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bpo-35983: skip trashcan for subclasses (GH-11841)

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Add new trashcan macros to deal with a double deallocation that could occur when the `tp_dealloc` of a subclass calls the `tp_dealloc` of a base class and that base class uses the trashcan mechanism.

Patch by Jeroen Demeyer.
This commit is contained in:
Jeroen Demeyer 2019-05-10 19:21:11 +02:00 • committed by Antoine Pitrou
parent a2fedd8c91
commit 351c67416b
15 changed files with 189 additions and 121 deletions
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4
Modules/_elementtree.c
View file

@ -669,7 +669,7 @@ element_dealloc(ElementObject* self)
{
/* bpo-31095: UnTrack is needed before calling any callbacks */
PyObject_GC_UnTrack(self);
Py_TRASHCAN_SAFE_BEGIN(self)
Py_TRASHCAN_BEGIN(self, element_dealloc)
if (self->weakreflist != NULL)
PyObject_ClearWeakRefs((PyObject *) self);
@ -680,7 +680,7 @@ element_dealloc(ElementObject* self)
RELEASE(sizeof(ElementObject), "destroy element");
Py_TYPE(self)->tp_free((PyObject *)self);
Py_TRASHCAN_SAFE_END(self)
Py_TRASHCAN_END
}
/* -------------------------------------------------------------------- */

76
Modules/_testcapimodule.c
View file

@ -5451,6 +5451,76 @@ recurse_infinitely_error_init(PyObject *self, PyObject *args, PyObject *kwds)
}
/* Test bpo-35983: create a subclass of "list" which checks that instances
* are not deallocated twice */
typedef struct {
PyListObject list;
int deallocated;
} MyListObject;
static PyObject *
MyList_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
PyObject* op = PyList_Type.tp_new(type, args, kwds);
((MyListObject*)op)->deallocated = 0;
return op;
}
void
MyList_dealloc(MyListObject* op)
{
if (op->deallocated) {
/* We cannot raise exceptions here but we still want the testsuite
* to fail when we hit this */
Py_FatalError("MyList instance deallocated twice");
}
op->deallocated = 1;
PyList_Type.tp_dealloc((PyObject *)op);
}
static PyTypeObject MyList_Type = {
PyVarObject_HEAD_INIT(NULL, 0)
"MyList",
sizeof(MyListObject),
0,
(destructor)MyList_dealloc, /* tp_dealloc */
0, /* tp_print */
0, /* tp_getattr */
0, /* tp_setattr */
0, /* tp_reserved */
0, /* tp_repr */
0, /* tp_as_number */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
0, /* tp_str */
0, /* tp_getattro */
0, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */
0, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
0, /* tp_richcompare */
0, /* tp_weaklistoffset */
0, /* tp_iter */
0, /* tp_iternext */
0, /* tp_methods */
0, /* tp_members */
0, /* tp_getset */
0, /* &PyList_Type */ /* tp_base */
0, /* tp_dict */
0, /* tp_descr_get */
0, /* tp_descr_set */
0, /* tp_dictoffset */
0, /* tp_init */
0, /* tp_alloc */
MyList_new, /* tp_new */
};
/* Test PEP 560 */
typedef struct {
@ -5564,6 +5634,12 @@ PyInit__testcapi(void)
Py_INCREF(&awaitType);
PyModule_AddObject(m, "awaitType", (PyObject *)&awaitType);
MyList_Type.tp_base = &PyList_Type;
if (PyType_Ready(&MyList_Type) < 0)
return NULL;
Py_INCREF(&MyList_Type);
PyModule_AddObject(m, "MyList", (PyObject *)&MyList_Type);
if (PyType_Ready(&GenericAlias_Type) < 0)
return NULL;
Py_INCREF(&GenericAlias_Type);