From c86a11221df7e37da389f9c6ce6e47ea22dc44ff Mon Sep 17 00:00:00 2001 From: Victor Stinner Date: Fri, 7 Feb 2020 01:24:29 +0100 Subject: [PATCH] bpo-39573: Add Py_SET_REFCNT() function (GH-18389) Add a Py_SET_REFCNT() function to set the reference counter of an object. --- Doc/c-api/structures.rst | 7 +++++++ Include/object.h | 5 +++++ .../2020-02-07-00-23-44.bpo-39573.nRD1q7.rst | 2 ++ Modules/_testcapimodule.c | 15 ++++++++------- Objects/moduleobject.c | 2 +- Objects/object.c | 9 +++++---- Objects/unicodeobject.c | 4 ++-- 7 files changed, 30 insertions(+), 14 deletions(-) create mode 100644 Misc/NEWS.d/next/C API/2020-02-07-00-23-44.bpo-39573.nRD1q7.rst diff --git a/Doc/c-api/structures.rst b/Doc/c-api/structures.rst index 0c661389021..100573c5693 100644 --- a/Doc/c-api/structures.rst +++ b/Doc/c-api/structures.rst @@ -79,6 +79,13 @@ the definition of all other Python objects. (((PyObject*)(o))->ob_refcnt) +.. c:function:: void Py_SET_REFCNT(PyObject *o, Py_ssize_t refcnt) + + Set the object *o* reference counter to *refcnt*. + + .. versionadded:: 3.9 + + .. c:macro:: Py_SIZE(o) This macro is used to access the :attr:`ob_size` member of a Python object. diff --git a/Include/object.h b/Include/object.h index 38794a0e98c..0b630513375 100644 --- a/Include/object.h +++ b/Include/object.h @@ -123,6 +123,11 @@ typedef struct { #define Py_TYPE(ob) (_PyObject_CAST(ob)->ob_type) #define Py_SIZE(ob) (_PyVarObject_CAST(ob)->ob_size) +static inline void _Py_SET_REFCNT(PyObject *ob, Py_ssize_t refcnt) { + ob->ob_refcnt = refcnt; +} +#define Py_SET_REFCNT(ob, refcnt) _Py_SET_REFCNT(_PyObject_CAST(ob), refcnt) + /* Type objects contain a string containing the type name (to help somewhat in debugging), the allocation parameters (see PyObject_New() and diff --git a/Misc/NEWS.d/next/C API/2020-02-07-00-23-44.bpo-39573.nRD1q7.rst b/Misc/NEWS.d/next/C API/2020-02-07-00-23-44.bpo-39573.nRD1q7.rst new file mode 100644 index 00000000000..310933a6d40 --- /dev/null +++ b/Misc/NEWS.d/next/C API/2020-02-07-00-23-44.bpo-39573.nRD1q7.rst @@ -0,0 +1,2 @@ +Add a :c:func:`Py_SET_REFCNT` function to set the reference counter of an +object. diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c index 27db86a70b9..d8bf3735046 100644 --- a/Modules/_testcapimodule.c +++ b/Modules/_testcapimodule.c @@ -3551,7 +3551,7 @@ slot_tp_del(PyObject *self) /* Temporarily resurrect the object. */ assert(Py_REFCNT(self) == 0); - Py_REFCNT(self) = 1; + Py_SET_REFCNT(self, 1); /* Save the current exception, if any. */ PyErr_Fetch(&error_type, &error_value, &error_traceback); @@ -3574,7 +3574,8 @@ slot_tp_del(PyObject *self) * cause a recursive call. */ assert(Py_REFCNT(self) > 0); - if (--Py_REFCNT(self) == 0) { + Py_SET_REFCNT(self, Py_REFCNT(self) - 1); + if (Py_REFCNT(self) == 0) { /* this is the normal path out */ return; } @@ -3585,7 +3586,7 @@ slot_tp_del(PyObject *self) { Py_ssize_t refcnt = Py_REFCNT(self); _Py_NewReference(self); - Py_REFCNT(self) = refcnt; + Py_SET_REFCNT(self, refcnt); } assert(!PyType_IS_GC(Py_TYPE(self)) || _PyObject_GC_IS_TRACKED(self)); /* If Py_REF_DEBUG macro is defined, _Py_NewReference() increased @@ -4621,7 +4622,7 @@ check_pyobject_uninitialized_is_freed(PyObject *self, PyObject *Py_UNUSED(args)) return NULL; } /* Initialize reference count to avoid early crash in ceval or GC */ - Py_REFCNT(op) = 1; + Py_SET_REFCNT(op, 1); /* object