+static int parse_fdname(const char *fdname, char **session_id, dev_t *dev) {
+ _cleanup_strv_free_ char **parts = NULL;
+ _cleanup_free_ char *id = NULL;
+ unsigned int major, minor;
+ int r;
+
+ parts = strv_split(fdname, "-");
+ if (!parts)
+ return -ENOMEM;
+ if (strv_length(parts) != 5)
+ return -EINVAL;
+
+ if (!streq(parts[0], "session"))
+ return -EINVAL;
+
+ id = strdup(parts[1]);
+ if (!id)
+ return -ENOMEM;
+
+ if (!streq(parts[2], "device"))
+ return -EINVAL;
+
+ r = safe_atou(parts[3], &major);
+ if (r < 0)
+ return r;
+ r = safe_atou(parts[4], &minor);
+ if (r < 0)
+ return r;
+
+ *dev = makedev(major, minor);
+ *session_id = TAKE_PTR(id);
+
+ return 0;
+}
+
+static int manager_attach_fds(Manager *m) {
+ _cleanup_strv_free_ char **fdnames = NULL;
+ int n, i, fd;
+
+ /* Upon restart, PID1 will send us back all fds of session devices
+ * that we previously opened. Each file descriptor is associated
+ * with a given session. The session ids are passed through FDNAMES. */
+
+ n = sd_listen_fds_with_names(true, &fdnames);
+ if (n <= 0)
+ return n;
+
+ for (i = 0; i < n; i++) {
+ _cleanup_free_ char *id = NULL;
+ dev_t dev;
+ struct stat st;
+ SessionDevice *sd;
+ Session *s;
+ int r;
+
+ fd = SD_LISTEN_FDS_START + i;
+
+ r = parse_fdname(fdnames[i], &id, &dev);
+ if (r < 0) {
+ log_debug_errno(r, "Failed to parse fd name %s: %m", fdnames[i]);
+ close_nointr(fd);
+ continue;
+ }
+
+ s = hashmap_get(m->sessions, id);
+ if (!s) {
+ /* If the session doesn't exist anymore, the associated session
+ * device attached to this fd doesn't either. Let's simply close
+ * this fd. */
+ log_debug("Failed to attach fd for unknown session: %s", id);
+ close_nointr(fd);
+ continue;
+ }
+
+ if (fstat(fd, &st) < 0) {
+ /* The device is allowed to go away at a random point, in which
+ * case fstat failing is expected. */
+ log_debug_errno(errno, "Failed to stat device fd for session %s: %m", id);
+ close_nointr(fd);
+ continue;
+ }
+
+ if (!S_ISCHR(st.st_mode) || st.st_rdev != dev) {
+ log_debug("Device fd doesn't point to the expected character device node");
+ close_nointr(fd);
+ continue;
+ }
+
+ sd = hashmap_get(s->devices, &dev);
+ if (!sd) {
+ /* Weird, we got an fd for a session device which wasn't
+ * recorded in the session state file... */
+ log_warning("Got fd for missing session device [%u:%u] in session %s",
+ major(dev), minor(dev), s->id);
+ close_nointr(fd);
+ continue;
+ }
+
+ log_debug("Attaching fd to session device [%u:%u] for session %s",
+ major(dev), minor(dev), s->id);
+
+ session_device_attach_fd(sd, fd, s->was_active);
+ }
+
+ return 0;
+}
+