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switch-root: move switch_root() call into its own .c file

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This commit is contained in:
Lennart Poettering 2012-05-21 19:33:39 +02:00
parent 97a66e9470
commit 416693175b
4 changed files with 164 additions and 90 deletions
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4
Makefile.am
View File

@ -789,7 +789,9 @@ libsystemd_core_la_SOURCES = \
src/core/special.h \
src/core/bus-errors.h \
src/core/build.h \
src/core/sysfs-show.h
src/core/sysfs-show.h \
src/core/switch-root.h \
src/core/switch-root.c
nodist_libsystemd_core_la_SOURCES = \
src/core/load-fragment-gperf.c \

98
src/core/main.c
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@ -49,6 +49,7 @@
#include "virt.h"
#include "watchdog.h"
#include "path-util.h"
#include "switch-root.h"
#include "mount-setup.h"
#include "loopback-setup.h"
@ -1173,90 +1174,6 @@ static void test_cgroups(void) {
sleep(10);
}
static int do_switch_root(const char *switch_root) {
int r=0;
/* 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 switch_root_stat, sb;
bool remove_old_root;
if (path_equal(switch_root, "/"))
return 0;
if (stat(switch_root, &switch_root_stat) != 0) {
r = -errno;
log_error("failed to stat directory %s", switch_root);
goto fail;
}
remove_old_root = in_initrd();
for (i = 0; umounts[i] != NULL; i++) {
char newmount[PATH_MAX];
snprintf(newmount, sizeof(newmount), "%s%s", switch_root, umounts[i]);
if ((stat(newmount, &sb) != 0) || (sb.st_dev != switch_root_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) {
log_error("failed to mount moving %s to %s",
umounts[i], newmount);
log_error("forcing unmount of %s", umounts[i]);
umount2(umounts[i], MNT_FORCE);
}
}
if (chdir(switch_root)) {
r = -errno;
log_error("failed to change directory to %s", switch_root);
goto fail;
}
if (remove_old_root)
cfd = open("/", O_RDONLY);
if (mount(switch_root, "/", NULL, MS_MOVE, NULL) < 0) {
r = -errno;
log_error("failed to mount moving %s to /", switch_root);
goto fail;
}
if (chroot(".")) {
r = -errno;
log_error("failed to change root");
goto fail;
}
if (cfd >= 0) {
struct stat rb;
if (fstat(cfd, &rb)) {
log_error("failed to stat old root directory");
goto fail;
}
rm_rf_children(cfd, false, false, &rb);
close(cfd);
cfd=-1;
}
return 0;
fail:
if (cfd >= 0)
close(cfd);
log_error("Failed to switch root, ignoring: %s", strerror(-r));
return r;
}
int main(int argc, char *argv[]) {
Manager *m = NULL;
int r, retval = EXIT_FAILURE;
@ -1271,7 +1188,7 @@ int main(int argc, char *argv[]) {
int j;
bool loaded_policy = false;
bool arm_reboot_watchdog = false;
char *switch_root = NULL, *switch_root_init = NULL;
char *switch_root_dir = NULL, *switch_root_init = NULL;
#ifdef HAVE_SYSV_COMPAT
if (getpid() != 1 && strstr(program_invocation_short_name, "init")) {
@ -1673,7 +1590,7 @@ int main(int argc, char *argv[]) {
case MANAGER_SWITCH_ROOT:
/* Steal the switch root parameters */
switch_root = m->switch_root;
switch_root_dir = m->switch_root;
switch_root_init = m->switch_root_init;
m->switch_root = m->switch_root_init = NULL;
@ -1728,8 +1645,11 @@ finish:
* rebooted while we do that */
watchdog_close(true);
if (switch_root)
do_switch_root(switch_root);
if (switch_root_dir) {
r = switch_root(switch_root_dir);
if (r < 0)
log_error("Failed to switch root, ignoring: %s", strerror(-r));
}
args_size = MAX(6, argc+1);
args = newa(const char*, args_size);
@ -1750,7 +1670,7 @@ finish:
i = 0;
args[i++] = SYSTEMD_BINARY_PATH;
if (switch_root)
if (switch_root_dir)
args[i++] = "--switchedroot";
args[i++] = arg_running_as == MANAGER_SYSTEM ? "--system" : "--user";
args[i++] = "--deserialize";

125
src/core/switch-root.c Normal file
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@ -0,0 +1,125 @@
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2012 Harald Hoyer, 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 <sys/stat.h>
#include <stdbool.h>
#include <errno.h>
#include <string.h>
#include <sys/mount.h>
#include <unistd.h>
#include <fcntl.h>
#include "util.h"
#include "path-util.h"
#include "switch-root.h"
int switch_root(const char *new_root) {
/* Don't try to unmount/move the old "/", there's no way to do it. */
static const char move_mounts[] =
"/dev\0"
"/proc\0"
"/sys\0"
"/run\0";
int r, old_root_fd = -1;
struct stat new_root_stat;
bool old_root_remove;
const char *i;
if (path_equal(new_root, "/"))
return 0;
old_root_remove = in_initrd();
if (stat(new_root, &new_root_stat) < 0) {
r = -errno;
log_error("Failed to stat directory %s: %m", new_root);
goto fail;
}
NULSTR_FOREACH(i, move_mounts) {
char new_mount[PATH_MAX];
struct stat sb;
snprintf(new_mount, sizeof(new_mount), "%s%s", new_root, i);
char_array_0(new_mount);
if ((stat(new_mount, &sb) < 0) ||
sb.st_dev != new_root_stat.st_dev) {
/* Mount point seems to be mounted already or
* stat failed. Unmount the old mount
* point. */
if (umount2(i, MNT_DETACH) < 0)
log_warning("Failed to unmount %s: %m", i);
continue;
}
if (mount(i, new_mount, NULL, MS_MOVE, NULL) < 0) {
log_error("Failed to move mount %s to %s, forcing unmount: %m", i, new_mount);
if (umount2(i, MNT_FORCE) < 0)
log_warning("Failed to unmount %s: %m", i);
}
}
if (chdir(new_root) < 0) {
r = -errno;
log_error("Failed to change directory to %s: %m", new_root);
goto fail;
}
if (old_root_remove) {
old_root_fd = open("/", O_RDONLY|O_NONBLOCK|O_CLOEXEC|O_NOCTTY|O_DIRECTORY);
if (old_root_fd < 0)
log_warning("Failed to open root directory: %m");
}
if (mount(new_root, "/", NULL, MS_MOVE, NULL) < 0) {
r = -errno;
log_error("Failed to mount moving %s to /: %m", new_root);
goto fail;
}
if (chroot(".") < 0) {
r = -errno;
log_error("Failed to change root: %m");
goto fail;
}
if (old_root_fd >= 0) {
struct stat rb;
if (fstat(old_root_fd, &rb) < 0)
log_warning("Failed to stat old root directory, leaving: %m");
else
rm_rf_children(old_root_fd, false, false, &rb);
}
r = 0;
fail:
if (old_root_fd >= 0)
close_nointr_nofail(old_root_fd);
return r;
}

27
src/core/switch-root.h Normal file
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@ -0,0 +1,27 @@
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
#ifndef fooswitchroothfoo
#define fooswitchroothfoo
/***
This file is part of systemd.
Copyright 2012 Harald Hoyer, 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/>.
***/
int switch_root(const char *switch_root);
#endif