/Python/errors.c

  1
  2/* Error handling */
  3
  4#include "Python.h"
  5
  6#ifndef __STDC__
  7#ifndef MS_WINDOWS
  8extern char *strerror(int);
  9#endif
 10#endif
 11
 12#ifdef MS_WINDOWS
 13#include "windows.h"
 14#include "winbase.h"
 15#endif
 16
 17#include <ctype.h>
 18
 19#ifdef __cplusplus
 20extern "C" {
 21#endif
 22
 23
 24void
 25PyErr_Restore(PyObject *type, PyObject *value, PyObject *traceback)
 26{
 27	PyThreadState *tstate = PyThreadState_GET();
 28	PyObject *oldtype, *oldvalue, *oldtraceback;
 29
 30	if (traceback != NULL && !PyTraceBack_Check(traceback)) {
 31		/* XXX Should never happen -- fatal error instead? */
 32		/* Well, it could be None. */
 33		Py_DECREF(traceback);
 34		traceback = NULL;
 35	}
 36
 37	/* Save these in locals to safeguard against recursive
 38	   invocation through Py_XDECREF */
 39	oldtype = tstate->curexc_type;
 40	oldvalue = tstate->curexc_value;
 41	oldtraceback = tstate->curexc_traceback;
 42
 43	tstate->curexc_type = type;
 44	tstate->curexc_value = value;
 45	tstate->curexc_traceback = traceback;
 46
 47	Py_XDECREF(oldtype);
 48	Py_XDECREF(oldvalue);
 49	Py_XDECREF(oldtraceback);
 50}
 51
 52void
 53PyErr_SetObject(PyObject *exception, PyObject *value)
 54{
 55	Py_XINCREF(exception);
 56	Py_XINCREF(value);
 57	PyErr_Restore(exception, value, (PyObject *)NULL);
 58}
 59
 60void
 61PyErr_SetNone(PyObject *exception)
 62{
 63	PyErr_SetObject(exception, (PyObject *)NULL);
 64}
 65
 66void
 67PyErr_SetString(PyObject *exception, const char *string)
 68{
 69	PyObject *value = PyString_FromString(string);
 70	PyErr_SetObject(exception, value);
 71	Py_XDECREF(value);
 72}
 73
 74
 75PyObject *
 76PyErr_Occurred(void)
 77{
 78	PyThreadState *tstate = PyThreadState_GET();
 79
 80	return tstate->curexc_type;
 81}
 82
 83
 84int
 85PyErr_GivenExceptionMatches(PyObject *err, PyObject *exc)
 86{
 87	if (err == NULL || exc == NULL) {
 88		/* maybe caused by "import exceptions" that failed early on */
 89		return 0;
 90	}
 91	if (PyTuple_Check(exc)) {
 92		Py_ssize_t i, n;
 93		n = PyTuple_Size(exc);
 94		for (i = 0; i < n; i++) {
 95			/* Test recursively */
 96		     if (PyErr_GivenExceptionMatches(
 97			     err, PyTuple_GET_ITEM(exc, i)))
 98		     {
 99			     return 1;
100		     }
101		}
102		return 0;
103	}
104	/* err might be an instance, so check its class. */
105	if (PyExceptionInstance_Check(err))
106		err = PyExceptionInstance_Class(err);
107
108	if (PyExceptionClass_Check(err) && PyExceptionClass_Check(exc)) {
109		int res = 0;
110		PyObject *exception, *value, *tb;
111		PyErr_Fetch(&exception, &value, &tb);
112		res = PyObject_IsSubclass(err, exc);
113		/* This function must not fail, so print the error here */
114		if (res == -1) {
115			PyErr_WriteUnraisable(err);
116			res = 0;
117		}
118		PyErr_Restore(exception, value, tb);
119		return res;
120	}
121
122	return err == exc;
123}
124
125
126int
127PyErr_ExceptionMatches(PyObject *exc)
128{
129	return PyErr_GivenExceptionMatches(PyErr_Occurred(), exc);
130}
131
132
133/* Used in many places to normalize a raised exception, including in
134   eval_code2(), do_raise(), and PyErr_Print()
135*/
136void
137PyErr_NormalizeException(PyObject **exc, PyObject **val, PyObject **tb)
138{
139	PyObject *type = *exc;
140	PyObject *value = *val;
141	PyObject *inclass = NULL;
142	PyObject *initial_tb = NULL;
143	PyThreadState *tstate = NULL;
144
145	if (type == NULL) {
146		/* There was no exception, so nothing to do. */
147		return;
148	}
149
150	/* If PyErr_SetNone() was used, the value will have been actually
151	   set to NULL.
