1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License, Version 1.0 only 6 * (the "License"). You may not use this file except in compliance 7 * with the License. 8 * 9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 * or http://www.opensolaris.org/os/licensing. 11 * See the License for the specific language governing permissions 12 * and limitations under the License. 13 * 14 * When distributing Covered Code, include this CDDL HEADER in each 15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 * If applicable, add the following below this CDDL HEADER, with the 17 * fields enclosed by brackets "[]" replaced with your own identifying 18 * information: Portions Copyright [yyyy] [name of copyright owner] 19 * 20 * CDDL HEADER END 21 */ 22 /* 23 * Copyright 1997 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 /* Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T */ 28 /* All Rights Reserved */ 29 30 /* 31 * Portions of this source code were derived from Berkeley 4.3 BSD 32 * under license from the Regents of the University of California. 33 */ 34 35 #pragma ident "%Z%%M% %I% %E% SMI" 36 37 /*LINTLIBRARY*/ 38 39 #include <sys/types.h> 40 #include <sys/file.h> 41 #include <fcntl.h> 42 #include <errno.h> 43 44 int 45 flock(int fd, int operation) 46 { 47 struct flock fl; 48 int cmd; 49 int ret; 50 51 /* initialize the flock struct to set lock on entire file */ 52 fl.l_whence = 0; 53 fl.l_start = 0; 54 fl.l_len = 0; 55 fl.l_type = 0; 56 57 /* In non-blocking lock, use F_SETLK for cmd, F_SETLKW otherwise */ 58 if (operation & LOCK_NB) { 59 cmd = F_SETLK; 60 operation &= ~LOCK_NB; /* turn off this bit */ 61 } else 62 cmd = F_SETLKW; 63 64 switch (operation) { 65 case LOCK_UN: 66 fl.l_type |= F_UNLCK; 67 break; 68 case LOCK_SH: 69 fl.l_type |= F_RDLCK; 70 break; 71 case LOCK_EX: 72 fl.l_type |= F_WRLCK; 73 break; 74 default: 75 errno = EINVAL; 76 return (-1); 77 } 78 79 ret = fcntl(fd, cmd, &fl); 80 81 if (ret == -1 && errno == EACCES) 82 errno = EWOULDBLOCK; 83 84 return (ret); 85 } 86