/* Method object implementation */

#include "Python.h"

#include "pycore_call.h"          // _Py_CheckFunctionResult()

#include "pycore_ceval.h"         // _Py_EnterRecursiveCallTstate()

#include "pycore_freelist.h"

#include "pycore_object.h"

#include "pycore_pyerrors.h"

#include "pycore_pystate.h"       // _PyThreadState_GET()

#include "pycore_weakref.h"       // FT_CLEAR_WEAKREFS()

/* undefine macro trampoline to PyCFunction_NewEx */

#undef PyCFunction_New

/* undefine macro trampoline to PyCMethod_New */

#undef PyCFunction_NewEx

/* Forward declarations */

static PyObject * cfunction_vectorcall_FASTCALL(

    PyObject *func, PyObject *const *args, size_t nargsf, PyObject *kwnames);

static PyObject * cfunction_vectorcall_FASTCALL_KEYWORDS(

    PyObject *func, PyObject *const *args, size_t nargsf, PyObject *kwnames);

static PyObject * cfunction_vectorcall_FASTCALL_KEYWORDS_METHOD(

    PyObject *func, PyObject *const *args, size_t nargsf, PyObject *kwnames);

static PyObject * cfunction_vectorcall_NOARGS(

    PyObject *func, PyObject *const *args, size_t nargsf, PyObject *kwnames);

static PyObject * cfunction_vectorcall_O(

    PyObject *func, PyObject *const *args, size_t nargsf, PyObject *kwnames);

static PyObject * cfunction_call(

    PyObject *func, PyObject *args, PyObject *kwargs);

PyObject *

PyCFunction_New(PyMethodDef *ml, PyObject *self)

{

    return PyCFunction_NewEx(ml, self, NULL);

}

PyObject *

PyCFunction_NewEx(PyMethodDef *ml, PyObject *self, PyObject *module)

{

    return PyCMethod_New(ml, self, module, NULL);

}

PyObject *

PyCMethod_New(PyMethodDef *ml, PyObject *self, PyObject *module, PyTypeObject *cls)

{

    /* Figure out correct vectorcall function to use */

    vectorcallfunc vectorcall;

    switch (ml->ml_flags & (METH_VARARGS | METH_FASTCALL | METH_NOARGS |

                            METH_O | METH_KEYWORDS | METH_METHOD))

    {

        case METH_VARARGS:

        case METH_VARARGS | METH_KEYWORDS:

            /* For METH_VARARGS functions, it's more efficient to use tp_call

             * instead of vectorcall. */

            vectorcall = NULL;

            break;

        case METH_FASTCALL:

            vectorcall = cfunction_vectorcall_FASTCALL;

            break;

        case METH_FASTCALL | METH_KEYWORDS:

            vectorcall = cfunction_vectorcall_FASTCALL_KEYWORDS;

            break;

        case METH_NOARGS:

            vectorcall = cfunction_vectorcall_NOARGS;

            break;

        case METH_O:

            vectorcall = cfunction_vectorcall_O;

            break;

        case METH_METHOD | METH_FASTCALL | METH_KEYWORDS:

            vectorcall = cfunction_vectorcall_FASTCALL_KEYWORDS_METHOD;

            break;

        default:

            PyErr_Format(PyExc_SystemError,

                         "%s() method: bad call flags", ml->ml_name);

            return NULL;

    }

    PyCFunctionObject *op = NULL;

    if (ml->ml_flags & METH_METHOD) {

        if (!cls) {

            PyErr_SetString(PyExc_SystemError,

                            "attempting to create PyCMethod with a METH_METHOD "

                            "flag but no class");

            return NULL;

        }

        PyCMethodObject *om = _Py_FREELIST_POP(PyCMethodObject, pycmethodobject);

        if (om == NULL) {

            om = PyObject_GC_New(PyCMethodObject, &PyCMethod_Type);

            if (om == NULL) {

                return NULL;

            }

        }

        om->mm_class = (PyTypeObject*)Py_NewRef(cls);

        op = (PyCFunctionObject *)om;

    } else {

        if (cls) {

            PyErr_SetString(PyExc_SystemError,

                            "attempting to create PyCFunction with class "

                            "but no METH_METHOD flag");

            return NULL;

        }

        op = _Py_FREELIST_POP(PyCFunctionObject, pycfunctionobject);

        if (op == NULL) {

            op = PyObject_GC_New(PyCFunctionObject, &PyCFunction_Type);

            if (op == NULL) {

                return NULL;

