77 lines
2.2 KiB
C
77 lines
2.2 KiB
C
/* $NetBSD: flock.c,v 1.6 2008/04/28 20:24:12 martin Exp $ */
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/*-
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* Copyright (c) 2001 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 Todd Vierling.
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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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/*
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* Emulate flock() with fcntl(), where available.
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* Otherwise, don't do locking; just pretend success.
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*/
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#include "nbtool_config.h"
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#if !HAVE_FLOCK
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#include <errno.h>
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#include <fcntl.h>
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int flock(int fd, int op) {
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int rc = 0;
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#if defined(F_SETLK) && defined(F_SETLKW)
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struct flock fl = {0};
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switch (op & (LOCK_EX|LOCK_SH|LOCK_UN)) {
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case LOCK_EX:
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fl.l_type = F_WRLCK;
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break;
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case LOCK_SH:
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fl.l_type = F_RDLCK;
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break;
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case LOCK_UN:
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fl.l_type = F_UNLCK;
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break;
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default:
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errno = EINVAL;
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return -1;
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}
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fl.l_whence = SEEK_SET;
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rc = fcntl(fd, op & LOCK_NB ? F_SETLK : F_SETLKW, &fl);
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if (rc && (errno == EAGAIN))
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errno = EWOULDBLOCK;
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#endif
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return rc;
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}
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#endif
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