[perl-Glib-Object-Introspection] Fix stack handling when there are more parameters after a callback parameter

[Torsten Schönfeld <tsch src gnome org>]

commit 8ce5cf4237b7ac0a30d28e11584929b8d818c974
Author: Torsten Schönfeld <kaffeetisch gmx de>
Date:   Sun Aug 8 18:54:55 2010 +0200

    Fix stack handling when there are more parameters after a callback parameter
    
    The destroy notify pointer associated to the callback is not provided by the
    user, so we need to adjust the stack offset to make sure no Perl value is
    'swallowed'.

 GObjectIntrospection.xs |   16 ++++++++++++----
 1 files changed, 12 insertions(+), 4 deletions(-)
---
diff --git a/GObjectIntrospection.xs b/GObjectIntrospection.xs
index 096d0aa..7a9d8c9 100644
--- a/GObjectIntrospection.xs
+++ b/GObjectIntrospection.xs
@@ -54,6 +54,7 @@ typedef struct {
  * to later calls of sv_to_arg. */
 typedef struct {
 	guint current_pos;
+	gint dynamic_stack_offset;
 	GSList * callback_infos;
 	GSList * free_after_call;
 } GPerlI11nInvocationInfo;
@@ -161,6 +162,10 @@ handle_callback_arg (GIArgInfo * arg_info,
 		if (invocation_info->current_pos == callback_info->notify_pos) {
 			dwarn ("      destroy notify for callback %p\n",
 			       callback_info);
+			/* Decrease the dynamic stack offset so that this
+			 * destroy notify callback doesn't consume any Perl
+			 * value from the stack. */
+			invocation_info->dynamic_stack_offset--;
 			return release_callback;
 		}
 	}
@@ -1681,6 +1686,7 @@ PPCODE:
 	}
 
 	method_offset = is_method ? 1 : 0;
+	invocation_info.dynamic_stack_offset = 0;
 
 	for (i = 0 ; i < n_args ; i++) {
 		GIArgInfo * arg_info =
@@ -1689,22 +1695,24 @@ PPCODE:
 		 * the function has been invoked */
 		GITypeInfo * arg_type = g_arg_info_get_type (arg_info);
 		gboolean may_be_null = g_arg_info_may_be_null (arg_info);
+		guint perl_stack_pos = i + method_offset + stack_offset
+			+ invocation_info.dynamic_stack_offset;
 
 		/* FIXME: Is it right to just add method_offset here?  I'm
 		 * confused about the relation of the numbers in
 		 * g_callable_info_get_arg and g_arg_info_get_closure and
 		 * g_arg_info_get_destroy. */
-		invocation_info.current_pos = method_offset + i;
+		invocation_info.current_pos = i + method_offset;
 
 		dwarn ("  arg tag: %d (%s)\n",
 		       g_type_info_get_tag (arg_type),
 		       g_type_tag_to_string (g_type_info_get_tag (arg_type)));
 
 		/* FIXME: Check that i+method_offset+stack_offset<items before
-		 * calling ST, and generate a usage methods otherwise. */
+		 * calling ST, and generate a usage message otherwise. */
 		switch (g_arg_info_get_direction (arg_info)) {
 		    case GI_DIRECTION_IN:
-			sv_to_arg (ST (i + method_offset + stack_offset),
+			sv_to_arg (ST (perl_stack_pos),
 			           &in_args[n_in_args], arg_info, arg_type,
 			           may_be_null, &invocation_info);
 			arg_types[i + method_offset] =
@@ -1725,7 +1733,7 @@ PPCODE:
 		    {
 			GArgument * temp =
 				gperl_alloc_temp (sizeof (GArgument));
-			sv_to_arg (ST (i + method_offset + stack_offset),
+			sv_to_arg (ST (perl_stack_pos),
 			           temp, arg_info, arg_type, may_be_null,
 			           &invocation_info);
 			in_args[n_in_args].v_pointer =