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 #include <sys/ioctl.h>
32 #include <sys/time.h>
33 #include <err.h>
34 #include <errno.h>
35 #include <fcntl.h>
36 #include <stdio.h>
37 #include <stdlib.h>
38 #include <strings.h>
39 #include <termios.h>
40 #include <unistd.h>
41
42 /* screen doesn't support ESC[18t (return terminal size) so do it the hard way */
43 static const char query[] =
44 "\0337" /* Save cursor position */
45 "\033[r" /* Scroll whole screen */
46 "\033[999;999H" /* Move cursor */
47 "\033[6n" /* Get cursor position */
48 "\0338"; /* Restore cursor position */
49
50 static void
usage(void)51 usage(void)
52 {
53
54 fprintf(stderr, "usage: resizewin [-z]\n");
55 exit(1);
56 }
57
58 int
main(int argc,char ** argv)59 main(int argc, char **argv)
60 {
61 struct termios old, new;
62 struct winsize w;
63 struct timeval then, now;
64 char data[20];
65 int ch, cnt, error, fd, ret, zflag;
66
67 error = 0;
68 zflag = 0;
69 while ((ch = getopt(argc, argv, "z")) != -1) {
70 switch (ch) {
71 case 'z':
72 zflag = 1;
73 break;
74 case '?':
75 default:
76 usage();
77 }
78 }
79 argc -= optind;
80 if (argc != 0)
81 usage();
82
83 if ((fd = open("/dev/tty", O_RDWR | O_NONBLOCK)) == -1)
84 exit(1);
85
86 if (zflag) {
87 if (ioctl(fd, TIOCGWINSZ, &w) == -1)
88 exit(1);
89 if (w.ws_row != 0 && w.ws_col != 0)
90 exit(0);
91 }
92
93 /* Disable echo, flush the input, and drain the output */
94 if (tcgetattr(fd, &old) == -1)
95 exit(1);
96
97 new = old;
98 new.c_cflag |= (CLOCAL | CREAD);
99 new.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
100 if (tcsetattr(fd, TCSAFLUSH, &new) == -1)
101 exit(1);
102
103 if (write(fd, query, sizeof(query) - 1) != sizeof(query) - 1) {
104 error = 1;
105 goto out;
106 }
107
108 /* Read the response */
109 bzero(data, sizeof(data));
110 gettimeofday(&then, NULL);
111 cnt = 0;
112 while (1) {
113 ret = read(fd, data + cnt, 1);
114
115 if (ret == -1) {
116 if (errno == EAGAIN) {
117 gettimeofday(&now, NULL);
118 timersub(&now, &then, &now);
119 if (now.tv_sec >= 2) {
120 warnx("timeout reading from terminal");
121 error = 1;
122 goto out;
123 }
124
125 usleep(20000);
126 continue;
127 }
128 error = 1;
129 goto out;
130 }
131 if (data[cnt] == 'R')
132 break;
133
134 cnt++;
135 if (cnt == sizeof(data) - 2) {
136 warnx("response too long");
137 error = 1;
138 goto out;
139 }
140 }
141
142 /* Parse */
143 if (sscanf(data, "\033[%hu;%huR", &w.ws_row, &w.ws_col) != 2) {
144 error = 1;
145 warnx("unable to parse response");
146 goto out;
147 }
148
149 /* Finally, what we want */
150 if (ioctl(fd, TIOCSWINSZ, &w) == -1)
151 error = 1;
152 out:
153 /* Restore echo */
154 tcsetattr(fd, TCSANOW, &old);
155
156 close(fd);
157 exit(error);
158 }
159