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britanicus 1 Newbie Poster

This is a part the extension module im writing for python using c++. ( The complete source is available as an attachment )

#include <python2.6/Python.h>
#include <iostream>
#include <fstream>
#include "structmember.h"

using namespace std;

typedef struct {
	PyObject_HEAD
	fstream file;
} CppFileObject;

static int CppFile_init( CppFileObject *self, PyObject *args ) {

	PyObject *fn;
	if ( !PyArg_UnpackTuple( args, "s:CppFile", 1, 1, &fn ) ) {
		return -1;
	}

	char *filename = PyString_AS_STRING( fn );
	self->file.open( filename, ios::in | ios::out );

	return 0;
}

This compiles perfectly. However the problem is when I use the module, it throws a Segmentation Fault.

>>> import cppfile
>>> print cppfile
<module 'cppfile' from 'cppfile.so'>
>>> cf = cppfile.CppFile( "file" )
Segmentation Fault

I figured out that the problem is with line 21

self->file.open( filename, ios::in | ios::out );

though i do not know what it is. Could someone please guide me as to what exactly the problem is?

/*
	*
	* Copyright 2011 Britanicus <marcusbritanicus@gmail.com>
	*

	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*

	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	* GNU General Public License for more details.
	*

	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
	* MA 02110-1301, USA.
	*
*/

#include <python2.6/Python.h>
#include <iostream>
#include <fstream>
#include "structmember.h"

using namespace std;

typedef struct {
	PyObject_HEAD
	fstream file;
} CppFileObject;

static int CppFile_init( CppFileObject *self, PyObject *args ) {

	PyObject *fn;
	if ( !PyArg_UnpackTuple( args, "s:CppFile", 1, 1, &fn ) ) {
		return -1;
	}

	char *filename = PyString_AS_STRING( fn );
	self->file.open( filename, ios::in | ios::out );

	return 0;
}

static PyObject *CppFile_new( PyTypeObject *type, PyObject *args, PyObject *kwds ) {

	CppFileObject *self;
	self = (CppFileObject *)type->tp_alloc(type, 0);

	PyObject *fn;
	if ( !PyArg_UnpackTuple( args, "s:CppFile", 1, 1, &fn ) ) {
		return Py_None;
	}

	char *filename = PyString_AS_STRING( fn );
	self->file.open( filename, ios::in | ios::out );

	return (PyObject *)self;
}

static PyObject *CppFile_seek( CppFileObject *self, PyObject *args ) {

	PyObject *pos;
	if ( !PyArg_UnpackTuple( args, "l:CppFile", 1, 1, &pos ) ) {
		return PyInt_FromLong( -1 );
	}

	self->file.seekp( PyLong_AsLong( pos ) );
	return PyInt_FromLong( 0 );
}

static PyObject *CppFile_tell( CppFileObject *self ) {

	int pos = self->file.tellp();
	return PyInt_FromLong( pos );
}

static PyObject *CppFile_write( CppFileObject *self, PyObject *args ) {

	PyObject *data;
	if ( !PyArg_UnpackTuple( args, "s:CppFile", 1, 1, &data ) ) {
		return PyInt_FromLong( -1 );
	}

	self->file << PyString_AsString( data ) << flush;
	return PyInt_FromLong( 0 );
}

static PyObject *CppFile_close( CppFileObject *self ) {

	self->file << flush;
	self->file.close();

	return Py_None;
}

static PyMemberDef CppFile_members[] = {
	{NULL} /* Sentinel */
};

static PyMethodDef CppFile_methods[] = {
	{ "write", ( PyCFunction )CppFile_write, METH_VARARGS, "write data into the file" },
	{ "seek", ( PyCFunction )CppFile_seek, METH_VARARGS, "seek to position" },
	{ "tell", ( PyCFunction )CppFile_tell, METH_VARARGS, "tell the current position" },
	{ "close", ( PyCFunction )CppFile_close, METH_VARARGS, "close the file" },
	{NULL} /* Sentinel */
};

static PyTypeObject CppFileType = {
	PyObject_HEAD_INIT( NULL )
	0,						 						/*ob_size*/
	"CppFile",										/*tp_name*/
	sizeof( CppFileObject ),								/*tp_basicsize*/
	0,						 						/*tp_itemsize*/
	0,												/*tp_dealloc*/
	0,												/*tp_print*/
	0,												/*tp_getattr*/
	0,												/*tp_setattr*/
	0,												/*tp_compare*/
	0,												/*tp_repr*/
	0,												/*tp_as_number*/
	0,												/*tp_as_sequence*/
	0,												/*tp_as_mapping*/
	0,												/*tp_hash */
	0,												/*tp_call*/
	0,												/*tp_str*/
	0,												/*tp_getattro*/
	0,												/*tp_setattro*/
	0,												/*tp_as_buffer*/
	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,		/*tp_flags*/
	"CppFile objects",								/* tp_doc */
	0,												/* tp_traverse */
	0,												/* tp_clear */
	0,												/* tp_richcompare */
	0,												/* tp_weaklistoffset */
	0,												/* tp_iter */
	0,												/* tp_iternext */
	CppFile_methods,								/* tp_methods */
	CppFile_members,								/* tp_members */
	0,												/* tp_getset */
	0,												/* tp_base */
	0,												/* tp_dict */
	0,												/* tp_descr_get */
	0,												/* tp_descr_set */
	0,												/* tp_dictoffset */
	( initproc )CppFile_init,						/* tp_init */
	0,												/* tp_alloc */
	CppFile_new,									/* tp_new */
};

static PyMethodDef module_methods[] = {
	{NULL} /* Sentinel */
};

#ifndef PyMODINIT_FUNC	/* declarations for DLL import/export */
#define PyMODINIT_FUNC void
#endif

PyMODINIT_FUNC initcppfile( void ) {
	PyObject* m;

	if ( PyType_Ready( &CppFileType ) < 0 )
		return;

	m = Py_InitModule3(
		"cppfile",
		module_methods,
		"Example module that creates an extension type."
	);

	if ( m == NULL )
		return;

	Py_INCREF( &CppFileType );
	PyModule_AddObject( m, "CppFile", ( PyObject * )&CppFileType );
}
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