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mirror of https://github.com/python/cpython.git synced 2024-11-25 09:39:56 +01:00
cpython/Objects/classobject.c
Dino Viehland 5a1618a2c8
gh-118362: Fix thread safety around lookups from the type cache in the face of concurrent mutators (#118454)
Add _PyType_LookupRef and use incref before setting attribute on type
Makes setting an attribute on a class and signaling type modified atomic
Avoid adding re-entrancy exposing the type cache in an inconsistent state by decrefing after type is updated
2024-05-06 10:50:35 -07:00

553 lines
15 KiB
C

/* Class object implementation (dead now except for methods) */
#include "Python.h"
#include "pycore_call.h" // _PyObject_VectorcallTstate()
#include "pycore_ceval.h" // _PyEval_GetBuiltin()
#include "pycore_object.h"
#include "pycore_pyerrors.h"
#include "pycore_pystate.h" // _PyThreadState_GET()
#include "clinic/classobject.c.h"
#define TP_DESCR_GET(t) ((t)->tp_descr_get)
/*[clinic input]
class method "PyMethodObject *" "&PyMethod_Type"
[clinic start generated code]*/
/*[clinic end generated code: output=da39a3ee5e6b4b0d input=b16e47edf6107c23]*/
PyObject *
PyMethod_Function(PyObject *im)
{
if (!PyMethod_Check(im)) {
PyErr_BadInternalCall();
return NULL;
}
return ((PyMethodObject *)im)->im_func;
}
PyObject *
PyMethod_Self(PyObject *im)
{
if (!PyMethod_Check(im)) {
PyErr_BadInternalCall();
return NULL;
}
return ((PyMethodObject *)im)->im_self;
}
static PyObject *
method_vectorcall(PyObject *method, PyObject *const *args,
size_t nargsf, PyObject *kwnames)
{
assert(Py_IS_TYPE(method, &PyMethod_Type));
PyThreadState *tstate = _PyThreadState_GET();
PyObject *self = PyMethod_GET_SELF(method);
PyObject *func = PyMethod_GET_FUNCTION(method);
Py_ssize_t nargs = PyVectorcall_NARGS(nargsf);
assert(nargs == 0 || args[nargs-1]);
PyObject *result;
if (nargsf & PY_VECTORCALL_ARGUMENTS_OFFSET) {
/* PY_VECTORCALL_ARGUMENTS_OFFSET is set, so we are allowed to mutate the vector */
PyObject **newargs = (PyObject**)args - 1;
nargs += 1;
PyObject *tmp = newargs[0];
newargs[0] = self;
assert(newargs[nargs-1]);
result = _PyObject_VectorcallTstate(tstate, func, newargs,
nargs, kwnames);
newargs[0] = tmp;
}
else {
Py_ssize_t nkwargs = (kwnames == NULL) ? 0 : PyTuple_GET_SIZE(kwnames);
Py_ssize_t totalargs = nargs + nkwargs;
if (totalargs == 0) {
return _PyObject_VectorcallTstate(tstate, func, &self, 1, NULL);
}
PyObject *newargs_stack[_PY_FASTCALL_SMALL_STACK];
PyObject **newargs;
if (totalargs <= (Py_ssize_t)Py_ARRAY_LENGTH(newargs_stack) - 1) {
newargs = newargs_stack;
}
else {
newargs = PyMem_Malloc((totalargs+1) * sizeof(PyObject *));
if (newargs == NULL) {
_PyErr_NoMemory(tstate);
return NULL;
}
}
/* use borrowed references */
newargs[0] = self;
/* bpo-37138: since totalargs > 0, it's impossible that args is NULL.
* We need this, since calling memcpy() with a NULL pointer is
* undefined behaviour. */
assert(args != NULL);
memcpy(newargs + 1, args, totalargs * sizeof(PyObject *));
result = _PyObject_VectorcallTstate(tstate, func,
newargs, nargs+1, kwnames);
if (newargs != newargs_stack) {
PyMem_Free(newargs);
}
}
return result;
}
/* Method objects are used for bound instance methods returned by
instancename.methodname. ClassName.methodname returns an ordinary
function.
