1 /* $NetBSD: flock.c,v 1.6 2008/04/28 20:24:12 martin Exp $ */ 2 3 /*- 4 * Copyright (c) 2001 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Todd Vierling. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 /* 33 * Emulate flock() with fcntl(), where available. 34 * Otherwise, don't do locking; just pretend success. 35 */ 36 37 #include "nbtool_config.h" 38 39 #if !HAVE_FLOCK 40 #include <errno.h> 41 #include <fcntl.h> 42 43 int flock(int fd, int op) { 44 int rc = 0; 45 46 #if defined(F_SETLK) && defined(F_SETLKW) 47 struct flock fl = {0}; 48 49 switch (op & (LOCK_EX|LOCK_SH|LOCK_UN)) { 50 case LOCK_EX: 51 fl.l_type = F_WRLCK; 52 break; 53 54 case LOCK_SH: 55 fl.l_type = F_RDLCK; 56 break; 57 58 case LOCK_UN: 59 fl.l_type = F_UNLCK; 60 break; 61 62 default: 63 errno = EINVAL; 64 return -1; 65 } 66 67 fl.l_whence = SEEK_SET; 68 rc = fcntl(fd, op & LOCK_NB ? F_SETLK : F_SETLKW, &fl); 69 70 if (rc && (errno == EAGAIN)) 71 errno = EWOULDBLOCK; 72 #endif 73 74 return rc; 75 } 76 #endif 77