Python/_warnings.c

   1 #include "Python.h"
   2 #include "frameobject.h"
   3
   4 #define MODULE_NAME "_warnings"
   5
   6 PyDoc_STRVAR(warnings__doc__,
   7 MODULE_NAME " provides basic warning filtering support.\n"
   8 "It is a helper module to speed up interpreter start-up.");
   9
  10 /* Both 'filters' and 'onceregistry' can be set in warnings.py;
  11    get_warnings_attr() will reset these variables accordingly. */
  12 static PyObject *_filters;  /* List */
  13 static PyObject *_once_registry;  /* Dict */
  14 static PyObject *_default_action; /* String */
  15
  16
  17 static int
  18 check_matched(PyObject *obj, PyObject *arg)
  19 {
  20     PyObject *result;
  21     int rc;
  22
  23     if (obj == Py_None)
  24         return 1;
  25     result = PyObject_CallMethod(obj, "match", "O", arg);
  26     if (result == NULL)
  27         return -1;
  28
  29     rc = PyObject_IsTrue(result);
  30     Py_DECREF(result);
  31     return rc;
  32 }
  33
  34 /*
  35    Returns a new reference.
  36    A NULL return value can mean false or an error.
  37 */
  38 static PyObject *
  39 get_warnings_attr(const char *attr)
  40 {
  41     static PyObject *warnings_str = NULL;
  42     PyObject *all_modules;
  43     PyObject *warnings_module;
  44     int result;
  45
  46     if (warnings_str == NULL) {
  47         warnings_str = PyString_InternFromString("warnings");
  48         if (warnings_str == NULL)
  49             return NULL;
  50     }
  51
  52     all_modules = PyImport_GetModuleDict();
  53     result = PyDict_Contains(all_modules, warnings_str);
  54     if (result == -1 || result == 0)
  55         return NULL;
  56
  57     warnings_module = PyDict_GetItem(all_modules, warnings_str);
  58     if (!PyObject_HasAttrString(warnings_module, attr))
  59             return NULL;
  60     return PyObject_GetAttrString(warnings_module, attr);
  61 }
  62
  63
  64 static PyObject *
  65 get_once_registry(void)
  66 {
  67     PyObject *registry;
  68
  69     registry = get_warnings_attr("onceregistry");
  70     if (registry == NULL) {
  71         if (PyErr_Occurred())
  72             return NULL;
  73         return _once_registry;
  74     }
  75     Py_DECREF(_once_registry);
  76     _once_registry = registry;
  77     return registry;
  78 }
  79
  80
  81 static PyObject *
  82 get_default_action(void)
  83 {
  84     PyObject *default_action;
  85
  86     default_action = get_warnings_attr("defaultaction");
  87     if (default_action == NULL) {
  88         if (PyErr_Occurred()) {
  89             return NULL;
  90         }
  91         return _default_action;
  92     }
  93
  94     Py_DECREF(_default_action);
  95     _default_action = default_action;
  96     return default_action;
  97 }
  98
  99
 100 /* The item is a borrowed reference. */
 101 static const char *
 102 get_filter(PyObject *category, PyObject *text, Py_ssize_t lineno,
 103            PyObject *module, PyObject **item)
 104 {
 105     PyObject *action;
 106     Py_ssize_t i;
 107     PyObject *warnings_filters;
 108
 109     warnings_filters = get_warnings_attr("filters");
 110     if (warnings_filters == NULL) {
 111         if (PyErr_Occurred())
 112             return NULL;
 113     }
 114     else {
 115         Py_DECREF(_filters);
 116         _filters = warnings_filters;
 117     }
 118
 119     if (!PyList_Check(_filters)) {
 120         PyErr_SetString(PyExc_ValueError,
 121                         MODULE_NAME ".filters must be a list");
 122         return NULL;
 123     }
 124
 125     /* _filters could change while we are iterating over it. */
 126     for (i = 0; i < PyList_GET_SIZE(_filters); i++) {
 127         PyObject *tmp_item, *action, *msg, *cat, *mod, *ln_obj;
 128         Py_ssize_t ln;