152	*/
153	if (!value) {
154		value = Py_None;
155		Py_INCREF(value);
156	}
157
158	if (PyExceptionInstance_Check(value))
159		inclass = PyExceptionInstance_Class(value);
160
161	/* Normalize the exception so that if the type is a class, the
162	   value will be an instance.
163	*/
164	if (PyExceptionClass_Check(type)) {
165		/* if the value was not an instance, or is not an instance
166		   whose class is (or is derived from) type, then use the
167		   value as an argument to instantiation of the type
168		   class.
169		*/
170		if (!inclass || !PyObject_IsSubclass(inclass, type)) {
171			PyObject *args, *res;
172
173			if (value == Py_None)
174				args = PyTuple_New(0);
175			else if (PyTuple_Check(value)) {
176				Py_INCREF(value);
177				args = value;
178			}
179			else
180				args = PyTuple_Pack(1, value);
181
182			if (args == NULL)
183				goto finally;
184			res = PyEval_CallObject(type, args);
185			Py_DECREF(args);
186			if (res == NULL)
187				goto finally;
188			Py_DECREF(value);
189			value = res;
190		}
191		/* if the class of the instance doesn't exactly match the
192		   class of the type, believe the instance
193		*/
194		else if (inclass != type) {
195 			Py_DECREF(type);
196			type = inclass;
197			Py_INCREF(type);
198		}
199	}
200	*exc = type;
201	*val = value;
202	return;
203finally:
204	Py_DECREF(type);
205	Py_DECREF(value);
206	/* If the new exception doesn't set a traceback and the old
207	   exception had a traceback, use the old traceback for the
208	   new exception.  It's better than nothing.
209	*/
210	initial_tb = *tb;
211	PyErr_Fetch(exc, val, tb);
212	if (initial_tb != NULL) {
213		if (*tb == NULL)
214			*tb = initial_tb;
215		else
216			Py_DECREF(initial_tb);
217	}
218	/* normalize recursively */
219	tstate = PyThreadState_GET();
220	if (++tstate->recursion_depth > Py_GetRecursionLimit()) {
221	    --tstate->recursion_depth;
222	    /* throw away the old exception... */
223	    Py_DECREF(*exc);
224	    Py_DECREF(*val);
225	    /* ... and use the recursion error instead */
226	    *exc = PyExc_RuntimeError;
227	    *val = PyExc_RecursionErrorInst;
228	    Py_INCREF(*exc);
229	    Py_INCREF(*val);
230	    /* just keeping the old traceback */
231	    return;
232	}
233	PyErr_NormalizeException(exc, val, tb);
234	--tstate->recursion_depth;
235}
236
237
238void
239PyErr_Fetch(PyObject **p_type, PyObject **p_value, PyObject **p_traceback)
240{
241	PyThreadState *tstate = PyThreadState_GET();
242
243	*p_type = tstate->curexc_type;
244	*p_value = tstate->curexc_value;
245	*p_traceback = tstate->curexc_traceback;
246
247	tstate->curexc_type = NULL;
248	tstate->curexc_value = NULL;
249	tstate->curexc_traceback = NULL;
250}
251
252void
253PyErr_Clear(void)
254{
255	PyErr_Restore(NULL, NULL, NULL);
256}
257
258/* Convenience functions to set a type error exception and return 0 */
259
260int
261PyErr_BadArgument(void)
262{
263	PyErr_SetString(PyExc_TypeError,
264			"bad argument type for built-in operation");
