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 "includes.h" 38 39 #ifndef HAVE_FLOCK 40 #include <errno.h> 41 #include <fcntl.h> 42 43 int 44 flock(int fd, int op) 45 { 46 int rc = 0; 47 48 #if defined(F_SETLK) && defined(F_SETLKW) 49 struct flock fl = {0}; 50 51 switch (op & (LOCK_EX|LOCK_SH|LOCK_UN)) { 52 case LOCK_EX: 53 fl.l_type = F_WRLCK; 54 break; 55 56 case LOCK_SH: 57 fl.l_type = F_RDLCK; 58 break; 59 60 case LOCK_UN: 61 fl.l_type = F_UNLCK; 62 break; 63 64 default: 65 errno = EINVAL; 66 return -1; 67 } 68 69 fl.l_whence = SEEK_SET; 70 rc = fcntl(fd, op & LOCK_NB ? F_SETLK : F_SETLKW, &fl); 71 72 if (rc && (errno == EAGAIN)) 73 errno = EWOULDBLOCK; 74 #else 75 rc = -1; 76 errno = ENOSYS; 77 #endif 78 79 return rc; 80 } 81 #endif 82