1 
2 /* Method object implementation */
3 
4 #include "Python.h"
5 #include "structmember.h"
6 
7 /* Free list for method objects to safe malloc/free overhead
8  * The m_self element is used to chain the objects.
9  */
10 static PyCFunctionObject *free_list = NULL;
11 static int numfree = 0;
12 #ifndef PyCFunction_MAXFREELIST
13 #define PyCFunction_MAXFREELIST 256
14 #endif
15 
16 /* undefine macro trampoline to PyCFunction_NewEx */
17 #undef PyCFunction_New
18 
19 PyAPI_FUNC(PyObject *)
PyCFunction_New(PyMethodDef * ml,PyObject * self)20 PyCFunction_New(PyMethodDef *ml, PyObject *self)
21 {
22     return PyCFunction_NewEx(ml, self, NULL);
23 }
24 
25 PyObject *
PyCFunction_NewEx(PyMethodDef * ml,PyObject * self,PyObject * module)26 PyCFunction_NewEx(PyMethodDef *ml, PyObject *self, PyObject *module)
27 {
28     PyCFunctionObject *op;
29     op = free_list;
30     if (op != NULL) {
31         free_list = (PyCFunctionObject *)(op->m_self);
32         (void)PyObject_INIT(op, &PyCFunction_Type);
33         numfree--;
34     }
35     else {
36         op = PyObject_GC_New(PyCFunctionObject, &PyCFunction_Type);
37         if (op == NULL)
38             return NULL;
39     }
40     op->m_weakreflist = NULL;
41     op->m_ml = ml;
42     Py_XINCREF(self);
43     op->m_self = self;
44     Py_XINCREF(module);
45     op->m_module = module;
46     _PyObject_GC_TRACK(op);
47     return (PyObject *)op;
48 }
49 
50 PyCFunction
PyCFunction_GetFunction(PyObject * op)51 PyCFunction_GetFunction(PyObject *op)
52 {
53     if (!PyCFunction_Check(op)) {
54         PyErr_BadInternalCall();
55         return NULL;
56     }
57     return PyCFunction_GET_FUNCTION(op);
58 }
59 
60 PyObject *
PyCFunction_GetSelf(PyObject * op)61 PyCFunction_GetSelf(PyObject *op)
62 {
63     if (!PyCFunction_Check(op)) {
64         PyErr_BadInternalCall();
65         return NULL;
66     }
67     return PyCFunction_GET_SELF(op);
68 }
69 
70 int
PyCFunction_GetFlags(PyObject * op)71 PyCFunction_GetFlags(PyObject *op)
72 {
73     if (!PyCFunction_Check(op)) {
74         PyErr_BadInternalCall();
75         return -1;
76     }
77     return PyCFunction_GET_FLAGS(op);
78 }
79 
80 PyObject *
PyCFunction_Call(PyObject * func,PyObject * args,PyObject * kwds)81 PyCFunction_Call(PyObject *func, PyObject *args, PyObject *kwds)
82 {
83     PyCFunctionObject* f = (PyCFunctionObject*)func;
84     PyCFunction meth = PyCFunction_GET_FUNCTION(func);
85     PyObject *self = PyCFunction_GET_SELF(func);
86     PyObject *arg, *res;
87     Py_ssize_t size;
88     int flags;
89 
90     /* PyCFunction_Call() must not be called with an exception set,
91        because it may clear it (directly or indirectly) and so the
92        caller loses its exception */
93     assert(!PyErr_Occurred());
94 
95     flags = PyCFunction_GET_FLAGS(func) & ~(METH_CLASS | METH_STATIC | METH_COEXIST);
96 
97     if (flags == (METH_VARARGS | METH_KEYWORDS)) {
98         res = (*(PyCFunctionWithKeywords)meth)(self, args, kwds);
99     }
100     else if (flags == METH_FASTCALL) {
101         PyObject **stack = &PyTuple_GET_ITEM(args, 0);
102         Py_ssize_t nargs = PyTuple_GET_SIZE(args);
103         res = _PyCFunction_FastCallDict(func, stack, nargs, kwds);
104     }
105     else {
106         if (kwds != NULL && PyDict_Size(kwds) != 0) {
107             PyErr_Format(PyExc_TypeError, "%.200s() takes no keyword arguments",
108                          f->m_ml->ml_name);
109             return NULL;
110         }
111 
112         switch (flags) {
113         case METH_VARARGS:
114             res = (*meth)(self, args);
115             break;
116 
117         case METH_NOARGS:
118             size = PyTuple_GET_SIZE(args);
119             if (size != 0) {
120                 PyErr_Format(PyExc_TypeError,
121                     "%.200s() takes no arguments (%zd given)",
