-
-int machine_id_setup(const char *root) {
- const char *etc_machine_id, *run_machine_id;
- _cleanup_close_ int fd = -1;
- bool writable = true;
- struct stat st;
- char id[34]; /* 32 + \n + \0 */
- int r;
-
- if (isempty(root)) {
- etc_machine_id = "/etc/machine-id";
- run_machine_id = "/run/machine-id";
- } else {
- char *x;
-
- x = strjoina(root, "/etc/machine-id");
- etc_machine_id = path_kill_slashes(x);
-
- x = strjoina(root, "/run/machine-id");
- run_machine_id = path_kill_slashes(x);
- }
-
- RUN_WITH_UMASK(0000) {
- /* We create this 0444, to indicate that this isn't really
- * something you should ever modify. Of course, since the file
- * will be owned by root it doesn't matter much, but maybe
- * people look. */
-
- mkdir_parents(etc_machine_id, 0755);
- fd = open(etc_machine_id, O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444);
- if (fd < 0) {
- int old_errno = errno;
-
- fd = open(etc_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY);
- if (fd < 0) {
- if (old_errno == EROFS && errno == ENOENT)
- log_error("System cannot boot: Missing /etc/machine-id and /etc is mounted read-only.\n"
- "Booting up is supported only when:\n"
- "1) /etc/machine-id exists and is populated.\n"
- "2) /etc/machine-id exists and is empty.\n"
- "3) /etc/machine-id is missing and /etc is writable.\n");
- else
- log_error_errno(errno, "Cannot open %s: %m", etc_machine_id);
- return -errno;
- }
-
- writable = false;
- }
- }
-
- if (fstat(fd, &st) < 0)
- return log_error_errno(errno, "fstat() failed: %m");
-
- if (S_ISREG(st.st_mode) && get_valid_machine_id(fd, id) == 0)
- return 0;
-
- /* Hmm, so, the id currently stored is not useful, then let's
- * generate one */
-
- r = generate(id, root);
- if (r < 0)
- return r;
-
- if (S_ISREG(st.st_mode) && writable)
- if (write_machine_id(fd, id) == 0)
- return 0;
-
- fd = safe_close(fd);
-
- /* Hmm, we couldn't write it? So let's write it to
- * /run/machine-id as a replacement */
-
- RUN_WITH_UMASK(0022) {
- r = write_string_file(run_machine_id, id);
- }
- if (r < 0) {
- log_error_errno(r, "Cannot write %s: %m", run_machine_id);
- unlink(run_machine_id);
- return r;
- }
-
- /* And now, let's mount it over */
- r = mount(run_machine_id, etc_machine_id, NULL, MS_BIND, NULL);
- if (r < 0) {
- log_error_errno(errno, "Failed to mount %s: %m", etc_machine_id);
- unlink_noerrno(run_machine_id);
- return -errno;
- }
-
- log_info("Installed transient %s file.", etc_machine_id);
-
- /* Mark the mount read-only */
- if (mount(NULL, etc_machine_id, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, NULL) < 0)
- log_warning_errno(errno, "Failed to make transient %s read-only: %m", etc_machine_id);
-
- return 0;
-}