summaryrefslogtreecommitdiff
path: root/miscutils/microcom.c
blob: 817ef55ac292e0e89ec55f4f5979b6388e8da3ca (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
/* vi: set sw=4 ts=4: */
/*
 * bare bones 'talk to modem' program - similar to 'cu -l $device'
 * inspired by mgetty's microcom
 *
 * Copyright (C) 2007 by Vladimir Dronnikov <dronnikov@gmail.ru>
 *
 * Licensed under GPLv2, see file LICENSE in this tarball for details.
 */
#include "libbb.h"

/* All known arches use small ints for signals */
static volatile smallint signalled;

static void signal_handler(int signo)
{
	signalled = signo;
}

// set raw tty mode
static void xget1(int fd, struct termios *t, struct termios *oldt)
{ 
	tcgetattr(fd, oldt);
	*t = *oldt;
	cfmakeraw(t);
//	t->c_lflag &= ~(ISIG|ICANON|ECHO|IEXTEN);
//	t->c_iflag &= ~(BRKINT|IXON|ICRNL);
//	t->c_oflag &= ~(ONLCR);
//	t->c_cc[VMIN]  = 1;
//	t->c_cc[VTIME] = 0;
}

static int xset1(int fd, struct termios *tio, const char *device)
{
	int ret = tcsetattr(fd, TCSAFLUSH, tio);

	if (ret) {
		bb_perror_msg("can't tcsetattr for %s", device);
	}
	return ret;
}

int microcom_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int microcom_main(int argc, char **argv)
{
	int sfd;
	int nfd;
	struct pollfd pfd[2];
	struct termios tio0, tiosfd, tio;
	char *device_lock_file;
	enum {
		OPT_X = 1 << 0, // do not respect Ctrl-X, Ctrl-@
		OPT_s = 1 << 1, // baudrate
		OPT_d = 1 << 2, // wait for device response, msecs
		OPT_t = 1 << 3, // timeout, ms
	};
	speed_t speed = 9600;
	int delay = -1;
	int timeout = -1;

	// fetch options
	char *opt_s;
	char *opt_d;
	char *opt_t;
	unsigned opts;
	opt_complementary = "=1"; /* exactly one arg should be there */
	opts = getopt32(argv, "Xs:d:t:", &opt_s, &opt_d, &opt_t);

	// apply options
	if (opts & OPT_s)
		speed = xatoi_u(opt_s);
	if (opts & OPT_d)
		delay = xatoi_u(opt_d);
	if (opts & OPT_t)
		timeout = xatoi_u(opt_t);

//	argc -= optind;
	argv += optind;

	// try to create lock file in /var/lock
	device_lock_file = (char *)bb_basename(argv[0]);
	device_lock_file = xasprintf("/var/lock/LCK..%s", device_lock_file);
	sfd = open(device_lock_file, O_CREAT | O_WRONLY | O_TRUNC | O_EXCL, 0644);
	if (sfd < 0) {
		if (errno == EEXIST)
			bb_perror_msg_and_die("can't create %s", device_lock_file);
		if (ENABLE_FEATURE_CLEAN_UP)
			free(device_lock_file);
		device_lock_file = NULL;
	}
	if (sfd > 0) {
		// %4d to make mgetty happy. It treats 4-bytes lock files as binary,
		// not text, PID. Making 5+ char file. Brrr...
		char *s = xasprintf("%4d\n", getpid());
		write(sfd, s, strlen(s));
		if (ENABLE_FEATURE_CLEAN_UP)
			free(s);
		close(sfd);
	}

	// setup signals
	sig_catch(SIGHUP,  signal_handler);
	sig_catch(SIGINT,  signal_handler);
	sig_catch(SIGTERM, signal_handler);
	sig_catch(SIGPIPE, signal_handler);

	// error exit code if we fail to open the device
	signalled = 1;

	// open device
	sfd = open_or_warn(argv[0], O_RDWR | O_NOCTTY | O_NONBLOCK);
	if (sfd < 0)
		goto done;
	fcntl(sfd, F_SETFL, O_RDWR | O_NOCTTY);

	// put stdin to "raw mode" (if stdin is a TTY),
	// handle one character at a time
	if (isatty(STDIN_FILENO)) {
		xget1(STDIN_FILENO, &tio, &tio0);
		if (xset1(STDIN_FILENO, &tio, "stdin"))
			goto done;
	}

	// same thing for modem
	xget1(sfd, &tio, &tiosfd);
	// order device to hang up at exit
	tio.c_cflag |= (CREAD|HUPCL);
//	if (!istty)
//		tio.c_iflag |= (IGNCR);
	// set device speed
	cfsetspeed(&tio, tty_value_to_baud(speed));
	if (xset1(sfd, &tio, argv[0]))
		goto restore0_and_done;

	// main loop: check with poll(), then read/write bytes across
	pfd[0].fd = sfd;
	pfd[0].events = POLLIN;
	pfd[1].fd = STDIN_FILENO;
	pfd[1].events = POLLIN;

	signalled = 0;
	nfd = 2;
	while (!signalled && safe_poll(pfd, nfd, timeout) > 0) {
		char c;
		if (pfd[0].revents) {
serial_ready:
			// read from device -> write to stdout
			if (safe_read(sfd, &c, 1) > 0)
				write(STDOUT_FILENO, &c, 1);
			// else { EOF/error - what to do? }
		}
		if (pfd[1].revents) {
			pfd[1].revents = 0;
			// read from stdin -> write to device
			if (safe_read(STDIN_FILENO, &c, 1) < 1) {
				// don't poll stdin anymore if we got EOF/error
				nfd--;
				continue;
			}
			// do we need special processing?
			if (!(opts & OPT_X)) {
				// ^@ sends Break
				if (VINTR == c) {
					tcsendbreak(sfd, 0);
					continue;
				}
				// ^X exits
				if (24 == c)
					break;
			}
			write(sfd, &c, 1);
			if (delay >= 0 && safe_poll(pfd, 1, delay) > 0)
				goto serial_ready;
		}
	}

	tcsetattr(sfd, TCSAFLUSH, &tiosfd);

restore0_and_done:
	if (isatty(STDIN_FILENO))
		tcsetattr(STDIN_FILENO, TCSAFLUSH, &tio0);

done:
	if (device_lock_file)
		unlink(device_lock_file);

	return signalled;
}