WP Sunrise file for nested subdirectory multisite installation.

sunrise.php

<?php

if ( defined( 'DOMAIN_CURRENT_SITE' ) && defined( 'PATH_CURRENT_SITE' ) ) {
    $current_site->id = (defined( 'SITE_ID_CURRENT_SITE' ) ? constant('SITE_ID_CURRENT_SITE') : 1);
    $current_site->domain = $domain = DOMAIN_CURRENT_SITE;
    $current_site->path  = $path = PATH_CURRENT_SITE;

    if ( defined( 'BLOGID_CURRENT_SITE' ) )
        $current_site->blog_id = BLOGID_CURRENT_SITE;

    $url = parse_url( $_SERVER['REQUEST_URI'], PHP_URL_PATH );

    $patharray = (array) explode( '/', trim( $url, '/' ));
    $blogsearch = '';

    if ( count( $patharray )){
        foreach( $patharray as $pathpart ){
            $pathsearch .= '/'. $pathpart;
            $blogsearch .= $wpdb->prepare(" OR (domain = %s AND path = %s) ", $domain, $pathsearch .'/' );
        }
    }

    $current_blog = $wpdb->get_row( $wpdb->prepare("SELECT *, LENGTH( path ) as pathlen FROM $wpdb->blogs WHERE domain = %s AND path = '/'", $domain, $path) . $blogsearch .'ORDER BY pathlen DESC LIMIT 1');

    $blog_id = $current_blog->blog_id;
    $public  = $current_blog->public;
    $site_id = $current_blog->site_id;

    $current_site = pu_get_current_site_name( $current_site );
}

function pu_get_current_site_name( $current_site ) {
    global $wpdb;
    $current_site->site_name = wp_cache_get( $current_site->id . ':current_site_name', "site-options" );
    if ( !$current_site->site_name ) {
        $current_site->site_name = $wpdb->get_var( $wpdb->prepare( "SELECT meta_value FROM $wpdb->sitemeta WHERE site_id = %d AND meta_key = 'site_name'", $current_site->id ) );
        if ( $current_site->site_name == null )
            $current_site->site_name = ucfirst( $current_site->domain );
        wp_cache_set( $current_site->id . ':current_site_name', $current_site->site_name, 'site-options');
    }
    return $current_site;
}