 129         int is_subclass, good_msg, good_mod;
 130
 131         tmp_item = *item = PyList_GET_ITEM(_filters, i);
 132         if (PyTuple_Size(tmp_item) != 5) {
 133             PyErr_Format(PyExc_ValueError,
 134                          MODULE_NAME ".filters item %zd isn't a 5-tuple", i);
 135             return NULL;
 136         }
 137
 138         /* Python code: action, msg, cat, mod, ln = item */
 139         action = PyTuple_GET_ITEM(tmp_item, 0);
 140         msg = PyTuple_GET_ITEM(tmp_item, 1);
 141         cat = PyTuple_GET_ITEM(tmp_item, 2);
 142         mod = PyTuple_GET_ITEM(tmp_item, 3);
 143         ln_obj = PyTuple_GET_ITEM(tmp_item, 4);
 144
 145         good_msg = check_matched(msg, text);
 146         good_mod = check_matched(mod, module);
 147         is_subclass = PyObject_IsSubclass(category, cat);
 148         ln = PyInt_AsSsize_t(ln_obj);
 149         if (good_msg == -1 || good_mod == -1 || is_subclass == -1 ||
 150             (ln == -1 && PyErr_Occurred()))
 151             return NULL;
 152
 153         if (good_msg && is_subclass && good_mod && (ln == 0 || lineno == ln))
 154             return PyString_AsString(action);
 155     }
 156
 157     action = get_default_action();
 158     if (action != NULL) {
 159         return PyString_AsString(action);
 160     }
 161
 162     PyErr_SetString(PyExc_ValueError,
 163                     MODULE_NAME ".defaultaction not found");
 164     return NULL;
 165 }
 166
 167
 168 static int
 169 already_warned(PyObject *registry, PyObject *key, int should_set)
 170 {
 171     PyObject *already_warned;
 172
 173     if (key == NULL)
 174         return -1;
 175
 176     already_warned = PyDict_GetItem(registry, key);
 177     if (already_warned != NULL) {
 178         int rc = PyObject_IsTrue(already_warned);
 179         if (rc != 0)
 180             return rc;
 181     }
 182
 183     /* This warning wasn't found in the registry, set it. */
 184     if (should_set)
 185         return PyDict_SetItem(registry, key, Py_True);
 186     return 0;
 187 }
 188
 189 /* New reference. */
 190 static PyObject *
 191 normalize_module(PyObject *filename)
 192 {
 193     PyObject *module;
 194     const char *mod_str;
 195     Py_ssize_t len;
 196
 197     int rc = PyObject_IsTrue(filename);
 198     if (rc == -1)
 199         return NULL;
 200     else if (rc == 0)
 201         return PyString_FromString("<unknown>");
 202
 203     mod_str = PyString_AsString(filename);
 204     if (mod_str == NULL)
 205             return NULL;
 206     len = PyString_Size(filename);
 207     if (len < 0)
 208         return NULL;
 209     if (len >= 3 &&
 210         strncmp(mod_str + (len - 3), ".py", 3) == 0) {
 211         module = PyString_FromStringAndSize(mod_str, len-3);
 212     }
 213     else {
 214         module = filename;
 215         Py_INCREF(module);
 216     }
 217     return module;
 218 }
 219
 220 static int
 221 update_registry(PyObject *registry, PyObject *text, PyObject *category,
 222                 int add_zero)
 223 {
 224     PyObject *altkey, *zero = NULL;
 225     int rc;
 226
 227     if (add_zero) {
 228         zero = PyInt_FromLong(0);
 229         if (zero == NULL)
 230             return -1;
 231         altkey = PyTuple_Pack(3, text, category, zero);
 232     }
 233     else
 234         altkey = PyTuple_Pack(2, text, category);
 235
 236     rc = already_warned(registry, altkey, 1);
 237     Py_XDECREF(zero);
 238     Py_XDECREF(altkey);
 239     return rc;
 240 }
 241
 242 static void
 243 show_warning(PyObject *filename, int lineno, PyObject *text, PyObject
 244                 *category, PyObject *sourceline)
 245 {
 246     PyObject *f_stderr;
 247     PyObject *name;
 248     char lineno_str[128];
 249
