logind: fix PropertiesChanged parser

The current parser directly reads a BOOLEAN on the PropertiesChanged
signal for 'Active' properties. However, all property-values are packed in
a VARIANT, otherwise, we wouldn't know the type. Fix the parser to recurse
into the variant before reading the boolean.

To avoid such bugs in the future, we extract the 'Active' parser into a
helper function parse_active(), which is then shared between the
PropertiesChanged and Get handlers.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Reviewed-by: Bryce Harrington <bryce@osg.samsung.com>
Tested-by: nerdopolis <bluescreen_avenger@verizon.net>

src/logind-util.c

@@ -287,33 +287,18 @@ weston_logind_set_active(struct weston_logind *wl, bool active)
 }
 
 static void
-get_active_cb(DBusPendingCall *pending, void *data)
+parse_active(struct weston_logind *wl, DBusMessage *m, DBusMessageIter *iter)
 {
-	struct weston_logind *wl = data;
-	DBusMessage *m;
-	DBusMessageIter iter, sub;
-	int type;
+	DBusMessageIter sub;
 	dbus_bool_t b;
 
-	dbus_pending_call_unref(wl->pending_active);
-	wl->pending_active = NULL;
-
-	m = dbus_pending_call_steal_reply(pending);
-	if (!m)
+	if (dbus_message_iter_get_arg_type(iter) != DBUS_TYPE_VARIANT)
 		return;
 
-	type = dbus_message_get_type(m);
-	if (type != DBUS_MESSAGE_TYPE_METHOD_RETURN)
-		goto err_unref;
-
-	if (!dbus_message_iter_init(m, &iter) ||
-	    dbus_message_iter_get_arg_type(&iter) != DBUS_TYPE_VARIANT)
-		goto err_unref;
-
-	dbus_message_iter_recurse(&iter, &sub);
+	dbus_message_iter_recurse(iter, &sub);
 
 	if (dbus_message_iter_get_arg_type(&sub) != DBUS_TYPE_BOOLEAN)
-		goto err_unref;
+		return;
 
 	dbus_message_iter_get_basic(&sub, &b);
 
@@ -322,8 +307,28 @@ get_active_cb(DBusPendingCall *pending, void *data)
 	 * other backends, we immediately forward the Active-change event. */
 	if (!wl->sync_drm || !b)
 		weston_logind_set_active(wl, b);
+}
+
+static void
+get_active_cb(DBusPendingCall *pending, void *data)
+{
+	struct weston_logind *wl = data;
+	DBusMessageIter iter;
+	DBusMessage *m;
+	int type;
+
+	dbus_pending_call_unref(wl->pending_active);
+	wl->pending_active = NULL;
+
+	m = dbus_pending_call_steal_reply(pending);
+	if (!m)
+		return;
+
+	type = dbus_message_get_type(m);
+	if (type == DBUS_MESSAGE_TYPE_METHOD_RETURN &&
+	    dbus_message_iter_init(m, &iter))
+		parse_active(wl, m, &iter);
 
-err_unref:
 	dbus_message_unref(m);
 }
 
@@ -408,7 +413,6 @@ property_changed(struct weston_logind *wl, DBusMessage *m)
 {
 	DBusMessageIter iter, sub, entry;
 	const char *interface, *name;
-	dbus_bool_t b;
 
 	if (!dbus_message_iter_init(m, &iter) ||
 	    dbus_message_iter_get_arg_type(&iter) != DBUS_TYPE_STRING)
@@ -433,13 +437,9 @@ property_changed(struct weston_logind *wl, DBusMessage *m)
 			goto error;
 
 		if (!strcmp(name, "Active")) {
-			if (dbus_message_iter_get_arg_type(&entry) == DBUS_TYPE_BOOLEAN) {
-				dbus_message_iter_get_basic(&entry, &b);
-				if (!b)
-					weston_logind_set_active(wl, false);
+			parse_active(wl, m, &entry);
 			return;
 		}
-		}
 
 		dbus_message_iter_next(&sub);
 	}