sysvipc/ftok.c

   1 /* Copyright (C) 1995-2022 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <sys/ipc.h>
  19 #include <sys/stat.h>
  20
  21 key_t
  22 ftok (const char *pathname, int proj_id)
  23 {
  24   struct __stat64_t64 st;
  25   key_t key;
  26
  27   if (__stat64_time64 (pathname, &st) < 0)
  28     return (key_t) -1;
  29
  30   key = ((st.st_ino & 0xffff) | ((st.st_dev & 0xff) << 16)
  31          | ((proj_id & 0xff) << 24));
  32
  33   return key;
  34 }