cpython/Python/errors.c

/***********************************************************
Copyright (c) 2000, BeOpen.com.
Copyright (c) 1995-2000, Corporation for National Research Initiatives.
Copyright (c) 1990-1995, Stichting Mathematisch Centrum.
All rights reserved.

See the file "Misc/COPYRIGHT" for information on usage and
redistribution of this file, and for a DISCLAIMER OF ALL WARRANTIES.
******************************************************************/

/* Error handling */

#include "Python.h"

#ifdef macintosh
extern char *PyMac_StrError(int);
#undef strerror
#define strerror PyMac_StrError
#endif /* macintosh */

#ifndef __STDC__
#ifndef MS_WINDOWS
extern char *strerror(int);
#endif
#endif

#ifdef MS_WIN32
#include "windows.h"
#include "winbase.h"
#endif

void
PyErr_Restore(PyObject *type, PyObject *value, PyObject *traceback)
{
	PyThreadState *tstate = PyThreadState_GET();
	PyObject *oldtype, *oldvalue, *oldtraceback;

	if (traceback != NULL && !PyTraceBack_Check(traceback)) {
		/* XXX Should never happen -- fatal error instead? */
		Py_DECREF(traceback);
		traceback = NULL;
	}

	/* Save these in locals to safeguard against recursive
	   invocation through Py_XDECREF */
	oldtype = tstate->curexc_type;
	oldvalue = tstate->curexc_value;
	oldtraceback = tstate->curexc_traceback;

	tstate->curexc_type = type;
	tstate->curexc_value = value;
	tstate->curexc_traceback = traceback;

	Py_XDECREF(oldtype);
	Py_XDECREF(oldvalue);
	Py_XDECREF(oldtraceback);
}

void
PyErr_SetObject(PyObject *exception, PyObject *value)
{
	Py_XINCREF(exception);
	Py_XINCREF(value);
	PyErr_Restore(exception, value, (PyObject *)NULL);
}

void
PyErr_SetNone(PyObject *exception)
{
	PyErr_SetObject(exception, (PyObject *)NULL);
}

void
PyErr_SetString(PyObject *exception, const char *string)
{
	PyObject *value = PyString_FromString(string);
	PyErr_SetObject(exception, value);
	Py_XDECREF(value);
}


PyObject *
PyErr_Occurred(void)
{
	PyThreadState *tstate = PyThreadState_Get();

	return tstate->curexc_type;
}


int
PyErr_GivenExceptionMatches(PyObject *err, PyObject *exc)
{
	if (err == NULL || exc == NULL) {
		/* maybe caused by "import exceptions" that failed early on */
		return 0;
	}
	if (PyTuple_Check(exc)) {
		int i, n;
		n = PyTuple_Size(exc);
		for (i = 0; i < n; i++) {
			/* Test recursively */
		     if (PyErr_GivenExceptionMatches(
			     err, PyTuple_GET_ITEM(exc, i)))
		     {
			     return 1;
		     }
		}
		return 0;
	}
	/* err might be an instance, so check its class. */
	if (PyInstance_Check(err))
		err = (PyObject*)((PyInstanceObject*)err)->in_class;

	if (PyClass_Check(err) && PyClass_Check(exc))
		return PyClass_IsSubclass(err, exc);

	return err == exc;
}


int
PyErr_ExceptionMatches(PyObject *exc)
{
	return PyErr_GivenExceptionMatches(PyErr_Occurred(), exc);
}


/* Used in many places to normalize a raised exception, including in
   eval_code2(), do_raise(), and PyErr_Print()
*/
void
PyErr_NormalizeException(PyObject **exc, PyObject **val, PyObject **tb)
{
	PyObject *type = *exc;
	PyObject *value = *val;
	PyObject *inclass = NULL;

	if (type == NULL) {
		/* This is a bug.  Should never happen.  Don't dump core. */
		PyErr_SetString(PyExc_SystemError,
			"PyErr_NormalizeException() called without exception");
	}

	/* If PyErr_SetNone() was used, the value will have been actually
	   set to NULL.
	*/
	if (!value) {
		value = Py_None;
		Py_INCREF(value);
	}

	if (PyInstance_Check(value))
		inclass = (PyObject*)((PyInstanceObject*)value)->in_class;

