sysdeps/mach/hurd/chroot.c

   1 /* Copyright (C) 1991,92,93,94,95,97,99,2001 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, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <string.h>
  20 #include <unistd.h>
  21
  22 #include <hurd.h>
  23 #include <hurd/port.h>
  24
  25 /* Make PATH be the root directory (the starting point for absolute
  26    paths).  Note that while on traditional UNIX systems this call is
  27    restricted to the super-user, it isn't on the Hurd.  */
  28 int
  29 chroot (const char *path)
  30 {
  31   const char *lookup;
  32   size_t len;
  33   file_t dir, root;
  34   error_t err;
  35
  36   /* Append trailing "/." to directory name to force ENOTDIR if it's not a
  37      directory and EACCES if we don't have search permission.  */
  38   len = strlen (path);
  39   if (len >= 2 && path[len - 2] == '/' && path[len - 1] == '.')
  40     lookup = path;
  41   else
  42     {
  43       char *n = alloca (len + 3);
  44       memcpy (n, path, len);
  45       n[len] = '/';
  46       n[len + 1] = '.';
  47       n[len + 2] = '\0';
  48       lookup = n;
  49     }
  50
  51   dir = __file_name_lookup (lookup, 0, 0);
  52   if (dir == MACH_PORT_NULL)
  53     return -1;
  54
  55   /* Prevent going through DIR's ..  */
  56   err = __file_reparent (dir, MACH_PORT_NULL, &root);
  57   __mach_port_deallocate (__mach_task_self (), dir);
  58   if (err)
  59     return __hurd_fail (err);
  60
  61   _hurd_port_set (&_hurd_ports[INIT_PORT_CRDIR], root);
  62   return 0;
  63 }