1 /* $OpenBSD: lockf.c,v 1.3 2003/06/11 21:03:10 deraadt Exp $ */ 2 /* $NetBSD: lockf.c,v 1.1 1997/12/20 20:23:18 kleink Exp $ */ 3 4 /*- 5 * Copyright (c) 1997 The NetBSD Foundation, Inc. 6 * All rights reserved. 7 * 8 * This code is derived from software contributed to The NetBSD Foundation 9 * by Klaus Klein. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the NetBSD 22 * Foundation, Inc. and its contributors. 23 * 4. Neither the name of The NetBSD Foundation nor the names of its 24 * contributors may be used to endorse or promote products derived 25 * from this software without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 28 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 29 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 30 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 31 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 32 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 33 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 34 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 35 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 36 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 37 * POSSIBILITY OF SUCH DAMAGE. 38 */ 39 40 #if defined(LIBC_SCCS) && !defined(lint) 41 static char rcsid[] = "$OpenBSD: lockf.c,v 1.3 2003/06/11 21:03:10 deraadt Exp $"; 42 #endif /* LIBC_SCCS and not lint */ 43 44 #include <errno.h> 45 #include <fcntl.h> 46 #include <unistd.h> 47 48 int 49 lockf(int filedes, int function, off_t size) 50 { 51 struct flock fl; 52 int cmd; 53 54 fl.l_start = 0; 55 fl.l_len = size; 56 fl.l_whence = SEEK_CUR; 57 58 switch (function) { 59 case F_ULOCK: 60 cmd = F_SETLK; 61 fl.l_type = F_UNLCK; 62 break; 63 case F_LOCK: 64 cmd = F_SETLKW; 65 fl.l_type = F_WRLCK; 66 break; 67 case F_TLOCK: 68 cmd = F_SETLK; 69 fl.l_type = F_WRLCK; 70 break; 71 case F_TEST: 72 fl.l_type = F_WRLCK; 73 if (fcntl(filedes, F_GETLK, &fl) == -1) 74 return (-1); 75 if (fl.l_type == F_UNLCK || fl.l_pid == getpid()) 76 return (0); 77 errno = EAGAIN; 78 return (-1); 79 /* NOTREACHED */ 80 default: 81 errno = EINVAL; 82 return (-1); 83 /* NOTREACHED */ 84 } 85 86 return (fcntl(filedes, cmd, &fl)); 87 } 88