/* $NetBSD: flock.c,v 1.6 2008/04/28 20:24:12 martin Exp $ */ /*- * Copyright (c) 2001 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Todd Vierling. * * 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. */ /* * Emulate flock() with fcntl(), where available. * Otherwise, don't do locking; just pretend success. */ #include "includes.h" #ifndef HAVE_FLOCK #include <errno.h> #include <fcntl.h> int flock(int fd, int op) { int rc = 0; #if defined(F_SETLK) && defined(F_SETLKW) struct flock fl = {0}; switch (op & (LOCK_EX|LOCK_SH|LOCK_UN)) { case LOCK_EX: fl.l_type = F_WRLCK; break; case LOCK_SH: fl.l_type = F_RDLCK; break; case LOCK_UN: fl.l_type = F_UNLCK; break; default: errno = EINVAL; return -1; } fl.l_whence = SEEK_SET; rc = fcntl(fd, op & LOCK_NB ? F_SETLK : F_SETLKW, &fl); if (rc && (errno == EAGAIN)) errno = EWOULDBLOCK; #else rc = -1; errno = ENOSYS; #endif return rc; } #endif