server-main: Properly register to gnome-session

So far squeeboard only did half of the registration failing
to respond to the signals sent by the session.

This causes problems e.g. when exiting the session since the it
thinks the client hangs or is busy.

Closes: #274

src/server-main.c

@@ -138,6 +138,67 @@ static const struct wl_registry_listener registry_listener = {
 #define SESSION_NAME "sm.puri.OSK0"
 
 GDBusProxy *_proxy = NULL;
+GDBusProxy *_client_proxy = NULL;
+gchar      *_client_path = NULL;
+
+
+static void
+send_quit_response (GDBusProxy  *proxy)
+{
+    g_debug ("Calling EndSessionResponse");
+    g_dbus_proxy_call (proxy, "EndSessionResponse",
+        g_variant_new ("(bs)", TRUE, ""), G_DBUS_CALL_FLAGS_NONE,
+        G_MAXINT, NULL, NULL, NULL);
+}
+
+static void
+unregister_client (void)
+{
+    g_autoptr (GError) error = NULL;
+
+    g_return_if_fail (G_IS_DBUS_PROXY (_proxy));
+    g_return_if_fail (_client_path != NULL);
+
+    g_debug ("Unregistering client");
+
+    g_dbus_proxy_call_sync (_proxy,
+			    "UnregisterClient",
+			    g_variant_new ("(o)", _client_path),
+			    G_DBUS_CALL_FLAGS_NONE,
+			    G_MAXINT,
+			    NULL,
+			    &error);
+
+    if (error) {
+        g_warning ("Failed to unregister client: %s", error->message);
+    }
+
+    g_clear_object (&_client_proxy);
+    g_clear_pointer (&_client_path, g_free);
+}
+
+static void client_proxy_signal (GDBusProxy  *proxy,
+				 const gchar *sender_name,
+				 const gchar *signal_name,
+				 GVariant    *parameters,
+				 gpointer     user_data)
+{
+    if (g_str_equal (signal_name, "QueryEndSession")) {
+        g_debug ("Received QueryEndSession");
+        send_quit_response (proxy);
+    } else if (g_str_equal (signal_name, "CancelEndSession")) {
+        g_debug ("Received CancelEndSession");
+    } else if (g_str_equal (signal_name, "EndSession")) {
+        g_debug ("Received EndSession");
+        send_quit_response (proxy);
+        unregister_client ();
+	quit ();
+    } else if (g_str_equal (signal_name, "Stop")) {
+        g_debug ("Received Stop");
+        unregister_client ();
+        quit ();
+    }
+}
 
 static void
 session_register(void) {
@@ -158,7 +219,8 @@ session_register(void) {
         return;
     }
 
-    g_dbus_proxy_call_sync(_proxy, "RegisterClient",
+    g_autoptr (GVariant) res = NULL;
+    res = g_dbus_proxy_call_sync(_proxy, "RegisterClient",
         g_variant_new("(ss)", SESSION_NAME, autostart_id),
         G_DBUS_CALL_FLAGS_NONE, 1000, NULL, &error);
     if (error) {
@@ -167,6 +229,22 @@ session_register(void) {
         g_clear_error(&error);
         return;
     }
+
+    g_variant_get (res, "(o)", &_client_path);
+    g_debug ("Registered client at '%s'", _client_path);
+
+    _client_proxy = g_dbus_proxy_new_for_bus_sync (G_BUS_TYPE_SESSION,
+      0, NULL, "org.gnome.SessionManager", _client_path,
+      "org.gnome.SessionManager.ClientPrivate", NULL, &error);
+    if (error) {
+        g_warning ("Failed to get client proxy: %s", error->message);
+	g_clear_error (&error);
+	g_free (_client_path);
+	_client_path = NULL;
+	return;
+    }
+
+    g_signal_connect (_client_proxy, "g-signal", G_CALLBACK (client_proxy_signal), NULL);
 }
 
 int