text: /*	$NetBSD: lockf.c,v 1.1 1997/12/20 20:23:18 kleink Exp $	*/
  
  /*-
   * Copyright (c) 1997 The NetBSD Foundation, Inc.
   * All rights reserved.
   *
   * This code is derived from software contributed to The NetBSD Foundation
   * by Klaus Klein.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. All advertising materials mentioning features or use of this software
   *    must display the following acknowledgement:
   *        This product includes software developed by the NetBSD
   *        Foundation, Inc. and its contributors.
   * 4. Neither the name of The NetBSD Foundation nor the names of its
   *    contributors may be used to endorse or promote products derived
   *    from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
   * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
   * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   *
   * $FreeBSD: src/lib/libc/gen/lockf.c,v 1.5 2000/01/27 23:06:17 jasone Exp $
   * $DragonFly: src/lib/libc/gen/lockf.c,v 1.4 2005/11/13 00:07:42 swildner Exp $
   */
  
  #include "namespace.h"
  #include <errno.h>
  #include <fcntl.h>
  #include <unistd.h>
  #include "un-namespace.h"
  
  int
  lockf(int filedes, int function, off_t size)
  {
  	struct flock fl;
  	int cmd;
  
  	fl.l_start = 0;
  	fl.l_len = size;
  	fl.l_whence = SEEK_CUR;
  
  	switch (function) {
  	case F_ULOCK:
  		cmd = F_SETLK;
  		fl.l_type = F_UNLCK;
  		break;
  	case F_LOCK:
  		cmd = F_SETLKW;
  		fl.l_type = F_WRLCK;
  		break;
  	case F_TLOCK:
  		cmd = F_SETLK;
  		fl.l_type = F_WRLCK;
  		break;
  	case F_TEST:
  		fl.l_type = F_WRLCK;
  		if (_fcntl(filedes, F_GETLK, &fl) == -1)
  			return (-1);
  		if (fl.l_type == F_UNLCK || fl.l_pid == getpid())
  			return (0);
  		errno = EAGAIN;
  		return (-1);
  		/* NOTREACHED */
  	default:
  		errno = EINVAL;
  		return (-1);
  		/* NOTREACHED */
  	}
  
  	return (_fcntl(filedes, cmd, &fl));
  }
  