/*

 *  Advanced Linux Sound Architecture Control Program

 *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>

 *

 *

 *   This program is free software; you can redistribute it and/or modify

 *   it under the terms of the GNU General Public License as published by

 *   the Free Software Foundation; either version 2 of the License, or

 *   (at your option) any later version.

 *

 *   This program is distributed in the hope that it will be useful,

 *   but WITHOUT ANY WARRANTY; without even the implied warranty of

 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 *   GNU General Public License for more details.

 *

 *   You should have received a copy of the GNU General Public License

 *   along with this program; if not, write to the Free Software

 *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

 *

 */

#include "aconfig.h"

#include "version.h"

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <fcntl.h>

#include <errno.h>

#include <string.h>

#include <sys/stat.h>

#include "alsactl.h"

static int state_lock_(const char *file, int lock, int timeout, int _fd)

{

	int fd = -1, err = 0;

	struct flock lck;

	struct stat st;

	char lcktxt[14];

	char *nfile = lockfile;

	if (do_lock <= 0)

		return 0;

	lck.l_type = lock ? F_WRLCK : F_UNLCK;

	lck.l_whence = SEEK_SET;

	lck.l_start = 0;

	lck.l_len = 11;

	lck.l_pid = 0;

	if (lock) {

		snprintf(lcktxt, sizeof(lcktxt), "%10li\n", (long)getpid());

	} else {

		snprintf(lcktxt, sizeof(lcktxt), "%10s\n", "");

		fd = _fd;

	}

	while (fd < 0 && timeout-- > 0) {

		fd = open(nfile, O_RDWR);

		if (!lock && fd < 0) {

			err = -EIO;

			goto out;

		}

		if (fd < 0) {

			fd = open(nfile, O_RDWR|O_CREAT|O_EXCL, 0644);

			if (fd < 0) {

				if (errno == EBUSY || errno == EAGAIN) {

					sleep(1);

					timeout--;

				} else {

					err = -errno;

					goto out;

				}

			}

		}

	}

	if (fd < 0 && timeout <= 0) {

		err = -EBUSY;

		goto out;

	}

	if (fstat(fd, &st) < 0) {

		err = -errno;

		goto out;

	}

	if (st.st_size != 11 || !lock) {

		if (write(fd, lcktxt, 11) != 11) {

			err = -EIO;

			goto out;

		}

		if (lock && lseek(fd, 0, SEEK_SET)) {

			err = -errno;

			goto out;

		}

	}

	while (timeout > 0) {

		if (fcntl(fd, F_SETLK, &lck) < 0) {

			sleep(1);

			timeout--;

		} else {

			break;

		}

	}

	if (timeout <= 0) {

		err = -EBUSY;

		goto out;

	}

	if (lock) {

		if (write(fd, lcktxt, 11) != 11) {

			err = -EIO;

			goto out;

		}

		return fd;

	}

	err = 0;

out:

	if (fd >= 0)

		close(fd);

	return err;

}

int state_lock(const char *file, int timeout)

{

	int err;

	err = state_lock_(file, 1, timeout, -1);

	if (err < 0)

		error("file %s lock error: %s", file, strerror(-err));

	return err;

}

int state_unlock(int _fd, const char *file)

{

	int err;

	err = state_lock_(file, 0, 10, _fd);

	if (err < 0)

		error("file %s unlock error: %s", file, strerror(-err));

	return err;

}