PHP: File Upload

<?php
$message = "";

if(isset($_FILES["file_name"])) 
{
  $upload_dir = "/www/data/";
  $file_name  = $_FILES['file_name']['name'];
  $file_temp  = $_FILES['file_name']['tmp_name'];
  
  move_uploaded_file($file_temp,
                     $upload_dir.$file_name);

  $message = "
$file_name 
              ($file_size Byte) nach
              $upload_dir hochgeladen!
";
}

$html = <<< HTML
<form action="{$_SERVER['PHP_SELF']}"
      enctype="multipart/form-data"
      method="post">
<input type="file" name="file_name" />
<input type="submit" value="Kopieren" />
</form>
HTML;

echo $html.$message;
?>