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glibc  2.9
ftok.c
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00001 /* Copyright (C) 1995, 1996, 2000 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003    Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, August 1995.
00004 
00005    The GNU C Library is free software; you can redistribute it and/or
00006    modify it under the terms of the GNU Lesser General Public
00007    License as published by the Free Software Foundation; either
00008    version 2.1 of the License, or (at your option) any later version.
00009 
00010    The GNU C Library is distributed in the hope that it will be useful,
00011    but WITHOUT ANY WARRANTY; without even the implied warranty of
00012    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013    Lesser General Public License for more details.
00014 
00015    You should have received a copy of the GNU Lesser General Public
00016    License along with the GNU C Library; if not, write to the Free
00017    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00018    02111-1307 USA.  */
00019 
00020 #include <sys/ipc.h>
00021 #include <sys/stat.h>
00022 
00023 key_t
00024 ftok (pathname, proj_id)
00025      const char *pathname;
00026      int proj_id;
00027 {
00028   struct stat64 st;
00029   key_t key;
00030 
00031   if (__xstat64 (_STAT_VER, pathname, &st) < 0)
00032     return (key_t) -1;
00033 
00034   key = ((st.st_ino & 0xffff) | ((st.st_dev & 0xff) << 16)
00035         | ((proj_id & 0xff) << 24));
00036 
00037   return key;
00038 }