Create .tar archive of all files in directory

archive.php

<?php
  /******************************************************************************************************************
   * Source: http://www.emvee-solutions.com/blog/create-tar-files-archive-files-server-using-php-script/
   * 
   * Please note that the script wil by default tar all files and (sub)folders from the directory you uploaded the script to
   * into a file named archive.tar. You can overwrite the directory and archive name by calling the script with your own 
   * parameters, like this (replace the italic text for your own needs):
   *
   * http://domain.com/archive.php?targetname=achivename.tar&dir=relative/folder/to/put/in/archive/
   ******************************************************************************************************************/

  try {
    //make sure the script has enough time to run (300 seconds  = 5 minutes)
    ini_set('max_execution_time', '300');
    ini_set('set_time_limit', '0');
   
    $target = isset($_GET["targetname"]) ? $_GET["targetname"] : 'archive.tar'; //default to archive.tar
    $dir = isset($_GET["dir"]) ? $_GET["dir"] : './.'; //defaults to all in current dir
    
    //setup phar
    $phar = new PharData($target);
    $phar->buildFromDirectory(dirname(__FILE__) . '/'.$dir);
    echo 'Compressing all files done, check your server for the file ' .$target;
  } catch (Exception $e) {
    // handle errors
    echo 'An error has occured, details:';
    echo $e->getMessage();
  }
?>

how can i exclude some dirs of files? Eg got the error

An error has occured, details:Iterator RecursiveIteratorIterator returned a file that could not be opened "/var/www/public_html/.ftpquota"