usr/src/usr.bin/window/wwiomux.c

#ifndef lint
static char sccsid[] = "@(#)wwiomux.c   3.14 %G%";
#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>

/*
 * 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;
        int imask;
        register n;
        register char *p;
        char c;
        static struct timeval tv = { 0, 0 };
        char noblock;

loop:
        if (wwinterrupt())
                return;

        imask = 0;
        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)
                        imask |= 1 << w->ww_pty;
                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, (int *)0, (int *)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 || (imask & 1 << w->ww_pty) == 0)
                                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;
}