daemon: clean up greeter when unused

When user switching GDM needs to show a transient greeter for
the user to pick a name from the list and jump to that session.

After the user has been jumped to the selected session we don't
really have a use for the greeter session.  Historically, we've
kept it around anyway, though, because X by default jumps back
to the VT it started on when it exits, and we don't want the
user to get thrown to an empty VT after they log out.

This commit changes X to get started with the "-novtswitch"
option, so that it doesn't do the undesirable switch-on-exit
thing.

This allows us to clean up the useless greeter following user
switches.

Based on work by Josselin Mouette <joss@debian.org>

https://bugzilla.gnome.org/show_bug.cgi?id=618047

5 files changed, 78 insertions, 58 deletions

diff --git a/configure.ac b/configure.ac
index ecb7e1e5..d54f0f9e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -276,6 +276,11 @@ AC_ARG_WITH(at-spi-registryd-directory,
 AT_SPI_REGISTRYD_DIR=$with_at_spi_registryd_directory
 AC_SUBST(AT_SPI_REGISTRYD_DIR)
 
+AC_ARG_WITH(vt-switch-workaround,
+            AS_HELP_STRING([--with-vt-switch-workaround],
+	                   [Try to workaround missing -novtswitch option for X @<:@default=nor@:>@])],,
+            [with_vt_switch_workaround="no"])
+
 # Allow configuration of default PATH
 #
 withval=""
@@ -923,6 +928,14 @@ AM_CONDITIONAL(WITH_CONSOLE_KIT, test x$use_console_kit = xyes)
 AC_SUBST(WITH_CONSOLE_KIT)
 
 dnl ---------------------------------------------------------------------------
+dnl - Check for vt switch support
+dnl ---------------------------------------------------------------------------
+
+if test "x$with_vt_switch_workaround" != "xno" ; then
+	AC_DEFINE(WITH_VT_SWITCH_WORKAROUND, 1, [Define to enable workaround for missing -novtswitch feature])
+fi
+
+dnl ---------------------------------------------------------------------------
 dnl - Check for D-Bus
 dnl ---------------------------------------------------------------------------
 
diff --git a/daemon/gdm-server.c b/daemon/gdm-server.c
index 7135ffaf..8dacdb51 100644
--- a/daemon/gdm-server.c
+++ b/daemon/gdm-server.c
@@ -52,6 +52,12 @@
 
 extern char **environ;
 
+#ifdef WITH_VT_SWITCH_WORKAROUND
+#define X_SERVER_COMMAND_LINE X_SERVER " -br -verbose -logverbose 7"
+#else
+#define X_SERVER_COMMAND_LINE X_SERVER " -br -verbose -logverbose 7 -novtswitch"
+#endif
+
 #define GDM_SERVER_GET_PRIVATE(o) (G_TYPE_INSTANCE_GET_PRIVATE ((o), GDM_TYPE_SERVER, GdmServerPrivate))
 
 /* These are the servstat values, also used as server
@@ -941,7 +947,7 @@ gdm_server_init (GdmServer *server)
         server->priv = GDM_SERVER_GET_PRIVATE (server);
 
         server->priv->pid = -1;
-        server->priv->command = g_strdup (X_SERVER " -br -verbose -logverbose 7");
+        server->priv->command = g_strdup (X_SERVER_COMMAND_LINE);
         server->priv->log_dir = g_strdup (LOGDIR);
 
         add_ready_handler (server);
diff --git a/daemon/gdm-simple-slave.c b/daemon/gdm-simple-slave.c
index 7b9d7d8b..55c0f19a 100644
--- a/daemon/gdm-simple-slave.c
+++ b/daemon/gdm-simple-slave.c
@@ -463,12 +463,17 @@ start_session_timeout (GdmSimpleSlave *slave)
         if (migrated) {
                 destroy_session (slave);
 
-                /* We don't stop the slave here because
-                   when Xorg exits it switches to the VT it was
-                   started from.  That interferes with fast
-                   user switching. */
+#ifdef WITH_VT_SWITCH_WORKAROUND
+                /* If the X server doesn't support -novtswitch, then when the
+                 * user logs out from their session later, they're going to get thrown
+                 * back to the VT the greeter is currently running on. We keep the
+                 * greeter alive here, so when that happens the user doesn't see
+                 * a blank VT or some confusing thing.
+                 */
                 queue_greeter_reset (slave);
-
+#else
+                gdm_slave_stopped (GDM_SLAVE (slave));
+#endif
                 goto out;
         }
 
diff --git a/gui/libgdmgreeter/gdm-greeter-client.c b/gui/libgdmgreeter/gdm-greeter-client.c
index cb1ce00b..c712d2bd 100644
--- a/gui/libgdmgreeter/gdm-greeter-client.c
+++ b/gui/libgdmgreeter/gdm-greeter-client.c
@@ -54,6 +54,7 @@ struct GdmGreeterClientPrivate
 
 enum {
         PROP_0,
+        PROP_DISPLAY_IS_LOCAL
 };
 
 enum {
@@ -95,6 +96,13 @@ gdm_greeter_client_error_quark (void)
         return error_quark;
 }
 
+/**
+ * gdm_greeter_get_display_is_local:
+ *
+ * @client: a #GdmGreeterClient
+ *
+ * Returns: %TRUE if display is local display
+ */
 gboolean
 gdm_greeter_client_get_display_is_local (GdmGreeterClient *client)
 {
@@ -643,7 +651,8 @@ send_get_display_id (GdmGreeterClient *client,
         return ret;
 }
 
