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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 14:30:35 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 14:30:35 +0000
commit378c18e5f024ac5a8aef4cb40d7c9aa9633d144c (patch)
tree44dfb6ca500d32cabd450649b322a42e70a30683 /sys-utils/switch_root.c
parentInitial commit. (diff)
downloadutil-linux-378c18e5f024ac5a8aef4cb40d7c9aa9633d144c.tar.xz
util-linux-378c18e5f024ac5a8aef4cb40d7c9aa9633d144c.zip
Adding upstream version 2.38.1.upstream/2.38.1upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'sys-utils/switch_root.c')
-rw-r--r--sys-utils/switch_root.c283
1 files changed, 283 insertions, 0 deletions
diff --git a/sys-utils/switch_root.c b/sys-utils/switch_root.c
new file mode 100644
index 0000000..174eec6
--- /dev/null
+++ b/sys-utils/switch_root.c
@@ -0,0 +1,283 @@
+/*
+ * switchroot.c - switch to new root directory and start init.
+ *
+ * Copyright 2002-2009 Red Hat, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors:
+ * Peter Jones <pjones@redhat.com>
+ * Jeremy Katz <katzj@redhat.com>
+ */
+#include <sys/mount.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/statfs.h>
+#include <sys/param.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <ctype.h>
+#include <dirent.h>
+#include <getopt.h>
+
+#include "c.h"
+#include "nls.h"
+#include "closestream.h"
+#include "statfs_magic.h"
+
+#ifndef MS_MOVE
+#define MS_MOVE 8192
+#endif
+
+#ifndef MNT_DETACH
+#define MNT_DETACH 0x00000002 /* Just detach from the tree */
+#endif
+
+/* remove all files/directories below dirName -- don't cross mountpoints */
+static int recursiveRemove(int fd)
+{
+ struct stat rb;
+ DIR *dir;
+ int rc = -1;
+ int dfd;
+
+ if (!(dir = fdopendir(fd))) {
+ warn(_("failed to open directory"));
+ goto done;
+ }
+
+ /* fdopendir() precludes us from continuing to use the input fd */
+ dfd = dirfd(dir);
+ if (fstat(dfd, &rb)) {
+ warn(_("stat failed"));
+ goto done;
+ }
+
+ while(1) {
+ struct dirent *d;
+ int isdir = 0;
+
+ errno = 0;
+ if (!(d = readdir(dir))) {
+ if (errno) {
+ warn(_("failed to read directory"));
+ goto done;
+ }
+ break; /* end of directory */
+ }
+
+ if (!strcmp(d->d_name, ".") || !strcmp(d->d_name, ".."))
+ continue;
+#ifdef _DIRENT_HAVE_D_TYPE
+ if (d->d_type == DT_DIR || d->d_type == DT_UNKNOWN)
+#endif
+ {
+ struct stat sb;
+
+ if (fstatat(dfd, d->d_name, &sb, AT_SYMLINK_NOFOLLOW)) {
+ warn(_("stat of %s failed"), d->d_name);
+ continue;
+ }
+
+ /* skip if device is not the same */
+ if (sb.st_dev != rb.st_dev)
+ continue;
+
+ /* remove subdirectories */
+ if (S_ISDIR(sb.st_mode)) {
+ int cfd;
+
+ cfd = openat(dfd, d->d_name, O_RDONLY);
+ if (cfd >= 0)
+ recursiveRemove(cfd); /* it closes cfd too */
+ isdir = 1;
+ }
+ }
+
+ if (unlinkat(dfd, d->d_name, isdir ? AT_REMOVEDIR : 0))
+ warn(_("failed to unlink %s"), d->d_name);
+ }
+
+ rc = 0; /* success */
+done:
+ if (dir)
+ closedir(dir);
+ else
+ close(fd);
+ return rc;
+}
+
+static int switchroot(const char *newroot)
+{
+ /* Don't try to unmount the old "/", there's no way to do it. */
+ const char *umounts[] = { "/dev", "/proc", "/sys", "/run", NULL };
+ int i;
+ int cfd = -1;
+ struct stat newroot_stat, oldroot_stat, sb;
+
+ if (stat("/", &oldroot_stat) != 0) {
