1  /* Copyright (C) 1991-2023 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     <https://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  }