[libdazzle] prefs: track destruction state of pref widgets

[Christian Hergert <chergert src gnome org>]

commit 5780f3829c94c9a8458c149b474bcce5d373e181
Author: Christian Hergert <chergert redhat com>
Date:   Sun Sep 24 23:46:06 2017 -0700

    prefs: track destruction state of pref widgets
    
    We want to be sure we don't call gtk_widget_destroy() on
    something that is already in the destruction process. Also,
    we want to ensure that we aren't holding onto pointers to
    widgets after they've been destroyed.
    
    This avoids that by using an indirection structure that allows
    us to zero out the widget field on GtkWidget::destroy.

 src/prefs/dzl-preferences-view.c |   77 ++++++++++++++++++++++++++++++-------
 1 files changed, 62 insertions(+), 15 deletions(-)
---
diff --git a/src/prefs/dzl-preferences-view.c b/src/prefs/dzl-preferences-view.c
index 494c04f..48791c4 100644
--- a/src/prefs/dzl-preferences-view.c
+++ b/src/prefs/dzl-preferences-view.c
@@ -44,6 +44,13 @@ typedef struct
   guint                  last_widget_id;
 } DzlPreferencesViewPrivate;
 
+typedef struct
+{
+  GtkWidget *widget;
+  gulong     handler;
+  guint      id;
+} TrackedWidget;
+
 static void dzl_preferences_iface_init (DzlPreferencesInterface *iface);
 
 G_DEFINE_TYPE_WITH_CODE (DzlPreferencesView, dzl_preferences_view, GTK_TYPE_BIN,
@@ -51,6 +58,39 @@ G_DEFINE_TYPE_WITH_CODE (DzlPreferencesView, dzl_preferences_view, GTK_TYPE_BIN,
                          G_IMPLEMENT_INTERFACE (DZL_TYPE_PREFERENCES, dzl_preferences_iface_init))
 
 static void
+tracked_widget_free (gpointer data)
+{
+  TrackedWidget *tracked = data;
+
+  if (tracked->widget != NULL)
+    g_signal_handler_disconnect (tracked->widget, tracked->handler);
+  g_slice_free (TrackedWidget, tracked);
+}
+
+static void
+dzl_preferences_view_track (DzlPreferencesView *self,
+                            guint               id,
+                            GtkWidget          *widget)
+{
+  DzlPreferencesViewPrivate *priv = dzl_preferences_view_get_instance_private (self);
+  TrackedWidget *tracked;
+
+  g_assert (DZL_IS_PREFERENCES_VIEW (self));
+  g_assert (id > 0);
+  g_assert (GTK_IS_WIDGET (widget));
+
+  tracked = g_slice_new0 (TrackedWidget);
+  tracked->widget = widget;
+  tracked->id = id;
+  tracked->handler = g_signal_connect (widget,
+                                       "destroy",
+                                       G_CALLBACK (gtk_widget_destroyed),
+                                       &tracked->widget);
+
+  g_hash_table_insert (priv->widgets, GUINT_TO_POINTER (id), tracked);
+}
+
+static void
 dzl_preferences_view_refilter_cb (GtkWidget *widget,
                                   gpointer   user_data)
 {
@@ -269,7 +309,8 @@ dzl_preferences_view_init (DzlPreferencesView *self)
                            G_CONNECT_SWAPPED);
 
   priv->pages = g_sequence_new (NULL);
-  priv->widgets = g_hash_table_new (g_direct_hash, g_direct_equal);
+  priv->widgets = g_hash_table_new_full (g_direct_hash, g_direct_equal,
+                                         NULL, tracked_widget_free);
 
   priv->actions = G_ACTION_GROUP (g_simple_action_group_new ());
   g_action_map_add_action_entries (G_ACTION_MAP (priv->actions),
@@ -476,7 +517,7 @@ dzl_preferences_view_add_radio (DzlPreferences *preferences,
   dzl_preferences_group_add (group, GTK_WIDGET (widget));
 
   widget_id = ++priv->last_widget_id;
-  g_hash_table_insert (priv->widgets, GINT_TO_POINTER (widget_id), widget);
+  dzl_preferences_view_track (self, widget_id, GTK_WIDGET (widget));
 
   return widget_id;
 }
@@ -553,7 +594,7 @@ dzl_preferences_view_add_switch (DzlPreferences *preferences,
   dzl_preferences_group_add (group, GTK_WIDGET (widget));
 