122                     f->m_ml->ml_name, size);
123                 return NULL;
124             }
125 
126             res = (*meth)(self, NULL);
127             break;
128 
129         case METH_O:
130             size = PyTuple_GET_SIZE(args);
131             if (size != 1) {
132                 PyErr_Format(PyExc_TypeError,
133                     "%.200s() takes exactly one argument (%zd given)",
134                     f->m_ml->ml_name, size);
135                 return NULL;
136             }
137 
138             arg = PyTuple_GET_ITEM(args, 0);
139             res = (*meth)(self, arg);
140             break;
141 
142         default:
143             PyErr_SetString(PyExc_SystemError,
144                             "Bad call flags in PyCFunction_Call. "
145                             "METH_OLDARGS is no longer supported!");
146             return NULL;
147         }
148     }
149 
150     return _Py_CheckFunctionResult(func, res, NULL);
151 }
152 
153 PyObject *
_PyCFunction_FastCallDict(PyObject * func_obj,PyObject ** args,Py_ssize_t nargs,PyObject * kwargs)154 _PyCFunction_FastCallDict(PyObject *func_obj, PyObject **args, Py_ssize_t nargs,
155                           PyObject *kwargs)
156 {
157     PyCFunctionObject *func = (PyCFunctionObject*)func_obj;
158     PyCFunction meth = PyCFunction_GET_FUNCTION(func);
159     PyObject *self = PyCFunction_GET_SELF(func);
160     PyObject *result;
161     int flags;
162 
163     assert(PyCFunction_Check(func));
164     assert(func != NULL);
165     assert(nargs >= 0);
166     assert(nargs == 0 || args != NULL);
167     assert(kwargs == NULL || PyDict_Check(kwargs));
168 
169     /* _PyCFunction_FastCallDict() must not be called with an exception set,
170        because it may clear it (directly or indirectly) and so the
171        caller loses its exception */
172     assert(!PyErr_Occurred());
173 
174     flags = PyCFunction_GET_FLAGS(func) & ~(METH_CLASS | METH_STATIC | METH_COEXIST);
175 
176     switch (flags)
177     {
178     case METH_NOARGS:
179         if (kwargs != NULL && PyDict_Size(kwargs) != 0) {
180             PyErr_Format(PyExc_TypeError, "%.200s() takes no keyword arguments",
181                          func->m_ml->ml_name);
182             return NULL;
183         }
184 
185         if (nargs != 0) {
186             PyErr_Format(PyExc_TypeError,
187                 "%.200s() takes no arguments (%zd given)",
188                 func->m_ml->ml_name, nargs);
189             return NULL;
190         }
191 
192         result = (*meth) (self, NULL);
193         break;
194 
195     case METH_O:
196         if (kwargs != NULL && PyDict_Size(kwargs) != 0) {
197             PyErr_Format(PyExc_TypeError, "%.200s() takes no keyword arguments",
198                          func->m_ml->ml_name);
199             return NULL;
200         }
201 
202         if (nargs != 1) {
203             PyErr_Format(PyExc_TypeError,
204                 "%.200s() takes exactly one argument (%zd given)",
205                 func->m_ml->ml_name, nargs);
206             return NULL;
207         }
208 
209         result = (*meth) (self, args[0]);
210         break;
211 
212     case METH_VARARGS:
213     case METH_VARARGS | METH_KEYWORDS:
214     {
215         /* Slow-path: create a temporary tuple */
216         PyObject *tuple;
217 
218         if (!(flags & METH_KEYWORDS) && kwargs != NULL && PyDict_Size(kwargs) != 0) {
219             PyErr_Format(PyExc_TypeError,
220                          "%.200s() takes no keyword arguments",
221                          func->m_ml->ml_name);
222             return NULL;
223         }
224 
225         tuple = _PyStack_AsTuple(args, nargs);
226         if (tuple == NULL) {
227             return NULL;
228         }
229 
230         if (flags & METH_KEYWORDS) {
