/******************************************************************
 * A C extension module for Python, called "cenviron".  Wraps the 
 * C library's getenv/putenv routines for use in Python programs.  
 ******************************************************************/

#include <Python.h>
#include <stdlib.h>
#include <string.h>

/***********************/
/* 1) module functions */
/***********************/
 
static PyObject *                                   /* returns object */
wrap_getenv(PyObject *self, PyObject *args)         /* self not used */
{                                                   /* args from python */
    char *varName, *varValue;
    PyObject *returnObj = NULL;                         /* null=exception */

    if (PyArg_Parse(args, "s", &varName)) {             /* Python -> C */
        varValue = getenv(varName);                     /* call C getenv */
        if (varValue != NULL)
            returnObj = Py_BuildValue("s", varValue);   /* C -> Python */
        else
            PyErr_SetString(PyExc_SystemError, "Error calling getenv");
    }
    return returnObj;
}

static PyObject *
wrap_putenv(PyObject *self, PyObject *args)
{
    char *varName, *varValue, *varAssign;
    PyObject *returnObj = NULL;

    if (PyArg_Parse(args, "(ss)", &varName, &varValue))
    {
        varAssign = malloc(strlen(varName) + strlen(varValue) + 2);
        sprintf(varAssign, "%s=%s", varName, varValue);
        if (putenv(varAssign) == 0) {
            Py_INCREF(Py_None);                   /* C call success */
            returnObj = Py_None;                  /* reference None */
        }
        else
            PyErr_SetString(PyExc_SystemError, "Error calling putenv");
    }
    return returnObj;
}

/**************************/
/* 2) registration table  */
/**************************/

static struct PyMethodDef cenviron_methods[] = {
    {"getenv", wrap_getenv},
    {"putenv", wrap_putenv},        /* method name, address */
    {NULL, NULL}
};

/*************************/
/* 3) module initializer */
/*************************/

void initcenviron()                  /* called on first import */
{
    (void) Py_InitModule("cenviron", cenviron_methods);   /* mod name, table */
}