Function ttydev_open

components/lwp/terminal/freebsd/tty.c:258–371

* Operations that are exposed through the character device in /dev. */

 * Operations that are exposed through the character device in /dev.
 */
static int ttydev_open(struct lwp_tty *tp, int oflags, int devtype,
                       struct rt_thread *td)
{
    rt_device_t dev = &tp->parent;
    int error;

    error = 0;
    tty_lock(tp);
    if (tty_gone(tp))
    {
        /* Device is already gone. */
        tty_unlock(tp);
        return -ENXIO;
    }

    /*
     * Block when other processes are currently opening or closing
     * the TTY.
     */
    while (tp->t_flags & TF_OPENCLOSE)
    {
        error = tty_wait(tp, &tp->t_dcdwait);
        if (error != 0)
        {
            tty_unlock(tp);
            return error;
        }
    }
    tp->t_flags |= TF_OPENCLOSE;

    /*
     * Make sure the "tty" and "cua" device cannot be opened at the
     * same time.  The console is a "tty" device.
     */
    if (TTY_CALLOUT(tp, dev))
    {
        if (tp->t_flags & (TF_OPENED_CONS | TF_OPENED_IN))
        {
            error = EBUSY;
            goto done;
        }
    }
    else
    {
        if (tp->t_flags & TF_OPENED_OUT)
        {
            error = EBUSY;
            goto done;
        }
    }

    if (tp->t_flags & TF_EXCLUDE && priv_check(td, PRIV_TTY_EXCLUSIVE))
    {
        error = EBUSY;
        goto done;
    }

    if (!tty_opened(tp))