1 #include "Python.h" 2 #include "structmember.h" 3 4 5 #define GET_WEAKREFS_LISTPTR(o) \ 6 ((PyWeakReference **) PyObject_GET_WEAKREFS_LISTPTR(o)) 7 8 9 Py_ssize_t 10 _PyWeakref_GetWeakrefCount(PyWeakReference *head) 11 { 12 Py_ssize_t count = 0; 13 14 while (head != NULL) { 15 ++count; 16 head = head->wr_next; 17 } 18 return count; 19 } 20 21 22 static void 23 init_weakref(PyWeakReference *self, PyObject *ob, PyObject *callback) 24 { 25 self->hash = -1; 26 self->wr_object = ob; 27 Py_XINCREF(callback); 28 self->wr_callback = callback; 29 } 30 31 static PyWeakReference * 32 new_weakref(PyObject *ob, PyObject *callback) 33 { 34 PyWeakReference *result; 35 36 result = PyObject_GC_New(PyWeakReference, &_PyWeakref_RefType); 37 if (result) { 38 init_weakref(result, ob, callback); 39 PyObject_GC_Track(result); 40 } 41 return result; 42 } 43 44 45 /* This function clears the passed-in reference and removes it from the 46 * list of weak references for the referent. This is the only code that 47 * removes an item from the doubly-linked list of weak references for an 48 * object; it is also responsible for clearing the callback slot. 49 */ 50 static void 51 clear_weakref(PyWeakReference *self) 52 { 53 PyObject *callback = self->wr_callback; 54 55 if (PyWeakref_GET_OBJECT(self) != Py_None) { 56 PyWeakReference **list = GET_WEAKREFS_LISTPTR( 57 PyWeakref_GET_OBJECT(self)); 58 59 if (*list == self) 60 /* If 'self' is the end of the list (and thus self->wr_next == NULL) 61 then the weakref list itself (and thus the value of *list) will 62 end up being set to NULL. */ 63 *list = self->wr_next; 64 self->wr_object = Py_None; 65 if (self->wr_prev != NULL) 66 self->wr_prev->wr_next = self->wr_next; 67 if (self->wr_next != NULL) 68 self->wr_next->wr_prev = self->wr_prev; 69 self->wr_prev = NULL; 70 self->wr_next = NULL; 71 } 72 if (callback != NULL) { 73 Py_DECREF(callback); 74 self->wr_callback = NULL; 75 } 76 } 77 78 /* Cyclic gc uses this to *just* clear the passed-in reference, leaving 79 * the callback intact and uncalled. It must be possible to call self's 80 * tp_dealloc() after calling this, so self has to be left in a sane enough 81 * state for that to work. We expect tp_dealloc to decref the callback 82 * then. The reason for not letting clear_weakref() decref the callback 83 * right now is that if the callback goes away, that may in turn trigger 84 * another callback (if a weak reference to the callback exists) -- running 85 * arbitrary Python code in the middle of gc is a disaster. The convolution 86 * here allows gc to delay triggering such callbacks until the world is in 87 * a sane state again. 88 */ 89 void 90 _PyWeakref_ClearRef(PyWeakReference *self) 91 { 92 PyObject *callback; 93 94 assert(self != NULL); 95 assert(PyWeakref_Check(self)); 96 /* Preserve and restore the callback around clear_weakref. */ 97 callback = self->wr_callback; 98 self->wr_callback = NULL; 99 clear_weakref(self); 100 self->wr_callback = callback; 101 } 102 103 static void 104 weakref_dealloc(PyObject *self) 105 { 106 PyObject_GC_UnTrack(self); 107 clear_weakref((PyWeakReference *) self); 108 Py_TYPE(self)->tp_free(self); 109 } 110 111 112 static int 113 gc_traverse(PyWeakReference *self, visitproc visit, void *arg) 114 { 115 Py_VISIT(self->wr_callback); 116 return 0; 117 } 118 119 120 static int 121 gc_clear(PyWeakReference *self) 122 { 123 clear_weakref(self); 124 return 0; 125 } 126 127 128 static PyObject * 129 weakref_call(PyWeakReference *self, PyObject *args, PyObject *kw) 130 { 131 static char *kwlist[] = {NULL}; 132 133 if (PyArg_ParseTupleAndKeywords(args, kw, ":__call__", kwlist)) { 134 PyObject *object = PyWeakref_GET_OBJECT(self); 135 Py_INCREF(object); 136 return (object); 137 } 138 return NULL; 139 } 140 141 142 static long 143 weakref_hash(PyWeakReference *self) 144 { 145 if (self->hash != -1) 146 return self->hash; 147 if (PyWeakref_GET_OBJECT(self) == Py_None) { 148 PyErr_SetString(PyExc_TypeError, "weak object has gone away"); 149 return -1; 150 } 151 self->hash = PyObject_Hash(PyWeakref_GET_OBJECT(self)); 152 return self->hash; 153 } 154 155 156 static PyObject * 157 weakref_repr(PyWeakReference *self) 158 { 159 char buffer[256]; 160 if (PyWeakref_GET_OBJECT(self) == Py_None) { 161 PyOS_snprintf(buffer, sizeof(buffer), "<weakref at %p; dead>", self); 162 } 163 else { 164 char *name = NULL; 165 PyObject *nameobj = PyObject_GetAttrString(PyWeakref_GET_OBJECT(self), 166 "__name__"); 167 if (nameobj == NULL) 168 PyErr_Clear(); 169 else if (PyString_Check(nameobj)) 170 name = PyString_AS_STRING(nameobj); 171 PyOS_snprintf(buffer, sizeof(buffer), 172 name ? "<weakref at %p; to '%.50s' at %p (%s)>" 173 : "<weakref at %p; to '%.50s' at %p>", 174 self, 175 Py_TYPE(PyWeakref_GET_OBJECT(self))->tp_name, 176 PyWeakref_GET_OBJECT(self), 177 name); 178 Py_XDECREF(nameobj); 179 } 180 return PyString_FromString(buffer); 181 } 182 183 /* Weak references only support equality, not ordering. Two weak references 184 are equal if the underlying objects are equal. If the underlying object has 185 gone away, they are equal if they are identical. */ 186 187 static PyObject * 188 weakref_richcompare(PyWeakReference* self, PyWeakReference* other, int op) 189 { 190 if (op != Py_EQ || self->ob_type != other->ob_type) { 191 Py_INCREF(Py_NotImplemented); 192 return Py_NotImplemented; 193 } 194 if (PyWeakref_GET_OBJECT(self) == Py_None 195 || PyWeakref_GET_OBJECT(other) == Py_None) { 196 PyObject *res = self==other ? Py_True : Py_False; 197 Py_INCREF(res); 198 return res; 199 } 200 return PyObject_RichCompare(PyWeakref_GET_OBJECT(self), 201 PyWeakref_GET_OBJECT(other), op); 202 } 203 204 /* Given the head of an object's list of weak references, extract the 205 * two callback-less refs (ref and proxy). Used to determine if the 206 * shared references exist and to determine the back link for newly 207 * inserted references. 208 */ 209 static void 210 get_basic_refs(PyWeakReference *head, 211 PyWeakReference **refp, PyWeakReference **proxyp) 212 { 213 *refp = NULL; 214 *proxyp = NULL; 215 216 if (head != NULL && head->wr_callback == NULL) { 217 /* We need to be careful that the "basic refs" aren't 218 subclasses of the main types. That complicates this a 219 little. */ 220 if (PyWeakref_CheckRefExact(head)) { 221 *refp = head; 222 head = head->wr_next; 223 } 224 if (head != NULL 225 && head->wr_callback == NULL 226 && PyWeakref_CheckProxy(head)) { 227 *proxyp = head; 228 /* head = head->wr_next; */ 229 } 230 } 231 } 232 233 /* Insert 'newref' in the list after 'prev'. Both must be non-NULL. */ 234 static void 235 insert_after(PyWeakReference *newref, PyWeakReference *prev) 236 { 237 newref->wr_prev = prev; 238 newref->wr_next = prev->wr_next; 239 if (prev->wr_next != NULL) 240 prev->wr_next->wr_prev = newref; 241 prev->wr_next = newref; 242 } 243 244 /* Insert 'newref' at the head of the list; 