265	return 0;
266}
267
268PyObject *
269PyErr_NoMemory(void)
270{
271	if (PyErr_ExceptionMatches(PyExc_MemoryError))
272		/* already current */
273		return NULL;
274
275	/* raise the pre-allocated instance if it still exists */
276	if (PyExc_MemoryErrorInst)
277		PyErr_SetObject(PyExc_MemoryError, PyExc_MemoryErrorInst);
278	else
279		/* this will probably fail since there's no memory and hee,
280		   hee, we have to instantiate this class
281		*/
282		PyErr_SetNone(PyExc_MemoryError);
283
284	return NULL;
285}
286
287PyObject *
288PyErr_SetFromErrnoWithFilenameObject(PyObject *exc, PyObject *filenameObject)
289{
290	PyObject *v;
291	char *s;
292	int i = errno;
293#ifdef PLAN9
294	char errbuf[ERRMAX];
295#endif
296#ifdef MS_WINDOWS
297	char *s_buf = NULL;
298	char s_small_buf[28]; /* Room for "Windows Error 0xFFFFFFFF" */
299#endif
300#ifdef EINTR
301	if (i == EINTR && PyErr_CheckSignals())
302		return NULL;
303#endif
304#ifdef PLAN9
305	rerrstr(errbuf, sizeof errbuf);
306	s = errbuf;
307#else
308	if (i == 0)
309		s = "Error"; /* Sometimes errno didn't get set */
310	else
311#ifndef MS_WINDOWS
312		s = strerror(i);
313#else
314	{
315		/* Note that the Win32 errors do not lineup with the
316		   errno error.  So if the error is in the MSVC error
317		   table, we use it, otherwise we assume it really _is_
318		   a Win32 error code
319		*/
320		if (i > 0 && i < _sys_nerr) {
321			s = _sys_errlist[i];
322		}
323		else {
324			int len = FormatMessage(
325				FORMAT_MESSAGE_ALLOCATE_BUFFER |
326				FORMAT_MESSAGE_FROM_SYSTEM |
327				FORMAT_MESSAGE_IGNORE_INSERTS,
328				NULL,	/* no message source */
329				i,
330				MAKELANGID(LANG_NEUTRAL,
331					   SUBLANG_DEFAULT),
332				           /* Default language */
333				(LPTSTR) &s_buf,
334				0,	/* size not used */
335				NULL);	/* no args */
336			if (len==0) {
337				/* Only ever seen this in out-of-mem
338				   situations */
339				sprintf(s_small_buf, "Windows Error 0x%X", i);
340				s = s_small_buf;
341				s_buf = NULL;
342			} else {
343				s = s_buf;
344				/* remove trailing cr/lf and dots */
345				while (len > 0 && (s[len-1] <= ' ' || s[len-1] == '.'))
346					s[--len] = '\0';
347			}
348		}
349	}
350#endif /* Unix/Windows */
351#endif /* PLAN 9*/
352	if (filenameObject != NULL)
353		v = Py_BuildValue("(isO)", i, s, filenameObject);
354	else
355		v = Py_BuildValue("(is)", i, s);
356	if (v != NULL) {
357		PyErr_SetObject(exc, v);
358		Py_DECREF(v);
359	}
360#ifdef MS_WINDOWS
361	LocalFree(s_buf);
362#endif
363	return NULL;
364}
365
366
367PyObject *
368PyErr_SetFromErrnoWithFilename(PyObject *exc, char *filename)
369{
370	PyObject *name = filename ? PyString_FromString(filename) : NULL;
371	PyObject *result = PyErr_SetFromErrnoWithFilenameObject(exc, name);
372	Py_XDECREF(name);
373	return result;
374}
375
376#ifdef Py_WIN_WIDE_FILENAMES
377PyObject *
378PyErr_SetFromErrnoWithUnicodeFilename(PyObject *exc, Py_UNICODE *filename)
