Upload PHP

<html>
<head></head>
<body>
<p>Result:</p>
<br />
<?php
    $data = $_POST['data'];
    /*$decdata = urldecode($data);*/ //Fail function!!!
    $raw = base64_decode($data);
    $img = imagecreatefromstring($raw);

    //Useless Stuff
    /*echo 'Length:' . strlen($raw) . '<br>';
    echo 'Length Dec:' . strlen($decdata) . '<br>';

    $fp = fopen('received.txt', 'w');
    fwrite($fp, $data);
    fclose($fp);*/

    if(imagejpeg($img, 'image.jpg'))
    {
        echo '<p>written</p>';
    }
    else
    {
        echo '<p>failed</p>';
    }
?>
</body>
</html>