window: Avoid crash when closing window

We remove the pad controller before calling gtk_window_destroy() to
break a dependency cycle.

However, if for some reason the controller has already been removed
by the time we reach that part of our code, we access a pointer to
and already destroyed object.

Try to avoid this with a weak pointer, such that we skip the step
if the pointer is already NULL.

Presumably fixes https://gitlab.gnome.org/GNOME/nautilus/-/issues/2572

1 files changed, 12 insertions, 4 deletions

diff --git a/src/nautilus-window.c b/src/nautilus-window.c
index 5e251f095..1d927b622 100644
--- a/src/nautilus-window.c
+++ b/src/nautilus-window.c
@@ -1672,8 +1672,12 @@ nautilus_window_close (NautilusWindow *window)
      * Usually, reference cycles are resolved in dispose(), but GTK removes the
      * controllers in finalize(), so our only option is to manually remove it
      * here before starting the destruction of the window. */
-    gtk_widget_remove_controller (GTK_WIDGET (window),
-                                  GTK_EVENT_CONTROLLER (window->pad_controller));
+    if (window->pad_controller != NULL)
+    {
+        gtk_widget_remove_controller (GTK_WIDGET (window),
+                                      GTK_EVENT_CONTROLLER (window->pad_controller));
+        g_clear_weak_pointer (&window->pad_controller);
+    }
 
     gtk_window_destroy (GTK_WINDOW (window));
 }
@@ -2064,6 +2068,7 @@ nautilus_window_init (NautilusWindow *window)
 {
     GtkWindowGroup *window_group;
     GtkEventController *controller;
+    GtkPadController *pad_controller;
 
     g_type_ensure (NAUTILUS_TYPE_TOOLBAR);
     g_type_ensure (NAUTILUS_TYPE_GTK_PLACES_SIDEBAR);
@@ -2098,8 +2103,11 @@ nautilus_window_init (NautilusWindow *window)
     /* Attention: this creates a reference cycle: the pad controller owns a
      * reference to the window (as an action group) and the window (as a widget)
      * owns a reference to the pad controller. To break this, we must remove
-     * the controller from the window before destroying the window. */
-    window->pad_controller = gtk_pad_controller_new (G_ACTION_GROUP (window), NULL);
+     * the controller from the window before destroying the window. But we need
+     * to know the controller is still alive before trying to remove it, so a
+     * weak reference is added. */
+    pad_controller = gtk_pad_controller_new (G_ACTION_GROUP (window), NULL);
+    g_set_weak_pointer (&window->pad_controller, pad_controller);
     gtk_pad_controller_set_action_entries (window->pad_controller,
                                            pad_actions, G_N_ELEMENTS (pad_actions));
     gtk_widget_add_controller (GTK_WIDGET (window),