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