231             result = (*(PyCFunctionWithKeywords)meth) (self, tuple, kwargs);
232         }
233         else {
234             result = (*meth) (self, tuple);
235         }
236         Py_DECREF(tuple);
237         break;
238     }
239 
240     case METH_FASTCALL:
241     {
242         PyObject **stack;
243         PyObject *kwnames;
244         _PyCFunctionFast fastmeth = (_PyCFunctionFast)meth;
245 
246         stack = _PyStack_UnpackDict(args, nargs, kwargs, &kwnames, func_obj);
247         if (stack == NULL) {
248             return NULL;
249         }
250 
251         result = (*fastmeth) (self, stack, nargs, kwnames);
252         if (stack != args) {
253             PyMem_Free(stack);
254         }
255         Py_XDECREF(kwnames);
256         break;
257     }
258 
259     default:
260         PyErr_SetString(PyExc_SystemError,
261                         "Bad call flags in PyCFunction_Call. "
262                         "METH_OLDARGS is no longer supported!");
263         return NULL;
264     }
265 
266     result = _Py_CheckFunctionResult(func_obj, result, NULL);
267 
268     return result;
269 }
270 
271 PyObject *
_PyCFunction_FastCallKeywords(PyObject * func,PyObject ** stack,Py_ssize_t nargs,PyObject * kwnames)272 _PyCFunction_FastCallKeywords(PyObject *func, PyObject **stack,
273                               Py_ssize_t nargs, PyObject *kwnames)
274 {
275     PyObject *kwdict, *result;
276     Py_ssize_t nkwargs = (kwnames == NULL) ? 0 : PyTuple_GET_SIZE(kwnames);
277 
278     assert(PyCFunction_Check(func));
279     assert(nargs >= 0);
280     assert(kwnames == NULL || PyTuple_CheckExact(kwnames));
281     assert((nargs == 0 && nkwargs == 0) || stack != NULL);
282     /* kwnames must only contains str strings, no subclass, and all keys must
283        be unique */
284 
285     if (nkwargs > 0) {
286         kwdict = _PyStack_AsDict(stack + nargs, kwnames);
287         if (kwdict == NULL) {
288             return NULL;
289         }
290     }
291     else {
292         kwdict = NULL;
293     }
294 
295     result = _PyCFunction_FastCallDict(func, stack, nargs, kwdict);
296     Py_XDECREF(kwdict);
297     return result;
298 }
299 
300 /* Methods (the standard built-in methods, that is) */
301 
302 static void
meth_dealloc(PyCFunctionObject * m)303 meth_dealloc(PyCFunctionObject *m)
304 {
305     _PyObject_GC_UNTRACK(m);
306     if (m->m_weakreflist != NULL) {
307         PyObject_ClearWeakRefs((PyObject*) m);
308     }
309     Py_XDECREF(m->m_self);
310     Py_XDECREF(m->m_module);
311     if (numfree < PyCFunction_MAXFREELIST) {
312         m->m_self = (PyObject *)free_list;
313         free_list = m;
314         numfree++;
315     }
316     else {
317         PyObject_GC_Del(m);
318     }
319 }
320 
321 static PyObject *
meth_reduce(PyCFunctionObject * m)322 meth_reduce(PyCFunctionObject *m)
323 {
324     PyObject *builtins;
325     PyObject *getattr;
326     _Py_IDENTIFIER(getattr);
327 
328     if (m->m_self == NULL || PyModule_Check(m->m_self))
329         return PyUnicode_FromString(m->m_ml->ml_name);
330 
331     builtins = PyEval_GetBuiltins();
332     getattr = _PyDict_GetItemId(builtins, &PyId_getattr);
333     return Py_BuildValue("O(Os)", getattr, m->m_self, m->m_ml->ml_name);
334 }
335 
336 static PyMethodDef meth_methods[] = {
337     {"__reduce__", (PyCFunction)meth_reduce, METH_NOARGS, NULL},
338     {NULL, NULL}
339 };
340 
341 static PyObject *
meth_get__text_signature__(PyCFunctionObject * m,void * closure)342 meth_get__text_signature__(PyCFunctionObject *m, void *closure)
343 {
344     return _PyType_GetTextSignatureFromInternalDoc(m->m_ml->ml_name, m->m_ml->ml_doc);
345 }
346 
347 static PyObject *
meth_get__doc__(PyCFunctionObject * m,void * closure)348 meth_get__doc__(PyCFunctionObject *m, void *closure)
