From: Guido van Rossum <guido@python.org>
Date: Fri, 22 May 1998 00:53:24 +0000 (+0000)
Subject: In PyObject_IsTrue(), don't call function pointers that are NULL
X-Git-Tag: v1.5.2a1~569
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=1c4f45809994fcbebd3d43ec0c771b8900e205e8;p=python

In PyObject_IsTrue(), don't call function pointers that are NULL
(nb_nonzero, mp_length, sq_length).
---

diff --git a/Objects/object.c b/Objects/object.c
index 0588fea506..964c5c59f2 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -469,11 +469,14 @@ PyObject_IsTrue(v)
 	int res;
 	if (v == Py_None)
 		res = 0;
-	else if (v->ob_type->tp_as_number != NULL)
+	else if (v->ob_type->tp_as_number != NULL &&
+		 v->ob_type->tp_as_number->nb_nonzero != NULL)
 		res = (*v->ob_type->tp_as_number->nb_nonzero)(v);
-	else if (v->ob_type->tp_as_mapping != NULL)
+	else if (v->ob_type->tp_as_mapping != NULL &&
+		 v->ob_type->tp_as_mapping->mp_length != NULL)
 		res = (*v->ob_type->tp_as_mapping->mp_length)(v);
-	else if (v->ob_type->tp_as_sequence != NULL)
+	else if (v->ob_type->tp_as_sequence != NULL &&
+		 v->ob_type->tp_as_sequence->sq_length != NULL)
 		res = (*v->ob_type->tp_as_sequence->sq_length)(v);
 	else
 		res = 1;