reply_line(conn c, int state, const char *fmt, ...)
{
    int r;
    va_list ap;

    va_start(ap, fmt);
    r = vsnprintf(c->reply_buf, LINE_BUF_SIZE, fmt, ap);
    va_end(ap);

    /* Make sure the buffer was big enough. If not, we have a bug. */
    if (r >= LINE_BUF_SIZE) return reply_serr(c, MSG_INTERNAL_ERROR);

    return reply(c, c->reply_buf, r, state);
}

Unknown