usr/src/cmd/mailx/lock.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, 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 /*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
  23 /*        All Rights Reserved   */
  24
  25
  26 /*
  27  * University Copyright- Copyright (c) 1982, 1986, 1988
  28  * The Regents of the University of California
  29  * All Rights Reserved
  30  *
  31  * University Acknowledgment- Portions of this document are derived from
  32  * software developed by the University of California, Berkeley, and its
  33  * contributors.
  34  */
  35
  36 #pragma ident   "%Z%%M% %I%     %E% SMI"
  37
  38 /*
  39  * lock a file pointer
  40  */
  41
  42 #include <stdio.h>
  43 #include <string.h>
  44 #include <fcntl.h>
  45
  46 int
  47 lock(FILE *fp, char *mode, int blk)
  48 {
  49         struct flock    l;
  50
  51         l.l_type = !strcmp(mode, "r") ? F_RDLCK : F_WRLCK;
  52         l.l_whence = 0;
  53         l.l_start = l.l_len = 0L;
  54         return fcntl(fileno(fp), blk ? F_SETLKW : F_SETLK, &l);
  55 }