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/* $OpenBSD: lockf.c,v 1.5 2008/06/26 05:42:05 ray Exp $ */
/* $NetBSD: lockf.c,v 1.1 1997/12/20 20:23:18 kleink Exp $ */
/*-
* Copyright (c) 1997 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Klaus Klein.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
int
lockf(int filedes, int function, off_t size)
{
struct flock fl;
int cmd;
fl.l_start = 0;
fl.l_len = size;
fl.l_whence = SEEK_CUR;
switch (function) {
case F_ULOCK:
cmd = F_SETLK;
fl.l_type = F_UNLCK;
break;
case F_LOCK:
cmd = F_SETLKW;
fl.l_type = F_WRLCK;
break;
case F_TLOCK:
cmd = F_SETLK;
fl.l_type = F_WRLCK;
break;
case F_TEST:
fl.l_type = F_WRLCK;
if (fcntl(filedes, F_GETLK, &fl) == -1)
return (-1);
if (fl.l_type == F_UNLCK || fl.l_pid == getpid())
return (0);
errno = EAGAIN;
return (-1);
/* NOTREACHED */
default:
errno = EINVAL;
return (-1);
/* NOTREACHED */
}
return (fcntl(filedes, cmd, &fl));
}
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