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-rw-r--r--src/libsystemd-basic/src/fs-util.c782
1 files changed, 782 insertions, 0 deletions
diff --git a/src/libsystemd-basic/src/fs-util.c b/src/libsystemd-basic/src/fs-util.c
new file mode 100644
index 0000000000..070be9c568
--- /dev/null
+++ b/src/libsystemd-basic/src/fs-util.c
@@ -0,0 +1,782 @@
+/***
+ This file is part of systemd.
+
+ Copyright 2010 Lennart Poettering
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <dirent.h>
+#include <errno.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <time.h>
+#include <unistd.h>
+
+#include "systemd-basic/alloc-util.h"
+#include "systemd-basic/dirent-util.h"
+#include "systemd-basic/fd-util.h"
+#include "systemd-basic/fileio.h"
+#include "systemd-basic/fs-util.h"
+#include "systemd-basic/log.h"
+#include "systemd-basic/macro.h"
+#include "systemd-basic/missing.h"
+#include "systemd-basic/mkdir.h"
+#include "systemd-basic/parse-util.h"
+#include "systemd-basic/path-util.h"
+#include "systemd-basic/stat-util.h"
+#include "systemd-basic/stdio-util.h"
+#include "systemd-basic/string-util.h"
+#include "systemd-basic/strv.h"
+#include "systemd-basic/time-util.h"
+#include "systemd-basic/user-util.h"
+#include "systemd-basic/util.h"
+
+int unlink_noerrno(const char *path) {
+ PROTECT_ERRNO;
+ int r;
+
+ r = unlink(path);
+ if (r < 0)
+ return -errno;
+
+ return 0;
+}
+
+int rmdir_parents(const char *path, const char *stop) {
+ size_t l;
+ int r = 0;
+
+ assert(path);
+ assert(stop);
+
+ l = strlen(path);
+
+ /* Skip trailing slashes */
+ while (l > 0 && path[l-1] == '/')
+ l--;
+
+ while (l > 0) {
+ char *t;
+
+ /* Skip last component */
+ while (l > 0 && path[l-1] != '/')
+ l--;
+
+ /* Skip trailing slashes */
+ while (l > 0 && path[l-1] == '/')
+ l--;
+
+ if (l <= 0)
+ break;
+
+ t = strndup(path, l);
+ if (!t)
+ return -ENOMEM;
+
+ if (path_startswith(stop, t)) {
+ free(t);
+ return 0;
+ }
+
+ r = rmdir(t);
+ free(t);
+
+ if (r < 0)
+ if (errno != ENOENT)
+ return -errno;
+ }
+
+ return 0;
+}
+
+
+int rename_noreplace(int olddirfd, const char *oldpath, int newdirfd, const char *newpath) {
+ struct stat buf;
+ int ret;
+
+ ret = renameat2(olddirfd, oldpath, newdirfd, newpath, RENAME_NOREPLACE);
+ if (ret >= 0)
+ return 0;
+
+ /* renameat2() exists since Linux 3.15, btrfs added support for it later.
