RDSV3_PRINT_BUF_LEN
len += vsnprintf(msg_ptr, RDSV3_PRINT_BUF_LEN - len - 2, fmt, ap);
len = min(len, RDSV3_PRINT_BUF_LEN - 2);
static char rdsv3_print_buf[RDSV3_PRINT_BUF_LEN];