问简单文件下载器

EN

<?php

//Settings
$filesPath   = './files';
$fileName    = $_GET['file'];
$allowedExts = array('jpg','png','gif');


//Functions 
//Returns the extension portion of a filename.
function file_extension($fileName)
{
    $path_info = pathinfo($fileName);
    return strtolower($path_info['extension']);
}

//Validation and processing
//Check that a file is actually being requested
if (empty($fileName)) {
    die('no file was requested');
}

//Check that the file is allowed to be downloaded   
if (!in_array(file_extension($fileName), $allowedExts)) {
    die('you cannot download this file');
}

//Get the file  
if (file_exists($filesPath . DIRECTORY_SEPARATOR . $fileName)) {
    header('Content-Description: File Transfer');
    header('Content-Type: application/octet-stream');
    header('Content-Disposition: attachment; filename=' . basename($fileName));
    header('Content-Transfer-Encoding: binary');
    header('Expires: 0');
    header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
    header('Pragma: public');
    header('Content-Length: ' . filesize($fileName));
    ob_clean();
    flush();
    readfile($fileName);
    exit;
}
?>