-char *
+
+static char *
 gdm_greeter_client_call_get_display_id (GdmGreeterClient *client)
 {
         char *display_id;
@@ -779,9 +788,20 @@ client_dbus_filter_function (DBusConnection *connection,
         return DBUS_HANDLER_RESULT_HANDLED;
 }
 
+/**
+ * gdm_greeter_client_connect:
+ *
+ * @client: a #GdmGreeterClient
+ *
+ * Initiates a connection to GDM daemon "slave" process.
+ *
+ * This function should be called before doing other calls.
+ *
+ * Returns: %TRUE if connected, or %FALSE if unavailable
+ */
 gboolean
-gdm_greeter_client_start (GdmGreeterClient *client,
-                          GError          **error)
+gdm_greeter_client_connect (GdmGreeterClient  *client,
+                            GError           **error)
 {
         gboolean  ret;
         DBusError local_error;
@@ -833,61 +853,35 @@ gdm_greeter_client_start (GdmGreeterClient *client,
         return ret;
 }
 
-void
-gdm_greeter_client_stop (GdmGreeterClient *client)
-{
-        g_return_if_fail (GDM_IS_GREETER_CLIENT (client));
-
-}
-
 static void
-gdm_greeter_client_set_property (GObject        *object,
-                                 guint           prop_id,
-                                 const GValue   *value,
-                                 GParamSpec     *pspec)
+gdm_greeter_client_set_property (GObject      *object,
+                                 guint         prop_id,
+                                 const GValue *value,
+                                 GParamSpec   *pspec)
 {
-        switch (prop_id) {
-        default:
-                G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
-                break;
-        }
+        G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
 }
 
 static void
-gdm_greeter_client_get_property (GObject        *object,
-                                 guint           prop_id,
-                                 GValue         *value,
-                                 GParamSpec     *pspec)
+gdm_greeter_client_get_property (GObject    *object,
+                                 guint       prop_id,
+                                 GValue     *value,
+                                 GParamSpec *pspec)
 {
+        GdmGreeterClient *self;
+
+        self = GDM_GREETER_CLIENT (object);
+
         switch (prop_id) {
+        case PROP_DISPLAY_IS_LOCAL:
+                g_value_set_boolean (value, self->priv->display_is_local);
+                break;
         default:
                 G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
                 break;
         }
 }
 
-static GObject *
-gdm_greeter_client_constructor (GType                  type,
-                                 guint                  n_construct_properties,
-                                 GObjectConstructParam *construct_properties)
-{
-        GdmGreeterClient      *greeter_client;
-
-        greeter_client = GDM_GREETER_CLIENT (G_OBJECT_CLASS (gdm_greeter_client_parent_class)->constructor (type,
-                                                                                                            n_construct_properties,
-                                                                                                            construct_properties));
-
-        return G_OBJECT (greeter_client);
-}
-
-static void
-gdm_greeter_client_dispose (GObject *object)
-{
-        g_debug ("GdmGreeterClient: Disposing greeter_client");
-
-        G_OBJECT_CLASS (gdm_greeter_client_parent_class)->dispose (object);
-}
-
 static void
 gdm_greeter_client_class_init (GdmGreeterClientClass *klass)
 {
@@ -895,8 +889,6 @@ gdm_greeter_client_class_init (GdmGreeterClientClass *klass)
 
         object_class->get_property = gdm_greeter_client_get_property;
         object_class->set_property = gdm_greeter_client_set_property;
-        object_class->constructor = gdm_greeter_client_constructor;
-        object_class->dispose = gdm_greeter_client_dispose;
         object_class->finalize = gdm_greeter_client_finalize;
 
         g_type_class_add_private (klass, sizeof (GdmGreeterClientPrivate));
@@ -1032,6 +1024,14 @@ gdm_greeter_client_class_init (GdmGreeterClientClass *klass)
                               g_cclosure_marshal_generic,
                               G_TYPE_NONE,
                               1, G_TYPE_STRING);
+
+        g_object_class_install_property (object_class,
+                                         PROP_DISPLAY_IS_LOCAL,
+                                         g_param_spec_boolean ("display-is-local",
+                                                               "display is local",
+                                                               "display is local",
+                                                               FALSE,
+                                                               G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY));
 }
 
 static void
diff --git a/gui/libgdmgreeter/gdm-greeter-client.h b/gui/libgdmgreeter/gdm-greeter-client.h
index d0eaf58a..9b2be8d8 100644
--- a/gui/libgdmgreeter/gdm-greeter-client.h
+++ b/gui/libgdmgreeter/gdm-greeter-client.h
@@ -87,14 +87,10 @@ GQuark             gdm_greeter_client_error_quark                    (void);
 
 GdmGreeterClient * gdm_greeter_client_new                            (void);
 
-gboolean           gdm_greeter_client_start                          (GdmGreeterClient *client,
+gboolean           gdm_greeter_client_connect                        (GdmGreeterClient *client,
                                                                       GError          **error);
-void               gdm_greeter_client_stop                           (GdmGreeterClient *client);
-
 gboolean           gdm_greeter_client_get_display_is_local           (GdmGreeterClient *client);
 
-char *             gdm_greeter_client_call_get_display_id            (GdmGreeterClient *client);
-
 void               gdm_greeter_client_call_start_conversation        (GdmGreeterClient *client,
                                                                       const char       *service_name);
 void               gdm_greeter_client_call_begin_auto_login          (GdmGreeterClient *client,