'list' points to the variable 245 * that stores the head. 246 */ 247 static void 248 insert_head(PyWeakReference *newref, PyWeakReference **list) 249 { 250 PyWeakReference *next = *list; 251 252 newref->wr_prev = NULL; 253 newref->wr_next = next; 254 if (next != NULL) 255 next->wr_prev = newref; 256 *list = newref; 257 } 258 259 static int 260 parse_weakref_init_args(char *funcname, PyObject *args, PyObject *kwargs, 261 PyObject **obp, PyObject **callbackp) 262 { 263 /* XXX Should check that kwargs == NULL or is empty. */ 264 return PyArg_UnpackTuple(args, funcname, 1, 2, obp, callbackp); 265 } 266 267 static PyObject * 268 weakref___new__(PyTypeObject *type, PyObject *args, PyObject *kwargs) 269 { 270 PyWeakReference *self = NULL; 271 PyObject *ob, *callback = NULL; 272 273 if (parse_weakref_init_args("__new__", args, kwargs, &ob, &callback)) { 274 PyWeakReference *ref, *proxy; 275 PyWeakReference **list; 276 277 if (!PyType_SUPPORTS_WEAKREFS(Py_TYPE(ob))) { 278 PyErr_Format(PyExc_TypeError, 279 "cannot create weak reference to '%s' object", 280 Py_TYPE(ob)->tp_name); 281 return NULL; 282 } 283 if (callback == Py_None) 284 callback = NULL; 285 list = GET_WEAKREFS_LISTPTR(ob); 286 get_basic_refs(*list, &ref, &proxy); 287 if (callback == NULL && type == &_PyWeakref_RefType) { 288 if (ref != NULL) { 289 /* We can re-use an existing reference. */ 290 Py_INCREF(ref); 291 return (PyObject *)ref; 292 } 293 } 294 /* We have to create a new reference. */ 295 /* Note: the tp_alloc() can trigger cyclic GC, so the weakref 296 list on ob can be mutated. This means that the ref and 297 proxy pointers we got back earlier may have been collected, 298 so we need to compute these values again before we use 299 them. */ 300 self = (PyWeakReference *) (type->tp_alloc(type, 0)); 301 if (self != NULL) { 302 init_weakref(self, ob, callback); 303 if (callback == NULL && type == &_PyWeakref_RefType) { 304 insert_head(self, list); 305 } 306 else { 307 PyWeakReference *prev; 308 309 get_basic_refs(*list, &ref, &proxy); 310 prev = (proxy == NULL) ? ref : proxy; 311 if (prev == NULL) 312 insert_head(self, list); 313 else 314 insert_after(self, prev); 315 } 316 } 317 } 318 return (PyObject *)self; 319 } 320 321 static int 322 weakref___init__(PyObject *self, PyObject *args, PyObject *kwargs) 323 { 324 PyObject *tmp; 325 326 if (parse_weakref_init_args("__init__", args, kwargs, &tmp, &tmp)) 327 return 0; 328 else 329 return -1; 330 } 331 332 333 PyTypeObject 334 _PyWeakref_RefType = { 335 PyVarObject_HEAD_INIT(&PyType_Type, 0) 336 "weakref", 337 sizeof(PyWeakReference), 338 0, 339 weakref_dealloc, /*tp_dealloc*/ 340 0, /*tp_print*/ 341 0, /*tp_getattr*/ 342 0, /*tp_setattr*/ 343 0, /*tp_compare*/ 344 (reprfunc)weakref_repr, /*tp_repr*/ 345 0, /*tp_as_number*/ 346 0, /*tp_as_sequence*/ 347 0, /*tp_as_mapping*/ 348 (hashfunc)weakref_hash, /*tp_hash*/ 349 (ternaryfunc)weakref_call, /*tp_call*/ 350 0, /*tp_str*/ 351 0, /*tp_getattro*/ 352 0, /*tp_setattro*/ 353 0, /*tp_as_buffer*/ 354 Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_RICHCOMPARE 355 | Py_TPFLAGS_BASETYPE, /*tp_flags*/ 356 0, /*tp_doc*/ 357 (traverseproc)gc_traverse, /*tp_traverse*/ 358 (inquiry)gc_clear, /*tp_clear*/ 359 (richcmpfunc)weakref_richcompare, /*tp_richcompare*/ 360 0, /*tp_weaklistoffset*/ 361 0, /*tp_iter*/ 362 0, /*tp_iternext*/ 363 0, /*tp_methods*/ 364 0, /*tp_members*/ 365 0, /*tp_getset*/ 366 0, /*tp_base*/ 367 0, /*tp_dict*/ 