Function ptsdev_write

freebsd/kern/tty_pts.c:187–258

}

static int
ptsdev_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
    int flags, struct thread *td)
{
	struct tty *tp = fp->f_data;
	struct pts_softc *psc = tty_softc(tp);
	char ib[256], *ibstart;
	size_t iblen, rintlen;
	int error = 0;

	if (uio->uio_resid == 0)
		return (0);

	for (;;) {
		ibstart = ib;
		iblen = MIN(uio->uio_resid, sizeof ib);
		error = uiomove(ib, iblen, uio);

		tty_lock(tp);
		if (error != 0) {
			iblen = 0;
			goto done;
		}

		/*
		 * When possible, avoid the slow path. rint_bypass()
		 * copies all input to the input queue at once.
		 */
		MPASS(iblen > 0);
		do {
			rintlen = ttydisc_rint_simple(tp, ibstart, iblen);
			ibstart += rintlen;
			iblen -= rintlen;
			if (iblen == 0) {
				/* All data written. */
				break;
			}

			/* Maybe the device isn't used anyway. */
			if (psc->pts_flags & PTS_FINISHED) {
				error = EIO;
				goto done;
			}

			/* Wait for more data. */
			if (fp->f_flag & O_NONBLOCK) {
				error = EWOULDBLOCK;
				goto done;
			}

			/* Wake up users on the slave side. */
			ttydisc_rint_done(tp);
			error = cv_wait_sig(&psc->pts_inwait, tp->t_mtx);
			if (error != 0)
				goto done;
		} while (iblen > 0);

		if (uio->uio_resid == 0)