sysvipc/ftok.c

   1 /* Copyright (C) 1995, 1996 Free Software Foundation, Inc.
   2 This file is part of the GNU C Library.
   3 Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, August 1995.
   4
   5 The GNU C Library is free software; you can redistribute it and/or
   6 modify it under the terms of the GNU Library General Public License as
   7 published by the Free Software Foundation; either version 2 of the
   8 License, or (at your option) any later version.
   9
  10 The GNU C Library is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13 Library General Public License for more details.
  14
  15 You should have received a copy of the GNU Library General Public
  16 License along with the GNU C Library; see the file COPYING.LIB.  If
  17 not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18 Boston, MA 02111-1307, USA.  */
  19
  20 #include <sys/ipc.h>
  21 #include <sys/stat.h>
  22
  23 key_t
  24 ftok (pathname, proj_id)
  25      char *pathname;
  26      char proj_id;
  27 {
  28   struct stat st;
  29   key_t key;
  30
  31   if (__stat (pathname, &st) < 0)
  32     return (key_t) -1;
  33
  34   key = (st.st_ino & 0xffff) | ((st.st_dev & 0xff) << 16) | (proj_id << 24);
  35
  36   return key;
  37 }