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[WIP] bpo-35059: Add assertion to _PyObject_CAST() #10649

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[WIP] bpo-35059: Add assertion to _PyObject_CAST() #10649

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31 changes: 26 additions & 5 deletions Include/object.h
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Original file line number Diff line number Diff line change
Expand Up @@ -112,16 +112,37 @@ typedef struct _object {
struct _typeobject *ob_type;
} PyObject;

/* Cast argument to PyObject* type. */
#define _PyObject_CAST(op) ((PyObject*)(op))

typedef struct {
PyObject ob_base;
Py_ssize_t ob_size; /* Number of items in variable part */
} PyVarObject;

/* Cast argument to PyVarObject* type. */
#define _PyVarObject_CAST(op) ((PyVarObject*)(op))
/* sizeof(*op) doesn't work on Visual Studio with void*:
sizeof(void) raises a compilation error.

sizeof(*op) is incompatible with Py_LIMITED_API which doesn't define
structures. */
#if !defined(_MSC_VER) && !defined(Py_LIMITED_API)
/* _PyObject_CAST(op): Cast argument to PyObject* type.

Raise a compilation error if the argument type is PyObject or PyObject**.

Detect for example the bug "&item" instead of "item" in:

const char *func(PyObject *item) { return Py_TYPE(&item)->tp_name; }

Note: sizeof(op) doesn't evaluate 'op', so sizeof(op) has no side effect. */
# define _PyObject_CAST(op) \
((PyObject*)(op) + Py_BUILD_ASSERT_EXPR(sizeof(*(op)) != sizeof(op)))

/* _PyVarObject_CAST(op): Cast argument to PyVarObject* type.
Similar to _PyObject_CAST(). */
# define _PyVarObject_CAST(op) \
((PyVarObject*)(op) + Py_BUILD_ASSERT_EXPR(sizeof(*(op)) != sizeof(op)))
#else
# define _PyObject_CAST(op) ((PyObject*)(op))
# define _PyVarObject_CAST(op) ((PyVarObject*)(op))
#endif /* defined(_MSC_VER) */

#define Py_REFCNT(ob) (_PyObject_CAST(ob)->ob_refcnt)
#define Py_TYPE(ob) (_PyObject_CAST(ob)->ob_type)
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9 changes: 3 additions & 6 deletions Modules/_ssl.c
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Expand Up @@ -5983,12 +5983,9 @@ PyInit__ssl(void)
PyModule_AddIntConstant(m, "PROTO_TLSv1_2", PY_PROTO_TLSv1_2);
PyModule_AddIntConstant(m, "PROTO_TLSv1_3", PY_PROTO_TLSv1_3);

#define addbool(m, key, value) \
do { \
PyObject *bool_obj = (value) ? Py_True : Py_False; \
Py_INCREF(bool_obj); \
PyModule_AddObject((m), (key), bool_obj); \
} while (0)
#define addbool(m, v, b) \
Py_INCREF((b) ? Py_True : Py_False); \
PyModule_AddObject((m), (v), (b) ? Py_True : Py_False);

#if HAVE_SNI
addbool(m, "HAS_SNI", 1);
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3 changes: 1 addition & 2 deletions Objects/weakrefobject.c
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Expand Up @@ -833,8 +833,7 @@ PyWeakref_NewProxy(PyObject *ob, PyObject *callback)
to avoid violating the invariants of the list
of weakrefs for ob. */
Py_DECREF(result);
result = proxy;
Py_INCREF(result);
Py_INCREF(result = proxy);
goto skip_insert;
}
prev = ref;
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1 change: 1 addition & 0 deletions Python/pystate.c
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Expand Up @@ -2,6 +2,7 @@
/* Thread and interpreter state structures and their interfaces */

#include "Python.h"
#include "frameobject.h"
#include "pycore_pymem.h"
#include "pycore_pystate.h"

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