usr/src/lib/libc/port/gen/ftok.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 /*      Copyright (c) 1988 AT&T */
  28 /*        All Rights Reserved   */
  29
  30 #pragma ident   "%Z%%M% %I%     %E% SMI"
  31
  32 #pragma weak _ftok = ftok
  33
  34 #include "lint.h"
  35 #include "libc.h"
  36 #include <sys/types.h>
  37 #include <sys/stat.h>
  38 #include <sys/mkdev.h>
  39 #include <sys/nvpair.h>
  40 #include <fcntl.h>
  41 #include <attr.h>
  42
  43 key_t
  44 ftok(const char *path, int id)
  45 {
  46         struct stat64 st;
  47         nvlist_t *nvp;
  48         uint32_t devpiece;
  49         int error;
  50
  51         if (stat64(path, &st) < 0)
  52                 return ((key_t)-1);
  53
  54         /*
  55          * if getattrat works then extract the FSID from the nvlist
  56          * otherwise, just fall back and use the value from the stat data
  57          */
  58         if ((error = getattrat(AT_FDCWD, XATTR_VIEW_READONLY,
  59             path, &nvp)) == 0) {
  60                 uint64_t value;
  61
  62                 if ((error = libc_nvlist_lookup_uint64(nvp,
  63                     A_FSID, &value)) == 0)
  64                         devpiece = value & 0xfff;
  65                 libc_nvlist_free(nvp);
  66         }
  67
  68         if (error)
  69                 devpiece = st.st_dev & 0xfff;
  70
  71         return ((key_t)((key_t)id << 24 | devpiece << 12 |
  72             ((uint32_t)st.st_ino & 0x0fff)));
  73 }