extern boost::optional<boost::filesystem::path> relative_to_root (boost::filesystem::path root, boost::filesystem::path file);
extern std::string file_to_string (boost::filesystem::path, uintmax_t max_length = 1048576);
extern boost::optional<boost::filesystem::path> relative_to_root (boost::filesystem::path root, boost::filesystem::path file);
extern std::string file_to_string (boost::filesystem::path, uintmax_t max_length = 1048576);