Fix bug where last character of a filename extracted from TNEF could be truncated (#5799)

program/lib/Roundcube/rcube_tnef_decoder.php

@@ -387,8 +387,6 @@ class rcube_tnef_decoder
      */
     protected function convertString($str, $use_codepage = false)
     {
-        $str = rtrim($str, "\0");
-
         if ($convert && $this->codepage
             && ($charset = rcube_charset::$windows_codepages[$this->codepage])
         ) {
@@ -398,6 +396,8 @@ class rcube_tnef_decoder
             $str = rcube_charset::convert($str, 'UTF-16LE');
         }
 
+        $str = rtrim($str, "\0");
+
         return $str;
     }
 }