xref: /dragonfly/usr.bin/window/wwiomux.c (revision 19fe1c42)
1 /*
2  * Copyright (c) 1983, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * This code is derived from software contributed to Berkeley by
6  * Edward Wang at The University of California, Berkeley.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. All advertising materials mentioning features or use of this software
17  *    must display the following acknowledgement:
18  *	This product includes software developed by the University of
19  *	California, Berkeley and its contributors.
20  * 4. Neither the name of the University nor the names of its contributors
21  *    may be used to endorse or promote products derived from this software
22  *    without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34  * SUCH DAMAGE.
35  *
36  * @(#)wwiomux.c	8.1 (Berkeley) 6/6/93
37  * $FreeBSD: src/usr.bin/window/wwiomux.c,v 1.1.1.1.14.1 2001/05/17 09:45:01 obrien Exp $
38  * $DragonFly: src/usr.bin/window/wwiomux.c,v 1.3 2008/05/19 10:19:49 corecode Exp $
39  */
40 
41 #include "ww.h"
42 #include <sys/time.h>
43 #include <sys/types.h>
44 #include <sys/select.h>
45 #if !defined(OLD_TTY) && !defined(TIOCPKT_DATA)
46 #include <sys/ioctl.h>
47 #endif
48 #include <fcntl.h>
49 
50 /*
51  * Multiple window output handler.
52  * The idea is to copy window outputs to the terminal, via the
53  * display package.  We try to give wwcurwin highest priority.
54  * The only return conditions are when there is keyboard input
55  * and when a child process dies, which are serviced by signal
56  * catchers (wwrint() and wwchild()).
57  * When there's nothing to do, we sleep in a select().
58  * This can be done better with interrupt driven io.  But that's
59  * not supported on ptys, yet.
60  * The history of this routine is interesting.
61  */
62 wwiomux()
63 {
64 	register struct ww *w;
65 	fd_set imask;
66 	register n;
67 	register char *p;
68 	char c;
69 	struct timeval tv;
70 	char noblock = 0;
71 
72 	for (;;) {
73 		if (wwinterrupt()) {
74 			wwclrintr();
75 			return;
76 		}
77 
78 		FD_ZERO(&imask);
79 		n = -1;
80 		for (w = wwhead.ww_forw; w != &wwhead; w = w->ww_forw) {
81 			if (w->ww_pty < 0)
82 				continue;
83 			if (w->ww_obq < w->ww_obe) {
84 				if (w->ww_pty > n)
85 					n = w->ww_pty;
86 				FD_SET(w->ww_pty, &imask);
87 			}
88 			if (w->ww_obq > w->ww_obp && !w->ww_stopped)
89 				noblock = 1;
90 		}
91 
92 		if (!noblock) {
93 			if (wwcurwin != 0)
94 				wwcurtowin(wwcurwin);
95 			wwupdate();
96 			wwflush();
97 			(void) setjmp(wwjmpbuf);
98 			wwsetjmp = 1;
99 			if (wwinterrupt()) {
100 				wwsetjmp = 0;
101 				wwclrintr();
102 				return;
103 			}
104 			/*
105 			 * Defensive code.  If somebody else (for example,
106 			 * wall) clears the ASYNC flag on us, we will block
107 			 * forever.  So we need a finite timeout and set
108 			 * the flag again.  Anything more clever will probably
109 			 * need even more system calls.  (This is a bug
110 			 * in the kernel.)
111 			 * I don't like this one bit.
112 			 */
113 			(void) fcntl(0, F_SETFL, wwnewtty.ww_fflags);
114 			tv.tv_sec = 30;
115 			tv.tv_usec = 0;
116 		} else {
117 			tv.tv_sec = 0;
118 			tv.tv_usec = 10000;
119 		}
120 		wwnselect++;
121 		n = select(n + 1, &imask, (fd_set *)0, (fd_set *)0, &tv);
122 		wwsetjmp = 0;
123 		noblock = 0;
124 
125 		if (n < 0)
126 			wwnselecte++;
127 		else if (n == 0)
128 			wwnselectz++;
129 		else
130 			for (w = wwhead.ww_forw; w != &wwhead; w = w->ww_forw) {
131 				if (w->ww_pty < 0 ||
132 				    !FD_ISSET(w->ww_pty, &imask))
133 					continue;
134 				wwnwread++;
135 				p = w->ww_obq;
136 				if (w->ww_ispty) {
137 					if (p == w->ww_ob) {
138 						w->ww_obp++;
139 						w->ww_obq++;
140 					} else
141 						p--;
142 					c = *p;
143 				}
144 				n = read(w->ww_pty, p, w->ww_obe - p);
145 				if (n < 0) {
146 					wwnwreade++;
147 					(void) close(w->ww_pty);
148 					w->ww_pty = -1;
149 				} else if (n == 0) {
150 					wwnwreadz++;
151 					(void) close(w->ww_pty);
152 					w->ww_pty = -1;
153 				} else if (!w->ww_ispty) {
154 					wwnwreadd++;
155 					wwnwreadc += n;
156 					w->ww_obq += n;
157 				} else if (*p == TIOCPKT_DATA) {
158 					n--;
159 					wwnwreadd++;
160 					wwnwreadc += n;
161 					w->ww_obq += n;
162 				} else {
163 					wwnwreadp++;
164 					if (*p & TIOCPKT_STOP)
165 						w->ww_stopped = 1;
166 					if (*p & TIOCPKT_START)
167 						w->ww_stopped = 0;
168 					if (*p & TIOCPKT_FLUSHWRITE) {
169 						w->ww_stopped = 0;
170 						w->ww_obq = w->ww_obp =
171 							w->ww_ob;
172 					}
173 				}
174 				if (w->ww_ispty)
175 					*p = c;
176 			}
177 		/*
178 		 * Try the current window first, if there is output
179 		 * then process it and go back to the top to try again.
180 		 * This can lead to starvation of the other windows,
181 		 * but presumably that what we want.
182 		 * Update will eventually happen when output from wwcurwin
183 		 * dies down.
184 		 */
185 		if ((w = wwcurwin) != 0 && w->ww_pty >= 0 &&
186 		    w->ww_obq > w->ww_obp && !w->ww_stopped) {
187 			n = wwwrite(w, w->ww_obp, w->ww_obq - w->ww_obp);
188 			if ((w->ww_obp += n) == w->ww_obq)
189 				w->ww_obq = w->ww_obp = w->ww_ob;
190 			noblock = 1;
191 			continue;
192 		}
193 		for (w = wwhead.ww_forw; w != &wwhead; w = w->ww_forw)
194 			if (w->ww_pty >= 0 && w->ww_obq > w->ww_obp &&
195 			    !w->ww_stopped) {
196 				n = wwwrite(w, w->ww_obp,
197 					w->ww_obq - w->ww_obp);
198 				if ((w->ww_obp += n) == w->ww_obq)
199 					w->ww_obq = w->ww_obp = w->ww_ob;
200 				if (wwinterrupt())
201 					break;
202 			}
203 	}
204 }
205