+static bool device_supported(Manager *m) {
+ static int read_only = -1;
+ assert(m);
+
+ /* If /sys is read-only we don't support device units, and any
+ * attempts to start one should fail immediately. */
+
+ if (read_only < 0)
+ read_only = path_is_read_only_fs("/sys");
+
+ return read_only <= 0;
+}
+
+int device_found_node(Manager *m, const char *node, bool add, DeviceFound found, bool now) {
+ _cleanup_udev_device_unref_ struct udev_device *dev = NULL;
+ struct stat st;
+
+ assert(m);
+ assert(node);
+
+ /* This is called whenever we find a device referenced in
+ * /proc/swaps or /proc/self/mounts. Such a device might be
+ * mounted/enabled at a time where udev has not finished
+ * probing it yet, and we thus haven't learned about it
+ * yet. In this case we will set the device unit to
+ * "tentative" state. */
+
+ if (add) {
+ if (!path_startswith(node, "/dev"))
+ return 0;
+
+ if (stat(node, &st) < 0) {
+ if (errno == ENOENT)
+ return 0;
+
+ return log_error_errno(errno, "Failed to stat device node file %s: %m", node);
+ }
+
+ if (!S_ISBLK(st.st_mode) && !S_ISCHR(st.st_mode))
+ return 0;
+
+ dev = udev_device_new_from_devnum(m->udev, S_ISBLK(st.st_mode) ? 'b' : 'c', st.st_rdev);
+ if (!dev) {
+ if (errno == ENOENT)
+ return 0;
+
+ return log_oom();
+ }
+
+ /* If the device is known in the kernel and newly
+ * appeared, then we'll create a device unit for it,
+ * under the name referenced in /proc/swaps or
+ * /proc/self/mountinfo. */
+
+ (void) device_setup_unit(m, dev, node, false);
+ }
+
+ /* Update the device unit's state, should it exist */
+ return device_update_found_by_name(m, node, add, found, now);
+}
+