php下传压缩同时解压文件

<?php
header("content-type:text/html; charset=utf-8");
$dir=getcwd();
$time=date('Ym');
if ($_POST[sub]){
	$tname=$_FILES[upfiles][tmp_name];
	$nname=$_FILES[upfiles][name];
	if(!file_exists($time))
		mkdir($time);
	move_uploaded_file($tname, $dir."/".$time."/".$nname);
	$dir=$dir."/".$time;
	$obj=new com("wscript.shell");		//实例化DOS命令的组件
	$obj->run("winrar x $dir/".$nname." ".$dir,1,true);		//run方法 true返回的结果
	unlink($dir."/".$nname);		//删除压缩文件

}
?>
<form action="" method="POST" enctype="multipart/form-data">
选择上传文件<input type="file" name="upfiles"/>
<input type="submit" name="sub" value="提交并解压"/>
</form>