Fixed subdirectories on archive submission.

forms/submission.php

@@ -91,6 +91,9 @@ if ($fromform = $mform->get_data()) {
         // Read archive and split between required / additional files.
         for ($i = 0; $i < $zip->numFiles; $i++) {
             $filename = $zip->statIndex($i)['name'];
+            if (substr($filename, -1) == '/') { // Directory.
+                continue;
+            }
             $filecontent = file_get_contents('zip://' . $zipname . '#' . $filename);
             // Autodetect text file encode if not binary.
             if (! vpl_is_binary( $filename )) {