extern int asnprintf (char **ptr, size_t str_m, const char *fmt, /*args*/ ...);
extern int vasnprintf(char **ptr, size_t str_m, const char *fmt, va_list ap);
extern int asnprintf (char **ptr, size_t str_m, const char *fmt, /*args*/ ...);
extern int vasnprintf(char **ptr, size_t str_m, const char *fmt, va_list ap);