	/* Normalize the exception so that if the type is a class, the
	   value will be an instance.
	*/
	if (PyClass_Check(type)) {
		/* if the value was not an instance, or is not an instance
		   whose class is (or is derived from) type, then use the
		   value as an argument to instantiation of the type
		   class.
		*/
		if (!inclass || !PyClass_IsSubclass(inclass, type)) {
			PyObject *args, *res;

			if (value == Py_None)
				args = Py_BuildValue("()");
			else if (PyTuple_Check(value)) {
				Py_INCREF(value);
				args = value;
			}
			else
				args = Py_BuildValue("(O)", value);

			if (args == NULL)
				goto finally;
			res = PyEval_CallObject(type, args);
			Py_DECREF(args);
			if (res == NULL)
				goto finally;
			Py_DECREF(value);
			value = res;
		}
		/* if the class of the instance doesn't exactly match the
		   class of the type, believe the instance
		*/
		else if (inclass != type) {
 			Py_DECREF(type);
			type = inclass;
			Py_INCREF(type);
		}
	}
	*exc = type;
	*val = value;
	return;
finally:
	Py_DECREF(type);
	Py_DECREF(value);
	Py_XDECREF(*tb);
	PyErr_Fetch(exc, val, tb);
	/* normalize recursively */
	PyErr_NormalizeException(exc, val, tb);
}


void
PyErr_Fetch(PyObject **p_type, PyObject **p_value, PyObject **p_traceback)
{
	PyThreadState *tstate = PyThreadState_Get();

	*p_type = tstate->curexc_type;
	*p_value = tstate->curexc_value;
	*p_traceback = tstate->curexc_traceback;

	tstate->curexc_type = NULL;
	tstate->curexc_value = NULL;
	tstate->curexc_traceback = NULL;
}

void
PyErr_Clear(void)
{
	PyErr_Restore(NULL, NULL, NULL);
}

/* Convenience functions to set a type error exception and return 0 */

int
PyErr_BadArgument(void)
{
	PyErr_SetString(PyExc_TypeError,
			"illegal argument type for built-in operation");
	return 0;
}

PyObject *
PyErr_NoMemory(void)
{
	if (PyErr_ExceptionMatches(PyExc_MemoryError))
		/* already current */
		return NULL;

	/* raise the pre-allocated instance if it still exists */
	if (PyExc_MemoryErrorInst)
		PyErr_SetObject(PyExc_MemoryError, PyExc_MemoryErrorInst);
	else
		/* this will probably fail since there's no memory and hee,
		   hee, we have to instantiate this class
		*/
		PyErr_SetNone(PyExc_MemoryError);

	return NULL;
}

PyObject *
PyErr_SetFromErrnoWithFilename(PyObject *exc, char *filename)
{
	PyObject *v;
	char *s;
	int i = errno;
#ifdef MS_WIN32
	char *s_buf = NULL;
#endif
#ifdef EINTR
	if (i == EINTR && PyErr_CheckSignals())
		return NULL;
#endif
	if (i == 0)
		s = "Error"; /* Sometimes errno didn't get set */
	else
#ifndef MS_WIN32
		s = strerror(i);
#else
	{
		/* Note that the Win32 errors do not lineup with the
		   errno error.  So if the error is in the MSVC error
		   table, we use it, otherwise we assume it really _is_ 
		   a Win32 error code
		*/
		if (i > 0 && i < _sys_nerr) {
			s = _sys_errlist[i];
		}
		else {
			int len = FormatMessage(
				FORMAT_MESSAGE_ALLOCATE_BUFFER |
				FORMAT_MESSAGE_FROM_SYSTEM |
				FORMAT_MESSAGE_IGNORE_INSERTS,
				NULL,	/* no message source */
				i,
				MAKELANGID(LANG_NEUTRAL,
					   SUBLANG_DEFAULT),
				           /* Default language */
				(LPTSTR) &s_buf,
				0,	/* size not used */
				NULL);	/* no args */
			s = s_buf;
			/* remove trailing cr/lf and dots */
			while (len > 0 && (s[len-1] <= ' ' || s[len-1] == '.'))
				s[--len] = '\0';
		}
	}
#endif
	if (filename != NULL)
		v = Py_BuildValue("(iss)", i, s, filename);
	else
		v = Py_BuildValue("(is)", i, s);
	if (v != NULL) {
		PyErr_SetObject(exc, v);
		Py_DECREF(v);
	}
#ifdef MS_WIN32
	LocalFree(s_buf);
#endif
	return NULL;
}


