Method without return value in python c extension module

Question

I'm trying to create a script in python that sends data through a parallel port. I'm creating my own module in C language.

The problem is: when I try to execute my module, python crashes. No errors, no data, nothing. It simply closes.

This is my module:

#include <Python.h>
#include <sys/io.h>
#define BaseAddr 0x378

/*----------------------------------------------------------------------------------
Este es un módulo destinado a controlar el puerto paralelo.
Probablemente tenga que ser ejecutado como administrador.

Created by markmb
------------------------------------------------------------------------------------*/

static PyObject *
paralelo(PyObject *self, PyObject *args){
    int pin;
    ioperm(BaseAddr,3,1);
    if (!PyArg_ParseTuple(args, "i", &pin))
        return NULL;
    outb(pin,BaseAddr);
    ioperm(BaseAddr,3,0);
    return 1
}
PyMethodDef methods[] = {
    {"paralelo", paralelo, METH_VARARGS, "Sends data through a parallel port"},
    {NULL, NULL, 0, NULL}
};
PyMODINIT_FUNC
initparalelo(void){
    (void) Py_InitModule("paralelo", methods);
}

(It works without all python mess) I compile it through distutils and then, in terminal (using xubuntu), I put:

import paralelo
while True:
    paralelo.paralelo(255)

And here, it goes out of python, it puts "markmb@..."

Thanks in advance!

Answer 1

Returning NULL to the python/c API indicates that an error has occurred. But since you didn't actually set an exception you get the error:

SystemError: error return without exception set

If you are trying to return None, use:

return Py_BuildValue("");