+ * If it is not implemented, fallback to another method. */
+ if (!IN_SET(errno, EINVAL, ENOSYS))
+ return -errno;
+
+ /* The link()/unlink() fallback does not work on directories. But
+ * renameat() without RENAME_NOREPLACE gives the same semantics on
+ * directories, except when newpath is an *empty* directory. This is
+ * good enough. */
+ ret = fstatat(olddirfd, oldpath, &buf, AT_SYMLINK_NOFOLLOW);
+ if (ret >= 0 && S_ISDIR(buf.st_mode)) {
+ ret = renameat(olddirfd, oldpath, newdirfd, newpath);
+ return ret >= 0 ? 0 : -errno;
+ }
+
+ /* If it is not a directory, use the link()/unlink() fallback. */
+ ret = linkat(olddirfd, oldpath, newdirfd, newpath, 0);
+ if (ret < 0)
+ return -errno;
+
+ ret = unlinkat(olddirfd, oldpath, 0);
+ if (ret < 0) {
+ /* backup errno before the following unlinkat() alters it */
+ ret = errno;
+ (void) unlinkat(newdirfd, newpath, 0);
+ errno = ret;
+ return -errno;
+ }
+
+ return 0;
+}
+
+int readlinkat_malloc(int fd, const char *p, char **ret) {
+ size_t l = 100;
+ int r;
+
+ assert(p);
+ assert(ret);
+
+ for (;;) {
+ char *c;
+ ssize_t n;
+
+ c = new(char, l);
+ if (!c)
+ return -ENOMEM;
+
+ n = readlinkat(fd, p, c, l-1);
+ if (n < 0) {
+ r = -errno;
+ free(c);
+ return r;
+ }
+
+ if ((size_t) n < l-1) {
+ c[n] = 0;
+ *ret = c;
+ return 0;
+ }
+
+ free(c);
+ l *= 2;
+ }
+}
+
+int readlink_malloc(const char *p, char **ret) {
+ return readlinkat_malloc(AT_FDCWD, p, ret);
+}
+
+int readlink_value(const char *p, char **ret) {
+ _cleanup_free_ char *link = NULL;
+ char *value;
+ int r;
+
+ r = readlink_malloc(p, &link);
+ if (r < 0)
+ return r;
+
+ value = basename(link);
+ if (!value)
+ return -ENOENT;
+
+ value = strdup(value);
+ if (!value)
+ return -ENOMEM;
+
+ *ret = value;
+
+ return 0;
+}
+
+int readlink_and_make_absolute(const char *p, char **r) {
+ _cleanup_free_ char *target = NULL;
+ char *k;
+ int j;
+
+ assert(p);
+ assert(r);
+
+ j = readlink_malloc(p, &target);
+ if (j < 0)
+ return j;
+
+ k = file_in_same_dir(p, target);
+ if (!k)
+ return -ENOMEM;
+
+ *r = k;
+ return 0;
+}
+
+int readlink_and_canonicalize(const char *p, char **r) {
+ char *t, *s;
+ int j;
+
+ assert(p);
+ assert(r);
+
+ j = readlink_and_make_absolute(p, &t);
+ if (j < 0)
+ return j;
+
+ s = canonicalize_file_name(t);
+ if (s) {
+ free(t);
+ *r = s;
+ } else
+ *r = t;
+
+ path_kill_slashes(*r);
+
+ return 0;
+}
+
+int readlink_and_make_absolute_root(const char *root, const char *path, char **ret) {
+ _cleanup_free_ char *target = NULL, *t = NULL;
+ const char *full;
+ int r;
+
+ full = prefix_roota(root, path);
+ r = readlink_malloc(full, &target);
+ if (r < 0)
+ return r;
+
+ t = file_in_same_dir(path, target);
+ if (!t)
+ return -ENOMEM;
+
+ *ret = t;
+ t = NULL;
+
+ return 0;
+}
+
+int chmod_and_chown(const char *path, mode_t mode, uid_t uid, gid_t gid) {
+ assert(path);
+
+ /* Under the assumption that we are running privileged we
+ * first change the access mode and only then hand out
+ * ownership to avoid a window where access is too open. */
+
+ if (mode != MODE_INVALID)
+ if (chmod(path, mode) < 0)
+ return -errno;
+
+ if (uid != UID_INVALID || gid != GID_INVALID)
+ if (chown(path, uid, gid) < 0)
+ return -errno;
+
+ return 0;
+}
+
+int fchmod_umask(int fd, mode_t m) {
+ mode_t u;
+ int r;
+
+ u = umask(0777);
+ r = fchmod(fd, m & (~u)) < 0 ? -errno : 0;
