MAX_BPRINTF_BUF
char buf[MAX_BPRINTF_BUF];
ret = bstr_printf(data.buf, MAX_BPRINTF_BUF, fmt__str, data.bin_args);
ret = bstr_printf(data.buf, MAX_BPRINTF_BUF, fmt, data.bin_args);
ret = bstr_printf(data.buf, MAX_BPRINTF_BUF, fmt, data.bin_args);