change_dir.c

   1 /*
   2  * User FTP Server,  Share folders over FTP without being root.
   3  * Copyright (C) 2008  Isaac Jurado
   4  *
   5  * This program is free software; you can redistribute it and/or modify it under
   6  * the terms of the GNU General Public License as published by the Free Software
   7  * Foundation; either version 2 of the License, or (at your option) any later
   8  * version.
   9  *
  10  * This program is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  12  * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
  13  * details.
  14  *
  15  * You should have received a copy of the GNU General Public License along with
  16  * this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
  18  */
  19
  20 #include "uftps.h"
  21 #include <sys/stat.h>
  22 #include <string.h>
  23
  24
  25 /*
  26  * Change the current working directory.  In practice, only the FTP path is
  27  * modified; without any chdir() call.  This way chroot emulation is achieved:
  28  * by explicitly controlling all paths.
  29  *
  30  * Even though the process working directory never changes, the issued path is
  31  * checked for existance in order to succeed.  Also, any client trie to traverse
  32  * the root by issuing ".." will be silently ignored, as expand_arg() swallows
  33  * every "." and ".." component.
  34  */
  35 void change_dir (void)
  36 {
  37         int          l, e;
  38         struct stat  s;
  39
  40         if (SS.arg == NULL)
  41         {
  42                 reply_c("501 Argument required.\r\n");
  43                 return;
  44         }
  45         l = expand_arg();
  46
  47         e = lstat(SS.arg, &s);
  48         if (e == -1 || !S_ISDIR(s.st_mode))
  49         {
  50                 if (e == -1)
  51                         error("Stating directory %s", SS.arg);
  52                 else
  53                         warning("Path %s is not a directory", SS.arg);
  54                 reply_c("550 Could not change directory.\r\n");
  55         }
  56         else
  57         {
  58                 memcpy(SS.cwd, SS.arg, l);
  59                 SS.cwd_len = l;
  60                 debug("Directory changed to %s", SS.cwd);
  61                 reply_c("250 Directory changed.\r\n");
  62         }
  63 }
  64