+ umask(u);
+
+ return r;
+}
+
+int fd_warn_permissions(const char *path, int fd) {
+ struct stat st;
+
+ if (fstat(fd, &st) < 0)
+ return -errno;
+
+ if (st.st_mode & 0111)
+ log_warning("Configuration file %s is marked executable. Please remove executable permission bits. Proceeding anyway.", path);
+
+ if (st.st_mode & 0002)
+ log_warning("Configuration file %s is marked world-writable. Please remove world writability permission bits. Proceeding anyway.", path);
+
+ if (getpid() == 1 && (st.st_mode & 0044) != 0044)
+ 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);
+
+ return 0;
+}
+
+int touch_file(const char *path, bool parents, usec_t stamp, uid_t uid, gid_t gid, mode_t mode) {
+ _cleanup_close_ int fd;
+ int r;
+
+ assert(path);
+
+ if (parents)
+ mkdir_parents(path, 0755);
+
+ fd = open(path, O_WRONLY|O_CREAT|O_CLOEXEC|O_NOCTTY,
+ (mode == 0 || mode == MODE_INVALID) ? 0644 : mode);
+ if (fd < 0)
+ return -errno;
+
+ if (mode != MODE_INVALID) {
+ r = fchmod(fd, mode);
+ if (r < 0)
+ return -errno;
+ }
+
+ if (uid != UID_INVALID || gid != GID_INVALID) {
+ r = fchown(fd, uid, gid);
+ if (r < 0)
+ return -errno;
+ }
+
+ if (stamp != USEC_INFINITY) {
+ struct timespec ts[2];
+
+ timespec_store(&ts[0], stamp);
+ ts[1] = ts[0];
+ r = futimens(fd, ts);
+ } else
+ r = futimens(fd, NULL);
+ if (r < 0)
+ return -errno;
+
+ return 0;
+}
+
+int touch(const char *path) {
+ return touch_file(path, false, USEC_INFINITY, UID_INVALID, GID_INVALID, MODE_INVALID);
+}
+
+int symlink_idempotent(const char *from, const char *to) {
+ _cleanup_free_ char *p = NULL;
+ int r;
+
+ assert(from);
+ assert(to);
+
+ if (symlink(from, to) < 0) {
+ if (errno != EEXIST)
+ return -errno;
+
+ r = readlink_malloc(to, &p);
+ if (r < 0)
+ return r;
+
+ if (!streq(p, from))
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+int symlink_atomic(const char *from, const char *to) {
+ _cleanup_free_ char *t = NULL;
+ int r;
+
+ assert(from);
+ assert(to);
+
+ r = tempfn_random(to, NULL, &t);
+ if (r < 0)
+ return r;
+
+ if (symlink(from, t) < 0)
+ return -errno;
+
+ if (rename(t, to) < 0) {
+ unlink_noerrno(t);
+ return -errno;
+ }
+
+ return 0;
+}
+
+int mknod_atomic(const char *path, mode_t mode, dev_t dev) {
+ _cleanup_free_ char *t = NULL;
+ int r;
+
+ assert(path);
+
+ r = tempfn_random(path, NULL, &t);
+ if (r < 0)
+ return r;
+
+ if (mknod(t, mode, dev) < 0)
+ return -errno;
+
+ if (rename(t, path) < 0) {
+ unlink_noerrno(t);
+ return -errno;
+ }
+
+ return 0;
+}
+
+int mkfifo_atomic(const char *path, mode_t mode) {
+ _cleanup_free_ char *t = NULL;
+ int r;
+
+ assert(path);
+
+ r = tempfn_random(path, NULL, &t);
+ if (r < 0)
+ return r;
+
+ if (mkfifo(t, mode) < 0)
+ return -errno;
+
+ if (rename(t, path) < 0) {
+ unlink_noerrno(t);
+ return -errno;
+ }
+
+ return 0;
+}
+
+int get_files_in_directory(const char *path, char ***list) {
+ _cleanup_closedir_ DIR *d = NULL;
+ size_t bufsize = 0, n = 0;
+ _cleanup_strv_free_ char **l = NULL;
+
+ assert(path);
+
+ /* Returns all files in a directory in *list, and the number
+ * of files as return value. If list is NULL returns only the
+ * number. */
+
+ d = opendir(path);
+ if (!d)
+ return -errno;
+
+ for (;;) {
+ struct dirent *de;
+
+ errno = 0;
+ de = readdir(d);
+ if (!de && errno > 0)
+ return -errno;
+ if (!de)
+ break;
+