*/
PyObject *
PyMethod_New(PyObject *func, PyObject *self)
{
if (self == NULL) {
PyErr_BadInternalCall();
return NULL;
}
PyMethodObject *im = PyObject_GC_New(PyMethodObject, &PyMethod_Type);
if (im == NULL) {
return NULL;
}
im->im_weakreflist = NULL;
im->im_func = Py_NewRef(func);
im->im_self = Py_NewRef(self);
im->vectorcall = method_vectorcall;
_PyObject_GC_TRACK(im);
return (PyObject *)im;
}
/*[clinic input]
method.__reduce__
[clinic start generated code]*/
static PyObject *
method___reduce___impl(PyMethodObject *self)
/*[clinic end generated code: output=6c04506d0fa6fdcb input=143a0bf5e96de6e8]*/
{
PyObject *funcself = PyMethod_GET_SELF(self);
PyObject *func = PyMethod_GET_FUNCTION(self);
PyObject *funcname = PyObject_GetAttr(func, &_Py_ID(__name__));
if (funcname == NULL) {
return NULL;
}
return Py_BuildValue(
"N(ON)", _PyEval_GetBuiltin(&_Py_ID(getattr)), funcself, funcname);
}
static PyMethodDef method_methods[] = {
METHOD___REDUCE___METHODDEF
{NULL, NULL}
};
/* Descriptors for PyMethod attributes */
/* im_func and im_self are stored in the PyMethod object */
#define MO_OFF(x) offsetof(PyMethodObject, x)
static PyMemberDef method_memberlist[] = {
{"__func__", _Py_T_OBJECT, MO_OFF(im_func), Py_READONLY,
"the function (or other callable) implementing a method"},
{"__self__", _Py_T_OBJECT, MO_OFF(im_self), Py_READONLY,
"the instance to which a method is bound"},
{NULL} /* Sentinel */
};
/* Christian Tismer argued convincingly that method attributes should
(nearly) always override function attributes.
The one exception is __doc__; there's a default __doc__ which
should only be used for the class, not for instances */
static PyObject *
method_get_doc(PyMethodObject *im, void *context)
{
return PyObject_GetAttr(im->im_func, &_Py_ID(__doc__));
}
static PyGetSetDef method_getset[] = {
{"__doc__", (getter)method_get_doc, NULL, NULL},
{0}
};
static PyObject *
method_getattro(PyObject *obj, PyObject *name)
{
PyMethodObject *im = (PyMethodObject *)obj;
PyTypeObject *tp = Py_TYPE(obj);
PyObject *descr = NULL;
{
if (!_PyType_IsReady(tp)) {
if (PyType_Ready(tp) < 0)
return NULL;
}
descr = _PyType_LookupRef(tp, name);
}
if (descr != NULL) {
descrgetfunc f = TP_DESCR_GET(Py_TYPE(descr));
if (f != NULL) {
PyObject *res = f(descr, obj, (PyObject *)Py_TYPE(obj));
Py_DECREF(descr);
return res;
}
else {
return descr;
}
}
return PyObject_GetAttr(im->im_func, name);
}
/*[clinic input]
@classmethod
method.__new__ as method_new
function: object
instance: object
/
Create a bound instance method object.
[clinic start generated code]*/
static PyObject *
method_new_impl(PyTypeObject *type, PyObject *function, PyObject *instance)
/*[clinic end generated code: output=d33ef4ebf702e1f7 input=4e32facc3c3108ae]*/
{
if (!PyCallable_Check(function)) {
PyErr_SetString(PyExc_TypeError,
"first argument must be callable");
return NULL;
}
if (instance == NULL || instance == Py_None) {
PyErr_SetString(PyExc_TypeError,
"instance must not be None");
return NULL;
}
return PyMethod_New(function, instance);
}
static void
method_dealloc(PyMethodObject *im)
{
_PyObject_GC_UNTRACK(im);
if (im->im_weakreflist != NULL)
PyObject_ClearWeakRefs((PyObject *)im);
Py_DECREF(im->im_func);
Py_XDECREF(im->im_self);
PyObject_GC_Del(im);
}
static PyObject *
method_richcompare(PyObject *self, PyObject *other, int op)
{
PyMethodObject *a, *b;
PyObject *res;
int eq;
if ((op != Py_EQ && op != Py_NE) ||
!PyMethod_Check(self) ||
