Php出现了怪问题

我装了RH9.0+APACHE2.0+PHP4.22+MYSQL
出现了一个新问题，我用
<? if(isset($HTTP_POST_FILES['upfile']['name'])){
copy($HTTP_POST_FILES['upfile']['tmp_name'],$HTTP_POST_FILES['upfile']['name']);}
?>
<form name=dd method="post" action="index.php" enctype="multipart/form-data">
<input name=upfile type=file size=20>
<input name=submit type=submit value=upit>
</form>
上传的文件变大了一倍，请教高手怎么解决啊？