flock.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
* 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 1997 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/* 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.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
/*LINTLIBRARY*/
#include <sys/types.h>
#include <sys/file.h>
#include <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;
/* In non-blocking lock, use F_SETLK for cmd, F_SETLKW otherwise */
if (operation & LOCK_NB) {
cmd = F_SETLK;
operation &= ~LOCK_NB; /* turn off this bit */
} else
cmd = F_SETLKW;
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);
}