!PyMethod_Check(other))
{
Py_RETURN_NOTIMPLEMENTED;
}
a = (PyMethodObject *)self;
b = (PyMethodObject *)other;
eq = PyObject_RichCompareBool(a->im_func, b->im_func, Py_EQ);
if (eq == 1) {
eq = (a->im_self == b->im_self);
}
else if (eq < 0)
return NULL;
if (op == Py_EQ)
res = eq ? Py_True : Py_False;
else
res = eq ? Py_False : Py_True;
return Py_NewRef(res);
}
static PyObject *
method_repr(PyMethodObject *a)
{
PyObject *self = a->im_self;
PyObject *func = a->im_func;
PyObject *funcname, *result;
const char *defname = "?";
if (PyObject_GetOptionalAttr(func, &_Py_ID(__qualname__), &funcname) < 0 ||
(funcname == NULL &&
PyObject_GetOptionalAttr(func, &_Py_ID(__name__), &funcname) < 0))
{
return NULL;
}
if (funcname != NULL && !PyUnicode_Check(funcname)) {
Py_SETREF(funcname, NULL);
}
/* XXX Shouldn't use repr()/%R here! */
result = PyUnicode_FromFormat("<bound method %V of %R>",
funcname, defname, self);
Py_XDECREF(funcname);
return result;
}
static Py_hash_t
method_hash(PyMethodObject *a)
{
Py_hash_t x, y;
x = PyObject_GenericHash(a->im_self);
y = PyObject_Hash(a->im_func);
if (y == -1)
return -1;
x = x ^ y;
if (x == -1)
x = -2;
return x;
}
static int
method_traverse(PyMethodObject *im, visitproc visit, void *arg)
{
Py_VISIT(im->im_func);
Py_VISIT(im->im_self);
return 0;
}
static PyObject *
method_descr_get(PyObject *meth, PyObject *obj, PyObject *cls)
{
Py_INCREF(meth);
return meth;
}
PyTypeObject PyMethod_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
.tp_name = "method",
.tp_basicsize = sizeof(PyMethodObject),
.tp_dealloc = (destructor)method_dealloc,
.tp_vectorcall_offset = offsetof(PyMethodObject, vectorcall),
.tp_repr = (reprfunc)method_repr,
.tp_hash = (hashfunc)method_hash,
.tp_call = PyVectorcall_Call,
.tp_getattro = method_getattro,
.tp_setattro = PyObject_GenericSetAttr,
.tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
Py_TPFLAGS_HAVE_VECTORCALL,
.tp_doc = method_new__doc__,
.tp_traverse = (traverseproc)method_traverse,
.tp_richcompare = method_richcompare,
.tp_weaklistoffset = offsetof(PyMethodObject, im_weakreflist),
.tp_methods = method_methods,
.tp_members = method_memberlist,
.tp_getset = method_getset,
.tp_descr_get = method_descr_get,
.tp_new = method_new,
};
/* ------------------------------------------------------------------------
* instance method
*/
/*[clinic input]
class instancemethod "PyInstanceMethodObject *" "&PyInstanceMethod_Type"
[clinic start generated code]*/
/*[clinic end generated code: output=da39a3ee5e6b4b0d input=28c9762a9016f4d2]*/
PyObject *
PyInstanceMethod_New(PyObject *func) {
PyInstanceMethodObject *method;
method = PyObject_GC_New(PyInstanceMethodObject,
&PyInstanceMethod_Type);
if (method == NULL) return NULL;
method->func = Py_NewRef(func);
_PyObject_GC_TRACK(method);
return (PyObject *)method;
}
PyObject *
PyInstanceMethod_Function(PyObject *im)
{
if (!PyInstanceMethod_Check(im)) {
PyErr_BadInternalCall();
return NULL;
}
return PyInstanceMethod_GET_FUNCTION(im);
}
#define IMO_OFF(x) offsetof(PyInstanceMethodObject, x)
static PyMemberDef instancemethod_memberlist[] = {
{"__func__", _Py_T_OBJECT, IMO_OFF(func), Py_READONLY,
"the function (or other callable) implementing a method"},
{NULL} /* Sentinel */
};
static PyObject *
instancemethod_get_doc(PyObject *self, void *context)
{
return PyObject_GetAttr(PyInstanceMethod_GET_FUNCTION(self),
&_Py_ID(__doc__));
}
static PyGetSetDef instancemethod_getset[] = {
{"__doc__", (getter)instancemethod_get_doc, NULL, NULL},
