[Python-checkins] cpython (3.1): Issue #9756: When calling a method descriptor or a slot wrapper descriptor, the

[victor.stinner]

http://hg.python.org/cpython/rev/c5e6f997730e
changeset:   69741:c5e6f997730e
branch:      3.1
parent:      69733:c57fdce01eb8
user:        Victor Stinner <victor.stinner at haypocalc.com>
date:        Sun May 01 23:19:15 2011 +0200
summary:
  Issue #9756: When calling a method descriptor or a slot wrapper descriptor, the
check of the object type doesn't read the __class__ attribute anymore.  Fix a
crash if a class override its __class__ attribute (e.g. a proxy of the str
type).

files:
  Lib/test/test_descr.py |  16 ++++++++++++++++
  Misc/NEWS              |   5 +++++
  Objects/descrobject.c  |   9 ++++++---
  3 files changed, 27 insertions(+), 3 deletions(-)


diff --git a/Lib/test/test_descr.py b/Lib/test/test_descr.py
--- a/Lib/test/test_descr.py
+++ b/Lib/test/test_descr.py
@@ -4235,6 +4235,22 @@
         with self.assertRaises(AttributeError):
             del X.__abstractmethods__
 
+    def test_proxy_call(self):
+        class FakeStr:
+            __class__ = str
+
+        fake_str = FakeStr()
+        # isinstance() reads __class__
+        self.assertTrue(isinstance(fake_str, str))
+
+        # call a method descriptor
+        with self.assertRaises(TypeError):
+            str.split(fake_str)
+
+        # call a slot wrapper descriptor
+        with self.assertRaises(TypeError):
+            str.__add__(fake_str, "abc")
+
 
 class DictProxyTests(unittest.TestCase):
     def setUp(self):
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,11 @@
 Core and Builtins
 -----------------
 
+- Issue #9756: When calling a method descriptor or a slot wrapper descriptor,
+  the check of the object type doesn't read the __class__ attribute anymore.
+  Fix a crash if a class override its __class__ attribute (e.g. a proxy of the
+  str type).
+
 - Issue #6780: fix starts/endswith error message to mention that tuples are
   accepted too.
 
diff --git a/Objects/descrobject.c b/Objects/descrobject.c
--- a/Objects/descrobject.c
+++ b/Objects/descrobject.c
@@ -226,7 +226,8 @@
         return NULL;
     }
     self = PyTuple_GET_ITEM(args, 0);
-    if (!PyObject_IsInstance(self, (PyObject *)(descr->d_type))) {
+    if (!_PyObject_RealIsSubclass((PyObject *)Py_TYPE(self),
+                                  (PyObject *)(descr->d_type))) {
         PyErr_Format(PyExc_TypeError,
                      "descriptor '%V' "
                      "requires a '%.100s' object "
@@ -284,7 +285,8 @@
         return NULL;
     }
     self = PyTuple_GET_ITEM(args, 0);
-    if (!PyObject_IsInstance(self, (PyObject *)(descr->d_type))) {
+    if (!_PyObject_RealIsSubclass((PyObject *)Py_TYPE(self),
+                                  (PyObject *)(descr->d_type))) {
         PyErr_Format(PyExc_TypeError,
                      "descriptor '%V' "
                      "requires a '%.100s' object "
@@ -1065,7 +1067,8 @@
 
     assert(PyObject_TypeCheck(d, &PyWrapperDescr_Type));
     descr = (PyWrapperDescrObject *)d;
-    assert(PyObject_IsInstance(self, (PyObject *)(descr->d_type)));
+    assert(_PyObject_RealIsSubclass((PyObject *)Py_TYPE(self),
+                                    (PyObject *)(descr->d_type)));
 
     wp = PyObject_GC_New(wrapperobject, &wrappertype);
     if (wp != NULL) {

-- 
Repository URL: http://hg.python.org/cpython