1 /* vi: set sw=4 ts=4: */
2 /*
3 * bare bones 'talk to modem' program - similar to 'cu -l $device'
4 * inspired by mgetty's microcom
5 *
6 * Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com>
7 *
8 * Licensed under GPLv2, see file LICENSE in this source tree.
9 */
10 //config:config MICROCOM
11 //config: bool "microcom (5.7 kb)"
12 //config: default y
13 //config: help
14 //config: The poor man's minicom utility for chatting with serial port devices.
15
16 //applet:IF_MICROCOM(APPLET(microcom, BB_DIR_USR_BIN, BB_SUID_DROP))
17
18 //kbuild:lib-$(CONFIG_MICROCOM) += microcom.o
19
20 //usage:#define microcom_trivial_usage
21 //usage: "[-d DELAY_MS] [-t TIMEOUT_MS ] [-s SPEED] [-X] TTY"
22 //usage:#define microcom_full_usage "\n\n"
23 //usage: "Copy bytes from stdin to TTY and from TTY to stdout\n"
24 //usage: "\n -d DELAY Wait up to DELAY ms for TTY output before sending"
25 //usage: "\n every next byte to it"
26 //usage: "\n -t TIMEOUT Exit if both stdin and TTY are silent for TIMEOUT ms"
27 //usage: "\n -s SPEED Set serial line to SPEED"
28 //usage: "\n -X Disable special meaning of NUL and Ctrl-X from stdin"
29
30 #include "libbb.h"
31 #include "common_bufsiz.h"
32
33 // set raw tty mode
xget1(int fd,struct termios * t,struct termios * oldt)34 static void xget1(int fd, struct termios *t, struct termios *oldt)
35 {
36 get_termios_and_make_raw(fd, t, oldt, 0
37 | TERMIOS_CLEAR_ISIG /* ^C is ASCII char 3, not "interrupt me!" */
38 | TERMIOS_RAW_INPUT /* pass all chars verbatim, no special handling or translating CR->NL */
39 | TERMIOS_RAW_CRNL /* dont convert NL<->CR on output too */
40 );
41 }
42
xset1(int fd,struct termios * tio,const char * device)43 static int xset1(int fd, struct termios *tio, const char *device)
44 {
45 int ret = tcsetattr(fd, TCSAFLUSH, tio);
46
47 if (ret) {
48 bb_perror_msg("can't tcsetattr for %s", device);
49 }
50 return ret;
51 }
52
53 int microcom_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
microcom_main(int argc UNUSED_PARAM,char ** argv)54 int microcom_main(int argc UNUSED_PARAM, char **argv)
55 {
56 int sfd;
57 int nfd;
58 struct pollfd pfd[2];
59 struct termios tio0, tiosfd, tio;
60 char *device_lock_file;
61 enum {
62 OPT_X = 1 << 0, // do not respect Ctrl-X, Ctrl-@
63 OPT_s = 1 << 1, // baudrate
64 OPT_d = 1 << 2, // wait for device response, ms
65 OPT_t = 1 << 3, // timeout, ms
66 };
67 speed_t speed = 9600;
68 int delay = -1;
69 int timeout = -1;
70 unsigned opts;
71
72 // fetch options
73 opts = getopt32(argv, "^" "Xs:+d:+t:+" "\0" "=1",
74 &speed, &delay, &timeout
75 );
76 // argc -= optind;
77 argv += optind;
78
79 // try to create lock file in /var/lock
80 device_lock_file = (char *)bb_basename(argv[0]);
81 device_lock_file = xasprintf("/var/lock/LCK..%s", device_lock_file);
82 sfd = open(device_lock_file, O_CREAT | O_WRONLY | O_TRUNC | O_EXCL, 0644);
83 if (sfd < 0) {
84 // device already locked -> bail out
85 if (errno == EEXIST)
86 bb_perror_msg_and_die("can't create '%s'", device_lock_file);
87 // can't create lock -> don't care
88 if (ENABLE_FEATURE_CLEAN_UP)
89 free(device_lock_file);
90 device_lock_file = NULL;
91 } else {
92 // %4d to make concurrent mgetty (if any) happy.
93 // Mgetty treats 4-bytes lock files as binary,
94 // not text, PID. Making 5+ char file. Brrr...
95 fdprintf(sfd, "%4d\n", getpid());
96 close(sfd);
97 }
98
99 // setup signals
100 bb_signals(0
101 + (1 << SIGHUP)
102 + (1 << SIGINT)
103 + (1 << SIGTERM)
104 + (1 << SIGPIPE)
105 , record_signo);
106
107 // error exit code if we fail to open the device
108 bb_got_signal = 1;
109
110 // open device
111 sfd = open_or_warn(argv[0], O_RDWR | O_NOCTTY | O_NONBLOCK);
112 if (sfd < 0)
113 goto done;
114 fcntl(sfd, F_SETFL, O_RDWR);
115
116 // put device to "raw mode"
117 xget1(sfd, &tio, &tiosfd);
118 // set device speed
119 cfsetspeed(&tio, tty_value_to_baud(speed));
120 if (xset1(sfd, &tio, argv[0]))
121 goto done;
122
123 // put stdin to "raw mode" (if stdin is a TTY),
124 // handle one character at a time
125 if (isatty(STDIN_FILENO)) {
126 xget1(STDIN_FILENO, &tio, &tio0);
127 if (xset1(STDIN_FILENO, &tio, "stdin"))
128 goto done;
129 }
130
131 // main loop: check with poll(), then read/write bytes across
132 pfd[0].fd = sfd;
133 pfd[0].events = POLLIN;
134 pfd[1].fd = STDIN_FILENO;
135 pfd[1].events = POLLIN;
136
137 bb_got_signal = 0;
138 nfd = 2;
139 // Not safe_poll: we want to exit on signal
140 while (!bb_got_signal && poll(pfd, nfd, timeout) > 0) {
141 if (nfd > 1 && pfd[1].revents) {
142 char c;
143 // read from stdin -> write to device
144 if (safe_read(STDIN_FILENO, &c, 1) < 1) {
145 // don't poll stdin anymore if we got EOF/error
146 nfd--;
147 goto skip_write;
148 }
149 // do we need special processing?
150 if (!(opts & OPT_X)) {
151 // ^@ sends Break
152 if (VINTR == c) {
153 tcsendbreak(sfd, 0);
154 goto skip_write;
155 }
156 // ^X exits
157 if (24 == c)
158 break;
159 }
160 write(sfd, &c, 1);
161 if (delay >= 0)
162 safe_poll(pfd, 1, delay);
163 skip_write: ;
164 }
165 if (pfd[0].revents) {
166 ssize_t len;
167 #define iobuf bb_common_bufsiz1
168 setup_common_bufsiz();
169 // read from device -> write to stdout
170 len = safe_read(sfd, iobuf, COMMON_BUFSIZE);
171 if (len > 0)
172 full_write(STDOUT_FILENO, iobuf, len);
173 else {
174 // EOF/error -> bail out
175 bb_got_signal = SIGHUP;
176 break;
177 }
178 }
179 }
180
181 // restore device mode
182 tcsetattr(sfd, TCSAFLUSH, &tiosfd);
183
184 if (isatty(STDIN_FILENO))
185 tcsetattr(STDIN_FILENO, TCSAFLUSH, &tio0);
186
187 done:
188 if (device_lock_file)
189 unlink(device_lock_file);
190
191 return bb_got_signal;
192 }
193