From ab61fbccbd29973d11ade9c9349a054ec00a4eda Mon Sep 17 00:00:00 2001
From: Bertrand Lorentz <bertrand.lorentz@gmail.com>
Date: Sun, 18 Nov 2012 16:06:34 +0100
Subject: [PATCH] glib: Fix crash when freeing lists with elements typed as
 interfaces

If a GList or a GSList had its element type set to a GInterface, and if
the elements were marked as owned, it would end up freeing those
elements with g_free(), which would lead to a crash.

They need to be unreffed with g_object_unref, but the criteria for that
was whether the element type is assignable to GLib.Object. This is not
true for GInterface types.

We now first check if the element type is an opaque. If not, and if it's
assignable to GLib.IWrapper, we then use g_object_unref.

From what I can see, all GLib.IWrapper subclasses that not opaque can be
unreffed with g_object_unref.
---
 glib/ListBase.cs | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/glib/ListBase.cs b/glib/ListBase.cs
index d5360a347..3077b80b9 100644
--- a/glib/ListBase.cs
+++ b/glib/ListBase.cs
@@ -188,14 +188,17 @@ namespace GLib {
 
 		public void Empty ()
 		{
-			if (elements_owned)
-				for (uint i = 0; i < Count; i++)
-					if (typeof (GLib.Object).IsAssignableFrom (element_type))
-						g_object_unref (NthData (i));
-					else if (typeof (GLib.Opaque).IsAssignableFrom (element_type))
+			if (elements_owned) {
+				for (uint i = 0; i < Count; i++) {
+					if (typeof (GLib.Opaque).IsAssignableFrom (element_type)) {
 						GLib.Opaque.GetOpaque (NthData (i), element_type, true).Dispose ();
-					else 
+					} else if (typeof (GLib.IWrapper).IsAssignableFrom (element_type)) {
+						g_object_unref (NthData (i));
+					} else {
 						g_free (NthData (i));
+					}
+				}
+			}
 
 			if (managed)
 				FreeList ();