libudev: enumerate - allow to filter-out not-already-initialized devices

Makefile.am

@@ -34,9 +34,9 @@ DISTCHECK_HOOKS =
 # ------------------------------------------------------------------------------
 # libudev
 # ------------------------------------------------------------------------------
-LIBUDEV_CURRENT=9
-LIBUDEV_REVISION=4
-LIBUDEV_AGE=9
+LIBUDEV_CURRENT=10
+LIBUDEV_REVISION=0
+LIBUDEV_AGE=10
 
 SUBDIRS += libudev/docs
 

libudev/docs/libudev-sections.txt

@@ -45,6 +45,7 @@ udev_device_get_syspath
 udev_device_get_sysname
 udev_device_get_sysnum
 udev_device_get_devnode
+udev_device_get_is_initialized
 udev_device_get_devlinks_list_entry
 udev_device_get_properties_list_entry
 udev_device_get_tags_list_entry
@@ -89,6 +90,7 @@ udev_enumerate_add_match_sysattr
 udev_enumerate_add_nomatch_sysattr
 udev_enumerate_add_match_property
 udev_enumerate_add_match_tag
+udev_enumerate_add_match_is_initialized
 udev_enumerate_add_match_sysname
 udev_enumerate_add_syspath
 udev_enumerate_scan_devices

libudev/exported_symbols

@@ -28,6 +28,7 @@ udev_device_get_sysname
 udev_device_get_sysnum
 udev_device_get_subsystem
 udev_device_get_devtype
+udev_device_get_is_initialized
 udev_device_get_devlinks_list_entry
 udev_device_get_properties_list_entry
 udev_device_get_tags_list_entry
@@ -48,6 +49,7 @@ udev_enumerate_add_match_sysattr
 udev_enumerate_add_nomatch_sysattr
 udev_enumerate_add_match_property
 udev_enumerate_add_match_tag
+udev_enumerate_add_match_is_initialized
 udev_enumerate_add_match_sysname
 udev_enumerate_scan_devices
 udev_enumerate_scan_subsystems

libudev/libudev-device-private.c

@@ -114,7 +114,9 @@ int udev_device_update_db(struct udev_device *udev_device)
 	util_strscpyl(filename, sizeof(filename), udev_get_dev_path(udev), "/.udev/db/", id, NULL);
 
 	/* do not store anything for otherwise empty devices */
-	if (!has_info && udev_device_get_devnode(udev_device) == NULL) {
+	if (!has_info &&
+	    major(udev_device_get_devnum(udev_device)) == 0 &&
+	    udev_device_get_ifindex(udev_device) == 0) {
 		unlink(filename);
 		return 0;
 	}

libudev/libudev-device.c

@@ -81,6 +81,7 @@ struct udev_device {
 	bool info_loaded;
 	bool db_loaded;
 	bool uevent_loaded;
+	bool is_initialized;
 };
 
 struct udev_list_entry *udev_device_add_property(struct udev_device *udev_device, const char *key, const char *value)
@@ -249,6 +250,7 @@ int udev_device_read_db(struct udev_device *udev_device)
 		info(udev_device->udev, "no db file to read %s: %m\n", filename);
 		return -1;
 	}
+	udev_device->is_initialized = true;
 
 	while (fgets(line, sizeof(line), f)) {
 		ssize_t len;
@@ -1308,6 +1310,31 @@ const char *udev_device_get_id_filename(struct udev_device *udev_device)
 	return udev_device->id_filename;
 }
 
+/**
+ * udev_device_get_is_initialized:
+ * @udev_device: udev device
+ *
+ * Check if udev has already handled the device and has set up
+ * device node permissions and context, or has renamed a network
+ * device.
+ *
+ * For now, this is only implemented for devices with a device node
+ * or network interfaces. All other devices return 1 here.
+ *
+ * Returns: 1 if the device is set up. 0 otherwise.
+ **/
+int udev_device_get_is_initialized(struct udev_device *udev_device)
+{
+	if (!udev_device->info_loaded)
+		udev_device_read_db(udev_device);
+	return udev_device->is_initialized;
+}
+
+void udev_device_set_is_initialized(struct udev_device *udev_device)
+{
+	udev_device->is_initialized = true;
+}
+
 int udev_device_add_tag(struct udev_device *udev_device, const char *tag)
 {
 	if (strchr(tag, ':') != NULL || strchr(tag, ' ') != NULL)

libudev/libudev-enumerate.c

@@ -57,6 +57,7 @@ struct udev_enumerate {
 	unsigned int devices_cur;
 	unsigned int devices_max;
 	bool devices_uptodate:1;
+	bool match_is_initialized;
 };
 
 /**
@@ -456,6 +457,32 @@ int udev_enumerate_add_match_tag(struct udev_enumerate *udev_enumerate, const ch
 	return 0;
 }
 