+ dirent_ensure_type(d, de);
+
+ if (!dirent_is_file(de))
+ continue;
+
+ if (list) {
+ /* one extra slot is needed for the terminating NULL */
+ if (!GREEDY_REALLOC(l, bufsize, n + 2))
+ return -ENOMEM;
+
+ l[n] = strdup(de->d_name);
+ if (!l[n])
+ return -ENOMEM;
+
+ l[++n] = NULL;
+ } else
+ n++;
+ }
+
+ if (list) {
+ *list = l;
+ l = NULL; /* avoid freeing */
+ }
+
+ return n;
+}
+
+static int getenv_tmp_dir(const char **ret_path) {
+ const char *n;
+ int r, ret = 0;
+
+ assert(ret_path);
+
+ /* We use the same order of environment variables python uses in tempfile.gettempdir():
+ * https://docs.python.org/3/library/tempfile.html#tempfile.gettempdir */
+ FOREACH_STRING(n, "TMPDIR", "TEMP", "TMP") {
+ const char *e;
+
+ e = secure_getenv(n);
+ if (!e)
+ continue;
+ if (!path_is_absolute(e)) {
+ r = -ENOTDIR;
+ goto next;
+ }
+ if (!path_is_safe(e)) {
+ r = -EPERM;
+ goto next;
+ }
+
+ r = is_dir(e, true);
+ if (r < 0)
+ goto next;
+ if (r == 0) {
+ r = -ENOTDIR;
+ goto next;
+ }
+
+ *ret_path = e;
+ return 1;
+
+ next:
+ /* Remember first error, to make this more debuggable */
+ if (ret >= 0)
+ ret = r;
+ }
+
+ if (ret < 0)
+ return ret;
+
+ *ret_path = NULL;
+ return ret;
+}
+
+static int tmp_dir_internal(const char *def, const char **ret) {
+ const char *e;
+ int r, k;
+
+ assert(def);
+ assert(ret);
+
+ r = getenv_tmp_dir(&e);
+ if (r > 0) {
+ *ret = e;
+ return 0;
+ }
+
+ k = is_dir(def, true);
+ if (k == 0)
+ k = -ENOTDIR;
+ if (k < 0)
+ return r < 0 ? r : k;
+
+ *ret = def;
+ return 0;
+}
+
+int var_tmp_dir(const char **ret) {
+
+ /* Returns the location for "larger" temporary files, that is backed by physical storage if available, and thus
+ * even might survive a boot: /var/tmp. If $TMPDIR (or related environment variables) are set, its value is
+ * returned preferably however. Note that both this function and tmp_dir() below are affected by $TMPDIR,
+ * making it a variable that overrides all temporary file storage locations. */
+
+ return tmp_dir_internal("/var/tmp", ret);
+}
+
+int tmp_dir(const char **ret) {
+
+ /* Similar to var_tmp_dir() above, but returns the location for "smaller" temporary files, which is usually
+ * backed by an in-memory file system: /tmp. */
+
+ return tmp_dir_internal("/tmp", ret);
+}
+
+int inotify_add_watch_fd(int fd, int what, uint32_t mask) {
+ char path[strlen("/proc/self/fd/") + DECIMAL_STR_MAX(int) + 1];
+ int r;
+
+ /* This is like inotify_add_watch(), except that the file to watch is not referenced by a path, but by an fd */
+ xsprintf(path, "/proc/self/fd/%i", what);
+
+ r = inotify_add_watch(fd, path, mask);
+ if (r < 0)
+ return -errno;
+
+ return r;
+}
+
+int chase_symlinks(const char *path, const char *_root, char **ret) {
+ _cleanup_free_ char *buffer = NULL, *done = NULL, *root = NULL;
+ _cleanup_close_ int fd = -1;
+ unsigned max_follow = 32; /* how many symlinks to follow before giving up and returning ELOOP */
+ char *todo;
+ int r;
+
+ assert(path);
+
+ /* This is a lot like canonicalize_file_name(), but takes an additional "root" parameter, that allows following
+ * symlinks relative to a root directory, instead of the root of the host.
+ *
+ * Note that "root" matters only if we encounter an absolute symlink, it's unused otherwise. Most importantly
+ * this means the path parameter passed in is not prefixed by it.
