1 /* $NetBSD: lockf.c,v 1.2 2000/01/22 22:19:11 mycroft Exp $ */ 2 3 /*- 4 * Copyright (c) 1997 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Klaus Klein. 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 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 #include <sys/cdefs.h> 40 #if defined(LIBC_SCCS) && !defined(lint) 41 __RCSID("$NetBSD: lockf.c,v 1.2 2000/01/22 22:19:11 mycroft Exp $"); 42 #endif 43 44 #include "namespace.h" 45 #include <errno.h> 46 #include <fcntl.h> 47 #include <unistd.h> 48 49 #ifdef __weak_alias 50 __weak_alias(lockf,_lockf) 51 #endif 52 53 54 int 55 lockf(filedes, function, size) 56 int filedes; 57 int function; 58 off_t size; 59 { 60 struct flock fl; 61 int cmd; 62 63 fl.l_start = 0; 64 fl.l_len = size; 65 fl.l_whence = SEEK_CUR; 66 67 switch (function) { 68 case F_ULOCK: 69 cmd = F_SETLK; 70 fl.l_type = F_UNLCK; 71 break; 72 case F_LOCK: 73 cmd = F_SETLKW; 74 fl.l_type = F_WRLCK; 75 break; 76 case F_TLOCK: 77 cmd = F_SETLK; 78 fl.l_type = F_WRLCK; 79 break; 80 case F_TEST: 81 fl.l_type = F_WRLCK; 82 if (fcntl(filedes, F_GETLK, &fl) == -1) 83 return (-1); 84 if (fl.l_type == F_UNLCK || fl.l_pid == getpid()) 85 return (0); 86 errno = EAGAIN; 87 return (-1); 88 /* NOTREACHED */ 89 default: 90 errno = EINVAL; 91 return (-1); 92 /* NOTREACHED */ 93 } 94 95 return (fcntl(filedes, cmd, &fl)); 96 } 97