 250     PyOS_snprintf(lineno_str, sizeof(lineno_str), ":%d: ", lineno);
 251
 252     name = PyObject_GetAttrString(category, "__name__");
 253     if (name == NULL)  /* XXX Can an object lack a '__name__' attribute? */
 254             return;
 255
 256     f_stderr = PySys_GetObject("stderr");
 257     if (f_stderr == NULL) {
 258         fprintf(stderr, "lost sys.stderr\n");
 259         Py_DECREF(name);
 260         return;
 261     }
 262
 263     /* Print "filename:lineno: category: text\n" */
 264     PyFile_WriteObject(filename, f_stderr, Py_PRINT_RAW);
 265     PyFile_WriteString(lineno_str, f_stderr);
 266     PyFile_WriteObject(name, f_stderr, Py_PRINT_RAW);
 267     PyFile_WriteString(": ", f_stderr);
 268     PyFile_WriteObject(text, f_stderr, Py_PRINT_RAW);
 269     PyFile_WriteString("\n", f_stderr);
 270     Py_XDECREF(name);
 271
 272     /* Print "  source_line\n" */
 273     if (sourceline) {
 274         char *source_line_str = PyString_AS_STRING(sourceline);
 275         while (*source_line_str == ' ' || *source_line_str == '\t' ||
 276                 *source_line_str == '\014')
 277             source_line_str++;
 278
 279         PyFile_WriteString(source_line_str, f_stderr);
 280         PyFile_WriteString("\n", f_stderr);
 281     }
 282     else
 283         _Py_DisplaySourceLine(f_stderr, PyString_AS_STRING(filename),
 284                               lineno, 2);
 285     PyErr_Clear();
 286 }
 287
 288 static PyObject *
 289 warn_explicit(PyObject *category, PyObject *message,
 290               PyObject *filename, int lineno,
 291               PyObject *module, PyObject *registry, PyObject *sourceline)
 292 {
 293     PyObject *key = NULL, *text = NULL, *result = NULL, *lineno_obj = NULL;
 294     PyObject *item = Py_None;
 295     const char *action;
 296     int rc;
 297
 298     if (registry && !PyDict_Check(registry) && (registry != Py_None)) {
 299         PyErr_SetString(PyExc_TypeError, "'registry' must be a dict");
 300         return NULL;
 301     }
 302
 303     /* Normalize module. */
 304     if (module == NULL) {
 305         module = normalize_module(filename);
 306         if (module == NULL)
 307             return NULL;
 308     }
 309     else
 310         Py_INCREF(module);
 311
 312     /* Normalize message. */
 313     Py_INCREF(message);  /* DECREF'ed in cleanup. */
 314     rc = PyObject_IsInstance(message, PyExc_Warning);
 315     if (rc == -1) {
 316         goto cleanup;
 317     }
 318     if (rc == 1) {
 319         text = PyObject_Str(message);
 320         category = (PyObject*)message->ob_type;
 321     }
 322     else {
 323         text = message;
 324         message = PyObject_CallFunction(category, "O", message);
 325         if (message == NULL)
 326             goto cleanup;
 327     }
 328
 329     lineno_obj = PyInt_FromLong(lineno);
 330     if (lineno_obj == NULL)
 331         goto cleanup;
 332
 333     /* Create key. */
 334     key = PyTuple_Pack(3, text, category, lineno_obj);
 335     if (key == NULL)
 336         goto cleanup;
 337
 338     if ((registry != NULL) && (registry != Py_None)) {
 339         rc = already_warned(registry, key, 0);
 340         if (rc == -1)
 341             goto cleanup;
 342         else if (rc == 1)
 343             goto return_none;
 344         /* Else this warning hasn't been generated before. */
 345     }
 346
 347     action = get_filter(category, text, lineno, module, &item);
 348     if (action == NULL)
 349         goto cleanup;
 350
 351     if (strcmp(action, "error") == 0) {
 352         PyErr_SetObject(category, message);
 353         goto cleanup;
 354     }
 355
 356     /* Store in the registry that we've been here, *except* when the action
 357        is "always". */
 358     rc = 0;
