问带有readfile的损坏的zip

EN

<?php

set_time_limit();
$zipname = getcwd();
$zipname = substr($zipname,strrpos($zipname,'/')+1);
$zipname = $zipname.'.zip';
$zip = new ZipArchive;
$zip->open('./'.basename($zipname).'', ZipArchive::CREATE);
if ($dir_handle = opendir('./')) {
      while (false !== ($entry = readdir($dir_handle))) {
    if ($entry != "." && $entry != ".." && !strstr($entry,'.php')) {
        $zip->addFile($entry);
    }
  }
  closedir($dir_handle);
}
else {
die('file not found');
}

$zip->close();

header('Content-Type: application/zip');
header('Content-Disposition: attachment; filename="'.basename($zipname).'"');
header('Content-Length: ' . filesize($zipname));
header('Location: ./'.$zipname);
?>

unlink($zipname);

readfile($zipname);