class BackdropPrivateStreamWrapper

backdrop_class_list in includes/bootstrap.classes.inc

Lists all the classes used by Backdrop core.

hook_stream_wrappers in modules/system/system.api.php

Registers PHP stream wrapper implementations associated with a module.

system_stream_wrappers in modules/system/system.module

Implements hook_stream_wrappers().

class BackdropPrivateStreamWrapper extends BackdropLocalStreamWrapper {
  /**
   * Implements abstract public function getDirectoryPath()
   */
  public function getDirectoryPath() {
    return config_get('system.core', 'file_private_path');
  }

  /**
   * Overrides getExternalUrl().
   *
   * Return the HTML URI of a private file.
   */
  function getExternalUrl() {
    $path = str_replace('\\', '/', $this->getTarget());
    return url('system/files/' . $path, array('absolute' => TRUE));
  }
}