379{
380	PyObject *name = filename ?
381	                 PyUnicode_FromUnicode(filename, wcslen(filename)) :
382	                 NULL;
383	PyObject *result = PyErr_SetFromErrnoWithFilenameObject(exc, name);
384	Py_XDECREF(name);
385	return result;
386}
387#endif /* Py_WIN_WIDE_FILENAMES */
388
389PyObject *
390PyErr_SetFromErrno(PyObject *exc)
391{
392	return PyErr_SetFromErrnoWithFilenameObject(exc, NULL);
393}
394
395#ifdef MS_WINDOWS
396/* Windows specific error code handling */
397PyObject *PyErr_SetExcFromWindowsErrWithFilenameObject(
398	PyObject *exc,
399	int ierr,
400	PyObject *filenameObject)
401{
402	int len;
403	char *s;
404	char *s_buf = NULL; /* Free via LocalFree */
405	char s_small_buf[28]; /* Room for "Windows Error 0xFFFFFFFF" */
406	PyObject *v;
407	DWORD err = (DWORD)ierr;
408	if (err==0) err = GetLastError();
409	len = FormatMessage(
410		/* Error API error */
411		FORMAT_MESSAGE_ALLOCATE_BUFFER |
412		FORMAT_MESSAGE_FROM_SYSTEM |
413		FORMAT_MESSAGE_IGNORE_INSERTS,
414		NULL,	/* no message source */
415		err,
416		MAKELANGID(LANG_NEUTRAL,
417		SUBLANG_DEFAULT), /* Default language */
418		(LPTSTR) &s_buf,
419		0,	/* size not used */
420		NULL);	/* no args */
421	if (len==0) {
422		/* Only seen this in out of mem situations */
423		sprintf(s_small_buf, "Windows Error 0x%X", err);
424		s = s_small_buf;
425		s_buf = NULL;
426	} else {
427		s = s_buf;
428		/* remove trailing cr/lf and dots */
429		while (len > 0 && (s[len-1] <= ' ' || s[len-1] == '.'))
430			s[--len] = '\0';
431	}
432	if (filenameObject != NULL)
433		v = Py_BuildValue("(isO)", err, s, filenameObject);
434	else
435		v = Py_BuildValue("(is)", err, s);
436	if (v != NULL) {
437		PyErr_SetObject(exc, v);
438		Py_DECREF(v);
439	}
440	LocalFree(s_buf);
441	return NULL;
442}
443
444PyObject *PyErr_SetExcFromWindowsErrWithFilename(
445	PyObject *exc,
446	int ierr,
447	const char *filename)
448{
449	PyObject *name = filename ? PyString_FromString(filename) : NULL;
450	PyObject *ret = PyErr_SetExcFromWindowsErrWithFilenameObject(exc,
451	                                                             ierr,
452	                                                             name);
453	Py_XDECREF(name);
454	return ret;
455}
456
457#ifdef Py_WIN_WIDE_FILENAMES
458PyObject *PyErr_SetExcFromWindowsErrWithUnicodeFilename(
459	PyObject *exc,
460	int ierr,
461	const Py_UNICODE *filename)
462{
463	PyObject *name = filename ?
464	                 PyUnicode_FromUnicode(filename, wcslen(filename)) :
465	                 NULL;
466	PyObject *ret = PyErr_SetExcFromWindowsErrWithFilenameObject(exc,
467	                                                             ierr,
468	                                                             name);
469	Py_XDECREF(name);
470	return ret;
471}
472#endif /* Py_WIN_WIDE_FILENAMES */
473
474PyObject *PyErr_SetExcFromWindowsErr(PyObject *exc, int ierr)
475{
476	return PyErr_SetExcFromWindowsErrWithFilename(exc, ierr, NULL);
477}
478
479PyObject *PyErr_SetFromWindowsErr(int ierr)
480{
481	return PyErr_SetExcFromWindowsErrWithFilename(PyExc_WindowsError,
482						      ierr, NULL);
483}
484PyObject *PyErr_SetFromWindowsErrWithFilename(
485	int ierr,
486	const char *filename)
487{
488	PyObject *name = filename ? PyString_FromString(filename) : NULL;
489	PyObject *result = PyErr_SetExcFromWindowsErrWithFilenameObject(
490						      PyExc_WindowsError,
491						      ierr, name);
492	Py_XDECREF(name);
493	return result;
494}
495
496#ifdef Py_WIN_WIDE_FILENAMES
497PyObject *PyErr_SetFromWindowsErrWithUnicodeFilename(
498	int ierr,
499	const Py_UNICODE *filename)
