backupdata folder is not visible in directory resource any more, the backup files were not downloadable, but they might be stored in browser cache when teacher and student were logged from the same browser and computer account - MDL-6280 ; merged from MOODLE_16_STABLE

mod/resource/type/directory/resource.class.php

@@ -39,6 +39,9 @@ function display() {
             error("The value for 'subdir' contains illegal characters!");
         }
         $relativepath = "$relativepath$subdir";
+        if (stripos($relativepath, 'backupdata') !== FALSE) {
+            error("Access not allowed!");
+        }
 
         $subs = explode('/', $subdir);
         array_shift($subs);
@@ -99,7 +102,9 @@ function display() {
          "<th align=\"right\" class=\"header date\">$strmodified</th>".
          "</tr>";
     foreach ($files as $file) {
-        if (is_dir("$CFG->dataroot/$relativepath/$file")) {          // Must be a directory
+        if ($file == 'backupdata') {
+            continue;
+        } else if (is_dir("$CFG->dataroot/$relativepath/$file")) {          // Must be a directory
             $icon = "folder.gif";
             $relativeurl = "/view.php?blah";
             $filesize = display_size(get_directory_size("$CFG->dataroot/$relativepath/$file"));