1 /* $OpenBSD: lockf.c,v 1.5 2008/06/26 05:42:05 ray 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 * 20 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 23 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 30 * POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 #include <errno.h> 34 #include <fcntl.h> 35 #include <unistd.h> 36 37 int 38 lockf(int filedes, int function, off_t size) 39 { 40 struct flock fl; 41 int cmd; 42 43 fl.l_start = 0; 44 fl.l_len = size; 45 fl.l_whence = SEEK_CUR; 46 47 switch (function) { 48 case F_ULOCK: 49 cmd = F_SETLK; 50 fl.l_type = F_UNLCK; 51 break; 52 case F_LOCK: 53 cmd = F_SETLKW; 54 fl.l_type = F_WRLCK; 55 break; 56 case F_TLOCK: 57 cmd = F_SETLK; 58 fl.l_type = F_WRLCK; 59 break; 60 case F_TEST: 61 fl.l_type = F_WRLCK; 62 if (fcntl(filedes, F_GETLK, &fl) == -1) 63 return (-1); 64 if (fl.l_type == F_UNLCK || fl.l_pid == getpid()) 65 return (0); 66 errno = EAGAIN; 67 return (-1); 68 /* NOTREACHED */ 69 default: 70 errno = EINVAL; 71 return (-1); 72 /* NOTREACHED */ 73 } 74 75 return (fcntl(filedes, cmd, &fl)); 76 } 77