1/*
2 * resizewin
3 *
4 * Query terminal for size and inform the kernel
5 *
6 * Copyright 2015 EMC / Isilon Storage Division
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 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#include <sys/cdefs.h>
31__FBSDID("$FreeBSD: stable/11/usr.bin/resizewin/resizewin.c 324263 2017-10-04 11:39:44Z trasz $");
32#include <sys/ioctl.h>
33#include <sys/time.h>
34#include <err.h>
35#include <errno.h>
36#include <fcntl.h>
37#include <stdio.h>
38#include <stdlib.h>
39#include <strings.h>
40#include <termios.h>
41#include <unistd.h>
42
43/* screen doesn't support ESC[18t (return terminal size) so do it the hard way */
44static const char query[] =
45    "\0337"		/* Save cursor position */
46    "\033[r"		/* Scroll whole screen */
47    "\033[999;999H"	/* Move cursor */
48    "\033[6n"		/* Get cursor position */
49    "\0338";		/* Restore cursor position */
50
51static void
52usage(void)
53{
54
55	fprintf(stderr, "usage: resizewin [-z]\n");
56	exit(1);
57}
58
59int
60main(int argc, char **argv)
61{
62	struct termios old, new;
63	struct winsize w;
64	struct timeval then, now;
65	char data[20];
66	int ch, cnt, error, fd, ret, zflag;
67
68	error = 0;
69	zflag = 0;
70	while ((ch = getopt(argc, argv, "z")) != -1) {
71		switch (ch) {
72		case 'z':
73			zflag = 1;
74			break;
75		case '?':
76		default:
77			usage();
78		}
79	}
80	argc -= optind;
81	if (argc != 0)
82		usage();
83
84	if ((fd = open("/dev/tty", O_RDWR | O_NONBLOCK)) == -1)
85		exit(1);
86
87	if (zflag) {
88		if (ioctl(fd, TIOCGWINSZ, &w) == -1)
89			exit(1);
90		if (w.ws_row != 0 && w.ws_col != 0)
91			exit(0);
92	}
93
94	/* Disable echo, flush the input, and drain the output */
95	if (tcgetattr(fd, &old) == -1)
96		exit(1);
97
98	new = old;
99	new.c_cflag |= (CLOCAL | CREAD);
100	new.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
101	if (tcsetattr(fd, TCSAFLUSH, &new) == -1)
102		exit(1);
103
104	if (write(fd, query, sizeof(query)) != sizeof(query)) {
105		error = 1;
106		goto out;
107	}
108
109	/* Read the response */
110	bzero(data, sizeof(data));
111	gettimeofday(&then, NULL);
112	cnt = 0;
113	while (1) {
114		ret = read(fd, data + cnt, 1);
115
116		if (ret == -1) {
117			if (errno == EAGAIN) {
118				gettimeofday(&now, NULL);
119				timersub(&now, &then, &now);
120				if (now.tv_sec >= 2) {
121					warnx("timeout reading from terminal");
122					error = 1;
123					goto out;
124				}
125
126				usleep(20000);
127				continue;
128			}
129			error = 1;
130			goto out;
131		}
132		if (data[cnt] == 'R')
133			break;
134
135		cnt++;
136		if (cnt == sizeof(data) - 2) {
137			warnx("response too long");
138			error = 1;
139			goto out;
140		}
141	}
142
143	/* Parse */
144	if (sscanf(data, "\033[%hu;%huR", &w.ws_row, &w.ws_col) != 2) {
145		error = 1;
146		warnx("unable to parse response");
147		goto out;
148	}
149
150	/* Finally, what we want */
151	if (ioctl(fd, TIOCSWINSZ, &w) == -1)
152		error = 1;
153 out:
154	/* Restore echo */
155	tcsetattr(fd, TCSANOW, &old);
156
157	close(fd);
158	exit(error);
159}
160