368 0, /*tp_descr_get*/ 369 0, /*tp_descr_set*/ 370 0, /*tp_dictoffset*/ 371 weakref___init__, /*tp_init*/ 372 PyType_GenericAlloc, /*tp_alloc*/ 373 weakref___new__, /*tp_new*/ 374 PyObject_GC_Del, /*tp_free*/ 375 }; 376 377 378 static int 379 proxy_checkref(PyWeakReference *proxy) 380 { 381 if (PyWeakref_GET_OBJECT(proxy) == Py_None) { 382 PyErr_SetString(PyExc_ReferenceError, 383 "weakly-referenced object no longer exists"); 384 return 0; 385 } 386 return 1; 387 } 388 389 390 /* If a parameter is a proxy, check that it is still "live" and wrap it, 391 * replacing the original value with the raw object. Raises ReferenceError 392 * if the param is a dead proxy. 393 */ 394 #define UNWRAP(o) \ 395 if (PyWeakref_CheckProxy(o)) { \ 396 if (!proxy_checkref((PyWeakReference *)o)) \ 397 return NULL; \ 398 o = PyWeakref_GET_OBJECT(o); \ 399 } 400 401 #define UNWRAP_I(o) \ 402 if (PyWeakref_CheckProxy(o)) { \ 403 if (!proxy_checkref((PyWeakReference *)o)) \ 404 return -1; \ 405 o = PyWeakref_GET_OBJECT(o); \ 406 } 407 408 #define WRAP_UNARY(method, generic) \ 409 static PyObject * \ 410 method(PyObject *proxy) { \ 411 UNWRAP(proxy); \ 412 return generic(proxy); \ 413 } 414 415 #define WRAP_BINARY(method, generic) \ 416 static PyObject * \ 417 method(PyObject *x, PyObject *y) { \ 418 UNWRAP(x); \ 419 UNWRAP(y); \ 420 return generic(x, y); \ 421 } 422 423 /* Note that the third arg needs to be checked for NULL since the tp_call 424 * slot can receive NULL for this arg. 425 */ 426 #define WRAP_TERNARY(method, generic) \ 427 static PyObject * \ 428 method(PyObject *proxy, PyObject *v, PyObject *w) { \ 429 UNWRAP(proxy); \ 430 UNWRAP(v); \ 431 if (w != NULL) \ 432 UNWRAP(w); \ 433 return generic(proxy, v, w); \ 434 } 435 436 #define WRAP_METHOD(method, special) \ 437 static PyObject * \ 438 method(PyObject *proxy) { \ 439 UNWRAP(proxy); \ 440 return PyObject_CallMethod(proxy, special, ""); \ 441 } 442 443 444 /* direct slots */ 445 446 WRAP_BINARY(proxy_getattr, PyObject_GetAttr) 447 WRAP_UNARY(proxy_str, PyObject_Str) 448 WRAP_TERNARY(proxy_call, PyEval_CallObjectWithKeywords) 449 450 static PyObject * 451 proxy_repr(PyWeakReference *proxy) 452 { 453 char buf[160]; 454 PyOS_snprintf(buf, sizeof(buf), 455 "<weakproxy at %p to %.100s at %p>", proxy, 456 Py_TYPE(PyWeakref_GET_OBJECT(proxy))->tp_name, 457 PyWeakref_GET_OBJECT(proxy)); 458 return PyString_FromString(buf); 459 } 460 461 462 static int 463 proxy_setattr(PyWeakReference *proxy, PyObject *name, PyObject *value) 464 { 465 if (!proxy_checkref(proxy)) 466 return -1; 467 return PyObject_SetAttr(PyWeakref_GET_OBJECT(proxy), name, value); 468 } 469 470 static int 471 proxy_compare(PyObject *proxy, PyObject *v) 472 { 473 UNWRAP_I(proxy); 474 UNWRAP_I(v); 475 return PyObject_Compare(proxy, v); 476 } 477 478 /* number slots */ 479 WRAP_BINARY(proxy_add, PyNumber_Add) 480 WRAP_BINARY(proxy_sub, PyNumber_Subtract) 481 WRAP_BINARY(proxy_mul, PyNumber_Multiply) 482 WRAP_BINARY(proxy_div, PyNumber_Divide) 483 WRAP_BINARY(proxy_floor_div, PyNumber_FloorDivide) 484 WRAP_BINARY(proxy_true_div, PyNumber_TrueDivide) 485 WRAP_BINARY(proxy_mod, PyNumber_Remainder) 486 WRAP_BINARY(proxy_divmod, PyNumber_Divmod) 487 WRAP_TERNARY(proxy_pow, PyNumber_Power) 488 WRAP_UNARY(proxy_neg, PyNumber_Negative) 489 WRAP_UNARY(proxy_pos, PyNumber_Positive) 490 WRAP_UNARY(proxy_abs, PyNumber_Absolute) 491 WRAP_UNARY(proxy_invert, PyNumber_Invert) 492 