+ *
+ * Algorithmically this operates on two path buffers: "done" are the components of the path we already
+ * processed and resolved symlinks, "." and ".." of. "todo" are the components of the path we still need to
+ * process. On each iteration, we move one component from "todo" to "done", processing it's special meaning
+ * each time. The "todo" path always starts with at least one slash, the "done" path always ends in no
+ * slash. We always keep an O_PATH fd to the component we are currently processing, thus keeping lookup races
+ * at a minimum. */
+
+ r = path_make_absolute_cwd(path, &buffer);
+ if (r < 0)
+ return r;
+
+ if (_root) {
+ r = path_make_absolute_cwd(_root, &root);
+ if (r < 0)
+ return r;
+ }
+
+ fd = open("/", O_CLOEXEC|O_NOFOLLOW|O_PATH);
+ if (fd < 0)
+ return -errno;
+
+ todo = buffer;
+ for (;;) {
+ _cleanup_free_ char *first = NULL;
+ _cleanup_close_ int child = -1;
+ struct stat st;
+ size_t n, m;
+
+ /* Determine length of first component in the path */
+ n = strspn(todo, "/"); /* The slashes */
+ m = n + strcspn(todo + n, "/"); /* The entire length of the component */
+
+ /* Extract the first component. */
+ first = strndup(todo, m);
+ if (!first)
+ return -ENOMEM;
+
+ todo += m;
+
+ /* Just a single slash? Then we reached the end. */
+ if (isempty(first) || path_equal(first, "/"))
+ break;
+
+ /* Just a dot? Then let's eat this up. */
+ if (path_equal(first, "/."))
+ continue;
+
+ /* Two dots? Then chop off the last bit of what we already found out. */
+ if (path_equal(first, "/..")) {
+ _cleanup_free_ char *parent = NULL;
+ int fd_parent = -1;
+
+ if (isempty(done) || path_equal(done, "/"))
+ return -EINVAL;
+
+ parent = dirname_malloc(done);
+ if (!parent)
+ return -ENOMEM;
+
+ /* Don't allow this to leave the root dir */
+ if (root &&
+ path_startswith(done, root) &&
+ !path_startswith(parent, root))
+ return -EINVAL;
+
+ free_and_replace(done, parent);
+
+ fd_parent = openat(fd, "..", O_CLOEXEC|O_NOFOLLOW|O_PATH);
+ if (fd_parent < 0)
+ return -errno;
+
+ safe_close(fd);
+ fd = fd_parent;
+
+ continue;
+ }
+
+ /* Otherwise let's see what this is. */
+ child = openat(fd, first + n, O_CLOEXEC|O_NOFOLLOW|O_PATH);
+ if (child < 0)
+ return -errno;
+
+ if (fstat(child, &st) < 0)
+ return -errno;
+
+ if (S_ISLNK(st.st_mode)) {
+ _cleanup_free_ char *destination = NULL;
+
+ /* This is a symlink, in this case read the destination. But let's make sure we don't follow
+ * symlinks without bounds. */
+ if (--max_follow <= 0)
+ return -ELOOP;
+
+ r = readlinkat_malloc(fd, first + n, &destination);
+ if (r < 0)
+ return r;
+ if (isempty(destination))
+ return -EINVAL;
+
+ if (path_is_absolute(destination)) {
+
+ /* An absolute destination. Start the loop from the beginning, but use the root
+ * directory as base. */
+
+ safe_close(fd);
+ fd = open(root ?: "/", O_CLOEXEC|O_NOFOLLOW|O_PATH);
+ if (fd < 0)
+ return -errno;
+
+ free_and_replace(buffer, destination);
+
+ todo = buffer;
+ free(done);
+
+ /* Note that we do not revalidate the root, we take it as is. */
+ if (isempty(root))
+ done = NULL;
+ else {
+ done = strdup(root);
+ if (!done)
+ return -ENOMEM;
+ }
+
+ } else {
+ char *joined;
+
+ /* A relative destination. If so, this is what we'll prefix what's left to do with what
+ * we just read, and start the loop again, but remain in the current directory. */
+
+ joined = strjoin("/", destination, todo, NULL);
+ if (!joined)
+ return -ENOMEM;
+
+ free(buffer);
+ todo = buffer = joined;
+ }
+
+ continue;
+ }
+
+ /* If this is not a symlink, then let's just add the name we read to what we already verified. */
+ if (!done) {
+ done = first;
+ first = NULL;
+ } else {
+ if (!strextend(&done, first, NULL))
+ return -ENOMEM;
+ }
+
+ /* And iterate again, but go one directory further down. */
+ safe_close(fd);
+ fd = child;
+ child = -1;
+ }
+
+ if (!done) {
+ /* Special case, turn the empty string into "/", to indicate the root directory. */
+ done = strdup("/");
+ if (!done)
+ return -ENOMEM;
+ }
+
+ *ret = done;
+ done = NULL;
+
+ return 0;
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-01 12:28:42 +0000