1 /* $NetBSD: lockf.c,v 1.3 2008/04/28 20:22:59 martin 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 * 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 #include <sys/cdefs.h> 33 #if defined(LIBC_SCCS) && !defined(lint) 34 __RCSID("$NetBSD: lockf.c,v 1.3 2008/04/28 20:22:59 martin Exp $"); 35 #endif 36 37 #include "namespace.h" 38 #include <errno.h> 39 #include <fcntl.h> 40 #include <unistd.h> 41 42 #ifdef __weak_alias 43 __weak_alias(lockf,_lockf) 44 #endif 45 46 47 int 48 lockf(filedes, function, size) 49 int filedes; 50 int function; 51 off_t size; 52 { 53 struct flock fl; 54 int cmd; 55 56 fl.l_start = 0; 57 fl.l_len = size; 58 fl.l_whence = SEEK_CUR; 59 60 switch (function) { 61 case F_ULOCK: 62 cmd = F_SETLK; 63 fl.l_type = F_UNLCK; 64 break; 65 case F_LOCK: 66 cmd = F_SETLKW; 67 fl.l_type = F_WRLCK; 68 break; 69 case F_TLOCK: 70 cmd = F_SETLK; 71 fl.l_type = F_WRLCK; 72 break; 73 case F_TEST: 74 fl.l_type = F_WRLCK; 75 if (fcntl(filedes, F_GETLK, &fl) == -1) 76 return (-1); 77 if (fl.l_type == F_UNLCK || fl.l_pid == getpid()) 78 return (0); 79 errno = EAGAIN; 80 return (-1); 81 /* NOTREACHED */ 82 default: 83 errno = EINVAL; 84 return (-1); 85 /* NOTREACHED */ 86 } 87 88 return (fcntl(filedes, cmd, &fl)); 89 } 90