WRAP_BINARY(proxy_lshift, PyNumber_Lshift) 493 WRAP_BINARY(proxy_rshift, PyNumber_Rshift) 494 WRAP_BINARY(proxy_and, PyNumber_And) 495 WRAP_BINARY(proxy_xor, PyNumber_Xor) 496 WRAP_BINARY(proxy_or, PyNumber_Or) 497 WRAP_UNARY(proxy_int, PyNumber_Int) 498 WRAP_UNARY(proxy_long, PyNumber_Long) 499 WRAP_UNARY(proxy_float, PyNumber_Float) 500 WRAP_BINARY(proxy_iadd, PyNumber_InPlaceAdd) 501 WRAP_BINARY(proxy_isub, PyNumber_InPlaceSubtract) 502 WRAP_BINARY(proxy_imul, PyNumber_InPlaceMultiply) 503 WRAP_BINARY(proxy_idiv, PyNumber_InPlaceDivide) 504 WRAP_BINARY(proxy_ifloor_div, PyNumber_InPlaceFloorDivide) 505 WRAP_BINARY(proxy_itrue_div, PyNumber_InPlaceTrueDivide) 506 WRAP_BINARY(proxy_imod, PyNumber_InPlaceRemainder) 507 WRAP_TERNARY(proxy_ipow, PyNumber_InPlacePower) 508 WRAP_BINARY(proxy_ilshift, PyNumber_InPlaceLshift) 509 WRAP_BINARY(proxy_irshift, PyNumber_InPlaceRshift) 510 WRAP_BINARY(proxy_iand, PyNumber_InPlaceAnd) 511 WRAP_BINARY(proxy_ixor, PyNumber_InPlaceXor) 512 WRAP_BINARY(proxy_ior, PyNumber_InPlaceOr) 513 WRAP_UNARY(proxy_index, PyNumber_Index) 514 515 static int 516 proxy_nonzero(PyWeakReference *proxy) 517 { 518 PyObject *o = PyWeakref_GET_OBJECT(proxy); 519 if (!proxy_checkref(proxy)) 520 return -1; 521 return PyObject_IsTrue(o); 522 } 523 524 static void 525 proxy_dealloc(PyWeakReference *self) 526 { 527 if (self->wr_callback != NULL) 528 PyObject_GC_UnTrack((PyObject *)self); 529 clear_weakref(self); 530 PyObject_GC_Del(self); 531 } 532 533 /* sequence slots */ 534 535 static PyObject * 536 proxy_slice(PyWeakReference *proxy, Py_ssize_t i, Py_ssize_t j) 537 { 538 if (!proxy_checkref(proxy)) 539 return NULL; 540 return PySequence_GetSlice(PyWeakref_GET_OBJECT(proxy), i, j); 541 } 542 543 static int 544 proxy_ass_slice(PyWeakReference *proxy, Py_ssize_t i, Py_ssize_t j, PyObject *value) 545 { 546 if (!proxy_checkref(proxy)) 547 return -1; 548 return PySequence_SetSlice(PyWeakref_GET_OBJECT(proxy), i, j, value); 549 } 550 551 static int 552 proxy_contains(PyWeakReference *proxy, PyObject *value) 553 { 554 if (!proxy_checkref(proxy)) 555 return -1; 556 return PySequence_Contains(PyWeakref_GET_OBJECT(proxy), value); 557 } 558 559 560 /* mapping slots */ 561 562 static Py_ssize_t 563 proxy_length(PyWeakReference *proxy) 564 { 565 if (!proxy_checkref(proxy)) 566 return -1; 567 return PyObject_Length(PyWeakref_GET_OBJECT(proxy)); 568 } 569 570 WRAP_BINARY(proxy_getitem, PyObject_GetItem) 571 572 static int 573 proxy_setitem(PyWeakReference *proxy, PyObject *key, PyObject *value) 574 { 575 if (!proxy_checkref(proxy)) 576 return -1; 577 578 if (value == NULL) 579 return PyObject_DelItem(PyWeakref_GET_OBJECT(proxy), key); 580 else 581 return PyObject_SetItem(PyWeakref_GET_OBJECT(proxy), key, value); 582 } 583 584 /* iterator slots */ 585 586 static PyObject * 587 proxy_iter(PyWeakReference *proxy) 588 { 589 if (!proxy_checkref(proxy)) 590 return NULL; 591 return PyObject_GetIter(PyWeakref_GET_OBJECT(proxy)); 592 } 593 594 static PyObject * 595 proxy_iternext(PyWeakReference *proxy) 596 { 597 if (!proxy_checkref(proxy)) 598 return NULL; 599 return PyIter_Next(PyWeakref_GET_OBJECT(proxy)); 600 } 601 602 603 WRAP_METHOD(proxy_unicode, "__unicode__"); 604 605 606 static PyMethodDef proxy_methods[] = { 607 {"__unicode__", (PyCFunction)proxy_unicode, METH_NOARGS}, 608 {NULL, NULL} 609 }; 610 611 612 static PyNumberMethods proxy_as_number = { 613 proxy_add, /*nb_add*/ 614 proxy_sub, /*nb_subtract*/ 