fields like ob_type are uninitialized! */ return test_pyobject_is_freed("check_pyobject_uninitialized_is_freed", op); } @@ -4636,7 +4637,7 @@ check_pyobject_forbidden_bytes_is_freed(PyObject *self, PyObject *Py_UNUSED(args return NULL; } /* Initialize reference count to avoid early crash in ceval or GC */ - Py_REFCNT(op) = 1; + Py_SET_REFCNT(op, 1); /* ob_type field is after the memory block: part of "forbidden bytes" when using debug hooks on memory allocators! */ return test_pyobject_is_freed("check_pyobject_forbidden_bytes_is_freed", op); @@ -4652,7 +4653,7 @@ check_pyobject_freed_is_freed(PyObject *self, PyObject *Py_UNUSED(args)) } Py_TYPE(op)->tp_dealloc(op); /* Reset reference count to avoid early crash in ceval or GC */ - Py_REFCNT(op) = 1; + Py_SET_REFCNT(op, 1); /* object memory is freed! */ return test_pyobject_is_freed("check_pyobject_freed_is_freed", op); } @@ -5134,7 +5135,7 @@ negative_refcount(PyObject *self, PyObject *Py_UNUSED(args)) } assert(Py_REFCNT(obj) == 1); - Py_REFCNT(obj) = 0; + Py_SET_REFCNT(obj, 0); /* Py_DECREF() must call _Py_NegativeRefcount() and abort Python */ Py_DECREF(obj); diff --git a/Objects/moduleobject.c b/Objects/moduleobject.c index 49cfd574d56..da329b4fbac 100644 --- a/Objects/moduleobject.c +++ b/Objects/moduleobject.c @@ -51,7 +51,7 @@ PyModuleDef_Init(struct PyModuleDef* def) return NULL; if (def->m_base.m_index == 0) { max_module_number++; - Py_REFCNT(def) = 1; + Py_SET_REFCNT(def, 1); Py_TYPE(def) = &PyModuleDef_Type; def->m_base.m_index = max_module_number; } diff --git a/Objects/object.c b/Objects/object.c index f9682fe5b1f..aca20e8d096 100644 --- a/Objects/object.c +++ b/Objects/object.c @@ -213,7 +213,7 @@ PyObject_CallFinalizerFromDealloc(PyObject *self) } /* Temporarily resurrect the object. */ - Py_REFCNT(self) = 1; + Py_SET_REFCNT(self, 1); PyObject_CallFinalizer(self); @@ -223,7 +223,8 @@ PyObject_CallFinalizerFromDealloc(PyObject *self) /* Undo the temporary resurrection; can't use DECREF here, it would * cause a recursive call. */ - if (--Py_REFCNT(self) == 0) { + Py_SET_REFCNT(self, Py_REFCNT(self) - 1); + if (Py_REFCNT(self) == 0) { return 0; /* this is the normal path out */ } @@ -231,7 +232,7 @@ PyObject_CallFinalizerFromDealloc(PyObject *self) * never happened. */ Py_ssize_t refcnt = Py_REFCNT(self); _Py_NewReference(self); - Py_REFCNT(self) = refcnt; + Py_SET_REFCNT(self, refcnt); _PyObject_ASSERT(self, (!PyType_IS_GC(Py_TYPE(self)) @@ -1818,7 +1819,7 @@ _Py_NewReference(PyObject *op) #ifdef Py_REF_DEBUG _Py_RefTotal++; #endif - Py_REFCNT(op) = 1; + Py_SET_REFCNT(op, 1); #ifdef Py_TRACE_REFS _Py_AddToAllObjects(op, 1); #endif diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c index 7c8bc06252a..fa48ee1ac78 100644 --- a/Objects/unicodeobject.c +++ b/Objects/unicodeobject.c @@ -1903,7 +1903,7 @@ unicode_dealloc(PyObject *unicode) case SSTATE_INTERNED_MORTAL: /* revive dead object temporarily for DelItem */ - Py_REFCNT(unicode) = 3; + Py_SET_REFCNT(unicode, 3); if (PyDict_DelItem(interned, unicode) != 0) { _PyErr_WriteUnraisableMsg("deletion of interned string failed", NULL); @@ -15367,7 +15367,7 @@ PyUnicode_InternInPlace(PyObject **p) } /* The two references in interned are not counted by refcnt. The deallocator will take care of this */ - Py_REFCNT(s) -= 2; + Py_SET_REFCNT(s, Py_REFCNT(s) - 2); _PyUnicode_STATE(s).interned = SSTATE_INTERNED_MORTAL; }