I'm running into a problem when trying to perform a callback to a Python
function from a C extension. Specifically, the callback is being made by
a pthread that seems to cause the problem. If I call the callback from
the parent process, it works fine. The PyObject is static, and holds the
same value in both Parent and thread, so I'm at a loss as to what would be
different in the pthread from the parent that would cause a segfault on
the callback. The machine specifics are an x86 intel processor with
RedHat linux.
Here is some clips of the C callback code showing how I'm storing the
callback, then what the actual callback function is like. Any ideas?
The function being called is a simply to display the string of text, and
execution never seems to reach back to the Python code at all.
Thanks,
Travis B.
/* callback function to the Python code */
static PyObject * my_callback = NULL;
/* setting callback function */
static PyObject * my_set_callback(PyObject *dummy, PyObject *args)
{
PyObject *result = NULL;
PyObject *temp;
PyObject *arglist;
if (PyArg_ParseTuple(args, "O:set_callback", &temp)) {
if (!PyCallable_Check(temp)) {
PyErr_SetString(PyExc_TypeError,
"parameter must be callable");
return NULL;
}
Py_XINCREF(temp); /* Add a reference to new callback */
Py_XDECREF(my_callback); /* Dispose of previous callback */
my_callback = temp; /* Remember new callback */
/* return "None" */
Py_INCREF(Py_None);
result = Py_None;
}
return result;
}
/* calling callback */
void callback(char * str) {
PyObject *arglist;
PyObject *result;
if(str == NULL)
return;
if(my_callback == NULL) {
printf("no callback function provided, returning...\n");
return;
}
/* Time to call the callback */
arglist = Py_BuildValue("(s)", str);
result = PyEval_CallObject(my_callback, arglist);
Py_DECREF(arglist);
if(result == NULL)
return;
Py_DECREF(result);
}
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