PyObject *
PyErr_SetFromErrno(PyObject *exc)
{
	return PyErr_SetFromErrnoWithFilename(exc, NULL);
}

#ifdef MS_WINDOWS 
/* Windows specific error code handling */
PyObject *PyErr_SetFromWindowsErrWithFilename(
	int ierr,
	const char *filename)
{
	int len;
	char *s;
	PyObject *v;
	DWORD err = (DWORD)ierr;
	if (err==0) err = GetLastError();
	len = FormatMessage(
		/* Error API error */
		FORMAT_MESSAGE_ALLOCATE_BUFFER |
		FORMAT_MESSAGE_FROM_SYSTEM |
		FORMAT_MESSAGE_IGNORE_INSERTS,
		NULL,	/* no message source */
		err,
		MAKELANGID(LANG_NEUTRAL,
		SUBLANG_DEFAULT), /* Default language */
		(LPTSTR) &s,
		0,	/* size not used */
		NULL);	/* no args */
	/* remove trailing cr/lf and dots */
	while (len > 0 && (s[len-1] <= ' ' || s[len-1] == '.'))
		s[--len] = '\0';
	if (filename != NULL)
		v = Py_BuildValue("(iss)", err, s, filename);
	else
		v = Py_BuildValue("(is)", err, s);
	if (v != NULL) {
		PyErr_SetObject(PyExc_WindowsError, v);
		Py_DECREF(v);
	}
	LocalFree(s);
	return NULL;
}

PyObject *PyErr_SetFromWindowsErr(int ierr)
{
	return PyErr_SetFromWindowsErrWithFilename(ierr, NULL);

}
#endif /* MS_WINDOWS */

void
PyErr_BadInternalCall(void)
{
	PyErr_SetString(PyExc_SystemError,
			"bad argument to internal function");
}


PyObject *
PyErr_Format(PyObject *exception, const char *format, ...)
{
	va_list vargs;
	char buffer[500]; /* Caller is responsible for limiting the format */

	va_start(vargs, format);

	vsprintf(buffer, format, vargs);
	PyErr_SetString(exception, buffer);
	return NULL;
}


PyObject *
PyErr_NewException(char *name, PyObject *base, PyObject *dict)
{
	char *dot;
	PyObject *modulename = NULL;
	PyObject *classname = NULL;
	PyObject *mydict = NULL;
	PyObject *bases = NULL;
	PyObject *result = NULL;
	dot = strrchr(name, '.');
	if (dot == NULL) {
		PyErr_SetString(PyExc_SystemError,
			"PyErr_NewException: name must be module.class");
		return NULL;
	}
	if (base == NULL)
		base = PyExc_Exception;
	if (!PyClass_Check(base)) {
		/* Must be using string-based standard exceptions (-X) */
		return PyString_FromString(name);
	}
	if (dict == NULL) {
		dict = mydict = PyDict_New();
		if (dict == NULL)
			goto failure;
	}
	if (PyDict_GetItemString(dict, "__module__") == NULL) {
		modulename = PyString_FromStringAndSize(name, (int)(dot-name));
		if (modulename == NULL)
			goto failure;
		if (PyDict_SetItemString(dict, "__module__", modulename) != 0)
			goto failure;
	}
	classname = PyString_FromString(dot+1);
	if (classname == NULL)
		goto failure;
	bases = Py_BuildValue("(O)", base);
	if (bases == NULL)
		goto failure;
	result = PyClass_New(bases, dict, classname);
  failure:
	Py_XDECREF(bases);
	Py_XDECREF(mydict);
	Py_XDECREF(classname);
	Py_XDECREF(modulename);
	return result;
}