extern void checked_fread (void* ptr, size_t size, FILE* stream, boost::filesystem::path path);
extern void checked_fwrite (void const * ptr, size_t size, FILE* stream, boost::filesystem::path path);
extern size_t utf8_strlen (std::string s);
extern void checked_fread (void* ptr, size_t size, FILE* stream, boost::filesystem::path path);
extern void checked_fwrite (void const * ptr, size_t size, FILE* stream, boost::filesystem::path path);
extern size_t utf8_strlen (std::string s);