CDiskStorage::sendFile

public function sendFile($file)
{
	/** @var File $file */
	$file = File::loadById($file['extra']['id']);
	if(!$file->canRead($this->storage->getCurrentUserSecurityContext()))
	{
		throw new CWebDavAccessDeniedException;
	}

	return CFile::viewByUser($file->getFile(), array("force_download" => true));
}