Py_INCREF() incomprehension

Tue Apr 26 05:48:15 EDT 2011

Hello Python users,
I'm working on a Python module in C - that's a cryptographic module,
which uses a 3rd-party lib from a provider (a bank).
This module will encrypt and decrypt the messages for the provider web service.
Here is a part of source:
static PyObject*
mycrypt_encrypt(PyObject *self, PyObject *args)
{
 int cRes = 0;
 int OutLen = 0;
 char * url;
 char * path;
 if (!PyArg_ParseTuple(args, "ss", &url, &path)) {
 return NULL;
 }
 OutLen = strlen(url)*4;
 outdata=calloc(OutLen, sizeof(char));
 if (!outdata) {
 handle_err(UER_NOMEM);
 return NULL;
 }
 cRes = ekiEncodeUrl (url, strlen(url)+1, outdata, &OutLen, 1, path);
 if (cRes == 0) {
 return Py_BuildValue("s", outdata);
 } else {
 handle_err(cRes);
 return NULL;
 }
 return Py_None;
}
where ekiEncodeUrl is in a 3rd-party library.
I should call this function from Python like this:
import mycrypt
message = "PID=IEB0001&MSGT=10&TRID=000000012345678"
crypted = mycrypt(mymessage, "/path/to/key");
Everything works fine, but sorry for the recurrent question: where
should I use the Py_INCREF()/Py_DECREF() in code above?
Thank you,
cheers:
a.