xref: /illumos-gate/usr/src/ucblib/libucb/port/sys/flock.c (revision 7a5aac98)

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 * Copyright 2015 Joyent, Inc.
 */

/*	Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T	*/
/*	  All Rights Reserved  	*/

/*
 * Portions of this source code were derived from Berkeley 4.3 BSD
 * under license from the Regents of the University of California.
 */

/*LINTLIBRARY*/

#include <sys/types.h>
#include <sys/file.h>
#include <sys/fcntl.h>
#include <errno.h>

int
flock(int fd, int operation)
{
	struct flock	fl;
	int	cmd;
	int	ret;

	/* initialize the flock struct to set lock on entire file */
	fl.l_whence = 0;
	fl.l_start = 0;
	fl.l_len = 0;
	fl.l_type = 0;

	if (operation & LOCK_NB) {
		cmd = F_FLOCK;
		operation &= ~LOCK_NB;	/* turn off this bit */
	} else
		cmd = F_FLOCKW;

	switch (operation) {
	case LOCK_UN:
		fl.l_type |= F_UNLCK;
		break;
	case LOCK_SH:
		fl.l_type |= F_RDLCK;
		break;
	case LOCK_EX:
		fl.l_type |= F_WRLCK;
		break;
	default:
		errno = EINVAL;
		return (-1);
	}

	ret = fcntl(fd, cmd, &fl);

	if (ret == -1 && errno == EACCES)
		errno = EWOULDBLOCK;

	return (ret);
}