OpenSolaris_b135/cmd/mailx/lock.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (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 (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
/*	  All Rights Reserved  	*/


/*
 * University Copyright- Copyright (c) 1982, 1986, 1988
 * The Regents of the University of California   
 * All Rights Reserved
 *
 * University Acknowledgment- Portions of this document are derived from
 * software developed by the University of California, Berkeley, and its
 * contributors.
 */

#pragma ident	"%Z%%M%	%I%	%E% SMI"

/*
 * lock a file pointer
 */

#include <stdio.h>
#include <string.h>
#include <fcntl.h>

int
lock(FILE *fp, char *mode, int blk)
{
	struct flock	l;

	l.l_type = !strcmp(mode, "r") ? F_RDLCK : F_WRLCK;
	l.l_whence = 0;
	l.l_start = l.l_len = 0L;
	return fcntl(fileno(fp), blk ? F_SETLKW : F_SETLK, &l);
}