Segmentation fault (core dumped). Using C module in python -

i newbie in python , trying launch python script module writen on c. getting segmentation fault (core dumped) error when trying launch python script. here c code:

// input_device.c   #include "python.h"  #include "input.h"  static pyobject* input_device_open(pyobject* self, pyobject* id) {     int fd, nr;     pyobject* pyfd;      if (!pyint_check(id))         return null;      nr = (int)pyint_aslong(id);     fd = device_open(nr, 0);     if (fd == -1)         return null;     pyfd = pyint_fromlong(fd);     py_incref(pyfd);     return pyfd; }  static pymethoddef module_methods[] = {     { "device_open", (pycfunction)input_device_open, meth_varargs, "..." },     { null, null, 0, null } };  pymodinit_func initinput_device(void) {     py_initmodule4("input_device", module_methods, "wrapper methods", 0, python_api_version); } 

and python script:

from input_device import device_open device_open(1) 

could take , point me in right direction, doing wrong. in advance.

is legitimate return null without setting exception, or making sure 1 has been set function have called? thought null signal python go exception raise user.

i not sure py_incref(pyfd); necessary; doesn't object have refcount of 1 upon creation?