extern int ust_safe_vsnprintf(char *str, size_t n, const char *fmt, va_list ap);
extern int ust_safe_snprintf(char *str, size_t n, const char *fmt, ...);
extern int ust_safe_vsnprintf(char *str, size_t n, const char *fmt, va_list ap);
extern int ust_safe_snprintf(char *str, size_t n, const char *fmt, ...);