500{
501	PyObject *name = filename ?
502	                 PyUnicode_FromUnicode(filename, wcslen(filename)) :
503	                 NULL;
504	PyObject *result = PyErr_SetExcFromWindowsErrWithFilenameObject(
505						      PyExc_WindowsError,
506						      ierr, name);
507	Py_XDECREF(name);
508	return result;
509}
510#endif /* Py_WIN_WIDE_FILENAMES */
511#endif /* MS_WINDOWS */
512
513void
514_PyErr_BadInternalCall(const char *filename, int lineno)
515{
516	PyErr_Format(PyExc_SystemError,
517		     "%s:%d: bad argument to internal function",
518		     filename, lineno);
519}
520
521/* Remove the preprocessor macro for PyErr_BadInternalCall() so that we can
522   export the entry point for existing object code: */
523#undef PyErr_BadInternalCall
524void
525PyErr_BadInternalCall(void)
526{
527	PyErr_Format(PyExc_SystemError,
528		     "bad argument to internal function");
529}
530#define PyErr_BadInternalCall() _PyErr_BadInternalCall(__FILE__, __LINE__)
531
532
533
534PyObject *
535PyErr_Format(PyObject *exception, const char *format, ...)
536{
537	va_list vargs;
538	PyObject* string;
539
540#ifdef HAVE_STDARG_PROTOTYPES
541	va_start(vargs, format);
542#else
543	va_start(vargs);
544#endif
545
546	string = PyString_FromFormatV(format, vargs);
547	PyErr_SetObject(exception, string);
548	Py_XDECREF(string);
549	va_end(vargs);
550	return NULL;
551}
552
553
554
555PyObject *
556PyErr_NewException(char *name, PyObject *base, PyObject *dict)
557{
558	char *dot;
559	PyObject *modulename = NULL;
560	PyObject *classname = NULL;
561	PyObject *mydict = NULL;
562	PyObject *bases = NULL;
563	PyObject *result = NULL;
564	dot = strrchr(name, '.');
565	if (dot == NULL) {
566		PyErr_SetString(PyExc_SystemError,
567			"PyErr_NewException: name must be module.class");
568		return NULL;
569	}
570	if (base == NULL)
571		base = PyExc_Exception;
572	if (dict == NULL) {
573		dict = mydict = PyDict_New();
574		if (dict == NULL)
575			goto failure;
576	}
577	if (PyDict_GetItemString(dict, "__module__") == NULL) {
578		modulename = PyString_FromStringAndSize(name,
579						     (Py_ssize_t)(dot-name));
580		if (modulename == NULL)
581			goto failure;
582		if (PyDict_SetItemString(dict, "__module__", modulename) != 0)
583			goto failure;
584	}
585	if (PyTuple_Check(base)) {
586		bases = base;
587		/* INCREF as we create a new ref in the else branch */
588		Py_INCREF(bases);
589	} else {
590		bases = PyTuple_Pack(1, base);
591		if (bases == NULL)
592			goto failure;
593	}
594	/* Create a real new-style class. */
595	result = PyObject_CallFunction((PyObject *)&PyType_Type, "sOO",
596				       dot+1, bases, dict);
597  failure:
598	Py_XDECREF(bases);
599	Py_XDECREF(mydict);
600	Py_XDECREF(classname);
601	Py_XDECREF(modulename);
602	return result;
603}
604
605/* Call when an exception has occurred but there is no way for Python
606   to handle it.  Examples: exception in __del__ or during GC. */
607void
608PyErr_WriteUnraisable(PyObject *obj)
609{
610	PyObject *f, *t, *v, *tb;
611	PyErr_Fetch(&t, &v, &tb);
612	f = PySys_GetObject("stderr");
613	if (f != NULL) {
614		PyFile_WriteString("Exception ", f);
615		if (t) {
616			PyObject* moduleName;
617			char* className;
618			assert(PyExceptionClass_Check(t));
619			className = PyExceptionClass_Name(t);
620			if (className != NULL) {
621				char *dot = strrchr(className, '.');
622				if (dot != NULL)
623					className = dot+1;
624			}
625
626			moduleName = PyObject_GetAttrString(t, "__module__");
627			if (moduleName == NULL)
628				PyFile_WriteString("<unknown>", f);
629			else {
630				char* modstr = PyString_AsString(moduleName);
631				if (modstr &&
632				    strcmp(modstr, "exceptions") != 0)
633				{
634					PyFile_WriteString(modstr, f);
635					PyFile_WriteString(".", f);
636				}
637			}
638			if (className == NULL)
639				PyFile_WriteString("<unknown>", f);
640			else
641				PyFile_WriteString(className, f);
642			if (v && v != Py_None) {
643				PyFile_WriteString(": ", f);
644				PyFile_WriteObject(v, f, 0);
645			}
646			Py_XDECREF(moduleName);
647		}
648		PyFile_WriteString(" in ", f);
649		PyFile_WriteObject(obj, f, 0);
650		PyFile_WriteString(" ignored\n", f);
651		PyErr_Clear(); /* Just in case */
652	}
653	Py_XDECREF(t);
654	Py_XDECREF(v);
655	Py_XDECREF(tb);
656}
657
658extern PyObject *PyModule_GetWarningsModule(void);
659
660
661/* Set file and line information for the current exception.