   widget_id = ++priv->last_widget_id;
-  g_hash_table_insert (priv->widgets, GINT_TO_POINTER (widget_id), widget);
+  dzl_preferences_view_track (self, widget_id, GTK_WIDGET (widget));
 
   return widget_id;
 }
@@ -616,7 +657,7 @@ dzl_preferences_view_add_spin_button (DzlPreferences *preferences,
   dzl_preferences_group_add (group, GTK_WIDGET (widget));
 
   widget_id = ++priv->last_widget_id;
-  g_hash_table_insert (priv->widgets, GINT_TO_POINTER (widget_id), widget);
+  dzl_preferences_view_track (self, widget_id, GTK_WIDGET (widget));
 
   return widget_id;
 }
@@ -674,7 +715,7 @@ dzl_preferences_view_add_font_button (DzlPreferences *preferences,
   dzl_preferences_group_add (group, GTK_WIDGET (widget));
 
   widget_id = ++priv->last_widget_id;
-  g_hash_table_insert (priv->widgets, GINT_TO_POINTER (widget_id), widget);
+  dzl_preferences_view_track (self, widget_id, GTK_WIDGET (widget));
 
   return widget_id;
 }
@@ -738,7 +779,7 @@ dzl_preferences_view_add_file_chooser (DzlPreferences       *preferences,
   dzl_preferences_group_add (group, GTK_WIDGET (widget));
 
   widget_id = ++priv->last_widget_id;
-  g_hash_table_insert (priv->widgets, GINT_TO_POINTER (widget_id), widget);
+  dzl_preferences_view_track (self, widget_id, GTK_WIDGET (widget));
 
   return widget_id;
 }
@@ -797,7 +838,7 @@ dzl_preferences_view_add_custom (DzlPreferences *preferences,
 
   dzl_preferences_group_add (group, GTK_WIDGET (container));
 
-  g_hash_table_insert (priv->widgets, GINT_TO_POINTER (widget_id), widget);
+  dzl_preferences_view_track (self, widget_id, GTK_WIDGET (widget));
 
   return widget_id;
 }
@@ -808,20 +849,25 @@ dzl_preferences_view_remove_id (DzlPreferences *preferences,
 {
   DzlPreferencesView *self = (DzlPreferencesView *)preferences;
   DzlPreferencesViewPrivate *priv = dzl_preferences_view_get_instance_private (self);
-  GtkWidget *widget;
+  TrackedWidget *tracked;
 
   g_assert (DZL_IS_PREFERENCES_VIEW (self));
   g_assert (widget_id);
 
-  widget = g_hash_table_lookup (priv->widgets, GINT_TO_POINTER (widget_id));
-  if (widget != NULL)
+  tracked = g_hash_table_lookup (priv->widgets, GUINT_TO_POINTER (widget_id));
+
+  if (tracked != NULL)
     {
-      if (g_hash_table_remove (priv->widgets, GINT_TO_POINTER (widget_id)))
+      GtkWidget *widget = tracked->widget;
+
+      g_hash_table_remove (priv->widgets, GUINT_TO_POINTER (widget_id));
+
+      if (widget != NULL && !gtk_widget_in_destruction (widget))
         {
           GtkWidget *parent = gtk_widget_get_ancestor (widget, GTK_TYPE_LIST_BOX_ROW);
 
           /* in case we added our own row ancestor, destroy it */
-          if (parent != NULL)
+          if (parent != NULL && !gtk_widget_in_destruction (parent))
             gtk_widget_destroy (parent);
           else
             gtk_widget_destroy (widget);
@@ -830,8 +876,6 @@ dzl_preferences_view_remove_id (DzlPreferences *preferences,
         }
     }
 
-  g_warning ("No Preferences widget with number %i could be found and thus removed.", widget_id);
-
   return FALSE;
 }
 
@@ -874,10 +918,13 @@ dzl_preferences_view_get_widget (DzlPreferences *preferences,
 {
   DzlPreferencesView *self = (DzlPreferencesView *)preferences;
   DzlPreferencesViewPrivate *priv = dzl_preferences_view_get_instance_private (self);
+  TrackedWidget *tracked;
 
   g_assert (DZL_IS_PREFERENCES_VIEW (self));
 
-  return g_hash_table_lookup (priv->widgets, GINT_TO_POINTER (widget_id));
+  tracked = g_hash_table_lookup (priv->widgets, GINT_TO_POINTER (widget_id));
+
+  return tracked ? tracked->widget : NULL;
 }
 
 static void