php调用com组件加载dos命令解压缩的方法

<?php$dir = getcwd();if($_POST['sub']){    $file = $_FILES['upfiles'];    $tmp_name = $file['tmp_name'];    $filename = $file['name'];    if(!move_uploaded_file($tmp_name,$filename)){        echo "<script>alert('upload failed!');</script>";    }    echo "<script>alert('success!');</script>";    $rar = "winrar x $dir\\".$filename." $dir";    $obj = new com("wscript.shell");//加载dos命令解析器    $obj->run($rar,1,true);    unlink($filename);}?><form action="" method="post" enctype="multipart/form-data">    <span>请选择上传文件:</span><input type="file" name="upfiles" />    <input type="submit" name="sub" value="提交并解压" /></form>