1 /* $NetBSD: lockf.c,v 1.1 1997/12/20 20:23:18 kleink 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 #if defined(LIBC_SCCS) && !defined(lint) 40 static char rcsid[] = "$NetBSD: lockf.c,v 1.1 1997/12/20 20:23:18 kleink Exp $"; 41 #endif /* LIBC_SCCS and not lint */ 42 43 #include <errno.h> 44 #include <fcntl.h> 45 #include <unistd.h> 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