615 proxy_mul, /*nb_multiply*/ 616 proxy_div, /*nb_divide*/ 617 proxy_mod, /*nb_remainder*/ 618 proxy_divmod, /*nb_divmod*/ 619 proxy_pow, /*nb_power*/ 620 proxy_neg, /*nb_negative*/ 621 proxy_pos, /*nb_positive*/ 622 proxy_abs, /*nb_absolute*/ 623 (inquiry)proxy_nonzero, /*nb_nonzero*/ 624 proxy_invert, /*nb_invert*/ 625 proxy_lshift, /*nb_lshift*/ 626 proxy_rshift, /*nb_rshift*/ 627 proxy_and, /*nb_and*/ 628 proxy_xor, /*nb_xor*/ 629 proxy_or, /*nb_or*/ 630 0, /*nb_coerce*/ 631 proxy_int, /*nb_int*/ 632 proxy_long, /*nb_long*/ 633 proxy_float, /*nb_float*/ 634 0, /*nb_oct*/ 635 0, /*nb_hex*/ 636 proxy_iadd, /*nb_inplace_add*/ 637 proxy_isub, /*nb_inplace_subtract*/ 638 proxy_imul, /*nb_inplace_multiply*/ 639 proxy_idiv, /*nb_inplace_divide*/ 640 proxy_imod, /*nb_inplace_remainder*/ 641 proxy_ipow, /*nb_inplace_power*/ 642 proxy_ilshift, /*nb_inplace_lshift*/ 643 proxy_irshift, /*nb_inplace_rshift*/ 644 proxy_iand, /*nb_inplace_and*/ 645 proxy_ixor, /*nb_inplace_xor*/ 646 proxy_ior, /*nb_inplace_or*/ 647 proxy_floor_div, /*nb_floor_divide*/ 648 proxy_true_div, /*nb_true_divide*/ 649 proxy_ifloor_div, /*nb_inplace_floor_divide*/ 650 proxy_itrue_div, /*nb_inplace_true_divide*/ 651 proxy_index, /*nb_index*/ 652 }; 653 654 static PySequenceMethods proxy_as_sequence = { 655 (lenfunc)proxy_length, /*sq_length*/ 656 0, /*sq_concat*/ 657 0, /*sq_repeat*/ 658 0, /*sq_item*/ 659 (ssizessizeargfunc)proxy_slice, /*sq_slice*/ 660 0, /*sq_ass_item*/ 661 (ssizessizeobjargproc)proxy_ass_slice, /*sq_ass_slice*/ 662 (objobjproc)proxy_contains, /* sq_contains */ 663 }; 664 665 static PyMappingMethods proxy_as_mapping = { 666 (lenfunc)proxy_length, /*mp_length*/ 667 proxy_getitem, /*mp_subscript*/ 668 (objobjargproc)proxy_setitem, /*mp_ass_subscript*/ 669 }; 670 671 672 PyTypeObject 673 _PyWeakref_ProxyType = { 674 PyVarObject_HEAD_INIT(&PyType_Type, 0) 675 "weakproxy", 676 sizeof(PyWeakReference), 677 0, 678 /* methods */ 679 (destructor)proxy_dealloc, /* tp_dealloc */ 680 0, /* tp_print */ 681 0, /* tp_getattr */ 682 0, /* tp_setattr */ 683 proxy_compare, /* tp_compare */ 684 (reprfunc)proxy_repr, /* tp_repr */ 685 &proxy_as_number, /* tp_as_number */ 686 &proxy_as_sequence, /* tp_as_sequence */ 687 &proxy_as_mapping, /* tp_as_mapping */ 688 0, /* tp_hash */ 689 0, /* tp_call */ 690 proxy_str, /* tp_str */ 691 proxy_getattr, /* tp_getattro */ 692 (setattrofunc)proxy_setattr, /* tp_setattro */ 693 0, /* tp_as_buffer */ 694 Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC 695 | Py_TPFLAGS_CHECKTYPES, /* tp_flags */ 696 0, /* tp_doc */ 697 (traverseproc)gc_traverse, /* tp_traverse */ 698 (inquiry)gc_clear, /* tp_clear */ 699 0, /* tp_richcompare */ 700 0, /* tp_weaklistoffset */ 701 (getiterfunc)proxy_iter, /* tp_iter */ 702 (iternextfunc)proxy_iternext, /* tp_iternext */ 703 proxy_methods, /* tp_methods */ 704 }; 705 706 707 PyTypeObject 708 _PyWeakref_CallableProxyType = { 709 PyVarObject_HEAD_INIT(&PyType_Type, 0) 710 "weakcallableproxy", 711 sizeof(PyWeakReference), 712 0, 713 /* methods */ 714 (destructor)proxy_dealloc, /* tp_dealloc */ 715 0, /* tp_print */ 716 0, /* tp_getattr */ 717 0, /* tp_setattr */ 718 proxy_compare, /* tp_compare */ 719 (unaryfunc)proxy_repr, /* tp_repr */ 720 &proxy_as_number, /* tp_as_number */ 721 &proxy_as_sequence, /* tp_as_sequence */ 722 &proxy_as_mapping, /* tp_as_mapping */ 723 0, /* tp_hash */ 724 proxy_call, /* tp_call */ 725 proxy_str, /* tp_str */ 