 359     if (strcmp(action, "always") != 0) {
 360         if (registry != NULL && registry != Py_None &&
 361                 PyDict_SetItem(registry, key, Py_True) < 0)
 362             goto cleanup;
 363         else if (strcmp(action, "ignore") == 0)
 364             goto return_none;
 365         else if (strcmp(action, "once") == 0) {
 366             if (registry == NULL || registry == Py_None) {
 367                 registry = get_once_registry();
 368                 if (registry == NULL)
 369                     goto cleanup;
 370             }
 371             /* _once_registry[(text, category)] = 1 */
 372             rc = update_registry(registry, text, category, 0);
 373         }
 374         else if (strcmp(action, "module") == 0) {
 375             /* registry[(text, category, 0)] = 1 */
 376             if (registry != NULL && registry != Py_None)
 377                 rc = update_registry(registry, text, category, 0);
 378         }
 379         else if (strcmp(action, "default") != 0) {
 380             PyObject *to_str = PyObject_Str(item);
 381             const char *err_str = "???";
 382
 383             if (to_str != NULL)
 384                 err_str = PyString_AS_STRING(to_str);
 385             PyErr_Format(PyExc_RuntimeError,
 386                         "Unrecognized action (%s) in warnings.filters:\n %s",
 387                         action, err_str);
 388             Py_XDECREF(to_str);
 389             goto cleanup;
 390         }
 391     }
 392
 393     if (rc == 1)  /* Already warned for this module. */
 394         goto return_none;
 395     if (rc == 0) {
 396         PyObject *show_fxn = get_warnings_attr("showwarning");
 397         if (show_fxn == NULL) {
 398             if (PyErr_Occurred())
 399                 goto cleanup;
 400             show_warning(filename, lineno, text, category, sourceline);
 401         }
 402         else {
 403               PyObject *res;
 404
 405               if (!PyMethod_Check(show_fxn) && !PyFunction_Check(show_fxn)) {
 406                   PyErr_SetString(PyExc_TypeError,
 407                                   "warnings.showwarning() must be set to a "
 408                                   "function or method");
 409                   Py_DECREF(show_fxn);
 410                   goto cleanup;
 411               }
 412
 413               res = PyObject_CallFunctionObjArgs(show_fxn, message, category,
 414                                                   filename, lineno_obj,
 415                                                   NULL);
 416               Py_DECREF(show_fxn);
 417               Py_XDECREF(res);
 418               if (res == NULL)
 419                   goto cleanup;
 420         }
 421     }
 422     else /* if (rc == -1) */
 423         goto cleanup;
 424
 425  return_none:
 426     result = Py_None;
 427     Py_INCREF(result);
 428
 429  cleanup:
 430     Py_XDECREF(key);
 431     Py_XDECREF(text);
 432     Py_XDECREF(lineno_obj);
 433     Py_DECREF(module);
 434     Py_XDECREF(message);
 435     return result;  /* Py_None or NULL. */
 436 }
 437
 438 /* filename, module, and registry are new refs, globals is borrowed */
 439 /* Returns 0 on error (no new refs), 1 on success */
 440 static int
 441 setup_context(Py_ssize_t stack_level, PyObject **filename, int *lineno,
 442               PyObject **module, PyObject **registry)
 443 {
 444     PyObject *globals;
 445
 446     /* Setup globals and lineno. */
 447     PyFrameObject *f = PyThreadState_GET()->frame;
 448     while (--stack_level > 0 && f != NULL)
 449         f = f->f_back;
 450
 451     if (f == NULL) {
 452         globals = PyThreadState_Get()->interp->sysdict;
 453         *lineno = 1;
 454     }
 455     else {
 456         globals = f->f_globals;
