diff options
Diffstat (limited to 'src/volatile-root/volatile-root.c')
| -rw-r--r-- | src/volatile-root/volatile-root.c | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/src/volatile-root/volatile-root.c b/src/volatile-root/volatile-root.c new file mode 100644 index 0000000000..3c0b6fa1de --- /dev/null +++ b/src/volatile-root/volatile-root.c @@ -0,0 +1,157 @@ +/*** + This file is part of systemd. + + Copyright 2016 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/mount.h> + +#include "alloc-util.h" +#include "fs-util.h" +#include "mkdir.h" +#include "mount-util.h" +#include "stat-util.h" +#include "volatile-util.h" +#include "string-util.h" +#include "path-util.h" + +static int make_volatile(const char *path) { + _cleanup_free_ char *old_usr = NULL; + int r; + + r = path_is_mount_point(path, NULL, AT_SYMLINK_FOLLOW); + if (r < 0) + return log_error_errno(r, "Couldn't determine whether %s is a mount point: %m", path); + if (r == 0) { + log_error("%s is not a mount point.", path); + return -EINVAL; + } + + r = path_is_temporary_fs(path); + if (r < 0) + return log_error_errno(r, "Couldn't determine whether %s is a temporary file system: %m", path); + if (r > 0) { + log_info("%s already is a temporary file system.", path); + return 0; + } + + r = chase_symlinks("/usr", path, CHASE_PREFIX_ROOT, &old_usr); + if (r < 0) + return log_error_errno(r, "/usr not available in old root: %m"); + + r = mkdir_p("/run/systemd/volatile-sysroot", 0700); + if (r < 0) + return log_error_errno(r, "Couldn't generate volatile sysroot directory: %m"); + + r = mount_verbose(LOG_ERR, "tmpfs", "/run/systemd/volatile-sysroot", "tmpfs", MS_STRICTATIME, "mode=755"); + if (r < 0) + goto finish_rmdir; + + if (mkdir("/run/systemd/volatile-sysroot/usr", 0755) < 0) { + r = -errno; + goto finish_umount; + } + + r = mount_verbose(LOG_ERR, old_usr, "/run/systemd/volatile-sysroot/usr", NULL, MS_BIND|MS_REC, NULL); + if (r < 0) + goto finish_umount; + + r = bind_remount_recursive("/run/systemd/volatile-sysroot/usr", true, NULL); + if (r < 0) + goto finish_umount; + + r = umount_recursive(path, 0); + if (r < 0) { + log_error_errno(r, "Failed to unmount %s: %m", path); + goto finish_umount; + } + + if (mount(NULL, "/", NULL, MS_SLAVE|MS_REC, NULL) < 0) + log_warning_errno(errno, "Failed to remount %s MS_SLAVE|MS_REC: %m", path); + + r = mount_verbose(LOG_ERR, "/run/systemd/volatile-sysroot", path, NULL, MS_MOVE, NULL); + +finish_umount: + (void) umount_recursive("/run/systemd/volatile-sysroot", 0); + +finish_rmdir: + (void) rmdir("/run/systemd/volatile-sysroot"); + + return r; +} + +int main(int argc, char *argv[]) { + VolatileMode m = _VOLATILE_MODE_INVALID; + const char *path; + int r; + + log_set_target(LOG_TARGET_AUTO); + log_parse_environment(); + log_open(); + + if (argc > 3) { + log_error("Too many arguments. Expected directory and mode."); + r = -EINVAL; + goto finish; + } + + r = query_volatile_mode(&m); + if (r < 0) { + log_error_errno(r, "Failed to determine volatile mode from kernel command line."); + goto finish; + } + if (r == 0 && argc >= 2) { + /* The kernel command line always wins. However if nothing was set there, the argument passed here wins instead. */ + m = volatile_mode_from_string(argv[1]); + if (m < 0) { + log_error("Couldn't parse volatile mode: %s", argv[1]); + r = -EINVAL; + goto finish; + } + } + + if (argc < 3) + path = "/sysroot"; + else { + path = argv[2]; + + if (isempty(path)) { + log_error("Directory name cannot be empty."); + r = -EINVAL; + goto finish; + } + if (!path_is_absolute(path)) { + log_error("Directory must be specified as absolute path."); + r = -EINVAL; + goto finish; + } + if (path_equal(path, "/")) { + log_error("Directory cannot be the root directory."); + r = -EINVAL; + goto finish; + } + } + + if (m != VOLATILE_YES) { + r = 0; + goto finish; + } + + r = make_volatile(path); + +finish: + return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS; +} |