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gh-94673: Hide Objects in PyTypeObject Behind Accessors #104074

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Merged
ericsnowcurrently merged 4 commits into from
May 2, 2023
Merged

gh-94673: Hide Objects in PyTypeObject Behind Accessors #104074

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6423170
Clean up the accessors for tp_subclasses.
ericsnowcurrently May 2, 2023
bd5c65f
Add accessors for tp_mro.
ericsnowcurrently May 2, 2023
81258e6
Add accessors for tp_bases.
ericsnowcurrently May 2, 2023
f141579
Add accessors for tp_dict.
ericsnowcurrently May 2, 2023
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Add accessors for tp_bases.
  • Loading branch information
@ericsnowcurrently
ericsnowcurrently committed May 2, 2023
commit 81258e6585060bc22bbf2324fe00d4e6de6b1b63
1 change: 1 addition & 0 deletions Include/internal/pycore_typeobject.h
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Original file line number Diff line number Diff line change
Expand Up @@ -109,6 +109,7 @@ extern static_builtin_state * _PyStaticType_GetState(PyInterpreterState *, PyTyp
extern void _PyStaticType_ClearWeakRefs(PyInterpreterState *, PyTypeObject *type);
extern void _PyStaticType_Dealloc(PyInterpreterState *, PyTypeObject *);

extern PyObject * _PyType_GetBases(PyTypeObject *type);
extern PyObject * _PyType_GetMRO(PyTypeObject *type);
extern PyObject* _PyType_GetSubclasses(PyTypeObject *);

Expand Down
60 changes: 43 additions & 17 deletions Objects/typeobject.c
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Expand Up @@ -169,6 +169,31 @@ static_builtin_state_clear(PyInterpreterState *interp, PyTypeObject *self)

/* accessors for objects stored on PyTypeObject */

static inline PyObject *
lookup_tp_bases(PyTypeObject *self)
{
return self->tp_bases;
}

PyObject *
_PyType_GetBases(PyTypeObject *self)
{
return lookup_tp_bases(self);
}

static inline void
set_tp_bases(PyTypeObject *self, PyObject *bases)
{
self->tp_bases = bases;
}

static inline void
clear_tp_bases(PyTypeObject *self)
{
Py_CLEAR(self->tp_bases);
}


static inline PyObject *
lookup_tp_mro(PyTypeObject *self)
{
Expand Down Expand Up @@ -730,7 +755,7 @@ assign_version_tag(PyInterpreterState *interp, PyTypeObject *type)
assert (type->tp_version_tag != 0);
}

PyObject *bases = type->tp_bases;
PyObject *bases = lookup_tp_bases(type);
Py_ssize_t n = PyTuple_GET_SIZE(bases);
for (Py_ssize_t i = 0; i < n; i++) {
PyObject *b = PyTuple_GET_ITEM(bases, i);
Expand Down Expand Up @@ -969,7 +994,7 @@ type_set_abstractmethods(PyTypeObject *type, PyObject *value, void *context)
static PyObject *
type_get_bases(PyTypeObject *type, void *context)
{
return Py_NewRef(type->tp_bases);
return Py_NewRef(lookup_tp_bases(type));
}

static PyTypeObject *best_base(PyObject *);
Expand Down Expand Up @@ -1113,11 +1138,11 @@ type_set_bases(PyTypeObject *type, PyObject *new_bases, void *context)
return -1;
}

PyObject *old_bases = type->tp_bases;
PyObject *old_bases = lookup_tp_bases(type);
assert(old_bases != NULL);
PyTypeObject *old_base = type->tp_base;

type->tp_bases = Py_NewRef(new_bases);
set_tp_bases(type, Py_NewRef(new_bases));
type->tp_base = (PyTypeObject *)Py_NewRef(new_base);

PyObject *temp = PyList_New(0);
Expand All @@ -1132,7 +1157,7 @@ type_set_bases(PyTypeObject *type, PyObject *new_bases, void *context)
/* Take no action in case if type->tp_bases has been replaced
through reentrance. */
int res;
if (type->tp_bases == new_bases) {
if (lookup_tp_bases(type) == new_bases) {
/* any base that was in __bases__ but now isn't, we
need to remove |type| from its tp_subclasses.
conversely, any class now in __bases__ that wasn't
Expand Down Expand Up @@ -1171,10 +1196,10 @@ type_set_bases(PyTypeObject *type, PyObject *new_bases, void *context)
Py_DECREF(temp);

bail:
if (type->tp_bases == new_bases) {
if (lookup_tp_bases(type) == new_bases) {
assert(type->tp_base == new_base);

type->tp_bases = old_bases;
set_tp_bases(type, old_bases);
type->tp_base = old_base;

