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Issue python#5322: Fixed setting __new__ to a PyCFunction inside Python code.
Original patch by Andreas Stührk.
1 parent 9bd44d6 commit daf82f7

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3 files changed

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+127
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lines changed

‎Lib/test/test_descr.py

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Original file line numberDiff line numberDiff line change
@@ -3,6 +3,7 @@
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import sys
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import types
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import unittest
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import warnings
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import weakref
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from copy import deepcopy
@@ -1550,6 +1551,84 @@ class D(C):
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self.assertEqual(b.foo, 3)
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self.assertEqual(b.__class__, D)
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def test_bad_new(self):
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self.assertRaises(TypeError, object.__new__)
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self.assertRaises(TypeError, object.__new__, '')
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self.assertRaises(TypeError, list.__new__, object)
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self.assertRaises(TypeError, object.__new__, list)
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class C(object):
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__new__ = list.__new__
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self.assertRaises(TypeError, C)
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class C(list):
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__new__ = object.__new__
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self.assertRaises(TypeError, C)
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def test_object_new(self):
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class A(object):
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pass
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object.__new__(A)
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self.assertRaises(TypeError, object.__new__, A, 5)
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object.__init__(A())
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self.assertRaises(TypeError, object.__init__, A(), 5)
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class A(object):
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def __init__(self, foo):
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self.foo = foo
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object.__new__(A)
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object.__new__(A, 5)
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object.__init__(A(3))
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self.assertRaises(TypeError, object.__init__, A(3), 5)
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class A(object):
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def __new__(cls, foo):
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return object.__new__(cls)
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object.__new__(A)
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self.assertRaises(TypeError, object.__new__, A, 5)
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object.__init__(A(3))
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object.__init__(A(3), 5)
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class A(object):
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def __new__(cls, foo):
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return object.__new__(cls)
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def __init__(self, foo):
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self.foo = foo
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object.__new__(A)
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with warnings.catch_warnings(record=True) as w:
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warnings.simplefilter('always', DeprecationWarning)
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a = object.__new__(A, 5)
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self.assertEqual(type(a), A)
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self.assertEqual(len(w), 1)
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object.__init__(A(3))
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a = A(3)
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with warnings.catch_warnings(record=True) as w:
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warnings.simplefilter('always', DeprecationWarning)
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object.__init__(a, 5)
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self.assertEqual(a.foo, 3)
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self.assertEqual(len(w), 1)
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def test_restored_object_new(self):
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class A(object):
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def __new__(cls, *args, **kwargs):
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raise AssertionError
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self.assertRaises(AssertionError, A)
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class B(A):
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__new__ = object.__new__
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def __init__(self, foo):
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self.foo = foo
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with warnings.catch_warnings():
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warnings.simplefilter('error', DeprecationWarning)
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b = B(3)
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self.assertEqual(b.foo, 3)
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self.assertEqual(b.__class__, B)
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del B.__new__
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self.assertRaises(AssertionError, B)
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del A.__new__
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with warnings.catch_warnings():
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warnings.simplefilter('error', DeprecationWarning)
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b = B(3)
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self.assertEqual(b.foo, 3)
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self.assertEqual(b.__class__, B)
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def test_altmro(self):
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# Testing mro() and overriding it...
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class A(object):
@@ -3756,6 +3835,24 @@ def __init__(self, arg):
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self.assertEqual(isinstance(d, D), True)
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self.assertEqual(d.foo, 1)
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class C(object):
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@staticmethod
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def __new__(*args):
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return args
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self.assertEqual(C(1, 2), (C, 1, 2))
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class D(C):
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pass
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self.assertEqual(D(1, 2), (D, 1, 2))
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class C(object):
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@classmethod
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def __new__(*args):
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return args
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self.assertEqual(C(1, 2), (C, C, 1, 2))
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class D(C):
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pass
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self.assertEqual(D(1, 2), (D, D, 1, 2))
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def test_imul_bug(self):
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# Testing for __imul__ problems...
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# SF bug 544647

‎Misc/NEWS

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@@ -10,6 +10,9 @@ What's New in Python 2.7.13?
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Core and Builtins
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-----------------
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- Issue #5322: Fixed setting __new__ to a PyCFunction inside Python code.
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Original patch by Andreas Stührk.
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- Issue #28847: dubmdbm no longer writes the index file in when it is not
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changed and supports reading read-only files.
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‎Objects/typeobject.c

Lines changed: 27 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -6304,7 +6304,33 @@ update_one_slot(PyTypeObject *type, slotdef *p)
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sanity checks and constructing a new argument
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list. Cut all that nonsense short -- this speeds
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up instance creation tremendously. */
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specific = (void *)type->tp_new;
6307+
PyObject *self = PyCFunction_GET_SELF(descr);
6308+
if (!self || !PyType_Check(self)) {
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/* This should never happen because
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tp_new_wrapper expects a type for self.
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Use slot_tp_new which will call
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tp_new_wrapper which will raise an
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exception. */
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specific = (void *)slot_tp_new;
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}
6316+
else {
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specific = ((PyTypeObject *)self)->tp_new;
6318+
/* Check that the user does not do anything
6319+
silly and unsafe like object.__new__(dict).
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To do this, we check that the most derived
6321+
base that's not a heap type is this type. */
6322+
PyTypeObject *staticbase = type->tp_base;
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while (staticbase &&
6324+
(staticbase->tp_flags & Py_TPFLAGS_HEAPTYPE))
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staticbase = staticbase->tp_base;
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if (staticbase &&
6327+
staticbase->tp_new != specific)
6328+
/* Seems to be unsafe, better use
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slot_tp_new which will call
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tp_new_wrapper which will raise an
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exception if it is unsafe. */
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specific = (void *)slot_tp_new;
6333+
}
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/* XXX I'm not 100% sure that there isn't a hole
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in this reasoning that requires additional
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sanity checks. I'll buy the first person to

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