From aca91616f1c9845d860768f0f4d321cfdc515c62 Mon Sep 17 00:00:00 2001
From: Stefano Karapetsas <stefano@karapetsas.com>
Date: Sat, 13 Apr 2013 14:04:34 +0200
Subject: Add support to switch user with LightDM
 http://bazaar.launchpad.net/~lightdm-team/lightdm/trunk/view/head:/utils/gdmflexiserver
 Closes #22 (https://github.com/mate-desktop/mate-session-manager/issues/22)

---
 mate-session/gsm-manager.c | 86 ++++++++++++++++++++++++++++++++++++----------
 1 file changed, 67 insertions(+), 19 deletions(-)

diff --git a/mate-session/gsm-manager.c b/mate-session/gsm-manager.c
index de29f8f..02758f5 100644
--- a/mate-session/gsm-manager.c
+++ b/mate-session/gsm-manager.c
@@ -973,6 +973,20 @@ cancel_end_session (GsmManager *manager)
         start_phase (manager);
 }
 
+static gboolean
+is_program_in_path (const char *program)
+{
+        char *tmp = g_find_program_in_path (program);
+        if (tmp != NULL)
+        {
+                g_free (tmp);
+                return TRUE;
+        }
+        else
+        {
+                return FALSE;
+        }
+}
 
 static void
 manager_switch_user (GsmManager *manager)
@@ -981,41 +995,75 @@ manager_switch_user (GsmManager *manager)
         gboolean res;
         char    *command;
 
-        command = g_strdup_printf ("%s %s",
-                                   MDM_FLEXISERVER_COMMAND,
-                                   MDM_FLEXISERVER_ARGS);
+        if (is_program_in_path (MDM_FLEXISERVER_COMMAND)) {
+                /* MDM */
+                command = g_strdup_printf ("%s %s",
+                                           MDM_FLEXISERVER_COMMAND,
+                                           MDM_FLEXISERVER_ARGS);
 
-        error = NULL;
-        res = gdk_spawn_command_line_on_screen (gdk_screen_get_default (),
-                                                command,
-                                                &error);
+                error = NULL;
+                res = gdk_spawn_command_line_on_screen (gdk_screen_get_default (),
+                                                        command,
+                                                        &error);
 
-        g_free (command);
+                g_free (command);
 
-        if (! res) {
-                g_debug ("GsmManager: Unable to start MDM greeter: %s", error->message);
-                g_error_free (error);
-                
-                /* MDM not found, so we try to use gdmflexiserver from GDM */
-                
-                char    *gdm_command;
-
-                gdm_command = g_strdup_printf ("%s %s",
+                if (! res) {
+                        g_debug ("GsmManager: Unable to start MDM greeter: %s", error->message);
+                        g_error_free (error);
+                }
+        }
+        else if (is_program_in_path (GDM_FLEXISERVER_COMMAND)) {
+                /* GDM */
+                command = g_strdup_printf ("%s %s",
                                                GDM_FLEXISERVER_COMMAND,
                                                GDM_FLEXISERVER_ARGS);
                 
                 error = NULL;
                 res = gdk_spawn_command_line_on_screen (gdk_screen_get_default (),
-                                                gdm_command,
+                                                command,
                                                 &error);
 
-                g_free (gdm_command);
+                g_free (command);
                 
                 if (! res) {
                         g_debug ("GsmManager: Unable to start GDM greeter: %s", error->message);
                         g_error_free (error);
                 }
         }
+        else {
+                /* LightDM */
+                const gchar *xdg_seat_path = g_getenv ("XDG_SEAT_PATH");
+                if (xdg_seat_path != NULL) {
+                        GDBusProxyFlags flags = G_DBUS_PROXY_FLAGS_DO_NOT_AUTO_START;
+                        GDBusProxy *proxy = NULL;
+                        error = NULL;
+
+                        proxy = g_dbus_proxy_new_for_bus_sync(G_BUS_TYPE_SYSTEM,
+                                                              flags,
+                                                              NULL,
+                                                              "org.freedesktop.DisplayManager",
+                                                              xdg_seat_path,
+                                                              "org.freedesktop.DisplayManager.Seat",
+                                                              NULL,
+                                                              &error);
+                        if (proxy != NULL) {
+                                g_dbus_proxy_call (proxy,
+                                                   "SwitchToGreeter",
+                                                   g_variant_new ("()"),
+                                                   G_DBUS_CALL_FLAGS_NONE,
+                                                   -1,
+                                                   NULL,
+                                                   NULL,
+                                                   NULL);
+                                g_object_unref (proxy);
+                        }
+                        else {
+                                g_debug ("GsmManager: Unable to start LightDM greeter: %s", error->message);
+                                g_error_free (error);
+                        }
+                }
+        }
 }
 
 static gboolean
-- 
cgit v1.2.1