmp_dir(const char **ret_path) {
506 /* We use the same order of environment variables python uses in tempfile.gettempdir():
507 * https://docs.python.org/3/library/tempfile.html#tempfile.gettempdir */
508 FOREACH_STRING(n, "TMPDIR", "TEMP", "TMP") {
511 e = secure_getenv(n);
514 if (!path_is_absolute(e)) {
518 if (!path_is_safe(e)) {
535 /* Remember first error, to make this more debuggable */
547 static int tmp_dir_internal(const char *def, const char **ret) {
554 r = getenv_tmp_dir(&e);
560 k = is_dir(def, true);
564 return r < 0 ? r : k;
570 #if 0 /// UNNEEDED by elogind
571 int var_tmp_dir(const char **ret) {
573 /* Returns the location for "larger" temporary files, that is backed by physical storage if available, and thus
574 * even might survive a boot: /var/tmp. If $TMPDIR (or related environment variables) are set, its value is
575 * returned preferably however. Note that both this function and tmp_dir() below are affected by $TMPDIR,
576 * making it a variable that overrides all temporary file storage locations. */
578 return tmp_dir_internal("/var/tmp", ret);
582 int tmp_dir(const char **ret) {
584 /* Similar to var_tmp_dir() above, but returns the location for "smaller" temporary files, which is usually
585 * backed by an in-memory file system: /tmp. */
587 return tmp_dir_internal("/tmp", ret);
590 #if 0 /// UNNEEDED by elogind
591 int inotify_add_watch_fd(int fd, int what, uint32_t mask) {
592 char path[strlen("/proc/self/fd/") + DECIMAL_STR_MAX(int) + 1];
595 /* This is like inotify_add_watch(), except that the file to watch is not referenced by a path, but by an fd */
596 xsprintf(path, "/proc/self/fd/%i", what);
598 r = inotify_add_watch(fd, path, mask);
606 int chase_symlinks(const char *path, const char *original_root, unsigned flags, char **ret) {
607 _cleanup_free_ char *buffer = NULL, *done = NULL, *root = NULL;
608 _cleanup_close_ int fd = -1;
609 unsigned max_follow = 32; /* how many symlinks to follow before giving up and returning ELOOP */
616 /* This is a lot like canonicalize_file_name(), but takes an additional "root" parameter, that allows following
617 * symlinks relative to a root directory, instead of the root of the host.
619 * Note that "root" primarily matters if we encounter an absolute symlink. It is also used when following
620 * relative symlinks to ensure they cannot be used to "escape" the root directory. The path parameter passed is
621 * assumed to be already prefixed by it, except if the CHASE_PREFIX_ROOT flag is set, in which case it is first
622 * prefixed accordingly.
624 * Algorithmically this operates on two path buffers: "done" are the components of the path we already
625 * processed and resolved symlinks, "." and ".." of. "todo" are the components of the path we still need to
626 * process. On each iteration, we move one component from "todo" to "done", processing it's special meaning
627 * each time. The "todo" path always starts with at least one slash, the "done" path always ends in no
628 * slash. We always keep an O_PATH fd to the component we are currently processing, thus keeping lookup races
631 * Suggested usage: whenever you want to canonicalize a path, use this function. Pass the absolute path you got
632 * as-is: fully qualified and relative to your host's root. Optionally, specify the root parameter to tell this
633 * function what to do when encountering a symlink with an absolute path as directory: prefix it by the
636 * Note: there's also chase_symlinks_prefix() (see below), which as first step prefixes the passed path by the
640 r = path_make_absolute_cwd(original_root, &root);
644 if (flags & CHASE_PREFIX_ROOT)
645 path = prefix_roota(root, path);
648 r = path_make_absolute_cwd(path, &buffer);
652 fd = open("/", O_CLOEXEC|O_NOFOLLOW|O_PATH);
658 _cleanup_free_ char *first = NULL;
659 _cleanup_close_ int child = -1;
663 /* Determine length of first component in the path */
664 n = strspn(todo, "/"); /* The slashes */
665 m = n + strcspn(todo + n, "/"); /* The entire length of the component */
667 /* Extract the first component. */
668 first = strndup(todo, m);
674 /* Just a single slash? Then we reached the end. */
675 if (isempty(first) || path_equal(first, "/"))
678 /* Just a dot? Then let's eat this up. */
679 if (path_equal(first, "/."))
682 /* Two dots? Then chop off the last bit of what we already found out. */
683 if (path_equal(first, "/..")) {
684 _cleanup_free_ char *parent = NULL;
687 /* If we already are at the top, then going up will not change anything. This is in-line with
688 * how the kernel handles this. */
689 if (isempty(done) || path_equal(done, "/"))
692 parent = dirname_malloc(done);
696 /* Don't allow this to leave the root dir. */
698 path_startswith(done, root) &&
699 !path_startswith(parent, root))
702 free_and_replace(done, parent);
704 fd_parent = openat(fd, "..", O_CLOEXEC|O_NOFOLLOW|O_PATH);
714 /* Otherwise let's see what this is. */
715 child = openat(fd, first + n, O_CLOEXEC|O_NOFOLLOW|O_PATH);
718 if (errno == ENOENT &&
719 (flags & CHASE_NONEXISTENT) &&
720 (isempty(todo) || path_is_safe(todo))) {
722 /* If CHASE_NONEXISTENT is set, and the path does not exist, then that's OK, return
723 * what we got so far. But don't allow this if the remaining path contains "../ or "./"
724 * or something else weird. */
726 if (!strextend(&done, first, todo, NULL))
736 if (fstat(child, &st) < 0)
738 if ((flags & CHASE_NO_AUTOFS) &&
739 fd_check_fstype(child, AUTOFS_SUPER_MAGIC) > 0)
742 if (S_ISLNK(st.st_mode)) {
745 _cleanup_free_ char *destination = NULL;
747 /* This is a symlink, in this case read the destination. But let's make sure we don't follow
748 * symlinks without bounds. */
749 if (--max_follow <= 0)
752 r = readlinkat_malloc(fd, first + n, &destination);
755 if (isempty(destination))
758 if (path_is_absolute(destination)) {
760 /* An absolute destination. Start the loop from the beginning, but use the root
761 * directory as base. */
764 fd = open(root ?: "/", O_CLOEXEC|O_NOFOLLOW|O_PATH);
770 /* Note that we do not revalidate the root, we take it as is. */
781 /* Prefix what's left to do with what we just read, and start the loop again,
782 * but remain in the current directory. */
784 joined = strjoin("/", destination, todo);
789 todo = buffer = joined;
794 /* If this is not a symlink, then let's just add the name we read to what we already verified. */
799 if (!strextend(&done, first, NULL))
803 /* And iterate again, but go one directory further down. */
810 /* Special case, turn the empty string into "/", to indicate the root directory. */