+/**
+ * udev_enumerate_add_match_is_initialized:
+ * @udev_enumerate: context
+ *
+ * Match only devices which udev has set up already. This makes
+ * sure, that the device node permissions and context are properly set
+ * and that network devices are fully renamed.
+ *
+ * Usually, devices which are found in the kernel but not already
+ * handled by udev, have still pending events. Services should subscribe
+ * to monitor events and wait for these devices to become ready, instead
+ * of using uninitialized devices.
+ *
+ * For now, this will not affect devices which do not have a device node
+ * and are not network interfaces.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ */
+int udev_enumerate_add_match_is_initialized(struct udev_enumerate *udev_enumerate)
+{
+	if (udev_enumerate == NULL)
+		return -EINVAL;
+	udev_enumerate->match_is_initialized = true;
+	return 0;
+}
+
 /**
  * udev_enumerate_add_match_sysname:
  * @udev_enumerate: context
@@ -601,6 +628,21 @@ static int scan_dir_and_add_devices(struct udev_enumerate *udev_enumerate,
 		if (dev == NULL)
 			continue;
 
+		if (udev_enumerate->match_is_initialized) {
+			/*
+			 * All devices with a device node or network interfaces
+			 * possibly need udev to adjust the device node permission
+			 * or context, or rename the interface before it can be
+			 * reliably used from other processes.
+			 *
+			 * For now, we can only check these types of devices, we
+			 * might not store a database, and have no way to find out
+			 * for all other types of devices.
+			 */
+			if (!udev_device_get_is_initialized(dev) &&
+			    (major(udev_device_get_devnum(dev)) > 0 || udev_device_get_ifindex(dev) > 0))
+				goto nomatch;
+		}
 		if (!match_tag(udev_enumerate, dev))
 			goto nomatch;
 		if (!match_property(udev_enumerate, dev))

libudev/libudev-private.h

@@ -87,6 +87,7 @@ const char *udev_device_get_sysname_old(struct udev_device *udev_device);
 int udev_device_set_devpath_old(struct udev_device *udev_device, const char *devpath_old);
 const char *udev_device_get_knodename(struct udev_device *udev_device);
 const char *udev_device_get_id_filename(struct udev_device *udev_device);
+void udev_device_set_is_initialized(struct udev_device *udev_device);
 int udev_device_add_tag(struct udev_device *udev_device, const char *tag);
 void udev_device_cleanup_tags_list(struct udev_device *udev_device);
 int udev_device_has_tag(struct udev_device *udev_device, const char *tag);

libudev/libudev.h

@@ -88,6 +88,7 @@ const char *udev_device_get_syspath(struct udev_device *udev_device);
 const char *udev_device_get_sysname(struct udev_device *udev_device);
 const char *udev_device_get_sysnum(struct udev_device *udev_device);
 const char *udev_device_get_devnode(struct udev_device *udev_device);
+int udev_device_get_is_initialized(struct udev_device *udev_device);
 struct udev_list_entry *udev_device_get_devlinks_list_entry(struct udev_device *udev_device);
 struct udev_list_entry *udev_device_get_properties_list_entry(struct udev_device *udev_device);
 struct udev_list_entry *udev_device_get_tags_list_entry(struct udev_device *udev_device);
@@ -141,6 +142,7 @@ int udev_enumerate_add_nomatch_sysattr(struct udev_enumerate *udev_enumerate, co
 int udev_enumerate_add_match_property(struct udev_enumerate *udev_enumerate, const char *property, const char *value);
 int udev_enumerate_add_match_sysname(struct udev_enumerate *udev_enumerate, const char *sysname);
 int udev_enumerate_add_match_tag(struct udev_enumerate *udev_enumerate, const char *tag);
+int udev_enumerate_add_match_is_initialized(struct udev_enumerate *udev_enumerate);
 int udev_enumerate_add_syspath(struct udev_enumerate *udev_enumerate, const char *syspath);
 /* run enumeration with active filters */
 int udev_enumerate_scan_devices(struct udev_enumerate *udev_enumerate);

libudev/test-libudev.c

@@ -354,6 +354,7 @@ static int test_enumerate(struct udev *udev, const char *subsystem)
 	if (udev_enumerate == NULL)
 		return -1;
 	udev_enumerate_add_match_subsystem(udev_enumerate,"block");
+	udev_enumerate_add_match_is_initialized(udev_enumerate);
 	udev_enumerate_scan_devices(udev_enumerate);
 	test_enumerate_print_list(udev_enumerate);
 	udev_enumerate_unref(udev_enumerate);

udev/udev-event.c

@@ -631,12 +631,7 @@ int udev_event_execute_rules(struct udev_event *event, struct udev_rules *rules)
 			/* set device node name */
 			util_strscpyl(filename, sizeof(filename), udev_get_dev_path(event->udev), "/", event->name, NULL);
 			udev_device_set_devnode(dev, filename);
-		}
 
-		udev_device_update_db(dev);
-		udev_device_tag_index(dev, event->dev_db, true);
-
-		if (major(udev_device_get_devnum(dev)) != 0) {
 			/* remove/update possible left-over symlinks from old database entry */
 			if (event->dev_db != NULL)
 				udev_node_update_old_links(dev, event->dev_db);
@@ -648,6 +643,10 @@ int udev_event_execute_rules(struct udev_event *event, struct udev_rules *rules)
 			err = udev_node_add(dev, event->mode, event->uid, event->gid);
 		}
 
+		udev_device_update_db(dev);
+		udev_device_tag_index(dev, event->dev_db, true);
+		udev_device_set_is_initialized(dev);
+
 		udev_device_unref(event->dev_db);
 		event->dev_db = NULL;
 	}