349 {
350     return _PyType_GetDocFromInternalDoc(m->m_ml->ml_name, m->m_ml->ml_doc);
351 }
352 
353 static PyObject *
meth_get__name__(PyCFunctionObject * m,void * closure)354 meth_get__name__(PyCFunctionObject *m, void *closure)
355 {
356     return PyUnicode_FromString(m->m_ml->ml_name);
357 }
358 
359 static PyObject *
meth_get__qualname__(PyCFunctionObject * m,void * closure)360 meth_get__qualname__(PyCFunctionObject *m, void *closure)
361 {
362     /* If __self__ is a module or NULL, return m.__name__
363        (e.g. len.__qualname__ == 'len')
364 
365        If __self__ is a type, return m.__self__.__qualname__ + '.' + m.__name__
366        (e.g. dict.fromkeys.__qualname__ == 'dict.fromkeys')
367 
368        Otherwise return type(m.__self__).__qualname__ + '.' + m.__name__
369        (e.g. [].append.__qualname__ == 'list.append') */
370     PyObject *type, *type_qualname, *res;
371     _Py_IDENTIFIER(__qualname__);
372 
373     if (m->m_self == NULL || PyModule_Check(m->m_self))
374         return PyUnicode_FromString(m->m_ml->ml_name);
375 
376     type = PyType_Check(m->m_self) ? m->m_self : (PyObject*)Py_TYPE(m->m_self);
377 
378     type_qualname = _PyObject_GetAttrId(type, &PyId___qualname__);
379     if (type_qualname == NULL)
380         return NULL;
381 
382     if (!PyUnicode_Check(type_qualname)) {
383         PyErr_SetString(PyExc_TypeError, "<method>.__class__."
384                         "__qualname__ is not a unicode object");
385         Py_XDECREF(type_qualname);
386         return NULL;
387     }
388 
389     res = PyUnicode_FromFormat("%S.%s", type_qualname, m->m_ml->ml_name);
390     Py_DECREF(type_qualname);
391     return res;
392 }
393 
394 static int
meth_traverse(PyCFunctionObject * m,visitproc visit,void * arg)395 meth_traverse(PyCFunctionObject *m, visitproc visit, void *arg)
396 {
397     Py_VISIT(m->m_self);
398     Py_VISIT(m->m_module);
399     return 0;
400 }
401 
402 static PyObject *
meth_get__self__(PyCFunctionObject * m,void * closure)403 meth_get__self__(PyCFunctionObject *m, void *closure)
404 {
405     PyObject *self;
406 
407     self = PyCFunction_GET_SELF(m);
408     if (self == NULL)
409         self = Py_None;
410     Py_INCREF(self);
411     return self;
412 }
413 
414 static PyGetSetDef meth_getsets [] = {
415     {"__doc__",  (getter)meth_get__doc__,  NULL, NULL},
416     {"__name__", (getter)meth_get__name__, NULL, NULL},
417     {"__qualname__", (getter)meth_get__qualname__, NULL, NULL},
418     {"__self__", (getter)meth_get__self__, NULL, NULL},
419     {"__text_signature__", (getter)meth_get__text_signature__, NULL, NULL},
420     {0}
421 };
422 
423 #define OFF(x) offsetof(PyCFunctionObject, x)
424 
425 static PyMemberDef meth_members[] = {
426     {"__module__",    T_OBJECT,     OFF(m_module), PY_WRITE_RESTRICTED},
427     {NULL}
428 };
429 
430 static PyObject *
meth_repr(PyCFunctionObject * m)431 meth_repr(PyCFunctionObject *m)
432 {
433     if (m->m_self == NULL || PyModule_Check(m->m_self))
434         return PyUnicode_FromFormat("<built-in function %s>",
435                                    m->m_ml->ml_name);
436     return PyUnicode_FromFormat("<built-in method %s of %s object at %p>",
437                                m->m_ml->ml_name,
438                                m->m_self->ob_type->tp_name,
439                                m->m_self);
440 }
441 
442 static PyObject *
meth_richcompare(PyObject * self,PyObject * other,int op)443 meth_richcompare(PyObject *self, PyObject *other, int op)
444 {
445     PyCFunctionObject *a, *b;
446     PyObject *res;
447     int eq;
448 
449     if ((op != Py_EQ && op != Py_NE) ||
450         !PyCFunction_Check(self) ||
451         !PyCFunction_Check(other))
452     {
453         Py_RETURN_NOTIMPLEMENTED;
454     }
455     a = (PyCFunctionObject *)self;
