sysdeps/mach/hurd/chroot.c

   1 /* Copyright (C) 1991-2017 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, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <string.h>
  19 #include <unistd.h>
  20
  21 #include <hurd.h>
  22 #include <hurd/port.h>
  23
  24 /* Make PATH be the root directory (the starting point for absolute
  25    paths).  Note that while on traditional UNIX systems this call is
  26    restricted to the super-user, it isn't on the Hurd.  */
  27 int
  28 chroot (const char *path)
  29 {
  30   const char *lookup;
  31   size_t len;
  32   file_t dir, root;
  33   error_t err;
  34
  35   /* Append trailing "/." to directory name to force ENOTDIR if it's not a
  36      directory and EACCES if we don't have search permission.  */
  37   len = strlen (path);
  38   if (len >= 2 && path[len - 2] == '/' && path[len - 1] == '.')
  39     lookup = path;
  40   else if (len == 0)
  41     /* Special-case empty file name according to POSIX.  */
  42     return __hurd_fail (ENOENT);
  43   else
  44     {
  45       char *n = alloca (len + 3);
  46       memcpy (n, path, len);
  47       n[len] = '/';
  48       n[len + 1] = '.';
  49       n[len + 2] = '\0';
  50       lookup = n;
  51     }
  52
  53   dir = __file_name_lookup (lookup, 0, 0);
  54   if (dir == MACH_PORT_NULL)
  55     return -1;
  56
  57   /* Prevent going through DIR's ..  */
  58   err = __file_reparent (dir, MACH_PORT_NULL, &root);
  59   __mach_port_deallocate (__mach_task_self (), dir);
  60   if (err)
  61     return __hurd_fail (err);
  62
  63   _hurd_port_set (&_hurd_ports[INIT_PORT_CRDIR], root);
  64   return 0;
  65 }