 457         *lineno = PyCode_Addr2Line(f->f_code, f->f_lasti);
 458     }
 459
 460     *module = NULL;
 461
 462     /* Setup registry. */
 463     assert(globals != NULL);
 464     assert(PyDict_Check(globals));
 465     *registry = PyDict_GetItemString(globals, "__warningregistry__");
 466     if (*registry == NULL) {
 467         int rc;
 468
 469         *registry = PyDict_New();
 470         if (*registry == NULL)
 471             return 0;
 472
 473          rc = PyDict_SetItemString(globals, "__warningregistry__", *registry);
 474          if (rc < 0)
 475             goto handle_error;
 476     }
 477     else
 478         Py_INCREF(*registry);
 479
 480     /* Setup module. */
 481     *module = PyDict_GetItemString(globals, "__name__");
 482     if (*module == NULL) {
 483         *module = PyString_FromString("<string>");
 484         if (*module == NULL)
 485             goto handle_error;
 486     }
 487     else
 488         Py_INCREF(*module);
 489
 490     /* Setup filename. */
 491     *filename = PyDict_GetItemString(globals, "__file__");
 492     if (*filename != NULL) {
 493             Py_ssize_t len = PyString_Size(*filename);
 494         const char *file_str = PyString_AsString(*filename);
 495             if (file_str == NULL || (len < 0 && PyErr_Occurred()))
 496             goto handle_error;
 497
 498         /* if filename.lower().endswith((".pyc", ".pyo")): */
 499         if (len >= 4 &&
 500             file_str[len-4] == '.' &&
 501             tolower(file_str[len-3]) == 'p' &&
 502             tolower(file_str[len-2]) == 'y' &&
 503             (tolower(file_str[len-1]) == 'c' ||
 504                 tolower(file_str[len-1]) == 'o'))
 505         {
 506             *filename = PyString_FromStringAndSize(file_str, len-1);
 507                 if (*filename == NULL)
 508                         goto handle_error;
 509             }
 510             else
 511             Py_INCREF(*filename);
 512     }
 513     else {
 514         const char *module_str = PyString_AsString(*module);
 515         if (module_str && strcmp(module_str, "__main__") == 0) {
 516             PyObject *argv = PySys_GetObject("argv");
 517             if (argv != NULL && PyList_Size(argv) > 0) {
 518                 int is_true;
 519                 *filename = PyList_GetItem(argv, 0);
 520                 Py_INCREF(*filename);
 521                 /* If sys.argv[0] is false, then use '__main__'. */
 522                 is_true = PyObject_IsTrue(*filename);
 523                 if (is_true < 0) {
 524                     Py_DECREF(*filename);
 525                     goto handle_error;
 526                 }
 527                 else if (!is_true) {
 528                     Py_DECREF(*filename);
 529                     *filename = PyString_FromString("__main__");
 530                     if (*filename == NULL)
 531                         goto handle_error;
 532                 }
 533             }
 534             else {
 535                 /* embedded interpreters don't have sys.argv, see bug #839151 */
 536                 *filename = PyString_FromString("__main__");
 537                     if (*filename == NULL)
 538                         goto handle_error;
 539             }
 540         }
 541         if (*filename == NULL) {
 542             *filename = *module;
 543             Py_INCREF(*filename);
 544         }
 545     }
 546
 547     return 1;
 548
 549  handle_error:
 550     /* filename not XDECREF'ed here as there is no way to jump here with a
 551        dangling reference. */
 552     Py_XDECREF(*registry);
 553     Py_XDECREF(*module);
 554     return 0;
 555 }
 556
 557 static PyObject *
 558 get_category(PyObject *message, PyObject *category)
 559 {