            }

        }

    }

    op->m_weakreflist = NULL;

    op->m_ml = ml;

    op->m_self = Py_XNewRef(self);

    op->m_module = Py_XNewRef(module);

    op->vectorcall = vectorcall;

    _PyObject_GC_TRACK(op);

    return (PyObject *)op;

}

PyCFunction

PyCFunction_GetFunction(PyObject *op)

{

    if (!PyCFunction_Check(op)) {

        PyErr_BadInternalCall();

        return NULL;

    }

    return PyCFunction_GET_FUNCTION(op);

}

PyObject *

PyCFunction_GetSelf(PyObject *op)

{

    if (!PyCFunction_Check(op)) {

        PyErr_BadInternalCall();

        return NULL;

    }

    return PyCFunction_GET_SELF(op);

}

int

PyCFunction_GetFlags(PyObject *op)

{

    if (!PyCFunction_Check(op)) {

        PyErr_BadInternalCall();

        return -1;

    }

    return PyCFunction_GET_FLAGS(op);

}

PyTypeObject *

PyCMethod_GetClass(PyObject *op)

{

    if (!PyCFunction_Check(op)) {

        PyErr_BadInternalCall();

        return NULL;

    }

    return PyCFunction_GET_CLASS(op);

}

/* Methods (the standard built-in methods, that is) */

static void

meth_dealloc(PyObject *self)

{

    PyCFunctionObject *m = _PyCFunctionObject_CAST(self);

    PyObject_GC_UnTrack(m);

    FT_CLEAR_WEAKREFS(self, m->m_weakreflist);

    // We need to access ml_flags here rather than later.

    // `m->m_ml` might have the same lifetime

    // as `m_self` when it's dynamically allocated.

    int ml_flags = m->m_ml->ml_flags;

    // Dereference class before m_self: PyCFunction_GET_CLASS accesses

    // PyMethodDef m_ml, which could be kept alive by m_self

    Py_XDECREF(PyCFunction_GET_CLASS(m));

    Py_XDECREF(m->m_self);

    Py_XDECREF(m->m_module);

    if (ml_flags & METH_METHOD) {

        assert(Py_IS_TYPE(self, &PyCMethod_Type));

        _Py_FREELIST_FREE(pycmethodobject, m, PyObject_GC_Del);

    }

    else {

        assert(Py_IS_TYPE(self, &PyCFunction_Type));

        _Py_FREELIST_FREE(pycfunctionobject, m, PyObject_GC_Del);

    }

}

static PyObject *

meth_reduce(PyObject *self, PyObject *Py_UNUSED(ignored))

{

    PyCFunctionObject *m = _PyCFunctionObject_CAST(self);

    if (m->m_self == NULL || PyModule_Check(m->m_self))

        return PyUnicode_FromString(m->m_ml->ml_name);

    return Py_BuildValue("N(Os)", _PyEval_GetBuiltin(&_Py_ID(getattr)),

                         m->m_self, m->m_ml->ml_name);

}

static PyMethodDef meth_methods[] = {

    {"__reduce__", meth_reduce, METH_NOARGS, NULL},

    {NULL, NULL}

};

static PyObject *

meth_get__text_signature__(PyObject *self, void *closure)

{

    PyCFunctionObject *m = _PyCFunctionObject_CAST(self);

    return _PyType_GetTextSignatureFromInternalDoc(m->m_ml->ml_name,

                                                   m->m_ml->ml_doc,

                                                   m->m_ml->ml_flags);

}

static PyObject *

meth_get__doc__(PyObject *self, void *closure)

{

    PyCFunctionObject *m = _PyCFunctionObject_CAST(self);

    return _PyType_GetDocFromInternalDoc(m->m_ml->ml_name, m->m_ml->ml_doc);

}

static PyObject *

meth_get__name__(PyObject *self, void *closure)

{

    PyCFunctionObject *m = _PyCFunctionObject_CAST(self);

    return PyUnicode_FromString(m->m_ml->ml_name);

}

static PyObject *

meth_get__qualname__(PyObject *self, void *closure)

{

    /* If __self__ is a module or NULL, return m.__name__

       (e.g. len.__qualname__ == 'len')

