4.3BSD-Reno/src/usr.bin/window/wwrint.c

/*
 * Copyright (c) 1983 Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Edward Wang at The University of California, Berkeley.
 *
 * Redistribution and use in source and binary forms are permitted provided
 * that: (1) source distributions retain this entire copyright notice and
 * comment, and (2) distributions including binaries display the following
 * acknowledgement:  ``This product includes software developed by the
 * University of California, Berkeley and its contributors'' in the
 * documentation or other materials provided with the distribution and in
 * all advertising materials mentioning features or use of this software.
 * Neither the name of the University nor the names of its contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#ifndef lint
static char sccsid[] = "@(#)wwrint.c	3.10 (Berkeley) 6/6/90";
#endif /* not lint */

#include "ww.h"
#include <fcntl.h>

/*
 * Tty input interrupt handler.
 * (1) Read input into buffer (wwib*).
 * (2) Set the interrupt flag if anything is read.
 * Currently, the last is used to get out of the blocking
 * select() in wwiomux().
 * To avoid race conditions, we only modify wwibq in here, except
 * when the buffer is empty; and everywhere else, we only change wwibp.
 * It should be completely safe.
 */
wwrint()
{
	register n;

	if (wwibp == wwibq)
		wwibp = wwibq = wwib;
	wwnread++;
	(void) fcntl(0, F_SETFL, FNDELAY|wwnewtty.ww_fflags);
	n = read(0, wwibq, wwibe - wwibq);
	(void) fcntl(0, F_SETFL, wwnewtty.ww_fflags);
	if (n > 0) {
		wwibq += n;
		wwnreadc += n;
		wwsetintr();
	} else if (n == 0)
		wwnreadz++;
	else
		wwnreade++;
}