 560     int rc;
 561
 562     /* Get category. */
 563     rc = PyObject_IsInstance(message, PyExc_Warning);
 564     if (rc == -1)
 565         return NULL;
 566
 567     if (rc == 1)
 568         category = (PyObject*)message->ob_type;
 569     else if (category == NULL)
 570         category = PyExc_UserWarning;
 571
 572     /* Validate category. */
 573     rc = PyObject_IsSubclass(category, PyExc_Warning);
 574     if (rc == -1)
 575         return NULL;
 576     if (rc == 0) {
 577         PyErr_SetString(PyExc_ValueError,
 578                         "category is not a subclass of Warning");
 579         return NULL;
 580     }
 581
 582     return category;
 583 }
 584
 585 static PyObject *
 586 do_warn(PyObject *message, PyObject *category, Py_ssize_t stack_level)
 587 {
 588     PyObject *filename, *module, *registry, *res;
 589     int lineno;
 590
 591     if (!setup_context(stack_level, &filename, &lineno, &module, &registry))
 592         return NULL;
 593
 594     res = warn_explicit(category, message, filename, lineno, module, registry,
 595                         NULL);
 596     Py_DECREF(filename);
 597     Py_DECREF(registry);
 598     Py_DECREF(module);
 599     return res;
 600 }
 601
 602 static PyObject *
 603 warnings_warn(PyObject *self, PyObject *args, PyObject *kwds)
 604 {
 605     static char *kw_list[] = { "message", "category", "stacklevel", 0 };
 606     PyObject *message, *category = NULL;
 607     Py_ssize_t stack_level = 1;
 608
 609     if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|On:warn", kw_list,
 610                                      &message, &category, &stack_level))
 611         return NULL;
 612
 613     category = get_category(message, category);
 614     if (category == NULL)
 615         return NULL;
 616     return do_warn(message, category, stack_level);
 617 }
 618
 619 static PyObject *
 620 warnings_warn_explicit(PyObject *self, PyObject *args, PyObject *kwds)
 621 {
 622     static char *kwd_list[] = {"message", "category", "filename", "lineno",
 623                                 "module", "registry", "module_globals", 0};
 624     PyObject *message;
 625     PyObject *category;
 626     PyObject *filename;
 627     int lineno;
 628     PyObject *module = NULL;
 629     PyObject *registry = NULL;
 630     PyObject *module_globals = NULL;
 631
 632     if (!PyArg_ParseTupleAndKeywords(args, kwds, "OOOi|OOO:warn_explicit",
 633                 kwd_list, &message, &category, &filename, &lineno, &module,
 634                 &registry, &module_globals))
 635         return NULL;
 636
 637     if (module_globals) {
 638         static PyObject *get_source_name = NULL;
 639         static PyObject *splitlines_name = NULL;
 640         PyObject *loader;
 641         PyObject *module_name;
 642         PyObject *source;
 643         PyObject *source_list;
 644         PyObject *source_line;
 645         PyObject *returned;
 646
 647         if (get_source_name == NULL) {
 648             get_source_name = PyString_InternFromString("get_source");
 649             if (!get_source_name)
 650                 return NULL;
 651         }
 652         if (splitlines_name == NULL) {
 653             splitlines_name = PyString_InternFromString("splitlines");
 654             if (!splitlines_name)
 655                 return NULL;
 656         }
 657
 658         /* Check/get the requisite pieces needed for the loader. */
 659         loader = PyDict_GetItemString(module_globals, "__loader__");
 660         module_name = PyDict_GetItemString(module_globals, "__name__");
 661
 662         if (loader == NULL || module_name == NULL)
 663             goto standard_call;
 664
 665         /* Make sure the loader implements the optional get_source() method. */
