<?php
// $Id: xsend.module,v 1.8 2009-10-30 02:26:15 heshanmw Exp $

/**
 * @file
 * Enables the user to override the default PHP file transfer.
 * @author Heshan Wanigasooriya <heshanmw at gmail dor com>
 * @category file system
 * @copyright Heshan Wanigasooriya
 * @see #603488 patch by grendzy
 */

/**
 * Implementation of hook_menu_alter().
 * Override the default system/files menu handler.
 */
function xsend_menu_alter(&$items) {
  $items['system/files']['page callback'] = 'xsend_file_transfer';
}

/**
 * Transfer a private file with the X-Sendfile header.
 * This is adapted from file_download().
 * @see file_download()
 */
function xsend_file_transfer() {
  if (variable_get('file_transfer_handler', "file_transfer_default") == 'file_transfer_default') {
    $args = func_get_args();
    call_user_func_array('file_download', $args);
    exit();
  }

  // Merge remainder of arguments from GET['q'], into relative file path.
  $args = func_get_args();
  $filepath = implode('/', $args);

  if (file_exists(file_create_path($filepath))) {
    $headers = module_invoke_all('file_download', $filepath);
    if (in_array(-1, $headers)) {
      return drupal_access_denied();
    }
    if (count($headers)) {
      drupal_set_header('X-Sendfile: '. realpath(file_create_path($filepath)));
      foreach ($headers as $header) {
        // To prevent HTTP header injection, we delete new lines that are
        // not followed by a space or a tab.
        // See http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.2
        $header = preg_replace('/\r?\n(?!\t| )/', '', $header);
        drupal_set_header($header);
      }
      exit();
    }
  }
  return drupal_not_found();
}

/**
 * menu call back for admin settings
 */
function xsend_admin_settings() {
  $form = array();
  if(!in_array('mod_xsendfile', apache_get_modules())) {
    drupal_set_message('X-send file module for apache2 is not installed in your system. Untill you correctly install it do not enable this module.', 'error');
  }
  else {
    $form['settings_general'] = array(
        '#type' => 'fieldset',
        '#title' => 'Fast private file transfer settings',
        '#collapsible' => TRUE,
    );
    $form['settings_general']['file_transfer_handler'] = array(
        '#type' => 'radios',
        '#title' => 'Xsend private file transfer support',
        '#default_value' => variable_get('file_transfer_handler', "file_transfer_default"),
        '#options' => array("file_transfer_default"=>t('Disabled'), "file_transfer_xsendfile"=>t('Enabled - files are transferred by Drupal.')),
        '#description' => 'Enable X-send files support.'
    );
    return system_settings_form($form);
  }
}