726 proxy_getattr, /* tp_getattro */ 727 (setattrofunc)proxy_setattr, /* tp_setattro */ 728 0, /* tp_as_buffer */ 729 Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC 730 | Py_TPFLAGS_CHECKTYPES, /* tp_flags */ 731 0, /* tp_doc */ 732 (traverseproc)gc_traverse, /* tp_traverse */ 733 (inquiry)gc_clear, /* tp_clear */ 734 0, /* tp_richcompare */ 735 0, /* tp_weaklistoffset */ 736 (getiterfunc)proxy_iter, /* tp_iter */ 737 (iternextfunc)proxy_iternext, /* tp_iternext */ 738 }; 739 740 741 742 PyObject * 743 PyWeakref_NewRef(PyObject *ob, PyObject *callback) 744 { 745 PyWeakReference *result = NULL; 746 PyWeakReference **list; 747 PyWeakReference *ref, *proxy; 748 749 if (!PyType_SUPPORTS_WEAKREFS(Py_TYPE(ob))) { 750 PyErr_Format(PyExc_TypeError, 751 "cannot create weak reference to '%s' object", 752 Py_TYPE(ob)->tp_name); 753 return NULL; 754 } 755 list = GET_WEAKREFS_LISTPTR(ob); 756 get_basic_refs(*list, &ref, &proxy); 757 if (callback == Py_None) 758 callback = NULL; 759 if (callback == NULL) 760 /* return existing weak reference if it exists */ 761 result = ref; 762 if (result != NULL) 763 Py_INCREF(result); 764 else { 765 /* Note: new_weakref() can trigger cyclic GC, so the weakref 766 list on ob can be mutated. This means that the ref and 767 proxy pointers we got back earlier may have been collected, 768 so we need to compute these values again before we use 769 them. */ 770 result = new_weakref(ob, callback); 771 if (result != NULL) { 772 get_basic_refs(*list, &ref, &proxy); 773 if (callback == NULL) { 774 if (ref == NULL) 775 insert_head(result, list); 776 else { 777 /* Someone else added a ref without a callback 778 during GC. Return that one instead of this one 779 to avoid violating the invariants of the list 780 of weakrefs for ob. */ 781 Py_DECREF(result); 782 Py_INCREF(ref); 783 result = ref; 784 } 785 } 786 else { 787 PyWeakReference *prev; 788 789 prev = (proxy == NULL) ? ref : proxy; 790 if (prev == NULL) 791 insert_head(result, list); 792 else 793 insert_after(result, prev); 794 } 795 } 796 } 797 return (PyObject *) result; 798 } 799 800 801 PyObject * 802 PyWeakref_NewProxy(PyObject *ob, PyObject *callback) 803 { 804 PyWeakReference *result = NULL; 805 PyWeakReference **list; 806 PyWeakReference *ref, *proxy; 807 808 if (!PyType_SUPPORTS_WEAKREFS(Py_TYPE(ob))) { 809 PyErr_Format(PyExc_TypeError, 810 "cannot create weak reference to '%s' object", 811 Py_TYPE(ob)->tp_name); 812 return NULL; 813 } 814 list = GET_WEAKREFS_LISTPTR(ob); 815 get_basic_refs(*list, &ref, &proxy); 816 if (callback == Py_None) 817 callback = NULL; 818 if (callback == NULL) 819 /* attempt to return an existing weak reference if it exists */ 820 result = proxy; 821 if (result != NULL) 822 Py_INCREF(result); 823 else { 824 /* Note: new_weakref() can trigger cyclic GC, so the weakref 825 list on ob can be mutated. This means that the ref and 826 proxy pointers we got back earlier may have been collected, 827 so we need to compute these values again before we use 828 them. */ 829 result = new_weakref(ob, callback); 830 if (result != NULL) { 831 PyWeakReference *prev; 832 833 if (PyCallable_Check(ob)) 834 Py_TYPE(result) = &_PyWeakref_CallableProxyType; 835 else 836 Py_TYPE(result) = &_PyWeakref_ProxyType; 837 get_basic_refs(*list, &ref, &proxy); 838 if (callback == NULL) { 839 if (proxy != NULL) { 840 /* Someone else added a proxy without a callback 841 during GC. Return that one instead of