 666         if (!PyObject_HasAttrString(loader, "get_source"))
 667                 goto standard_call;
 668         /* Call get_source() to get the source code. */
 669         source = PyObject_CallMethodObjArgs(loader, get_source_name,
 670                                                 module_name, NULL);
 671         if (!source)
 672             return NULL;
 673         else if (source == Py_None) {
 674             Py_DECREF(Py_None);
 675             goto standard_call;
 676         }
 677
 678         /* Split the source into lines. */
 679         source_list = PyObject_CallMethodObjArgs(source, splitlines_name,
 680                                                     NULL);
 681         Py_DECREF(source);
 682         if (!source_list)
 683             return NULL;
 684
 685         /* Get the source line. */
 686         source_line = PyList_GetItem(source_list, lineno-1);
 687         if (!source_line) {
 688             Py_DECREF(source_list);
 689             return NULL;
 690         }
 691
 692         /* Handle the warning. */
 693         returned = warn_explicit(category, message, filename, lineno, module,
 694                             registry, source_line);
 695         Py_DECREF(source_list);
 696         return returned;
 697     }
 698
 699  standard_call:
 700     return warn_explicit(category, message, filename, lineno, module,
 701                                 registry, NULL);
 702 }
 703
 704
 705 /* Function to issue a warning message; may raise an exception. */
 706 int
 707 PyErr_WarnEx(PyObject *category, const char *text, Py_ssize_t stack_level)
 708 {
 709     PyObject *res;
 710     PyObject *message = PyString_FromString(text);
 711     if (message == NULL)
 712         return -1;
 713
 714     if (category == NULL)
 715         category = PyExc_RuntimeWarning;
 716
 717     res = do_warn(message, category, stack_level);
 718     Py_DECREF(message);
 719     if (res == NULL)
 720         return -1;
 721     Py_DECREF(res);
 722
 723     return 0;
 724 }
 725
 726 /* PyErr_Warn is only for backwards compatability and will be removed.
 727    Use PyErr_WarnEx instead. */
 728
 729 #undef PyErr_Warn
 730
 731 PyAPI_FUNC(int)
 732 PyErr_Warn(PyObject *category, char *text)
 733 {
 734     return PyErr_WarnEx(category, text, 1);
 735 }
 736
 737 /* Warning with explicit origin */
 738 int
 739 PyErr_WarnExplicit(PyObject *category, const char *text,
 740                    const char *filename_str, int lineno,
 741                    const char *module_str, PyObject *registry)
 742 {
 743     PyObject *res;
 744     PyObject *message = PyString_FromString(text);
 745     PyObject *filename = PyString_FromString(filename_str);
 746     PyObject *module = NULL;
 747     int ret = -1;
 748
 749     if (message == NULL || filename == NULL)
 750         goto exit;
 751     if (module_str != NULL) {
 752         module = PyString_FromString(module_str);
 753             if (module == NULL)
 754                 goto exit;
 755     }
 756
 757     if (category == NULL)
 758         category = PyExc_RuntimeWarning;
 759     res = warn_explicit(category, message, filename, lineno, module, registry,
 760                         NULL);
 761     if (res == NULL)
 762         goto exit;
 763     Py_DECREF(res);
 764     ret = 0;
 765
 766  exit:
 767     Py_XDECREF(message);
 768     Py_XDECREF(module);
 769     Py_XDECREF(filename);
 770     return ret;
 771 }
 772
 773
 774 PyDoc_STRVAR(warn_doc,
 775 "Issue a warning, or maybe ignore it or raise an exception.");
 776
 777 PyDoc_STRVAR(warn_explicit_doc,
 778 "Low-level inferface to warnings functionality.");
 779
 780 static PyMethodDef warnings_functions[] = {
 781     {"warn", (PyCFunction)warnings_warn, METH_VARARGS | METH_KEYWORDS,
