Issue #3024264 by roderik: Document and rename variables in DrupalKernel::findSitePath()

      return $test_db->getTestSitePath();

    }

    // Determine whether multi-site functionality is enabled.

    // Determine whether multi-site functionality is enabled. If not, return

    // the default directory.

    if (!file_exists($app_root . '/sites/sites.php')) {

      return 'sites/default';

    }

    // Otherwise, use find the site path using the request.

    // Pre-populate host and script variables, then include sites.php which may

    // populate $sites with a site-directory mapping.

    $script_name = $request->server->get('SCRIPT_NAME');

    if (!$script_name) {

      $script_name = $request->server->get('SCRIPT_FILENAME');

    $sites = [];

    include $app_root . '/sites/sites.php';

    $uri = explode('/', $script_name);

    $server = explode('.', implode('.', array_reverse(explode(':', rtrim($http_host, '.')))));

    for ($i = count($uri) - 1; $i > 0; $i--) {

      for ($j = count($server); $j > 0; $j--) {

        $dir = implode('.', array_slice($server, -$j)) . implode('.', array_slice($uri, 0, $i));

        if (isset($sites[$dir]) && file_exists($app_root . '/sites/' . $sites[$dir])) {

          $dir = $sites[$dir];

        }

        if (file_exists($app_root . '/sites/' . $dir . '/settings.php') || (!$require_settings && file_exists($app_root . '/sites/' . $dir))) {

          return "sites/$dir";

    // Construct an identifier from pieces of the (port plus) host plus script

    // path (excluding the filename). Loop over all possibilities starting from

    // most specific, then dropping pieces from the start of the port/hostname

    // while keeping the full path, then gradually dropping pieces from the end

    // of the path... until we find a directory corresponding to the identifier.

    $path_parts = explode('/', $script_name);

    $host_parts = explode('.', implode('.', array_reverse(explode(':', rtrim($http_host, '.')))));

    for ($i = count($path_parts) - 1; $i > 0; $i--) {

      for ($j = count($host_parts); $j > 0; $j--) {

        // Assume the path has a leading slash, so the imploded path parts are

        // either a path identifier with leading dot, or an empty string.

        $site_id = implode('.', array_slice($host_parts, -$j)) . implode('.', array_slice($path_parts, 0, $i));

        // If the identifier is a key in $sites, check for a directory matching

        // the corresponding value. Otherwise, check for a directory matching

        // the identifier.

        if (isset($sites[$site_id]) && file_exists($app_root . '/sites/' . $sites[$site_id])) {

          $site_id = $sites[$site_id];

        }

        if (file_exists($app_root . '/sites/' . $site_id . '/settings.php') || (!$require_settings && file_exists($app_root . '/sites/' . $site_id))) {

          return "sites/$site_id";

        }

      }

    }