private static function extract_subdir_path( $index_path ) {
		$index_code = file_get_contents( $index_path );

		if ( ! preg_match( '|^\s*require\s*\(?\s*(.+?)/wp-blog-header\.php([\'"])|m', $index_code, $matches ) ) {
			return false;
		}

		$wp_path_src = $matches[1] . $matches[2];
		$wp_path_src = Utils\replace_path_consts( $wp_path_src, $index_path );

		$wp_path = eval( "return $wp_path_src;" ); // phpcs:ignore Squiz.PHP.Eval.Discouraged

		if ( ! Utils\is_path_absolute( $wp_path ) ) {
			$wp_path = dirname( $index_path ) . "/$wp_path";
		}

		return $wp_path;
	}