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gh-99184: Bypass instance attribute access in repr of weakref.ref #99244

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Merged
merged 2 commits into from
Apr 24, 2023
Merged

gh-99184: Bypass instance attribute access in repr of weakref.ref #99244

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d0aad14
gh-99184: Bypass instance attribute access in `repr` of `weakref.ref`
sobolevn Nov 8, 2022
5ca1917
Merge branch 'main' into issue-99184
sobolevn Mar 27, 2023
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11 changes: 11 additions & 0 deletions Lib/test/test_weakref.py
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Original file line number Diff line number Diff line change
Expand Up @@ -116,6 +116,17 @@ def test_basic_ref(self):
del o
repr(wr)

def test_repr_failure_gh99184(self):
class MyConfig(dict):
def __getattr__(self, x):
return self[x]

obj = MyConfig(offset=5)
obj_weakref = weakref.ref(obj)

self.assertIn('MyConfig', repr(obj_weakref))
self.assertIn('MyConfig', str(obj_weakref))

def test_basic_callback(self):
self.check_basic_callback(C)
self.check_basic_callback(create_function)
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2022-11-08-12-36-25.gh-issue-99184.KIaqzz.rst
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@@ -0,0 +1,2 @@
Bypass instance attribute access of ``__name__`` in ``repr`` of
:class:`weakref.ref`.
5 changes: 1 addition & 4 deletions Objects/weakrefobject.c
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Expand Up @@ -170,10 +170,7 @@ weakref_repr(PyWeakReference *self)
}

Py_INCREF(obj);
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Do we still need it? 🤔

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Yes, without it:

Fatal Python error: _PyObject_AssertFailed: _PyObject_AssertFailed
Python runtime state: initialized

Current thread 0x00000001039365c0 (most recent call first):
  File "/Users/sobolev/Desktop/cpython/Lib/test/test_weakref.py", line 116 in test_basic_ref
  File "/Users/sobolev/Desktop/cpython/Lib/unittest/case.py", line 579 in _callTestMethod

if (_PyObject_LookupAttr(obj, &_Py_ID(__name__), &name) < 0) {
Py_DECREF(obj);
return NULL;
}
name = _PyObject_LookupSpecial(obj, &_Py_ID(__name__));
if (name == NULL || !PyUnicode_Check(name)) {
repr = PyUnicode_FromFormat(
"<weakref at %p; to '%s' at %p>",
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