[gdm] manager: stop transient greeter session when done with it

[Ray Strode <halfline src gnome org>]

commit 21905303afbd508f3bf599ad219c9209413c53a2
Author: Ray Strode <rstrode redhat com>
Date:   Wed Apr 5 12:11:20 2017 -0400

    manager: stop transient greeter session when done with it
    
    If we're running in legacy display mode, we currently can
    end up with a leaked greeter following user switching.
    That can happen if a user with an already running session
    is reauthenticated (so the login screen won't morph into the
    use session).
    
    This commit makes sure we kill the greeter session off in that
    case.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=780939

 daemon/gdm-manager.c |   20 ++++++++++++++++++++
 1 files changed, 20 insertions(+), 0 deletions(-)
---
diff --git a/daemon/gdm-manager.c b/daemon/gdm-manager.c
index 5d4d6c2..b909976 100644
--- a/daemon/gdm-manager.c
+++ b/daemon/gdm-manager.c
@@ -2022,6 +2022,26 @@ on_session_reauthenticated (GdmSession *session,
                             GdmManager *manager)
 {
         gboolean fail_if_already_switched = FALSE;
+
+        if (gdm_session_get_display_mode (session) == GDM_SESSION_DISPLAY_MODE_REUSE_VT) {
+                const char *seat_id;
+                char *session_id;
+
+                seat_id = gdm_session_get_display_seat_id (session);
+                if (get_login_window_session_id (seat_id, &session_id)) {
+                        GdmDisplay *display = gdm_display_store_find (manager->priv->display_store,
+                                                                      lookup_by_session_id,
+                                                                      (gpointer) session_id);
+
+                        if (display != NULL) {
+                                gdm_display_stop_greeter_session (display);
+                                gdm_display_unmanage (display);
+                                gdm_display_finish (display);
+                        }
+                }
+                g_free (session_id);
+        }
+
         /* There should already be a session running, so jump to its
          * VT. In the event we're already on the right VT, (i.e. user
          * used an unlock screen instead of a user switched login screen),