456     b = (PyCFunctionObject *)other;
457     eq = a->m_self == b->m_self;
458     if (eq)
459         eq = a->m_ml->ml_meth == b->m_ml->ml_meth;
460     if (op == Py_EQ)
461         res = eq ? Py_True : Py_False;
462     else
463         res = eq ? Py_False : Py_True;
464     Py_INCREF(res);
465     return res;
466 }
467 
468 static Py_hash_t
meth_hash(PyCFunctionObject * a)469 meth_hash(PyCFunctionObject *a)
470 {
471     Py_hash_t x, y;
472     if (a->m_self == NULL)
473         x = 0;
474     else {
475         x = PyObject_Hash(a->m_self);
476         if (x == -1)
477             return -1;
478     }
479     y = _Py_HashPointer((void*)(a->m_ml->ml_meth));
480     if (y == -1)
481         return -1;
482     x ^= y;
483     if (x == -1)
484         x = -2;
485     return x;
486 }
487 
488 
489 PyTypeObject PyCFunction_Type = {
490     PyVarObject_HEAD_INIT(&PyType_Type, 0)
491     "builtin_function_or_method",
492     sizeof(PyCFunctionObject),
493     0,
494     (destructor)meth_dealloc,                   /* tp_dealloc */
495     0,                                          /* tp_print */
496     0,                                          /* tp_getattr */
497     0,                                          /* tp_setattr */
498     0,                                          /* tp_reserved */
499     (reprfunc)meth_repr,                        /* tp_repr */
500     0,                                          /* tp_as_number */
501     0,                                          /* tp_as_sequence */
502     0,                                          /* tp_as_mapping */
503     (hashfunc)meth_hash,                        /* tp_hash */
504     PyCFunction_Call,                           /* tp_call */
505     0,                                          /* tp_str */
506     PyObject_GenericGetAttr,                    /* tp_getattro */
507     0,                                          /* tp_setattro */
508     0,                                          /* tp_as_buffer */
509     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,/* tp_flags */
510     0,                                          /* tp_doc */
511     (traverseproc)meth_traverse,                /* tp_traverse */
512     0,                                          /* tp_clear */
513     meth_richcompare,                           /* tp_richcompare */
514     offsetof(PyCFunctionObject, m_weakreflist), /* tp_weaklistoffset */
515     0,                                          /* tp_iter */
516     0,                                          /* tp_iternext */
517     meth_methods,                               /* tp_methods */
518     meth_members,                               /* tp_members */
519     meth_getsets,                               /* tp_getset */
520     0,                                          /* tp_base */
521     0,                                          /* tp_dict */
522 };
523 
524 /* Clear out the free list */
525 
526 int
PyCFunction_ClearFreeList(void)527 PyCFunction_ClearFreeList(void)
528 {
529     int freelist_size = numfree;
530 
531     while (free_list) {
532         PyCFunctionObject *v = free_list;
533         free_list = (PyCFunctionObject *)(v->m_self);
534         PyObject_GC_Del(v);
535         numfree--;
536     }
537     assert(numfree == 0);
538     return freelist_size;
539 }
540 
541 void
PyCFunction_Fini(void)542 PyCFunction_Fini(void)
543 {
544     (void)PyCFunction_ClearFreeList();
545 }
546 
547 /* Print summary info about the state of the optimized allocator */
548 void
_PyCFunction_DebugMallocStats(FILE * out)549 _PyCFunction_DebugMallocStats(FILE *out)
550 {
551     _PyDebugAllocatorStats(out,
552                            "free PyCFunctionObject",
553                            numfree, sizeof(PyCFunctionObject));
554 }
555