2.11BSD/src/ucb/window/wwiomux.c

#ifndef lint
static char sccsid[] = "@(#)wwiomux.c	3.15 9/19/85";
#endif

/*
 * Copyright (c) 1983 Regents of the University of California,
 * All rights reserved.  Redistribution permitted subject to
 * the terms of the Berkeley Software License Agreement.
 */

#include "ww.h"
#include <sys/time.h>
#include <sys/types.h>

/*
 * Multiple window output handler.
 * The idea is to copy window outputs to the terminal, via the
 * display package.  We try to give the top most window highest
 * priority.  The only return condition is when there is keyboard
 * input, which is serviced asynchronously by wwrint().
 * When there's nothing to do, we sleep in a select().
 * This can be done better with interrupt driven io.  But that's
 * not supported on ptys, yet.
 * The history of this routine is interesting.
 */
wwiomux()
{
	register struct ww *w;
	fd_set imask;
	register n;
	register char *p;
	char c;
	static struct timeval tv = { 0, 0 };
	char noblock;

loop:
	if (wwinterrupt())
		return;

	FD_ZERO(&imask);
	noblock = 0;
	for (w = wwhead.ww_forw; w != &wwhead; w = w->ww_forw) {
		if (w->ww_pty < 0)
			continue;
		if (w->ww_obq < w->ww_obe)
			FD_SET(w->ww_pty, &imask);
		if (w->ww_obq > w->ww_obp && !w->ww_stopped)
			noblock = 1;
	}

	if (!noblock) {
		if (wwcurwin != 0)
			wwcurtowin(wwcurwin);
		wwupdate();
		wwflush();
		if (setjmp(wwjmpbuf))
			return;
		wwsetjmp = 1;
		if (wwinterrupt()) {
			wwsetjmp = 0;
			return;
		}
	}
	wwnselect++;
	n = select(wwdtablesize, &imask, (fd_set *)0, (fd_set *)0,
		noblock ? &tv : (struct timeval *)0);
	wwsetjmp = 0;

	if (n < 0)
		wwnselecte++;
	else if (n == 0)
		wwnselectz++;
	else
		for (w = wwhead.ww_forw; w != &wwhead; w = w->ww_forw) {
			if (w->ww_pty < 0 || !FD_ISSET(w->ww_pty, &imask))
				continue;
			wwnwread++;
			p = w->ww_obq;
			if (w->ww_ispty) {
				if (p == w->ww_ob) {
					w->ww_obp++;
					w->ww_obq++;
				} else
					p--;
				c = *p;
			}
			n = read(w->ww_pty, p, w->ww_obe - p);
			if (n < 0) {
				wwnwreade++;
				(void) close(w->ww_pty);
				w->ww_pty = -1;
			} else if (n == 0) {
				wwnwreadz++;
				(void) close(w->ww_pty);
				w->ww_pty = -1;
			} else if (!w->ww_ispty) {
				wwnwreadd++;
				wwnwreadc += n;
				w->ww_obq += n;
			} else if (*p == TIOCPKT_DATA) {
				n--;
				wwnwreadd++;
				wwnwreadc += n;
				w->ww_obq += n;
			} else {
				wwnwreadp++;
				if (*p & TIOCPKT_STOP)
					w->ww_stopped = 1;
				if (*p & TIOCPKT_START)
					w->ww_stopped = 0;
				if (*p & TIOCPKT_FLUSHWRITE) {
					w->ww_stopped = 0;
					w->ww_obq = w->ww_obp = w->ww_ob;
				}
			}
			if (w->ww_ispty)
				*p = c;
		}
	for (w = wwhead.ww_forw; w != &wwhead; w = w->ww_forw)
		if (w->ww_pty >= 0 && w->ww_obq > w->ww_obp && !w->ww_stopped) {
			n = wwwrite(w, w->ww_obp, w->ww_obq - w->ww_obp);
			if ((w->ww_obp += n) == w->ww_obq)
				w->ww_obq = w->ww_obp = w->ww_ob;
			if (wwinterrupt())
				return;
			break;
		}
	goto loop;
}