Ticket #610: download.php

<?php defined('SYSPATH') or die('No direct script access.');
/**
 * Download helper class.
 *
 * $Id$
 *
 * @package    Core
 * @author     Kohana Team
 * @copyright  (c) 2007-2008 Kohana Team
 * @license    http://kohanaphp.com/license.html
 */
class download_Core {

    /**
     * Force a download of a file to the user's browser. This function is
     * binary-safe and will work with any MIME type that Kohana is aware of.
     *
     * @param   string  a file path or file name
     * @param   mixed   data to be sent if the filename does not exist
     * @param   float      size of block to be read from file at a time in megabytes
     * @return  void
     */
    public static function force($filename = '', $data = '', $blocksize = 1)
    {
        static $user_agent;

        if ($filename == '')
            return FALSE;
        
        if (valid::numeric($blocksize))
            $blocksize = abs($blocksize);
        else
            return FALSE;

        if (is_file($filename))
        {
            // Get the real path
            $filepath = str_replace('\\', '/', realpath($filename));

            // Get extension
            $extension = pathinfo($filepath, PATHINFO_EXTENSION);

            // Remove directory path from the filename
            $filename = end(explode('/', $filepath));

            // Set filesize
            $filesize = filesize($filepath);
        }
        else
        {
            // Grab the file extension
            $extension = end(explode('.', $filename));

            // Try to determine if the filename includes a file extension.
            // We need it in order to set the MIME type
            if (empty($data) OR $extension === $filename)
                return FALSE;

            // Set filesize
            $filesize = strlen($data);
        }

        // Set a default mime if we can't find it
        if (($mime = Config::item('mimes.'.$extension)) === NULL)
        {
            $mime = 'application/octet-stream';
        }
        else
        {
            $mime = current((array) $mime);
        }

        // Generate the server headers
        header('Content-Type: '.$mime);
        header('Content-Disposition: attachment; filename="'.$filename.'"');
        header('Content-Transfer-Encoding: binary');
        header('Expires: 0');
        header('Content-Length: '.$filesize);
        
        // IE headers
        if (Kohana::user_agent('browser') === 'Internet Explorer')
        {
            header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
            header('Pragma: public');
        }
        else
        {
            header('Pragma: no-cache');
        }

        if (isset($filepath))
        {
            // Convert blocksize to bytes
            $blocksize *= 1000000;
            
            // Open the file
            $handle = fopen($filepath, 'rb');
            
            // Loop through the file, 1MB at a time
            while ( ! feof($handle))
            {
                // Echo the result
                echo fread($handle, $blocksize);
                
                // Flush the output buffer to start sending data
                ob_flush();
                flush();
            }
            
            // Close the file
            fclose($handle);
        }
        else
        {
            // Send the file data
            echo $data;
        }
    }

} // End download