       If __self__ is a type, return m.__self__.__qualname__ + '.' + m.__name__

       (e.g. dict.fromkeys.__qualname__ == 'dict.fromkeys')

       Otherwise return type(m.__self__).__qualname__ + '.' + m.__name__

       (e.g. [].append.__qualname__ == 'list.append') */

    PyCFunctionObject *m = _PyCFunctionObject_CAST(self);

    if (m->m_self == NULL || PyModule_Check(m->m_self)) {

        return PyUnicode_FromString(m->m_ml->ml_name);

    }

    PyObject *type = PyType_Check(m->m_self) ? m->m_self : (PyObject*)Py_TYPE(m->m_self);

    PyObject *type_qualname = PyObject_GetAttr(type, &_Py_ID(__qualname__));

    if (type_qualname == NULL)

        return NULL;

    if (!PyUnicode_Check(type_qualname)) {

        PyErr_SetString(PyExc_TypeError, "<method>.__class__."

                        "__qualname__ is not a unicode object");

        Py_XDECREF(type_qualname);

        return NULL;

    }

    PyObject *res = PyUnicode_FromFormat("%S.%s", type_qualname, m->m_ml->ml_name);

    Py_DECREF(type_qualname);

    return res;

}

static int

meth_traverse(PyObject *self, visitproc visit, void *arg)

{

    PyCFunctionObject *m = _PyCFunctionObject_CAST(self);

    Py_VISIT(PyCFunction_GET_CLASS(m));

    Py_VISIT(m->m_self);

    Py_VISIT(m->m_module);

    return 0;

}

static PyObject *

meth_get__self__(PyObject *meth, void *closure)

{

    PyCFunctionObject *m = _PyCFunctionObject_CAST(meth);

    PyObject *self = PyCFunction_GET_SELF(m);

    if (self == NULL) {

        self = Py_None;

    }

    return Py_NewRef(self);

}

static PyGetSetDef meth_getsets[] = {

    {"__doc__",  meth_get__doc__,  NULL, NULL},

    {"__name__", meth_get__name__, NULL, NULL},

    {"__qualname__", meth_get__qualname__, NULL, NULL},

    {"__self__", meth_get__self__, NULL, NULL},

    {"__text_signature__", meth_get__text_signature__, NULL, NULL},

    {0}

};

#define OFF(x) offsetof(PyCFunctionObject, x)

static PyMemberDef meth_members[] = {

    {"__module__",    _Py_T_OBJECT,     OFF(m_module), 0},

    {NULL}

};

static PyObject *

meth_repr(PyObject *self)

{

    PyCFunctionObject *m = _PyCFunctionObject_CAST(self);

    if (m->m_self == NULL || PyModule_Check(m->m_self)) {

        return PyUnicode_FromFormat("<built-in function %s>",

                                    m->m_ml->ml_name);

    }

    return PyUnicode_FromFormat("<built-in method %s of %s object at %p>",

                                m->m_ml->ml_name,

                                Py_TYPE(m->m_self)->tp_name,

                                m->m_self);

}

static PyObject *

meth_richcompare(PyObject *self, PyObject *other, int op)

{

    PyCFunctionObject *a, *b;

    PyObject *res;

    int eq;

    if ((op != Py_EQ && op != Py_NE) ||

        !PyCFunction_Check(self) ||

        !PyCFunction_Check(other))

    {

        Py_RETURN_NOTIMPLEMENTED;

    }

    a = (PyCFunctionObject *)self;

    b = (PyCFunctionObject *)other;

    eq = a->m_self == b->m_self;

    if (eq)

        eq = a->m_ml->ml_meth == b->m_ml->ml_meth;

    if (op == Py_EQ)

        res = eq ? Py_True : Py_False;

    else

        res = eq ? Py_False : Py_True;

    return Py_NewRef(res);

}

static Py_hash_t

meth_hash(PyObject *self)

{

    PyCFunctionObject *a = _PyCFunctionObject_CAST(self);

    Py_hash_t x = PyObject_GenericHash(a->m_self);

    Py_hash_t y = Py_HashPointer((void*)(a->m_ml->ml_meth));

    x ^= y;

    if (x == -1) {

        x = -2;

    }

    return x;

}

PyTypeObject PyCFunction_Type = {

    PyVarObject_HEAD_INIT(&PyType_Type, 0)

