Modules/fcntlmodule.c

/***********************************************************
Copyright 1991-1995 by Stichting Mathematisch Centrum, Amsterdam,
The Netherlands.

                        All Rights Reserved

Permission to use, copy, modify, and distribute this software and its
documentation for any purpose and without fee is hereby granted,
provided that the above copyright notice appear in all copies and that
both that copyright notice and this permission notice appear in
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While CWI is the initial source for this software, a modified version
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REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF
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******************************************************************/

/* fcntl module */

#include "Python.h"

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#ifdef HAVE_SYS_FILE_H
#include <sys/file.h>
#endif

#include <sys/ioctl.h>
#include <fcntl.h>


/* fcntl(fd, opt, [arg]) */

static PyObject *
fcntl_fcntl(self, args)
	PyObject *self; /* Not used */
	PyObject *args;
{
	int fd;
	int code;
	int arg;
	int ret;
	char *str;
	int len;
	char buf[1024];

	if (PyArg_Parse(args, "(iis#)", &fd, &code, &str, &len)) {
		if (len > sizeof buf) {
			PyErr_SetString(PyExc_ValueError,
					"fcntl string arg too long");
			return NULL;
		}
		memcpy(buf, str, len);
		Py_BEGIN_ALLOW_THREADS
		ret = fcntl(fd, code, buf);
		Py_END_ALLOW_THREADS
		if (ret < 0) {
			PyErr_SetFromErrno(PyExc_IOError);
			return NULL;
		}
		return PyString_FromStringAndSize(buf, len);
	}

	PyErr_Clear();
	if (PyArg_Parse(args, "(ii)", &fd, &code))
		arg = 0;
	else {
		PyErr_Clear();
		if (!PyArg_Parse(args, "(iii)", &fd, &code, &arg))
			return NULL;
	}
	Py_BEGIN_ALLOW_THREADS
	ret = fcntl(fd, code, arg);
	Py_END_ALLOW_THREADS
	if (ret < 0) {
		PyErr_SetFromErrno(PyExc_IOError);
		return NULL;
	}
	return PyInt_FromLong((long)ret);
}


/* ioctl(fd, opt, [arg]) */

static PyObject *
fcntl_ioctl(self, args)
	PyObject *self; /* Not used */
	PyObject *args;
{
	int fd;
	int code;
	int arg;
	int ret;
	char *str;
	int len;
	char buf[1024];

	if (PyArg_Parse(args, "(iis#)", &fd, &code, &str, &len)) {
		if (len > sizeof buf) {
			PyErr_SetString(PyExc_ValueError,
					"ioctl string arg too long");
			return NULL;
		}
		memcpy(buf, str, len);
		Py_BEGIN_ALLOW_THREADS
		ret = ioctl(fd, code, buf);
		Py_END_ALLOW_THREADS
		if (ret < 0) {
			PyErr_SetFromErrno(PyExc_IOError);
			return NULL;
		}
		return PyString_FromStringAndSize(buf, len);
	}

	PyErr_Clear();
	if (PyArg_Parse(args, "(ii)", &fd, &code))
		arg = 0;
	else {
		PyErr_Clear();
		if (!PyArg_Parse(args, "(iii)", &fd, &code, &arg))
			return NULL;
	}
	Py_BEGIN_ALLOW_THREADS
	ret = ioctl(fd, code, arg);
	Py_END_ALLOW_THREADS
	if (ret < 0) {
		PyErr_SetFromErrno(PyExc_IOError);
		return NULL;
	}
	return PyInt_FromLong((long)ret);
}


/* flock(fd, operation) */

static PyObject *
fcntl_flock(self, args)
	PyObject *self; /* Not used */
	PyObject *args;
{
	int fd;
	int code;
	int ret;

	if (!PyArg_Parse(args, "(ii)", &fd, &code))
		return NULL;

	Py_BEGIN_ALLOW_THREADS
#ifdef HAVE_FLOCK
	ret = flock(fd, code);
#else

#ifndef LOCK_SH
#define LOCK_SH		1	/* shared lock */
#define LOCK_EX		2	/* exclusive lock */
#define LOCK_NB		4	/* don't block when locking */
#define LOCK_UN		8	/* unlock */
#endif
	{
		struct flock l;
		if (code == LOCK_UN)
			l.l_type = F_UNLCK;
		else if (code & LOCK_SH)
			l.l_type = F_RDLCK;
		else if (code & LOCK_EX)
			l.l_type = F_WRLCK;
		else {
			PyErr_SetString(PyExc_ValueError,
					"unrecognized flock argument");
			return NULL;
		}
		l.l_whence = l.l_start = l.l_len = 0;
		ret = fcntl(fd, (code & LOCK_NB) ? F_SETLK : F_SETLKW, &l);
	}
#endif /* HAVE_FLOCK */
	Py_END_ALLOW_THREADS
	if (ret < 0) {
		PyErr_SetFromErrno(PyExc_IOError);
		return NULL;
	}
	Py_INCREF(Py_None);
	return Py_None;
}

/* lockf(fd, operation) */
static PyObject *
fcntl_lockf(self, args)
	PyObject *self; /* Not used */
	PyObject *args;
{
	int fd, code, len = 0, start = 0, whence = 0, ret;

	if (!PyArg_ParseTuple(args, "ii|iii", &fd, &code, &len, 
			       &start, &whence))
	    return NULL;

	Py_BEGIN_ALLOW_THREADS
#ifndef LOCK_SH
#define LOCK_SH		1	/* shared lock */
#define LOCK_EX		2	/* exclusive lock */
#define LOCK_NB		4	/* don't block when locking */
#define LOCK_UN		8	/* unlock */
#endif
	{
		struct flock l;
		if (code == LOCK_UN)
			l.l_type = F_UNLCK;
		else if (code & LOCK_SH)
			l.l_type = F_RDLCK;
		else if (code & LOCK_EX)
			l.l_type = F_WRLCK;
		else {
			PyErr_SetString(PyExc_ValueError,
					"unrecognized flock argument");
			return NULL;
		}
		l.l_len = len;
		l.l_start = start;
		l.l_whence = whence;
		ret = fcntl(fd, (code & LOCK_NB) ? F_SETLK : F_SETLKW, &l);
	}
	Py_END_ALLOW_THREADS
	if (ret < 0) {
		PyErr_SetFromErrno(PyExc_IOError);
		return NULL;
	}
	Py_INCREF(Py_None);
	return Py_None;
}

/* List of functions */

static PyMethodDef fcntl_methods[] = {
	{"fcntl",	fcntl_fcntl},
	{"ioctl",	fcntl_ioctl},
	{"flock",	fcntl_flock},
	{"lockf",       fcntl_lockf, 1},
	{NULL,		NULL}		/* sentinel */
};


/* Module initialisation */

static int
ins(d, symbol, value)
        PyObject* d;
        char* symbol;
        long value;
{
        PyObject* v = PyInt_FromLong(value);
        if (!v || PyDict_SetItemString(d, symbol, v) < 0)
                return -1;

        Py_DECREF(v);
        return 0;
}

static int
all_ins(d)
        PyObject* d;
{
        if (ins(d, "LOCK_SH", (long)LOCK_SH)) return -1;
        if (ins(d, "LOCK_EX", (long)LOCK_EX)) return -1;
        if (ins(d, "LOCK_NB", (long)LOCK_NB)) return -1;
        if (ins(d, "LOCK_UN", (long)LOCK_UN)) return -1;
}

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

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

	/* Add some symbolic constants to the module */
	d = PyModule_GetDict(m);
	all_ins(d);

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