+ warn(_("stat of %s failed"), "/");
+ return -1;
+ }
+
+ if (stat(newroot, &newroot_stat) != 0) {
+ warn(_("stat of %s failed"), newroot);
+ return -1;
+ }
+
+ for (i = 0; umounts[i] != NULL; i++) {
+ char newmount[PATH_MAX];
+
+ snprintf(newmount, sizeof(newmount), "%s%s", newroot, umounts[i]);
+
+ if ((stat(umounts[i], &sb) == 0) && sb.st_dev == oldroot_stat.st_dev) {
+ /* mount point to move seems to be a normal directory or stat failed */
+ continue;
+ }
+
+ if ((stat(newmount, &sb) != 0) || (sb.st_dev != newroot_stat.st_dev)) {
+ /* mount point seems to be mounted already or stat failed */
+ umount2(umounts[i], MNT_DETACH);
+ continue;
+ }
+
+ if (mount(umounts[i], newmount, NULL, MS_MOVE, NULL) < 0) {
+ warn(_("failed to mount moving %s to %s"),
+ umounts[i], newmount);
+ warnx(_("forcing unmount of %s"), umounts[i]);
+ umount2(umounts[i], MNT_FORCE);
+ }
+ }
+
+ if (chdir(newroot)) {
+ warn(_("failed to change directory to %s"), newroot);
+ return -1;
+ }
+
+ cfd = open("/", O_RDONLY);
+ if (cfd < 0) {
+ warn(_("cannot open %s"), "/");
+ goto fail;
+ }
+
+ if (mount(newroot, "/", NULL, MS_MOVE, NULL) < 0) {
+ warn(_("failed to mount moving %s to /"), newroot);
+ goto fail;
+ }
+
+ if (chroot(".")) {
+ warn(_("failed to change root"));
+ goto fail;
+ }
+
+ if (chdir("/")) {
+ warn(_("cannot change directory to %s"), "/");
+ goto fail;
+ }
+
+ switch (fork()) {
+ case 0: /* child */
+ {
+ struct statfs stfs;
+
+ if (fstatfs(cfd, &stfs) == 0 &&
+ (F_TYPE_EQUAL(stfs.f_type, STATFS_RAMFS_MAGIC) ||
+ F_TYPE_EQUAL(stfs.f_type, STATFS_TMPFS_MAGIC)))
+ recursiveRemove(cfd);
+ else {
+ warn(_("old root filesystem is not an initramfs"));
+ close(cfd);
+ }
+ exit(EXIT_SUCCESS);
+ }
+ case -1: /* error */
+ break;
+
+ default: /* parent */
+ close(cfd);
+ return 0;
+ }
+
+fail:
+ if (cfd >= 0)
+ close(cfd);
+ return -1;
+}
+
+static void __attribute__((__noreturn__)) usage(void)
+{
+ FILE *output = stdout;
+ fputs(USAGE_HEADER, output);
+ fprintf(output, _(" %s [options] <newrootdir> <init> <args to init>\n"),
+ program_invocation_short_name);
+
+ fputs(USAGE_SEPARATOR, output);
+ fputs(_("Switch to another filesystem as the root of the mount tree.\n"), output);
+
+ fputs(USAGE_OPTIONS, output);
+ printf(USAGE_HELP_OPTIONS(16));
+ printf(USAGE_MAN_TAIL("switch_root(8)"));
+
+ exit(EXIT_SUCCESS);
+}
+
+int main(int argc, char *argv[])
+{
+ char *newroot, *init, **initargs;
+ int c;
+ static const struct option longopts[] = {
+ {"version", no_argument, NULL, 'V'},
+ {"help", no_argument, NULL, 'h'},
+ {NULL, 0, NULL, 0}
+ };
+
+ close_stdout_atexit();
+
+ while ((c = getopt_long(argc, argv, "+Vh", longopts, NULL)) != -1)
+ switch (c) {
+ case 'V':
+ print_version(EXIT_SUCCESS);
+ case 'h':
+ usage();
+ default:
+ errtryhelp(EXIT_FAILURE);
+ }
+ if (argc < 3) {
+ warnx(_("not enough arguments"));
+ errtryhelp(EXIT_FAILURE);
+ }
+
+ newroot = argv[1];
+ init = argv[2];
+ initargs = &argv[2];
+
+ if (!*newroot || !*init) {
+ warnx(_("bad usage"));
+ errtryhelp(EXIT_FAILURE);
+ }
+
+ if (switchroot(newroot))
+ errx(EXIT_FAILURE, _("failed. Sorry."));
+
+ if (access(init, X_OK))
+ warn(_("cannot access %s"), init);
+
+ execv(init, initargs);
+ errexec(init);
+}
+