lib/libc/gen/ftok.c

   1 /*
   2  * Copyright (c) 1994 SigmaSoft, Th. Lockert <tholo@sigmasoft.com>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. The name of the author may not be used to endorse or promote products
  14  *    derived from this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  20  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
  22  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  23  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  24  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  25  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  *
  27  * $FreeBSD: src/lib/libc/gen/ftok.c,v 1.5 1999/08/27 23:58:35 peter Exp $
  28  * $DragonFly: src/lib/libc/gen/ftok.c,v 1.3 2005/11/13 00:07:42 swildner Exp $
  29  */
  30
  31 #include <sys/types.h>
  32 #include <sys/stat.h>
  33 #include <sys/ipc.h>
  34
  35 key_t
  36 ftok(const char *path, int id)
  37 {
  38         struct stat st;
  39
  40         if (stat(path, &st) < 0)
  41                 return (key_t)-1;
  42
  43         return (key_t) (id << 24 | (st.st_dev & 0xff) << 16 | (st.st_ino & 0xffff));
  44 }