From: Lennart Poettering Date: Mon, 21 May 2012 17:33:39 +0000 (+0200) Subject: switch-root: move switch_root() call into its own .c file X-Git-Tag: v183~61 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=416693175bc317ef3fa4963af51a5ee077320d09;p=systemd switch-root: move switch_root() call into its own .c file --- diff --git a/Makefile.am b/Makefile.am index 7d6d744e..e9ac82c0 100644 --- a/Makefile.am +++ b/Makefile.am @@ -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 \ diff --git a/src/core/main.c b/src/core/main.c index 4d09cb71..22052220 100644 --- a/src/core/main.c +++ b/src/core/main.c @@ -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"; diff --git a/src/core/switch-root.c b/src/core/switch-root.c new file mode 100644 index 00000000..ed0a31e6 --- /dev/null +++ b/src/core/switch-root.c @@ -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 . +***/ + +#include +#include +#include +#include +#include +#include +#include + +#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; +} diff --git a/src/core/switch-root.h b/src/core/switch-root.h new file mode 100644 index 00000000..0c4cd1e4 --- /dev/null +++ b/src/core/switch-root.h @@ -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 . +***/ + +int switch_root(const char *switch_root); + +#endif