From f4402b64fd34b886a9d7e8c1e0833e4c3f7dcfe3 Mon Sep 17 00:00:00 2001
From: Rui Matos <tiagomatos@gmail.com>
Date: Tue, 26 Nov 2013 00:55:23 +0100
Subject: [PATCH] idle-monitor: Check if a monitor exists before creating a
 proxy for it

The fact that we know about a given device doesn't mean that mutter
also knows about it nor that it has created an idle monitor object on
the bus for it.

To fix this race, instead of immediately trying to create a proxy for
the bus object, we instantiate an object manager and ask it whether
the object we want already exists and if it doesn't we wait
(indefinitely) until it shows up.

https://bugzilla.gnome.org/show_bug.cgi?id=706229
---
 libgnome-desktop/gnome-idle-monitor.c | 109 +++++++++++++++++++++++-----------
 1 file changed, 73 insertions(+), 36 deletions(-)

diff --git a/libgnome-desktop/gnome-idle-monitor.c b/libgnome-desktop/gnome-idle-monitor.c
index 6af1343..539c99b 100644
--- a/libgnome-desktop/gnome-idle-monitor.c
+++ b/libgnome-desktop/gnome-idle-monitor.c
@@ -40,10 +40,12 @@ struct _GnomeIdleMonitorPrivate
 {
 	GCancellable        *cancellable;
 	MetaDBusIdleMonitor *proxy;
+	MetaDBusObjectManagerClient *om;
 	int                  name_watch_id;
 	GHashTable          *watches;
 	GHashTable          *watches_by_upstream_id;
 	GdkDevice           *device;
+	gchar               *path;
 };
 
 typedef struct
@@ -163,8 +165,10 @@ gnome_idle_monitor_dispose (GObject *object)
 	}
 
 	g_clear_object (&monitor->priv->proxy);
+	g_clear_object (&monitor->priv->om);
 	g_clear_pointer (&monitor->priv->watches, g_hash_table_destroy);
 	g_clear_object (&monitor->priv->device);
+	g_clear_pointer (&monitor->priv->path, g_free);
 
 	G_OBJECT_CLASS (gnome_idle_monitor_parent_class)->dispose (object);
 }
@@ -198,6 +202,15 @@ gnome_idle_monitor_set_property (GObject      *object,
 	{
 	case PROP_DEVICE:
 		monitor->priv->device = g_value_dup_object (value);
+
+		g_free (monitor->priv->path);
+		if (monitor->priv->device) {
+			monitor->priv->path = g_strdup_printf ("/org/gnome/Mutter/IdleMonitor/Device%d",
+							       gdk_x11_device_get_id (monitor->priv->device));
+		} else {
+			monitor->priv->path = g_strdup ("/org/gnome/Mutter/IdleMonitor/Core");
+		}
+
 		break;
 	default:
 		G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
@@ -220,57 +233,74 @@ add_known_watch (gpointer key,
 }
 
 static void
-on_proxy_acquired (GObject      *object,
-		   GAsyncResult *result,
-		   gpointer      user_data)
+connect_proxy (GDBusObject	*object,
+	       GnomeIdleMonitor	*monitor)
 {
-	GnomeIdleMonitor *monitor = user_data;
-	GError *error;
 	MetaDBusIdleMonitor *proxy;
 
-	error = NULL;
-	proxy = meta_dbus_idle_monitor_proxy_new_finish (result, &error);
+	proxy = meta_dbus_object_get_idle_monitor (META_DBUS_OBJECT (object));
 	if (!proxy) {
-		if (g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED)) {
-			g_error_free (error);
-			return;
-		}
-
-		g_warning ("Failed to acquire idle monitor proxy: %s", error->message);
-		g_error_free (error);
+		g_critical ("Unable to get idle monitor from object at %s",
+			    g_dbus_object_get_object_path (object));
 		return;
 	}
 
 	monitor->priv->proxy = proxy;
-
 	g_signal_connect_object (proxy, "watch-fired", G_CALLBACK (on_watch_fired), monitor, 0);
 	g_hash_table_foreach (monitor->priv->watches, add_known_watch, monitor);
 }
 
 static void
-connect_proxy (GnomeIdleMonitor *monitor,
-	       GDBusConnection  *connection,
-	       const char       *unique_name)
-{
-	char *path;
-	int device_id;
-
-	if (monitor->priv->device) {
-		/* FIXME! Gdk! WTF? */
-		device_id = gdk_x11_device_get_id (monitor->priv->device);
-	path = g_strdup_printf ("/org/gnome/Mutter/IdleMonitor/Device%d", device_id);
-	} else {
-		path = g_strdup ("/org/gnome/Mutter/IdleMonitor/Core");
+on_object_added (GDBusObjectManager	*manager,
+		 GDBusObject		*object,
+		 gpointer		 user_data)
+{
+	GnomeIdleMonitor *monitor = user_data;
+
+	if (!g_str_equal (monitor->priv->path, g_dbus_object_get_object_path (object)))
+		return;
+
+	connect_proxy (object, monitor);
+
+	g_signal_handlers_disconnect_by_func (manager, on_object_added, user_data);
+}
+
+static void
+get_proxy (GnomeIdleMonitor *monitor)
+{
+	GDBusObject *object;
+
+	object = g_dbus_object_manager_get_object (G_DBUS_OBJECT_MANAGER (monitor->priv->om),
+						   monitor->priv->path);
+	if (object) {
+		connect_proxy (object, monitor);
+		g_object_unref (object);
+		return;
 	}
 
-	meta_dbus_idle_monitor_proxy_new (connection,
-					  G_DBUS_PROXY_FLAGS_DO_NOT_LOAD_PROPERTIES,
-					  unique_name, path,
-					  monitor->priv->cancellable,
-					  on_proxy_acquired,
-					  monitor);
+	g_signal_connect_object (monitor->priv->om, "object-added",
+				 G_CALLBACK (on_object_added), monitor, 0);
+}
+
+static void
+on_object_manager_ready (GObject	*source,
+			 GAsyncResult	*res,
+			 gpointer	 user_data)
+{
+	GnomeIdleMonitor *monitor = user_data;
+	GDBusObjectManager *om;
+	GError *error = NULL;
+
+	om = meta_dbus_object_manager_client_new_finish (res, &error);
+	if (!om) {
+		if (!g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
+			g_warning ("Failed to acquire idle monitor object manager: %s", error->message);
+		g_error_free (error);
+		return;
+	}
 
-	g_free (path);
+	monitor->priv->om = META_DBUS_OBJECT_MANAGER_CLIENT (om);
+	get_proxy (monitor);
 }
 
 static void
@@ -281,7 +311,13 @@ on_name_appeared (GDBusConnection *connection,
 {
 	GnomeIdleMonitor *monitor = user_data;
 
-	connect_proxy (monitor, connection, name_owner);
+	meta_dbus_object_manager_client_new (connection,
+					     G_DBUS_OBJECT_MANAGER_CLIENT_FLAGS_NONE,
+					     name_owner,
+					     "/org/gnome/Mutter/IdleMonitor",
+					     monitor->priv->cancellable,
+					     on_object_manager_ready,
+					     monitor);
 }
 
 static void
@@ -305,6 +341,7 @@ on_name_vanished (GDBusConnection *connection,
 
 	g_hash_table_foreach (monitor->priv->watches, clear_watch, monitor);
 	g_clear_object (&monitor->priv->proxy);
+	g_clear_object (&monitor->priv->om);
 }
 
 static gboolean
-- 
1.8.3.1