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      1 /*	$NetBSD: amfs_link.c,v 1.1.1.3 2015/01/17 16:34:15 christos Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1997-2014 Erez Zadok
      5  * Copyright (c) 1990 Jan-Simon Pendry
      6  * Copyright (c) 1990 Imperial College of Science, Technology & Medicine
      7  * Copyright (c) 1990 The Regents of the University of California.
      8  * All rights reserved.
      9  *
     10  * This code is derived from software contributed to Berkeley by
     11  * Jan-Simon Pendry at Imperial College, London.
     12  *
     13  * Redistribution and use in source and binary forms, with or without
     14  * modification, are permitted provided that the following conditions
     15  * are met:
     16  * 1. Redistributions of source code must retain the above copyright
     17  *    notice, this list of conditions and the following disclaimer.
     18  * 2. Redistributions in binary form must reproduce the above copyright
     19  *    notice, this list of conditions and the following disclaimer in the
     20  *    documentation and/or other materials provided with the distribution.
     21  * 3. Neither the name of the University nor the names of its contributors
     22  *    may be used to endorse or promote products derived from this software
     23  *    without specific prior written permission.
     24  *
     25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     35  * SUCH DAMAGE.
     36  *
     37  *
     38  * File: am-utils/amd/amfs_link.c
     39  *
     40  */
     41 
     42 /*
     43  * Symbol-link file system
     44  */
     45 
     46 #ifdef HAVE_CONFIG_H
     47 # include <config.h>
     48 #endif /* HAVE_CONFIG_H */
     49 #include <am_defs.h>
     50 #include <amd.h>
     51 
     52 /* forward declarations */
     53 static int amfs_link_mount(am_node *mp, mntfs *mf);
     54 static int amfs_link_umount(am_node *mp, mntfs *mf);
     55 
     56 /*
     57  * Ops structures
     58  */
     59 am_ops amfs_link_ops =
     60 {
     61   "link",
     62   amfs_link_match,
     63   0,				/* amfs_link_init */
     64   amfs_link_mount,
     65   amfs_link_umount,
     66   amfs_error_lookup_child,
     67   amfs_error_mount_child,
     68   amfs_error_readdir,
     69   0,				/* amfs_link_readlink */
     70   0,				/* amfs_link_mounted */
     71   0,				/* amfs_link_umounted */
     72   amfs_generic_find_srvr,
     73   0,				/* nfs_fs_flags */
     74   0,				/* amfs_link_get_wchan */
     75 #ifdef HAVE_FS_AUTOFS
     76   AUTOFS_LINK_FS_FLAGS,
     77 #endif /* HAVE_FS_AUTOFS */
     78 };
     79 
     80 
     81 /*
     82  * SFS needs a link.
     83  */
     84 char *
     85 amfs_link_match(am_opts *fo)
     86 {
     87 
     88   if (!fo->opt_fs) {
     89     plog(XLOG_USER, "link: no fs specified");
     90     return 0;
     91   }
     92 
     93   /*
     94    * If the link target points to another mount point, then we could
     95    * end up with an unpleasant situation, where the link f/s simply
     96    * "assumes" the mntfs of that mount point.
     97    *
     98    * For example, if the link points to /usr, and /usr is a real ufs
     99    * filesystem, then the link f/s will use the inherited ufs mntfs,
    100    * and the end result will be that it will become unmountable.
    101    *
    102    * To prevent this, we use a hack: we prepend a dot ('.') to opt_fs if
    103    * its original value was an absolute path, so that it will never match
    104    * any other mntfs.
    105    *
    106    * XXX: a less hacky solution should be used...
    107    */
    108   if (fo->opt_fs[0] == '/') {
    109     char *link_hack = str3cat(NULL, ".", fo->opt_fs, "");
    110     if (fo->opt_sublink == NULL || fo->opt_sublink[0] == '\0')
    111       fo->opt_sublink = xstrdup(fo->opt_fs);
    112     XFREE(fo->opt_fs);
    113     fo->opt_fs = link_hack;
    114   }
    115 
    116   return xstrdup(fo->opt_fs);
    117 }
    118 
    119 
    120 static int
    121 amfs_link_mount(am_node *mp, mntfs *mf)
    122 {
    123   return 0;
    124 }
    125 
    126 
    127 static int
    128 amfs_link_umount(am_node *mp, mntfs *mf)
    129 {
    130   return 0;
    131 }
    132