[gnome-keyring] Die if the XDG session we were started under goes away

[Stefan Walter <stefw src gnome org>]

commit a6e91294dd629cd4a57dfaad461f1734ad1beb82
Author: Iain Lane <iain orangesquash org uk>
Date:   Tue Jul 19 17:36:07 2016 +0100

    Die if the XDG session we were started under goes away
    
    https://bugzilla.gnome.org/show_bug.cgi?id=768943

 daemon/gkd-main.c |  158 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 158 insertions(+), 0 deletions(-)
---
diff --git a/daemon/gkd-main.c b/daemon/gkd-main.c
index 28758ed..57b72a0 100644
--- a/daemon/gkd-main.c
+++ b/daemon/gkd-main.c
@@ -128,6 +128,7 @@ static guint timeout_id = 0;
 static gboolean initialization_completed = FALSE;
 static GMainLoop *loop = NULL;
 static int parent_wakeup_fd = -1;
+static GDBusConnection *system_bus_connection = NULL;
 
 static GOptionEntry option_entries[] = {
        { "start", 's', 0, G_OPTION_ARG_NONE, &run_for_start,
@@ -835,6 +836,155 @@ on_vanished_quit_loop (GDBusConnection *connection,
        g_main_loop_quit (user_data);
 }
 
+static void on_logind_session_property_get (GObject *connection,
+                                           GAsyncResult *res,
+                                           gpointer user_data G_GNUC_UNUSED)
+{
+       GError *error = NULL;
+       GVariant *result, *resultv;
+       const gchar *state;
+       gboolean should_quit;
+
+       result = g_dbus_connection_call_finish (G_DBUS_CONNECTION (connection), res, &error);
+
+       if (error) {
+               if (!g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
+                       g_critical ("%s Couldn't get session state: %s", G_STRLOC, error->message);
+               g_error_free (error);
+               return;
+       }
+
+       g_variant_get (result, "(v)", &resultv, NULL);
+       state = g_variant_get_string (resultv, NULL);
+
+       should_quit = g_strcmp0 (state, "closing") == 0;
+
+       g_clear_pointer (&result, g_variant_unref);
+       g_clear_pointer (&resultv, g_variant_unref);
+
+       /* yes, the session is closing, so we'll quit now */
+       if (should_quit)
+               cleanup_and_exit (0);
+}
+
+static void on_logind_session_properties_changed (GDBusConnection *connection,
+                                                 const gchar *sender_name G_GNUC_UNUSED,
+                                                 const gchar *object_path,
+                                                 const gchar *interface_name G_GNUC_UNUSED,
+                                                 const gchar *signal_name G_GNUC_UNUSED,
+                                                 GVariant *parameters,
+                                                 gpointer user_data G_GNUC_UNUSED)
+{
+       const gchar *prop_iface;
+       gboolean active;
+       GVariant* changed_properties;
+
+       g_variant_get (parameters, "(&s@a{sv}^as)", &prop_iface, &changed_properties, NULL);
+
+       if (g_variant_lookup (changed_properties, "Active", "b", &active, NULL)) {
+               if (!active) {
+                       /* ok, the session went inactive, let's see if that is because
+                        * it is closing */
+                       g_dbus_connection_call (
+                               connection,
+                               "org.freedesktop.login1",
+                               object_path,
+                               "org.freedesktop.DBus.Properties",
+                               "Get",
+                               g_variant_new ("(ss)", prop_iface, "State"),
+                               G_VARIANT_TYPE ("(v)"),
+                               G_DBUS_CALL_FLAGS_NONE,
+                               -1,
+                               NULL,
+                               on_logind_session_property_get,
+                               NULL
+                       );
+               }
+       }
+
+       g_variant_unref (changed_properties);
+}
+
+static void
+on_logind_object_path_get (GObject *connection,
+                          GAsyncResult *res,
+                          gpointer user_data G_GNUC_UNUSED)
+{
+       GError *error = NULL;
+       GVariant *result;
+       const gchar *object_path;
+       gchar *remote_error;
+       gboolean is_cancelled, is_name_has_no_owner;
+
+       result = g_dbus_connection_call_finish (G_DBUS_CONNECTION (connection), res, &error);
+
+       /* If there's an error we always want to quit - but we only tell the
+        * user about it if something went wrong. Cancelling the operation or
+        * not having logind available are okay. */
+       if (error) {
+               is_cancelled = g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED);
+
+               remote_error = g_dbus_error_get_remote_error (error);
+               is_name_has_no_owner = g_strcmp0 (remote_error, "org.freedesktop.DBus.Error.NameHasNoOwner") 
== 0;
+
+               if (!is_cancelled && !is_name_has_no_owner)
+                       g_critical ("%s Couldn't get object path: %s", G_STRLOC, error->message);
+
+               g_free (remote_error);
+               g_error_free (error);
+               return;
+       }
+
+       /* now we know which object path to look on, watch for
+        * PropertiesChanged. Note that, per logind's documentation, we only
+        * get notified for 'Active' changing */
+       g_variant_get (result, "(&o)", &object_path, NULL);
+
+       g_dbus_connection_signal_subscribe (
+               G_DBUS_CONNECTION (connection),
+               "org.freedesktop.login1",
+               "org.freedesktop.DBus.Properties",
+               "PropertiesChanged",
+               object_path,
+               NULL,
+               G_DBUS_SIGNAL_FLAGS_NONE,
+               on_logind_session_properties_changed,
+               NULL,
+               NULL
+       );
+
+       g_clear_pointer (&result, g_variant_unref);
+}
+
+static void
+start_watching_logind_for_session_closure ()
+{
+       g_return_if_fail (system_bus_connection != NULL);
+
+       const gchar *xdg_session_id;
+
+       xdg_session_id = g_getenv ("XDG_SESSION_ID");
+
+       if (!xdg_session_id)
+               return;
+
+       /* get the right object path */
+       g_dbus_connection_call (
+               system_bus_connection,
+               "org.freedesktop.login1",
+               "/org/freedesktop/login1",
+               "org.freedesktop.login1.Manager",
+               "GetSession",
+               g_variant_new ("(s)", xdg_session_id, NULL),
+               G_VARIANT_TYPE ("(o)"),
+               G_DBUS_CALL_FLAGS_NO_AUTO_START,
+               -1,
+               NULL,
+               on_logind_object_path_get,
+               NULL
+       );
+}
+
 int
 main (int argc, char *argv[])
 {
@@ -971,6 +1121,14 @@ main (int argc, char *argv[])
                        cleanup_and_exit (1);
        }
 
+       /* if we can get a connection to the system bus, watch it and then kill
+        * ourselves when our session closes */
+
+       system_bus_connection = g_bus_get_sync (G_BUS_TYPE_SYSTEM, NULL, NULL);
+
+       if (system_bus_connection)
+               start_watching_logind_for_session_closure ();
+
        signal (SIGPIPE, SIG_IGN);
 
        /* Print the environment and tell the parent we're done */