this one 842 to avoid violating the invariants of the list 843 of weakrefs for ob. */ 844 Py_DECREF(result); 845 Py_INCREF(result = proxy); 846 goto skip_insert; 847 } 848 prev = ref; 849 } 850 else 851 prev = (proxy == NULL) ? ref : proxy; 852 853 if (prev == NULL) 854 insert_head(result, list); 855 else 856 insert_after(result, prev); 857 skip_insert: 858 ; 859 } 860 } 861 return (PyObject *) result; 862 } 863 864 865 PyObject * 866 PyWeakref_GetObject(PyObject *ref) 867 { 868 if (ref == NULL || !PyWeakref_Check(ref)) { 869 PyErr_BadInternalCall(); 870 return NULL; 871 } 872 return PyWeakref_GET_OBJECT(ref); 873 } 874 875 /* Note that there's an inlined copy-paste of handle_callback() in gcmodule.c's 876 * handle_weakrefs(). 877 */ 878 static void 879 handle_callback(PyWeakReference *ref, PyObject *callback) 880 { 881 PyObject *cbresult = PyObject_CallFunctionObjArgs(callback, ref, NULL); 882 883 if (cbresult == NULL) 884 PyErr_WriteUnraisable(callback); 885 else 886 Py_DECREF(cbresult); 887 } 888 889 /* This function is called by the tp_dealloc handler to clear weak references. 890 * 891 * This iterates through the weak references for 'object' and calls callbacks 892 * for those references which have one. It returns when all callbacks have 893 * been attempted. 894 */ 895 void 896 PyObject_ClearWeakRefs(PyObject *object) 897 { 898 PyWeakReference **list; 899 900 if (object == NULL 901 || !PyType_SUPPORTS_WEAKREFS(Py_TYPE(object)) 902 || object->ob_refcnt != 0) { 903 PyErr_BadInternalCall(); 904 return; 905 } 906 list = GET_WEAKREFS_LISTPTR(object); 907 /* Remove the callback-less basic and proxy references */ 908 if (*list != NULL && (*list)->wr_callback == NULL) { 909 clear_weakref(*list); 910 if (*list != NULL && (*list)->wr_callback == NULL) 911 clear_weakref(*list); 912 } 913 if (*list != NULL) { 914 PyWeakReference *current = *list; 915 Py_ssize_t count = _PyWeakref_GetWeakrefCount(current); 916 int restore_error = PyErr_Occurred() ? 1 : 0; 917 PyObject *err_type = NULL, 918 *err_value = NULL, 919 *err_tb = NULL; 920 921 if (restore_error) 922 PyErr_Fetch(&err_type, &err_value, &err_tb); 923 if (count == 1) { 924 PyObject *callback = current->wr_callback; 925 926 current->wr_callback = NULL; 927 clear_weakref(current); 928 if (callback != NULL) { 929 if (current->ob_refcnt > 0) 930 handle_callback(current, callback); 931 Py_DECREF(callback); 932 } 933 } 934 else { 935 PyObject *tuple; 936 Py_ssize_t i = 0; 937 938 tuple = PyTuple_New(count * 2); 939 if (tuple == NULL) { 940 if (restore_error) 941 PyErr_Fetch(&err_type, &err_value, &err_tb); 942 return; 943 } 944 945 for (i = 0; i < count; ++i) { 946 PyWeakReference *next = current->wr_next; 947 948 if (current->ob_refcnt > 0) 949 { 950 Py_INCREF(current); 951 PyTuple_SET_ITEM(tuple, i * 2, (PyObject *) current); 952 PyTuple_SET_ITEM(tuple, i * 2 + 1, current->wr_callback); 953 } 954 else { 955 Py_DECREF(current->wr_callback); 956 } 957 current->wr_callback = NULL; 958 clear_weakref(current); 959 current = next; 960 } 961 for (i = 0; i < count; ++i) { 962 PyObject *callback = PyTuple_GET_ITEM(tuple, i * 2 + 1); 963 964 /* The tuple may have slots left to NULL */ 965 if (callback != NULL) { 966 PyObject *item = PyTuple_GET_ITEM(tuple, i * 2); 967 handle_callback((PyWeakReference *)item, callback); 968 } 969 } 970 Py_DECREF(tuple); 971 } 972 if (restore_error) 973 PyErr_Restore(err_type, err_value, err_tb); 974 } 975 } 976
