[gdm] user-switching: don't set PAM_TTY when using systemd

[Ray Strode <halfline src gnome org>]

commit 932c65c66d26915b40830a91762ae10ca95458a2
Author: Ray Strode <rstrode redhat com>
Date:   Mon Mar 19 14:05:18 2012 -0400

    user-switching: don't set PAM_TTY when using systemd
    
    It does it for us, and we don't know it anyway, so
    don't bother trying.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=655380

 daemon/gdm-server.c         |    8 ++++++++
 daemon/gdm-session-worker.c |    4 +++-
 2 files changed, 11 insertions(+), 1 deletions(-)
---
diff --git a/daemon/gdm-server.c b/daemon/gdm-server.c
index 53d7841..6d2d6cd 100644
--- a/daemon/gdm-server.c
+++ b/daemon/gdm-server.c
@@ -165,6 +165,14 @@ _gdm_server_query_ck_for_display_device (GdmServer *server)
 char *
 gdm_server_get_display_device (GdmServer *server)
 {
+#ifdef WITH_SYSTEMD
+        /* systemd finds the display device out on its own based on the display */
+        return NULL;
+#endif
+
+#ifndef WITH_CONSOLE_KIT
+        return NULL;
+#endif
         if (server->priv->display_device == NULL) {
                 server->priv->display_device =
                     _gdm_server_query_ck_for_display_device (server);
diff --git a/daemon/gdm-session-worker.c b/daemon/gdm-session-worker.c
index 1136bb4..57f1071 100644
--- a/daemon/gdm-session-worker.c
+++ b/daemon/gdm-session-worker.c
@@ -1142,7 +1142,9 @@ gdm_session_worker_initialize_pam (GdmSessionWorker *worker,
 
         /* set TTY */
         pam_tty = _get_tty_for_pam (x11_display_name, display_device);
-        error_code = pam_set_item (worker->priv->pam_handle, PAM_TTY, pam_tty);
+        if (pam_tty != NULL && pam_tty[0] != '\0') {
+                error_code = pam_set_item (worker->priv->pam_handle, PAM_TTY, pam_tty);
+        }
         g_free (pam_tty);
 
         if (error_code != PAM_SUCCESS) {