Fix for
[ 784825 ] fix obscure crash in descriptor handling Should be applied to release23-maint and in all likelyhood release22-maint, too. Certainly doesn't apply to release21-maint.
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@ -3938,6 +3938,36 @@ def filefault():
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except RuntimeError:
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pass
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def vicious_descriptor_nonsense():
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# A potential segfault spotted by Thomas Wouters in mail to
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# python-dev 2003-04-17, turned into an example & fixed by Michael
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# Hudson just less than four months later...
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if verbose:
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print "Testing vicious_descriptor_nonsense..."
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class Evil(object):
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def __hash__(self):
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return hash('attr')
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def __eq__(self, other):
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del C.attr
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return 0
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class Descr(object):
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def __get__(self, ob, type=None):
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return 1
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class C(object):
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attr = Descr()
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c = C()
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c.__dict__[Evil()] = 0
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vereq(c.attr, 1)
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# this makes a crash more likely:
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import gc; gc.collect()
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vereq(hasattr(c, 'attr'), False)
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def test_main():
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weakref_segfault() # Must be first, somehow
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do_this_first()
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@ -4029,6 +4059,7 @@ def test_main():
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proxysuper()
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carloverre()
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filefault()
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vicious_descriptor_nonsense()
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if verbose: print "All OK"
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@ -1412,12 +1412,15 @@ PyObject_GenericGetAttr(PyObject *obj, PyObject *name)
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}
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}
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Py_XINCREF(descr);
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f = NULL;
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if (descr != NULL &&
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PyType_HasFeature(descr->ob_type, Py_TPFLAGS_HAVE_CLASS)) {
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f = descr->ob_type->tp_descr_get;
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if (f != NULL && PyDescr_IsData(descr)) {
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res = f(descr, obj, (PyObject *)obj->ob_type);
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Py_DECREF(descr);
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goto done;
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}
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}
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@ -1445,6 +1448,7 @@ PyObject_GenericGetAttr(PyObject *obj, PyObject *name)
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res = PyDict_GetItem(dict, name);
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if (res != NULL) {
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Py_INCREF(res);
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Py_XDECREF(descr);
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goto done;
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}
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}
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@ -1452,12 +1456,13 @@ PyObject_GenericGetAttr(PyObject *obj, PyObject *name)
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if (f != NULL) {
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res = f(descr, obj, (PyObject *)obj->ob_type);
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Py_DECREF(descr);
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goto done;
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}
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if (descr != NULL) {
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Py_INCREF(descr);
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res = descr;
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/* descr was already increfed above */
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goto done;
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}
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@ -2010,6 +2010,7 @@ type_getattro(PyTypeObject *type, PyObject *name)
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return meta_get(meta_attribute, (PyObject *)type,
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(PyObject *)metatype);
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}
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Py_INCREF(meta_attribute);
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}
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/* No data descriptor found on metatype. Look in tp_dict of this
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@ -2018,6 +2019,9 @@ type_getattro(PyTypeObject *type, PyObject *name)
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if (attribute != NULL) {
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/* Implement descriptor functionality, if any */
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descrgetfunc local_get = attribute->ob_type->tp_descr_get;
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Py_XDECREF(meta_attribute);
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if (local_get != NULL) {
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/* NULL 2nd argument indicates the descriptor was
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* found on the target object itself (or a base) */
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@ -2031,13 +2035,16 @@ type_getattro(PyTypeObject *type, PyObject *name)
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/* No attribute found in local __dict__ (or bases): use the
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* descriptor from the metatype, if any */
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if (meta_get != NULL)
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return meta_get(meta_attribute, (PyObject *)type,
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(PyObject *)metatype);
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if (meta_get != NULL) {
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PyObject *res;
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res = meta_get(meta_attribute, (PyObject *)type,
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(PyObject *)metatype);
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Py_DECREF(meta_attribute);
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return res;
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}
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/* If an ordinary attribute was found on the metatype, return it now */
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if (meta_attribute != NULL) {
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Py_INCREF(meta_attribute);
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return meta_attribute;
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}
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