BrowserDownloadDestination.php in Backup and Migrate 8.4

Namespace

BackupMigrate\Core\Destination

File

lib/backup_migrate_core/src/Destination/BrowserDownloadDestination.php

<?php

namespace BackupMigrate\Core\Destination;

use BackupMigrate\Core\Exception\DestinationNotWritableException;
use BackupMigrate\Core\File\BackupFileReadableInterface;
use BackupMigrate\Core\Plugin\PluginCallerInterface;
use BackupMigrate\Core\Plugin\PluginCallerTrait;

/**
 * Class BrowserDownloadDestination.
 *
 * @package BackupMigrate\Core\Destination
 */
class BrowserDownloadDestination extends StreamDestination implements WritableDestinationInterface, PluginCallerInterface {
  use PluginCallerTrait;

  /**
   * {@inheritdoc}
   */
  function saveFile(BackupFileReadableInterface $file) {

    // Set some default download headers.
    $headers = [
      [
        'key' => 'Content-Disposition',
        'value' => 'attachment; filename="' . $file
          ->getFullName() . '"',
      ],
      [
        'key' => 'Cache-Control',
        'value' => 'no-cache',
      ],
    ];

    // Set a mime-type header.
    if ($mime = $file
      ->getMeta('mimetype')) {
      $headers[] = [
        'key' => 'Content-Type',
        'value' => $mime,
      ];
    }
    else {

      // Get the mime type for this file if possible.
      $mime = 'application/octet-stream';
      $mime = $this
        ->plugins()
        ->call('alterMime', $mime, [
        'ext' => $file
          ->getExtLast(),
      ]);
      $headers[] = [
        'key' => 'Content-Type',
        'value' => $mime,
      ];
    }

    // In some circumstances, web-servers will double compress gzipped files.
    // This may help aleviate that issue by disabling mod-deflate.
    if ($file
      ->getMeta('mimetype') == 'application/x-gzip') {
      if (function_exists('apache_setenv')) {
        apache_setenv('no-gzip', '1');
      }
      $headers[] = [
        'key' => 'Content-Encoding',
        'value' => 'gzip',
      ];
    }
    if ($size = $file
      ->getMeta('filesize')) {
      $headers[] = [
        'key' => 'Content-Length',
        'value' => $size,
      ];
    }

    // Suppress the warning you get when the buffer is empty.
    @ob_end_clean();
    if ($file
      ->openForRead()) {
      foreach ($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['value'] = preg_replace('/\\r?\\n(?!\\t| )/', '', $header['value']);
        header($header['key'] . ': ' . $header['value']);
      }

      // Transfer file in 1024 byte chunks to save memory usage.
      while ($data = $file
        ->readBytes(1024 * 512)) {
        print $data;
      }
      $file
        ->close();
    }

    // @TODO Throw exception.
  }

  /**
   * {@inheritdoc}
   */
  public function checkWritable() {

    // Check that we're running as a web process via a browser.
    // @TODO: we could check if the 'HTTP_ACCEPT' header contains the right mime but that is probably overkill.
    if (!isset($_SERVER['REQUEST_METHOD'])) {
      throw new DestinationNotWritableException("The download destination only works when accessed through a http client.");
    }
  }

}

Classes

Name	Description
BrowserDownloadDestination	Class BrowserDownloadDestination.