662   If the exception is not a SyntaxError, also sets additional attributes
663   to make printing of exceptions believe it is a syntax error. */
664
665void
666PyErr_SyntaxLocation(const char *filename, int lineno)
667{
668	PyObject *exc, *v, *tb, *tmp;
669
670	/* add attributes for the line number and filename for the error */
671	PyErr_Fetch(&exc, &v, &tb);
672	PyErr_NormalizeException(&exc, &v, &tb);
673	/* XXX check that it is, indeed, a syntax error. It might not
674	 * be, though. */
675	tmp = PyInt_FromLong(lineno);
676	if (tmp == NULL)
677		PyErr_Clear();
678	else {
679		if (PyObject_SetAttrString(v, "lineno", tmp))
680			PyErr_Clear();
681		Py_DECREF(tmp);
682	}
683	if (filename != NULL) {
684		tmp = PyString_FromString(filename);
685		if (tmp == NULL)
686			PyErr_Clear();
687		else {
688			if (PyObject_SetAttrString(v, "filename", tmp))
689				PyErr_Clear();
690			Py_DECREF(tmp);
691		}
692
693		tmp = PyErr_ProgramText(filename, lineno);
694		if (tmp) {
695			if (PyObject_SetAttrString(v, "text", tmp))
696				PyErr_Clear();
697			Py_DECREF(tmp);
698		}
699	}
700	if (PyObject_SetAttrString(v, "offset", Py_None)) {
701		PyErr_Clear();
702	}
703	if (exc != PyExc_SyntaxError) {
704		if (!PyObject_HasAttrString(v, "msg")) {
705			tmp = PyObject_Str(v);
706			if (tmp) {
707				if (PyObject_SetAttrString(v, "msg", tmp))
708					PyErr_Clear();
709				Py_DECREF(tmp);
710			} else {
711				PyErr_Clear();
712			}
713		}
714		if (!PyObject_HasAttrString(v, "print_file_and_line")) {
715			if (PyObject_SetAttrString(v, "print_file_and_line",
716						   Py_None))
717				PyErr_Clear();
718		}
719	}
720	PyErr_Restore(exc, v, tb);
721}
722
723/* com_fetch_program_text will attempt to load the line of text that
724   the exception refers to.  If it fails, it will return NULL but will
725   not set an exception.
726
727   XXX The functionality of this function is quite similar to the
728   functionality in tb_displayline() in traceback.c.
729*/
730
731PyObject *
732PyErr_ProgramText(const char *filename, int lineno)
733{
734	FILE *fp;
735	int i;
736	char linebuf[1000];
737
738	if (filename == NULL || *filename == '\0' || lineno <= 0)
739		return NULL;
740	fp = fopen(filename, "r" PY_STDIOTEXTMODE);
741	if (fp == NULL)
742		return NULL;
743	for (i = 0; i < lineno; i++) {
744		char *pLastChar = &linebuf[sizeof(linebuf) - 2];
745		do {
746			*pLastChar = '\0';
747			if (Py_UniversalNewlineFgets(linebuf, sizeof linebuf, fp, NULL) == NULL)
748				break;
749			/* fgets read *something*; if it didn't get as
750			   far as pLastChar, it must have found a newline
751			   or hit the end of the file; if pLastChar is \n,
752			   it obviously found a newline; else we haven't
753			   yet seen a newline, so must continue */
754		} while (*pLastChar != '\0' && *pLastChar != '\n');
755	}
756	fclose(fp);
757	if (i == lineno) {
758		char *p = linebuf;
759		while (*p == ' ' || *p == '\t' || *p == '\014')
760			p++;
761		return PyString_FromString(p);
762	}
763	return NULL;
764}
765
766#ifdef __cplusplus
767}
768#endif
769