magento2/app/code/Magento/Backup/Controller/Adminhtml/Index.php

<?php
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
namespace Magento\Backup\Controller\Adminhtml;

use Magento\Backend\App\Action;
use Magento\Backup\Helper\Data as Helper;
use Magento\Framework\App\ObjectManager;

/**
 * Backup admin controller
 *
 * @author      Magento Core Team <core@magentocommerce.com>
 * @api
 * @since 100.0.2
 * @SuppressWarnings(PHPMD.AllPurposeAction)
 */
abstract class Index extends Action
{
    /**
     * Authorization level of a basic admin session
     *
     * @see _isAllowed()
     */
    const ADMIN_RESOURCE = 'Magento_Backup::backup';

    /**
     * Core registry
     *
     * @var \Magento\Framework\Registry
     */
    protected $_coreRegistry = null;

    /**
     * @var \Magento\Framework\Backup\Factory
     */
    protected $_backupFactory;

    /**
     * @var \Magento\Framework\App\Response\Http\FileFactory
     */
    protected $_fileFactory;

    /**
     * @var \Magento\Backup\Model\BackupFactory
     */
    protected $_backupModelFactory;

    /**
     * @var \Magento\Framework\App\MaintenanceMode
     */
    protected $maintenanceMode;

    /**
     * @var Helper
     */
    private $helper;

    /**
     * @param \Magento\Backend\App\Action\Context $context
     * @param \Magento\Framework\Registry $coreRegistry
     * @param \Magento\Framework\Backup\Factory $backupFactory
     * @param \Magento\Framework\App\Response\Http\FileFactory $fileFactory
     * @param \Magento\Backup\Model\BackupFactory $backupModelFactory
     * @param \Magento\Framework\App\MaintenanceMode $maintenanceMode
     * @param Helper|null $helper
     */
    public function __construct(
        \Magento\Backend\App\Action\Context $context,
        \Magento\Framework\Registry $coreRegistry,
        \Magento\Framework\Backup\Factory $backupFactory,
        \Magento\Framework\App\Response\Http\FileFactory $fileFactory,
        \Magento\Backup\Model\BackupFactory $backupModelFactory,
        \Magento\Framework\App\MaintenanceMode $maintenanceMode,
        ?Helper $helper = null
    ) {
        $this->_coreRegistry = $coreRegistry;
        $this->_backupFactory = $backupFactory;
        $this->_fileFactory = $fileFactory;
        $this->_backupModelFactory = $backupModelFactory;
        $this->maintenanceMode = $maintenanceMode;
        $this->helper = $helper ?? ObjectManager::getInstance()->get(Helper::class);
        parent::__construct($context);
    }

    /**
     * @inheritDoc
     * @since 100.2.6
     */
    public function dispatch(\Magento\Framework\App\RequestInterface $request)
    {
        if (!$this->helper->isEnabled()) {
            return $this->_redirect('*/*/disabled');
        }

        return parent::dispatch($request);
    }
}