#include "Python.h"
#include <sys/resource.h>
#include <sys/time.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>

/* don't know why this isn't defined in a header file */
#ifndef getrusage
int getrusage(int who, struct rusage *rusage);
#endif

#ifndef getpagesize
int getpagesize(void);
#endif

#define doubletime(TV) ((double)(TV).tv_sec + (TV).tv_usec * 0.000001)

static PyObject *ResourceError;

static PyObject *
resource_getrusage(self, args)
	PyObject *self;
	PyObject *args;
{
	int who;
	struct rusage ru;

	if (!PyArg_ParseTuple(args, "i", &who))
		return NULL;

	if (getrusage(who, &ru) == -1) {
		if (errno == EINVAL) {
			PyErr_SetString(PyExc_ValueError,
					"invalid who parameter");
			return NULL;
		} 
		PyErr_SetFromErrno(ResourceError);
		return NULL;
	}

	/* Yeah, this 16-tuple is way ugly. It's probably a lot less
	   ugly than a dictionary with keys (or object attributes)
	   named things like 'ixrss'. 
	   */
	return Py_BuildValue(
		"ddiiiiiiiiiiiiii",
		doubletime(ru.ru_utime),     /* user time used */
		doubletime(ru.ru_stime),     /* system time used */
		ru.ru_maxrss,		     /* max. resident set size */
		ru.ru_ixrss,		     /* shared memory size */
		ru.ru_idrss,		     /* unshared memory size */
		ru.ru_isrss,		     /* unshared stack size */
		ru.ru_minflt,		     /* page faults not requiring I/O*/
		ru.ru_majflt,		     /* page faults requiring I/O */
		ru.ru_nswap,		     /* number of swap outs */
		ru.ru_inblock,		     /* block input operations */
		ru.ru_oublock,		     /* block output operations */
		ru.ru_msgsnd,		     /* messages sent */
		ru.ru_msgrcv,		     /* messages received */
		ru.ru_nsignals,		     /* signals received */
		ru.ru_nvcsw,		     /* voluntary context switchs */
		ru.ru_nivcsw		     /* involuntary context switchs */
		);
}


static PyObject *
resource_getrlimit(self, args)
	PyObject *self;
	PyObject *args;
{
	struct rlimit rl;
	int resource;

	if (!PyArg_ParseTuple(args, "i", &resource)) 
		return NULL;

	if (resource < 0 || resource >= RLIM_NLIMITS) {
		PyErr_SetString(PyExc_ValueError,
				"invalid resource specified");
		return NULL;
	}

	if (getrlimit(resource, &rl) == -1) {
		PyErr_SetFromErrno(ResourceError);
		return NULL;
	}
	return Py_BuildValue("ii", rl.rlim_cur, rl.rlim_max);
}

static PyObject *
resource_setrlimit(self, args)
	PyObject *self;
	PyObject *args;
{
	struct rlimit rl;
	int resource;

	if (!PyArg_ParseTuple(args, "i(ii)", &resource, &rl.rlim_cur, 
			      &rl.rlim_max)) 
		return NULL;

	if (resource < 0 || resource >= RLIM_NLIMITS) {
		PyErr_SetString(PyExc_ValueError,
				"invalid resource specified");
		return NULL;
	}

	rl.rlim_cur = rl.rlim_cur & RLIM_INFINITY;
	rl.rlim_max = rl.rlim_max & RLIM_INFINITY;
	if (setrlimit(resource, &rl) == -1) {
		if (errno == EINVAL) 
			PyErr_SetString(PyExc_ValueError,
					"current limit exceeds maximum limit");
		else if (errno == EPERM)
			PyErr_SetString(PyExc_ValueError,
					"not allowed to raise maximum limit");
		else
			PyErr_SetFromErrno(ResourceError);
		return NULL;
	}
	Py_INCREF(Py_None);
	return Py_None;
}

static PyObject *
resource_getpagesize(self, args)
	PyObject *self;
	PyObject *args;
{
	if (!PyArg_ParseTuple(args, ""))
		return NULL;
	return Py_BuildValue("i", getpagesize());
}

/* List of functions */

static struct PyMethodDef
resource_methods[] = {
	{"getrusage",    resource_getrusage,   1},
	{"getrlimit",    resource_getrlimit,   1},
	{"setrlimit",    resource_setrlimit,   1},
	{"getpagesize",  resource_getpagesize, 1},
	{NULL, NULL}			     /* sentinel */
};


/* Module initialization */

static void
ins(PyObject *dict, char *name, int value)
{
	PyObject *v = PyInt_FromLong((long) value);
	if (v) {
		PyDict_SetItemString(dict, name, v);
		Py_DECREF(v);
	}
	/* errors will be checked by initresource() */
}

void initresource()
{
	PyObject *m, *d;

	/* Create the module and add the functions */
	m = Py_InitModule("resource", resource_methods);

	/* Add some symbolic constants to the module */
	d = PyModule_GetDict(m);
	ResourceError = PyString_FromString("resource.error");
	PyDict_SetItemString(d, "error", ResourceError);

	/* insert constants */
#ifdef RLIMIT_CPU
	ins(d, "RLIMIT_CPU", RLIMIT_CPU);
#endif

#ifdef RLIMIT_FSIZE
	ins(d, "RLIMIT_FSIZE", RLIMIT_FSIZE);
#endif

#ifdef RLIMIT_DATA
	ins(d, "RLIMIT_DATA", RLIMIT_DATA);
#endif

#ifdef RLIMIT_STACK
	ins(d, "RLIMIT_STACK", RLIMIT_STACK);
#endif

#ifdef RLIMIT_CORE
	ins(d, "RLIMIT_CORE", RLIMIT_CORE);
#endif

#ifdef RLIMIT_NOFILE
	ins(d, "RLIMIT_NOFILE", RLIMIT_NOFILE);
#endif

#ifdef RLIMIT_OFILE
	ins(d, "RLIMIT_OFILE", RLIMIT_OFILE);
#endif

#ifdef RLIMIT_VMEM
	ins(d, "RLIMIT_VMEM", RLIMIT_VMEM);
#endif

#ifdef RLIMIT_AS
	ins(d, "RLIMIT_AS", RLIMIT_AS);
#endif

#ifdef RLIMIT_RSS
	ins(d, "RLIMIT_RSS", RLIMIT_RSS);
#endif

#ifdef RLIMIT_NPROC
	ins(d, "RLIMIT_NPROC", RLIMIT_NPROC);
#endif

#ifdef RLIMIT_MEMLOCK
	ins(d, "RLIMIT_MEMLOCK", RLIMIT_MEMLOCK);
#endif

#ifdef RUSAGE_SELF
	ins(d, "RUSAGE_SELF", RUSAGE_SELF);
#endif

#ifdef RUSAGE_CHILDERN
	ins(d, "RUSAGE_CHILDREN", RUSAGE_CHILDREN);
#endif

#ifdef RUSAGE_BOTH
	ins(d, "RUSAGE_BOTH", RUSAGE_BOTH);
#endif

	/* Check for errors */
	if (PyErr_Occurred())
		Py_FatalError("can't initialize module resource");
}