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 not,
  17    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      const char *pathname;
  26      int 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)
  35          | ((proj_id & 0xff) << 24));
  36
  37   return key;
  38 }