[pygobject] Fix mid-argument list callback user data expecting a tuple

[Simon Feltman <sfeltman src gnome org>]

commit 44d003798d9d14dde16fb44c69b94a411bdee26b
Author: Simon Feltman <sfeltman src gnome org>
Date:   Mon Jan 13 16:51:41 2014 -0800

    Fix mid-argument list callback user data expecting a tuple
    
    Ensure user data arguments are always packed into a tuple during callback
    marshaling. This fixes cases where there is mid-argument user data which is
    not in the form of a variable length tuple.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=722104

 gi/pygi-marshal-from-py.c |   16 +++++++++++++++-
 1 files changed, 15 insertions(+), 1 deletions(-)
---
diff --git a/gi/pygi-marshal-from-py.c b/gi/pygi-marshal-from-py.c
index ed2e582..41dcf54 100644
--- a/gi/pygi-marshal-from-py.c
+++ b/gi/pygi-marshal-from-py.c
@@ -1362,8 +1362,19 @@ _pygi_marshal_from_py_interface_callback (PyGIInvokeState   *state,
             /* NULL out user_data if it was not supplied and the default arg placeholder
              * was used instead.
              */
-            if (py_user_data == _PyGIDefaultArgPlaceholder)
+            if (py_user_data == _PyGIDefaultArgPlaceholder) {
                 py_user_data = NULL;
+            } else if (callable_cache->user_data_varargs_index < 0) {
+                /* For non-variable length user data, place the user data in a
+                 * single item tuple which is concatenated to the callbacks arguments.
+                 * This allows callback input arg marshaling to always expect a
+                 * tuple for user data. Note the
+                 */
+                py_user_data = Py_BuildValue("(O)", py_user_data, NULL);
+            } else {
+                /* increment the ref borrowed from PyTuple_GetItem above */
+                Py_INCREF (py_user_data);
+            }
         }
     }
 
@@ -1384,6 +1395,9 @@ _pygi_marshal_from_py_interface_callback (PyGIInvokeState   *state,
     closure = _pygi_make_native_closure (callable_info, callback_cache->scope, py_arg, py_user_data);
     arg->v_pointer = closure->closure;
 
+    /* always decref the user data as _pygi_make_native_closure adds its own ref */
+    Py_XDECREF (py_user_data);
+
     /* The PyGICClosure instance is used as user data passed into the C function.
      * The return trip to python will marshal this back and pull the python user data out.
      */