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glibc  2.9
chroot.c
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00001 /* Copyright (C) 1991,92,93,94,95,97,99,2001 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003 
00004    The GNU C Library is free software; you can redistribute it and/or
00005    modify it under the terms of the GNU Lesser General Public
00006    License as published by the Free Software Foundation; either
00007    version 2.1 of the License, or (at your option) any later version.
00008 
00009    The GNU C Library is distributed in the hope that it will be useful,
00010    but WITHOUT ANY WARRANTY; without even the implied warranty of
00011    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00012    Lesser General Public License for more details.
00013 
00014    You should have received a copy of the GNU Lesser General Public
00015    License along with the GNU C Library; if not, write to the Free
00016    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00017    02111-1307 USA.  */
00018 
00019 #include <string.h>
00020 #include <unistd.h>
00021 
00022 #include <hurd.h>
00023 #include <hurd/port.h>
00024 
00025 /* Make PATH be the root directory (the starting point for absolute
00026    paths).  Note that while on traditional UNIX systems this call is
00027    restricted to the super-user, it isn't on the Hurd.  */
00028 int
00029 chroot (const char *path)
00030 {
00031   const char *lookup;
00032   size_t len;
00033   file_t dir, root;
00034   error_t err;
00035 
00036   /* Append trailing "/." to directory name to force ENOTDIR if it's not a
00037      directory and EACCES if we don't have search permission.  */
00038   len = strlen (path);
00039   if (len >= 2 && path[len - 2] == '/' && path[len - 1] == '.')
00040     lookup = path;
00041   else
00042     {
00043       char *n = alloca (len + 3);
00044       memcpy (n, path, len);
00045       n[len] = '/';
00046       n[len + 1] = '.';
00047       n[len + 2] = '\0';
00048       lookup = n;
00049     }
00050 
00051   dir = __file_name_lookup (lookup, 0, 0);
00052   if (dir == MACH_PORT_NULL)
00053     return -1;
00054 
00055   /* Prevent going through DIR's ..  */
00056   err = __file_reparent (dir, MACH_PORT_NULL, &root);
00057   __mach_port_deallocate (__mach_task_self (), dir);
00058   if (err)
00059     return __hurd_fail (err);
00060 
00061   _hurd_port_set (&_hurd_ports[INIT_PORT_CRDIR], root);
00062   return 0;
00063 }