diff options
| -rw-r--r-- | Objects/typeobject.c | 103 | ||||
| -rw-r--r-- | Python/pylifecycle.c | 3 |
2 files changed, 82 insertions, 24 deletions
diff --git a/Objects/typeobject.c b/Objects/typeobject.c index 8510196..f9e6f63 100644 --- a/Objects/typeobject.c +++ b/Objects/typeobject.c @@ -65,6 +65,8 @@ lookup_maybe_method(PyObject *self, PyObject *attr, int *unbound); static int slot_tp_setattro(PyObject *self, PyObject *name, PyObject *value); +static inline PyTypeObject * subclass_from_ref(PyObject *ref); + /* * finds the beginning of the docstring's introspection signature. * if present, returns a pointer pointing to the first '('. @@ -309,12 +311,11 @@ PyType_Modified(PyTypeObject *type) Py_ssize_t i = 0; PyObject *ref; while (PyDict_Next(subclasses, &i, NULL, &ref)) { - assert(PyWeakref_CheckRef(ref)); - PyObject *obj = PyWeakref_GET_OBJECT(ref); - if (obj == Py_None) { + PyTypeObject *subclass = subclass_from_ref(ref); // borrowed + if (subclass == NULL) { continue; } - PyType_Modified(_PyType_CAST(obj)); + PyType_Modified(subclass); } } @@ -4211,23 +4212,48 @@ type_dealloc_common(PyTypeObject *type) } -void -_PyStaticType_Dealloc(PyTypeObject *type) +static void +clear_static_tp_subclasses(PyTypeObject *type) { - // If a type still has subtypes, it cannot be deallocated. - // A subtype can inherit attributes and methods of its parent type, - // and a type must no longer be used once it's deallocated. - if (type->tp_subclasses != NULL) { + if (type->tp_subclasses == NULL) { return; } + /* Normally it would be a problem to finalize the type if its + tp_subclasses wasn't cleared first. However, this is only + ever called at the end of runtime finalization, so we can be + more liberal in cleaning up. If the given type still has + subtypes at this point then some extension module did not + correctly finalize its objects. + + We can safely obliterate such subtypes since the extension + module and its objects won't be used again, except maybe if + the runtime were re-initialized. In that case the sticky + situation would only happen if the module were re-imported + then and only if the subtype were stored in a global and only + if that global were not overwritten during import. We'd be + fine since the extension is otherwise unsafe and unsupported + in that situation, and likely problematic already. + + In any case, this situation means at least some memory is + going to leak. This mostly only affects embedding scenarios. + */ + + // For now we just clear tp_subclasses. + + Py_CLEAR(type->tp_subclasses); +} + +void +_PyStaticType_Dealloc(PyTypeObject *type) +{ type_dealloc_common(type); Py_CLEAR(type->tp_dict); Py_CLEAR(type->tp_bases); Py_CLEAR(type->tp_mro); Py_CLEAR(type->tp_cache); - // type->tp_subclasses is NULL + clear_static_tp_subclasses(type); // PyObject_ClearWeakRefs() raises an exception if Py_REFCNT() != 0 if (Py_REFCNT(type) == 0) { @@ -4296,14 +4322,12 @@ _PyType_GetSubclasses(PyTypeObject *self) Py_ssize_t i = 0; PyObject *ref; // borrowed ref while (PyDict_Next(subclasses, &i, NULL, &ref)) { - assert(PyWeakref_CheckRef(ref)); - PyObject *obj = PyWeakref_GET_OBJECT(ref); // borrowed ref - if (obj == Py_None) { + PyTypeObject *subclass = subclass_from_ref(ref); // borrowed + if (subclass == NULL) { continue; } - assert(PyType_Check(obj)); - if (PyList_Append(list, obj) < 0) { + if (PyList_Append(list, _PyObject_CAST(subclass)) < 0) { Py_DECREF(list); return NULL; } @@ -6708,6 +6732,42 @@ add_all_subclasses(PyTypeObject *type, PyObject *bases) return res; } +static inline PyTypeObject * +subclass_from_ref(PyObject *ref) +{ + assert(PyWeakref_CheckRef(ref)); + PyObject *obj = PyWeakref_GET_OBJECT(ref); // borrowed ref + assert(obj != NULL); + if (obj == Py_None) { + return NULL; + } + assert(PyType_Check(obj)); + return _PyType_CAST(obj); +} + +static PyObject * +get_subclasses_key(PyTypeObject *type, PyTypeObject *base) +{ + PyObject *key = PyLong_FromVoidPtr((void *) type); + if (key != NULL) { + return key; + } + PyErr_Clear(); + + /* This basically means we're out of memory. + We fall back to manually traversing the values. */ + Py_ssize_t i = 0; + PyObject *ref; // borrowed ref + while (PyDict_Next((PyObject *)base->tp_subclasses, &i, &key, &ref)) { + PyTypeObject *subclass = subclass_from_ref(ref); // borrowed + if (subclass == type) { + return Py_NewRef(key); + } + } + /* It wasn't found. */ + return NULL; +} + static void remove_subclass(PyTypeObject *base, PyTypeObject *type) { @@ -6717,8 +6777,8 @@ remove_subclass(PyTypeObject *base, PyTypeObject *type) } assert(PyDict_CheckExact(subclasses)); - PyObject *key = PyLong_FromVoidPtr((void *) type); - if (key == NULL || PyDict_DelItem(subclasses, key)) { + PyObject *key = get_subclasses_key(type, base); + if (key != NULL && PyDict_DelItem(subclasses, key)) { /* This can happen if the type initialization errored out before the base subclasses were updated (e.g. a non-str __qualname__ was passed in the type dict). */ @@ -8811,13 +8871,10 @@ recurse_down_subclasses(PyTypeObject *type, PyObject *attr_name, Py_ssize_t i = 0; PyObject *ref; while (PyDict_Next(subclasses, &i, NULL, &ref)) { - assert(PyWeakref_CheckRef(ref)); - PyObject *obj = PyWeakref_GET_OBJECT(ref); - assert(obj != NULL); - if (obj == Py_None) { + PyTypeObject *subclass = subclass_from_ref(ref); // borrowed + if (subclass == NULL) { continue; } - PyTypeObject *subclass = _PyType_CAST(obj); /* Avoid recursing down into unaffected classes */ PyObject *dict = subclass->tp_dict; diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c index 13efa6f..11a4580 100644 --- a/Python/pylifecycle.c +++ b/Python/pylifecycle.c @@ -1672,9 +1672,10 @@ finalize_interp_types(PyInterpreterState *interp) _PyLong_FiniTypes(interp); _PyThread_FiniType(interp); _PyErr_FiniTypes(interp); - _PyTypes_Fini(interp); _PyTypes_FiniTypes(interp); + _PyTypes_Fini(interp); + // Call _PyUnicode_ClearInterned() before _PyDict_Fini() since it uses // a dict internally. _PyUnicode_ClearInterned(interp); |