{0}
};
static PyObject *
instancemethod_getattro(PyObject *self, PyObject *name)
{
PyTypeObject *tp = Py_TYPE(self);
PyObject *descr = NULL;
if (!_PyType_IsReady(tp)) {
if (PyType_Ready(tp) < 0)
return NULL;
}
descr = _PyType_LookupRef(tp, name);
if (descr != NULL) {
descrgetfunc f = TP_DESCR_GET(Py_TYPE(descr));
if (f != NULL) {
PyObject *res = f(descr, self, (PyObject *)Py_TYPE(self));
Py_DECREF(descr);
return res;
}
else {
return descr;
}
}
return PyObject_GetAttr(PyInstanceMethod_GET_FUNCTION(self), name);
}
static void
instancemethod_dealloc(PyObject *self) {
_PyObject_GC_UNTRACK(self);
Py_DECREF(PyInstanceMethod_GET_FUNCTION(self));
PyObject_GC_Del(self);
}
static int
instancemethod_traverse(PyObject *self, visitproc visit, void *arg) {
Py_VISIT(PyInstanceMethod_GET_FUNCTION(self));
return 0;
}
static PyObject *
instancemethod_call(PyObject *self, PyObject *arg, PyObject *kw)
{
return PyObject_Call(PyInstanceMethod_GET_FUNCTION(self), arg, kw);
}
static PyObject *
instancemethod_descr_get(PyObject *descr, PyObject *obj, PyObject *type) {
PyObject *func = PyInstanceMethod_GET_FUNCTION(descr);
if (obj == NULL) {
return Py_NewRef(func);
}
else
return PyMethod_New(func, obj);
}
static PyObject *
instancemethod_richcompare(PyObject *self, PyObject *other, int op)
{
PyInstanceMethodObject *a, *b;
PyObject *res;
int eq;
if ((op != Py_EQ && op != Py_NE) ||
!PyInstanceMethod_Check(self) ||
!PyInstanceMethod_Check(other))
{
Py_RETURN_NOTIMPLEMENTED;
}
a = (PyInstanceMethodObject *)self;
b = (PyInstanceMethodObject *)other;
eq = PyObject_RichCompareBool(a->func, b->func, Py_EQ);
if (eq < 0)
return NULL;
if (op == Py_EQ)
res = eq ? Py_True : Py_False;
else
res = eq ? Py_False : Py_True;
return Py_NewRef(res);
}
static PyObject *
instancemethod_repr(PyObject *self)
{
PyObject *func = PyInstanceMethod_Function(self);
PyObject *funcname, *result;
const char *defname = "?";
if (func == NULL) {
PyErr_BadInternalCall();
return NULL;
}
if (PyObject_GetOptionalAttr(func, &_Py_ID(__name__), &funcname) < 0) {
return NULL;
}
if (funcname != NULL && !PyUnicode_Check(funcname)) {
Py_SETREF(funcname, NULL);
}
result = PyUnicode_FromFormat("<instancemethod %V at %p>",
funcname, defname, self);
Py_XDECREF(funcname);
return result;
}
/*[clinic input]
@classmethod
instancemethod.__new__ as instancemethod_new
function: object
/
Bind a function to a class.
[clinic start generated code]*/
static PyObject *
instancemethod_new_impl(PyTypeObject *type, PyObject *function)
/*[clinic end generated code: output=5e0397b2bdb750be input=cfc54e8b973664a8]*/
{
if (!PyCallable_Check(function)) {
PyErr_SetString(PyExc_TypeError,
"first argument must be callable");
return NULL;
}
return PyInstanceMethod_New(function);
}
PyTypeObject PyInstanceMethod_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
.tp_name = "instancemethod",
.tp_basicsize = sizeof(PyInstanceMethodObject),
.tp_dealloc = instancemethod_dealloc,
.tp_repr = (reprfunc)instancemethod_repr,
.tp_call = instancemethod_call,
.tp_getattro = instancemethod_getattro,
.tp_setattro = PyObject_GenericSetAttr,
.tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,
.tp_doc = instancemethod_new__doc__,
.tp_traverse = instancemethod_traverse,
.tp_richcompare = instancemethod_richcompare,
.tp_members = instancemethod_memberlist,
.tp_getset = instancemethod_getset,
.tp_descr_get = instancemethod_descr_get,
.tp_new = instancemethod_new,
};