trait SidecarMetadataDestinationTrait in Backup and Migrate 8.4

trait SidecarMetadataDestinationTrait {
  use FileProcessorTrait;

  /**
   * {@inheritdoc}
   */
  protected function _loadFileMetadataArray(BackupFileInterface $file) {
    $info = [];
    $id = $file
      ->getFullName();
    $filename = $id . '.info';
    if ($this
      ->fileExists($filename)) {
      $meta_file = $this
        ->getFile($filename);
      $meta_file = $this
        ->loadFileForReading($meta_file);
      $info = $this
        ->_INIToArray($meta_file
        ->readAll());
    }
    return $info;
  }

  /**
   * {@inheritdoc}
   */
  protected function _saveFileMetadata(BackupFileInterface $file) {

    // Get the file metadata and convert to INI format.
    $meta = $file
      ->getMetaAll();
    $ini = $this
      ->_arrayToINI($meta);

    // Create an info file.
    $meta_file = $this
      ->getTempFileManager()
      ->pushExt($file, 'info');
    $meta_file
      ->write($ini);

    // Save the metadata.
    $this
      ->_saveFile($meta_file);
  }

  /**
   * {@inheritdoc}
   */
  public function deleteFile($id) {
    $this
      ->_deleteFile($id);
    $this
      ->_deleteFile($id . '.info');
  }

  /**
   * Parse an INI file's contents.
   *
   * For simplification this function only parses the simple subset of INI
   * syntax generated by SidecarMetadataDestinationTrait::_arrayToINI();
   *
   * @param $ini
   *
   * @return array
   */
  protected function _INIToArray($ini) {
    $out = [];
    $lines = explode("\n", $ini);
    foreach ($lines as $line) {
      $line = trim($line);

      // Skip comments (even though there probably won't be any.
      if (substr($line, 0, 1) == ';') {
        continue;
      }

      // Match the key and value using a simplified syntax.
      $matches = [];
      if (preg_match('/^([^=]+)\\s?=\\s?"(.*)"$/', $line, $matches)) {
        $key = $matches[1];
        $val = $matches[2];

        // Break up a key in the form a[b][c]
        $keys = explode('[', $key);
        $insert =& $out;
        foreach ($keys as $part) {
          $part = trim($part, ' ]');
          $insert[$part] = '';
          $insert =& $insert[$part];
        }
        $insert = $val;
      }
    }
    return $out;
  }

  /**
   * @param $data
   * @param string $prefix
   * @return string
   */
  protected function _arrayToINI($data, $prefix = '') {
    $content = "";
    foreach ($data as $key => $val) {
      if ($prefix) {
        $key = $prefix . '[' . $key . ']';
      }
      if (is_array($val)) {
        $content .= $this
          ->_arrayToINI($val, $key);
      }
      else {
        $content .= $key . " = \"" . $val . "\"\n";
      }
    }
    return $content;
  }

}