[Spice-devel] [PATCH spice-gtk] desktop-integration: Create D-Bus proxy only when bus name exists

[Pavel Grunt]

It avoids calling D-Bus methods when the bus name
"org.gnome.SessionManager" does not exist.

GSpice-WARNING **: Error calling 'org.gnome.SessionManager.Inhibit': GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.SessionManager was not provided by any .service files
---
The warning appears in other than Gnome desktop environment
---
 gtk/desktop-integration.c | 63 +++++++++++++++++++++++++++++++++--------------
 1 file changed, 45 insertions(+), 18 deletions(-)

diff --git a/gtk/desktop-integration.c b/gtk/desktop-integration.c
index c366fd0..bf6a9e3 100644
--- a/gtk/desktop-integration.c
+++ b/gtk/desktop-integration.c
@@ -44,6 +44,7 @@ struct _SpiceDesktopIntegrationPrivate {
     GObject *gnome_session_proxy; /* dummy */
 #endif
     guint gnome_automount_inhibit_cookie;
+    guint gdbus_watcher_id;
 };
 
 G_DEFINE_TYPE(SpiceDesktopIntegration, spice_desktop_integration, G_TYPE_OBJECT);
@@ -60,33 +61,57 @@ static void handle_dbus_call_error(const char *call, GError **_error)
     g_clear_error(_error);
 }
 
-static gboolean gnome_integration_init(SpiceDesktopIntegration *self)
+#if defined(USE_GDBUS)
+static void name_appeared_cb(GDBusConnection *connection,
+                             const gchar *name,
+                             const gchar *name_owner G_GNUC_UNUSED,
+                             gpointer data)
 {
-    G_GNUC_UNUSED SpiceDesktopIntegrationPrivate *priv = self->priv;
+    SpiceDesktopIntegration *self = SPICE_DESKTOP_INTEGRATION(data);
+    SpiceDesktopIntegrationPrivate *priv = self->priv;
     GError *error = NULL;
-    gboolean success = TRUE;
-
-#if defined(USE_GDBUS)
-    priv->gnome_session_proxy =
-        g_dbus_proxy_new_for_bus_sync(G_BUS_TYPE_SESSION,
-                                      G_DBUS_PROXY_FLAGS_NONE,
-                                      NULL,
-                                      "org.gnome.SessionManager",
-                                      "/org/gnome/SessionManager",
-                                      "org.gnome.SessionManager",
-                                      NULL,
-                                      &error);
-#else
-    success = FALSE;
-#endif
 
+    priv->gnome_session_proxy = g_dbus_proxy_new_sync(connection,
+                                                      G_DBUS_PROXY_FLAGS_NONE,
+                                                      NULL,
+                                                      name,
+                                                      "/org/gnome/SessionManager",
+                                                      "org.gnome.SessionManager",
+                                                      NULL,
+                                                      &error);
     if (error) {
         g_warning("Could not create org.gnome.SessionManager dbus proxy: %s",
                   error->message);
         g_clear_error(&error);
-        return FALSE;
     }
+}
+
+static void name_vanished_cb(GDBusConnection *connection G_GNUC_UNUSED,
+                             const gchar *name G_GNUC_UNUSED,
+                             gpointer data)
+{
+    SpiceDesktopIntegration *self = SPICE_DESKTOP_INTEGRATION(data);
+    SpiceDesktopIntegrationPrivate *priv = self->priv;
+
+    g_clear_object(&priv->gnome_session_proxy);
+}
+#endif
 
+static gboolean gnome_integration_init(SpiceDesktopIntegration *self)
+{
+    G_GNUC_UNUSED SpiceDesktopIntegrationPrivate *priv = self->priv;
+    gboolean success = FALSE;
+
+#if defined(USE_GDBUS)
+    priv->gdbus_watcher_id = g_bus_watch_name(G_BUS_TYPE_SESSION,
+                                              "org.gnome.SessionManager",
+                                              G_BUS_NAME_WATCHER_FLAGS_NONE,
+                                              name_appeared_cb,
+                                              name_vanished_cb,
+                                              self,
+                                              NULL);
+    success = TRUE;
+#endif
     return success;
 }
 
@@ -150,6 +175,8 @@ static void gnome_integration_dispose(SpiceDesktopIntegration *self)
 {
     SpiceDesktopIntegrationPrivate *priv = self->priv;
 
+    if (priv->gdbus_watcher_id)
+        g_bus_unwatch_name(priv->gdbus_watcher_id);
     g_clear_object(&priv->gnome_session_proxy);
 }
 
-- 
1.9.3