    "builtin_function_or_method",

    sizeof(PyCFunctionObject),

    0,

    meth_dealloc,                               /* tp_dealloc */

    offsetof(PyCFunctionObject, vectorcall),    /* tp_vectorcall_offset */

    0,                                          /* tp_getattr */

    0,                                          /* tp_setattr */

    0,                                          /* tp_as_async */

    meth_repr,                                  /* tp_repr */

    0,                                          /* tp_as_number */

    0,                                          /* tp_as_sequence */

    0,                                          /* tp_as_mapping */

    meth_hash,                                  /* tp_hash */

    cfunction_call,                             /* tp_call */

    0,                                          /* tp_str */

    PyObject_GenericGetAttr,                    /* tp_getattro */

    0,                                          /* tp_setattro */

    0,                                          /* tp_as_buffer */

    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |

    Py_TPFLAGS_HAVE_VECTORCALL,                 /* tp_flags */

    0,                                          /* tp_doc */

    meth_traverse,                /* tp_traverse */

    0,                                          /* tp_clear */

    meth_richcompare,                           /* tp_richcompare */

    offsetof(PyCFunctionObject, m_weakreflist), /* tp_weaklistoffset */

    0,                                          /* tp_iter */

    0,                                          /* tp_iternext */

    meth_methods,                               /* tp_methods */

    meth_members,                               /* tp_members */

    meth_getsets,                               /* tp_getset */

    0,                                          /* tp_base */

    0,                                          /* tp_dict */

};

PyTypeObject PyCMethod_Type = {

    PyVarObject_HEAD_INIT(&PyType_Type, 0)

    .tp_name = "builtin_method",

    .tp_basicsize = sizeof(PyCMethodObject),

    .tp_base = &PyCFunction_Type,

};

/* Vectorcall functions for each of the PyCFunction calling conventions,

 * except for METH_VARARGS (possibly combined with METH_KEYWORDS) which

 * doesn't use vectorcall.

 *

 * First, common helpers

 */

static inline int

cfunction_check_kwargs(PyThreadState *tstate, PyObject *func, PyObject *kwnames)

{

    assert(!_PyErr_Occurred(tstate));

    assert(PyCFunction_Check(func));

    if (kwnames && PyTuple_GET_SIZE(kwnames)) {

        PyObject *funcstr = _PyObject_FunctionStr(func);

        if (funcstr != NULL) {

            _PyErr_Format(tstate, PyExc_TypeError,

                         "%U takes no keyword arguments", funcstr);

            Py_DECREF(funcstr);

        }

        return -1;

    }

    return 0;

}

typedef void (*funcptr)(void);

static inline funcptr

cfunction_enter_call(PyThreadState *tstate, PyObject *func)

{

    if (_Py_EnterRecursiveCallTstate(tstate, " while calling a Python object")) {

        return NULL;

    }

    return (funcptr)PyCFunction_GET_FUNCTION(func);

}

/* Now the actual vectorcall functions */

static PyObject *

cfunction_vectorcall_FASTCALL(

    PyObject *func, PyObject *const *args, size_t nargsf, PyObject *kwnames)

{

    PyThreadState *tstate = _PyThreadState_GET();

    if (cfunction_check_kwargs(tstate, func, kwnames)) {

        return NULL;

    }

    Py_ssize_t nargs = PyVectorcall_NARGS(nargsf);

    PyCFunctionFast meth = (PyCFunctionFast)

                            cfunction_enter_call(tstate, func);

    if (meth == NULL) {

        return NULL;

    }

    PyObject *result = meth(PyCFunction_GET_SELF(func), args, nargs);

    _Py_LeaveRecursiveCallTstate(tstate);

    return result;

}

static PyObject *

cfunction_vectorcall_FASTCALL_KEYWORDS(

    PyObject *func, PyObject *const *args, size_t nargsf, PyObject *kwnames)

{

    PyThreadState *tstate = _PyThreadState_GET();

    Py_ssize_t nargs = PyVectorcall_NARGS(nargsf);

    PyCFunctionFastWithKeywords meth = (PyCFunctionFastWithKeywords)

                                        cfunction_enter_call(tstate, func);

    if (meth == NULL) {

        return NULL;

    }

    PyObject *result = meth(PyCFunction_GET_SELF(func), args, nargs, kwnames);

    _Py_LeaveRecursiveCallTstate(tstate);

    return result;

