lib/libc/gen/ftok.c

   1 /*      $NetBSD: ftok.c,v 1.11 2012/03/20 16:36:05 matt Exp $   */
   2
   3 /*
   4  * Copyright (c) 1994 SigmaSoft, Th. Lockert <tholo@sigmasoft.com>
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  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
  28 #include <sys/cdefs.h>
  29 #if defined(LIBC_SCCS) && !defined(lint)
  30 __RCSID("$NetBSD: ftok.c,v 1.11 2012/03/20 16:36:05 matt Exp $");
  31 #endif /* LIBC_SCCS and not lint */
  32
  33 #include "namespace.h"
  34 #include <sys/types.h>
  35 #include <sys/stat.h>
  36 #include <sys/ipc.h>
  37
  38 #include <assert.h>
  39 #include <errno.h>
  40
  41 #ifdef __weak_alias
  42 __weak_alias(ftok,_ftok)
  43 #endif
  44
  45 key_t
  46 ftok(const char *path, int id)
  47 {
  48         struct stat st;
  49
  50         _DIAGASSERT(path != NULL);
  51
  52         if (stat(path, &st) < 0)
  53                 return (key_t)-1;
  54
  55         return (key_t)
  56             (id << 24 | (st.st_dev & 0xff) << 16 | (st.st_ino & 0xffff));
  57 }