From: Guido van Rossum <guido@python.org>
Date: Fri, 25 Apr 2003 05:40:32 +0000 (+0000)
Subject: Backport the Carlo Verre fix.
X-Git-Tag: v2.2.3c1~56
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=4f017eb311454044f187d2e2930885c4da3d1eec;p=thirdparty%2FPython%2Fcpython.git

Backport the Carlo Verre fix.
---

diff --git a/Misc/NEWS b/Misc/NEWS
index ed690b5cb0fd..e1ec2511916e 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -2,6 +2,9 @@ What's New in Python 2.2.3 ?
 Release date: XX-XXX-2003
 ============================
 
+- It is no longer possible to use object.__setattr__ to circumvent the
+  restrictions on setting attributes of type objects.
+
 - Implemented os.fsync() for Windows, where it calls the MS _commit()
   function.  Before, there was no way in core Python to ensure file
   writes actually showed up on disk when necessary.
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index b674c337783c..e4b4c5c2d748 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -2594,6 +2594,24 @@ wrap_cmpfunc(PyObject *self, PyObject *args, void *wrapped)
 	return PyInt_FromLong((long)res);
 }
 
+/* Helper to check for object.__setattr__ or __delattr__ applied to a type.
+   This is called the Carlo Verre hack after its discoverer. */
+static int
+hackcheck(PyObject *self, setattrofunc func, char *what)
+{
+	PyTypeObject *type = self->ob_type;
+	while (type && type->tp_flags & Py_TPFLAGS_HEAPTYPE)
+		type = type->tp_base;
+	if (type->tp_setattro != func) {
+		PyErr_Format(PyExc_TypeError,
+			     "can't apply this %s to %s object",
+			     what,
+			     type->tp_name);
+		return 0;
+	}
+	return 1;
+}
+
 static PyObject *
 wrap_setattr(PyObject *self, PyObject *args, void *wrapped)
 {
@@ -2603,6 +2621,8 @@ wrap_setattr(PyObject *self, PyObject *args, void *wrapped)
 
 	if (!PyArg_ParseTuple(args, "OO", &name, &value))
 		return NULL;
+	if (!hackcheck(self, func, "__setattr__"))
+		return NULL;
 	res = (*func)(self, name, value);
 	if (res < 0)
 		return NULL;
@@ -2619,6 +2639,8 @@ wrap_delattr(PyObject *self, PyObject *args, void *wrapped)
 
 	if (!PyArg_ParseTuple(args, "O", &name))
 		return NULL;
+	if (!hackcheck(self, func, "__delattr__"))
+		return NULL;
 	res = (*func)(self, name, NULL);
 	if (res < 0)
 		return NULL;