1 /* $NetBSD: lockf.c,v 1.4 2012/06/25 22:32:43 abs 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 1.4 2012/06/25 22:32:43 abs 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(int filedes, int function, off_t size) 49 { 50 struct flock fl; 51 int cmd; 52 53 fl.l_start = 0; 54 fl.l_len = size; 55 fl.l_whence = SEEK_CUR; 56 57 switch (function) { 58 case F_ULOCK: 59 cmd = F_SETLK; 60 fl.l_type = F_UNLCK; 61 break; 62 case F_LOCK: 63 cmd = F_SETLKW; 64 fl.l_type = F_WRLCK; 65 break; 66 case F_TLOCK: 67 cmd = F_SETLK; 68 fl.l_type = F_WRLCK; 69 break; 70 case F_TEST: 71 fl.l_type = F_WRLCK; 72 if (fcntl(filedes, F_GETLK, &fl) == -1) 73 return (-1); 74 if (fl.l_type == F_UNLCK || fl.l_pid == getpid()) 75 return (0); 76 errno = EAGAIN; 77 return (-1); 78 /* NOTREACHED */ 79 default: 80 errno = EINVAL; 81 return (-1); 82 /* NOTREACHED */ 83 } 84 85 return (fcntl(filedes, cmd, &fl)); 86 } 87