}

static PyObject *

cfunction_vectorcall_FASTCALL_KEYWORDS_METHOD(

    PyObject *func, PyObject *const *args, size_t nargsf, PyObject *kwnames)

{

    PyThreadState *tstate = _PyThreadState_GET();

    PyTypeObject *cls = PyCFunction_GET_CLASS(func);

    Py_ssize_t nargs = PyVectorcall_NARGS(nargsf);

    PyCMethod meth = (PyCMethod)cfunction_enter_call(tstate, func);

    if (meth == NULL) {

        return NULL;

    }

    PyObject *result = meth(PyCFunction_GET_SELF(func), cls, args, nargs, kwnames);

    _Py_LeaveRecursiveCallTstate(tstate);

    return result;

}

static PyObject *

cfunction_vectorcall_NOARGS(

    PyObject *func, PyObject *const *args, size_t nargsf, PyObject *kwnames)

{

    PyThreadState *tstate = _PyThreadState_GET();

    if (cfunction_check_kwargs(tstate, func, kwnames)) {

        return NULL;

    }

    Py_ssize_t nargs = PyVectorcall_NARGS(nargsf);

    if (nargs != 0) {

        PyObject *funcstr = _PyObject_FunctionStr(func);

        if (funcstr != NULL) {

            _PyErr_Format(tstate, PyExc_TypeError,

                "%U takes no arguments (%zd given)", funcstr, nargs);

            Py_DECREF(funcstr);

        }

        return NULL;

    }

    PyCFunction meth = (PyCFunction)cfunction_enter_call(tstate, func);

    if (meth == NULL) {

        return NULL;

    }

    PyObject *result = _PyCFunction_TrampolineCall(

        meth, PyCFunction_GET_SELF(func), NULL);

    _Py_LeaveRecursiveCallTstate(tstate);

    return result;

}

static PyObject *

cfunction_vectorcall_O(

    PyObject *func, PyObject *const *args, size_t nargsf, PyObject *kwnames)

{

    PyThreadState *tstate = _PyThreadState_GET();

    if (cfunction_check_kwargs(tstate, func, kwnames)) {

        return NULL;

    }

    Py_ssize_t nargs = PyVectorcall_NARGS(nargsf);

    if (nargs != 1) {

        PyObject *funcstr = _PyObject_FunctionStr(func);

        if (funcstr != NULL) {

            _PyErr_Format(tstate, PyExc_TypeError,

                "%U takes exactly one argument (%zd given)", funcstr, nargs);

            Py_DECREF(funcstr);

        }

        return NULL;

    }

    PyCFunction meth = (PyCFunction)cfunction_enter_call(tstate, func);

    if (meth == NULL) {

        return NULL;

    }

    PyObject *result = _PyCFunction_TrampolineCall(

        meth, PyCFunction_GET_SELF(func), args[0]);

    _Py_LeaveRecursiveCallTstate(tstate);

    return result;

}

static PyObject *

cfunction_call(PyObject *func, PyObject *args, PyObject *kwargs)

{

    assert(kwargs == NULL || PyDict_Check(kwargs));

    PyThreadState *tstate = _PyThreadState_GET();

    assert(!_PyErr_Occurred(tstate));

    int flags = PyCFunction_GET_FLAGS(func);

    if (!(flags & METH_VARARGS)) {

        /* If this is not a METH_VARARGS function, delegate to vectorcall */

        return PyVectorcall_Call(func, args, kwargs);

    }

    /* For METH_VARARGS, we cannot use vectorcall as the vectorcall pointer

     * is NULL. This is intentional, since vectorcall would be slower. */

    PyCFunction meth = PyCFunction_GET_FUNCTION(func);

    PyObject *self = PyCFunction_GET_SELF(func);

    PyObject *result;

    if (flags & METH_KEYWORDS) {

        result = _PyCFunctionWithKeywords_TrampolineCall(

            *_PyCFunctionWithKeywords_CAST(meth),

            self, args, kwargs);

    }

    else {

        if (kwargs != NULL && PyDict_GET_SIZE(kwargs) != 0) {

            _PyErr_Format(tstate, PyExc_TypeError,

                          "%.200s() takes no keyword arguments",

                          ((PyCFunctionObject*)func)->m_ml->ml_name);

            return NULL;

        }

        result = _PyCFunction_TrampolineCall(meth, self, args);

    }

    return _Py_CheckFunctionResult(tstate, func, result, NULL);

}