read dir after post

<html>
<head>
<title>Data Request</title>
</head>
<body>
<h1 align="center">Dispatch Report</h1>
<h2 align="center">Wrong Arrives Report</h2>

<table align="center" border="2">
<tr>
<td>Select Shift<br>
<form method="post" action="" name="shiftfrm" id="shiftfrm">
<select name="shiftlist" id="shiftlist">
  <option value="" selected="selected">--------</option>
<?php
$dir = opendir ("files");
while (false !== ($file = readdir($dir))) {
    if($file!='.' && $file!='..') {
        echo '<option value="' . $file . '">' . $file . '</option>';
    }
}
?>
</select>
<input type="submit" id="submit" value="Submit"/>
</form>
</td></tr>

<?php
if(!empty($_POST['shiftlist'])) {
    $file = 'files/'.$_POST['shiftlist'];
    echo $file;
    if(file_exists($file)) {
        if( ($handle = fopen( $file, 'r' )) !== false )
        {
            $output = '<table align="center" width="" border="2">';
            while( ($data = fgetcsv( $handle )) !== false )
            {
                $output .= '<tr>';
                foreach( $data as $value )
                {
                    $output .= '<td>'.$value.'</td>';
                }
                $output .= '</tr>';
            }
            $output .= '</table>';
            echo $output;
            fclose( $handle );
        }
    }
}
?>

</table>

</body>
</html>