Py_DECREF(new_bases);
Expand Down Expand Up @@ -2268,7 +2293,7 @@ mro_implementation(PyTypeObject *type)
return NULL;
}

PyObject *bases = type->tp_bases;
PyObject *bases = lookup_tp_bases(type);
Py_ssize_t n = PyTuple_GET_SIZE(bases);
for (Py_ssize_t i = 0; i < n; i++) {
PyTypeObject *base = _PyType_CAST(PyTuple_GET_ITEM(bases, i));
Expand Down Expand Up @@ -2496,7 +2521,7 @@ mro_internal(PyTypeObject *type, PyObject **p_old_mro)
type_mro_modified(type, new_mro);
/* corner case: the super class might have been hidden
from the custom MRO */
type_mro_modified(type, type->tp_bases);
type_mro_modified(type, lookup_tp_bases(type));

// XXX Expand this to Py_TPFLAGS_IMMUTABLETYPE?
if (!(type->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN)) {
Expand Down Expand Up @@ -3098,7 +3123,7 @@ type_new_alloc(type_new_ctx *ctx)
type->tp_as_mapping = &et->as_mapping;
type->tp_as_buffer = &et->as_buffer;

type->tp_bases = Py_NewRef(ctx->bases);
set_tp_bases(type, Py_NewRef(ctx->bases));
type->tp_base = (PyTypeObject *)Py_NewRef(ctx->base);

type->tp_dealloc = subtype_dealloc;
Expand Down Expand Up @@ -3990,7 +4015,7 @@ PyType_FromMetaclass(PyTypeObject *metaclass, PyObject *module,
/* Set slots we have prepared */

type->tp_base = (PyTypeObject *)Py_NewRef(base);
type->tp_bases = bases;
set_tp_bases(type, bases);
bases = NULL; // We give our reference to bases to the type

type->tp_doc = tp_doc;
Expand Down Expand Up @@ -4573,9 +4598,10 @@ _PyDictKeys_DecRef(PyDictKeysObject *keys);
static void
type_dealloc_common(PyTypeObject *type)
{
if (type->tp_bases != NULL) {
PyObject *bases = lookup_tp_bases(type);
if (bases != NULL) {
PyObject *exc = PyErr_GetRaisedException();
remove_all_subclasses(type, type->tp_bases);
remove_all_subclasses(type, bases);
PyErr_SetRaisedException(exc);
}
}
Expand Down Expand Up @@ -4629,7 +4655,7 @@ clear_static_type_objects(PyInterpreterState *interp, PyTypeObject *type)
{
if (_Py_IsMainInterpreter(interp)) {
Py_CLEAR(type->tp_dict);
Py_CLEAR(type->tp_bases);
clear_tp_bases(type);
clear_tp_mro(type);
Py_CLEAR(type->tp_cache);
}
Expand Down Expand Up @@ -6652,7 +6678,7 @@ type_ready_set_bases(PyTypeObject *type)
}

/* Initialize tp_bases */
PyObject *bases = type->tp_bases;
PyObject *bases = lookup_tp_bases(type);
if (bases == NULL) {
PyTypeObject *base = type->tp_base;
if (base == NULL) {
Expand All @@ -6664,7 +6690,7 @@ type_ready_set_bases(PyTypeObject *type)
if (bases == NULL) {
return -1;
}
type->tp_bases = bases;
set_tp_bases(type, bases);
}
return 0;
}
Expand Down Expand Up @@ -6913,7 +6939,7 @@ type_ready_set_hash(PyTypeObject *type)
static int
type_ready_add_subclasses(PyTypeObject *type)
{
PyObject *bases = type->tp_bases;
PyObject *bases = lookup_tp_bases(type);
Py_ssize_t nbase = PyTuple_GET_SIZE(bases);
for (Py_ssize_t i = 0; i < nbase; i++) {
PyObject *b = PyTuple_GET_ITEM(bases, i);
Expand Down