1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
4 This file is part of systemd.
6 Copyright 2012 Harald Hoyer, Lennart Poettering
8 systemd is free software; you can redistribute it and/or modify it
9 under the terms of the GNU Lesser General Public License as published by
10 the Free Software Foundation; either version 2.1 of the License, or
11 (at your option) any later version.
13 systemd is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 Lesser General Public License for more details.
18 You should have received a copy of the GNU Lesser General Public License
19 along with systemd; If not, see <http://www.gnu.org/licenses/>.
26 #include <sys/mount.h>
31 #include "path-util.h"
32 #include "switch-root.h"
34 int switch_root(const char *new_root) {
36 /* Don't try to unmount/move the old "/", there's no way to do it. */
37 static const char move_mounts[] =
43 int r, old_root_fd = -1;
44 struct stat new_root_stat;
48 if (path_equal(new_root, "/"))
51 old_root_remove = in_initrd();
53 if (stat(new_root, &new_root_stat) < 0) {
55 log_error("Failed to stat directory %s: %m", new_root);
59 NULSTR_FOREACH(i, move_mounts) {
60 char new_mount[PATH_MAX];
63 snprintf(new_mount, sizeof(new_mount), "%s%s", new_root, i);
64 char_array_0(new_mount);
66 if ((stat(new_mount, &sb) < 0) ||
67 sb.st_dev != new_root_stat.st_dev) {
69 /* Mount point seems to be mounted already or
70 * stat failed. Unmount the old mount
72 if (umount2(i, MNT_DETACH) < 0)
73 log_warning("Failed to unmount %s: %m", i);
77 if (mount(i, new_mount, NULL, MS_MOVE, NULL) < 0) {
78 log_error("Failed to move mount %s to %s, forcing unmount: %m", i, new_mount);
80 if (umount2(i, MNT_FORCE) < 0)
81 log_warning("Failed to unmount %s: %m", i);
85 if (chdir(new_root) < 0) {
87 log_error("Failed to change directory to %s: %m", new_root);
91 if (old_root_remove) {
92 old_root_fd = open("/", O_RDONLY|O_NONBLOCK|O_CLOEXEC|O_NOCTTY|O_DIRECTORY);
94 log_warning("Failed to open root directory: %m");
97 if (mount(new_root, "/", NULL, MS_MOVE, NULL) < 0) {
99 log_error("Failed to mount moving %s to /: %m", new_root);
103 if (chroot(".") < 0) {
105 log_error("Failed to change root: %m");
109 if (old_root_fd >= 0) {
112 if (fstat(old_root_fd, &rb) < 0)
113 log_warning("Failed to stat old root directory, leaving: %m");
115 rm_rf_children(old_root_fd, false, false, &rb);
123 if (old_root_fd >= 0)
124 close_nointr_nofail(old_root_fd);