 782         warn_doc},
 783     {"warn_explicit", (PyCFunction)warnings_warn_explicit,
 784         METH_VARARGS | METH_KEYWORDS, warn_explicit_doc},
 785     /* XXX(brett.cannon): add showwarning? */
 786     /* XXX(brett.cannon): Reasonable to add formatwarning? */
 787     {NULL, NULL}                /* sentinel */
 788 };
 789
 790
 791 static PyObject *
 792 create_filter(PyObject *category, const char *action)
 793 {
 794     static PyObject *ignore_str = NULL;
 795     static PyObject *error_str = NULL;
 796     static PyObject *default_str = NULL;
 797     PyObject *action_obj = NULL;
 798     PyObject *lineno, *result;
 799
 800     if (!strcmp(action, "ignore")) {
 801         if (ignore_str == NULL) {
 802             ignore_str = PyString_InternFromString("ignore");
 803             if (ignore_str == NULL)
 804                 return NULL;
 805         }
 806         action_obj = ignore_str;
 807     }
 808     else if (!strcmp(action, "error")) {
 809         if (error_str == NULL) {
 810             error_str = PyString_InternFromString("error");
 811             if (error_str == NULL)
 812                 return NULL;
 813         }
 814         action_obj = error_str;
 815     }
 816     else if (!strcmp(action, "default")) {
 817         if (default_str == NULL) {
 818             default_str = PyString_InternFromString("default");
 819             if (default_str == NULL)
 820                 return NULL;
 821         }
 822         action_obj = default_str;
 823     }
 824     else {
 825         Py_FatalError("unknown action");
 826     }
 827
 828     /* This assumes the line number is zero for now. */
 829     lineno = PyInt_FromLong(0);
 830     if (lineno == NULL)
 831         return NULL;
 832     result = PyTuple_Pack(5, action_obj, Py_None, category, Py_None, lineno);
 833     Py_DECREF(lineno);
 834     return result;
 835 }
 836
 837 static PyObject *
 838 init_filters(void)
 839 {
 840     PyObject *filters = PyList_New(3);
 841     const char *bytes_action;
 842     if (filters == NULL)
 843         return NULL;
 844
 845     PyList_SET_ITEM(filters, 0,
 846                     create_filter(PyExc_PendingDeprecationWarning, "ignore"));
 847     PyList_SET_ITEM(filters, 1, create_filter(PyExc_ImportWarning, "ignore"));
 848     if (Py_BytesWarningFlag > 1)
 849         bytes_action = "error";
 850     else if (Py_BytesWarningFlag)
 851         bytes_action = "default";
 852     else
 853         bytes_action = "ignore";
 854     PyList_SET_ITEM(filters, 2, create_filter(PyExc_BytesWarning,
 855                     bytes_action));
 856
 857     if (PyList_GET_ITEM(filters, 0) == NULL ||
 858         PyList_GET_ITEM(filters, 1) == NULL ||
 859         PyList_GET_ITEM(filters, 2) == NULL) {
 860         Py_DECREF(filters);
 861         return NULL;
 862     }
 863
 864     return filters;
 865 }
 866
 867
 868 PyMODINIT_FUNC
 869 _PyWarnings_Init(void)
 870 {
 871     PyObject *m;
 872
 873     m = Py_InitModule3(MODULE_NAME, warnings_functions, warnings__doc__);
 874     if (m == NULL)
 875         return;
 876
 877     _filters = init_filters();
 878     if (_filters == NULL)
 879         return;
 880     Py_INCREF(_filters);
 881     if (PyModule_AddObject(m, "filters", _filters) < 0)
 882         return;
 883
 884     _once_registry = PyDict_New();
 885     if (_once_registry == NULL)
 886         return;
 887     Py_INCREF(_once_registry);
 888     if (PyModule_AddObject(m, "once_registry", _once_registry) < 0)
 889         return;
 890
 891     _default_action = PyString_FromString("default");
 892     if (_default_action == NULL)
 893         return;
 894     if (PyModule_AddObject(m, "default_action", _default_action) < 0)
 895         return;
 896 }