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/* SPDX-License-Identifier: LGPL-2.1+ */
#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;
}
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