usr/src/ucblib/libucb/port/sys/flock.c

   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 (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
  23  * Use is subject to license terms.
  24  * Copyright 2015 Joyent, Inc.
  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 /*LINTLIBRARY*/
  36
  37 #include <sys/types.h>
  38 #include <sys/file.h>
  39 #include <sys/fcntl.h>
  40 #include <errno.h>
  41
  42 int
  43 flock(int fd, int operation)
  44 {
  45         struct flock    fl;
  46         int     cmd;
  47         int     ret;
  48
  49         /* initialize the flock struct to set lock on entire file */
  50         fl.l_whence = 0;
  51         fl.l_start = 0;
  52         fl.l_len = 0;
  53         fl.l_type = 0;
  54
  55         if (operation & LOCK_NB) {
  56                 cmd = F_FLOCK;
  57                 operation &= ~LOCK_NB;  /* turn off this bit */
  58         } else
  59                 cmd = F_FLOCKW;
  60
  61         switch (operation) {
  62         case LOCK_UN:
  63                 fl.l_type |= F_UNLCK;
  64                 break;
  65         case LOCK_SH:
  66                 fl.l_type |= F_RDLCK;
  67                 break;
  68         case LOCK_EX:
  69                 fl.l_type |= F_WRLCK;
  70                 break;
  71         default:
  72                 errno = EINVAL;
  73                 return (-1);
  74         }
  75
  76         ret = fcntl(fd, cmd, &fl);
  77
  78         if (ret == -1 && errno == EACCES)
  79                 errno = EWOULDBLOCK;
  80
  81         return (ret);
  82 }