embedded python doesn't like socket.accept() and SegFaults

[Riccardo Di Meo]

Hi everyone,

I'm practicing with embedding python into C code and i have encountered 
a very strange problem: I'm unable to call the "accept" method of a 
(correctly created) server socket without receiving a "Segmentation 
fault" (inside the PyObject_CallMethod).

My code <seems> to be correct (at least it's correct enough for me to 
call .getsockname(),  .fileno() and other methods without problems), I'm 
pretty new to this thing though, therefore I'm confident I'm doing 
something very dumb.

Here is the C code:

------ extending.c
#include <python2.5/Python.h>

PyObject *new_server(long port)
{
  PyObject *pName,*pModule;
  PyObject *pFunction,*pArg;
  PyObject *pTuple,*pValue;

  // Import the module
  pName = PyString_FromString("extending");
  pModule = PyImport_Import(pName);
  Py_DECREF(pName);

  // Get the function
  pFunction = PyObject_GetAttrString(pModule,
                                     "server_socket");

  // Module not needed anymore
  Py_DECREF(pModule);

  // Build the arguments
  pArg=PyInt_FromLong(port);
  pTuple=PyTuple_New(1);
  PyTuple_SET_ITEM(pTuple,0,pArg);

  // Call the function
  pValue = PyObject_CallObject(pFunction,
                               pTuple);

  // Release the references
  Py_DECREF(pFunction);
  Py_DECREF(pTuple);

  if(pValue==NULL)
    printf("Error: server socket not created!\n");

  return pValue;
}

PyObject *accept(PyObject *server)
{
  PyObject *pValue;

  // Code fails here (it does NOT return NULL: just crashes!)
  // Note that other calls work fine (e.g. fileno, getsockname ecc)
  pValue = PyObject_CallMethod(server,
                               "accept",
                               NULL);
  return pValue;
}

int main(int argc,char *argv[])
{
  PyObject *server,*connection;

  // Boot python
  Py_Initialize();
  PySys_SetArgv(argc, argv);

  // Create the server
  server=new_server(23000);

  // Print it
  PyObject_Print(server,stderr,0);
  fprintf(stderr,"\n");

  // Wait for a connection
  connection=accept(server);

  // See what we got
  PyObject_Print(connection,stderr,0);
  fprintf(stderr,"\n");

  // We are done, hint the gc.
  Py_DECREF(connection);
  Py_DECREF(server);

  Py_Finalize();
  return 0;
}
----------

and this is the python script:

---------- extending.py
import socket

def server_socket(port):
    s=socket.socket()
    s.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,True)
    s.bind(("0.0.0.0",port))
    s.listen(10)
    return s
------------

as already mentioned, replacing the "accept" string with "fileno" or 
something else doesn't crash the interpreter.

Another thing worth mentioning, is that even inserting a s.accept() call 
in the python script (before the return) makes the bug appear (it 
doesn't seems related to my use of the PyObject_CallMethod function, then).

I have tried posting the problem  in IRC, searching google (no good 
matches) and debugging the code (however I'm afraid i don't have the 
python-lib with debugging  syms. compiled in, therefore it was quite a 
useless attempt...).

Any help about the code would be appreciated (even unrelated to the 
issue at hand: im quite new to this "embedding thing" and therefore  i 
gladly accept hints).

Thank you for your attention,
Riccardo Di Meo

PS: I'm also new to Usenet: is it fine to post the code in the body of 
the mail as i did (since it was small, i dared: however I'd like to know 
the correct etiquette)?