blob: 5e29a1acdd483ba51e4382807c24685f8aa1b577
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 | |
11 | //usage:#define microcom_trivial_usage |
12 | //usage: "[-d DELAY] [-t TIMEOUT] [-s SPEED] [-X] TTY" |
13 | //usage:#define microcom_full_usage "\n\n" |
14 | //usage: "Copy bytes for stdin to TTY and from TTY to stdout\n" |
15 | //usage: "\n -d Wait up to DELAY ms for TTY output before sending every" |
16 | //usage: "\n next byte to it" |
17 | //usage: "\n -t Exit if both stdin and TTY are silent for TIMEOUT ms" |
18 | //usage: "\n -s Set serial line to SPEED" |
19 | //usage: "\n -X Disable special meaning of NUL and Ctrl-X from stdin" |
20 | |
21 | #include "libbb.h" |
22 | |
23 | // set raw tty mode |
24 | static void xget1(int fd, struct termios *t, struct termios *oldt) |
25 | { |
26 | tcgetattr(fd, oldt); |
27 | *t = *oldt; |
28 | cfmakeraw(t); |
29 | // t->c_lflag &= ~(ISIG|ICANON|ECHO|IEXTEN); |
30 | // t->c_iflag &= ~(BRKINT|IXON|ICRNL); |
31 | // t->c_oflag &= ~(ONLCR); |
32 | // t->c_cc[VMIN] = 1; |
33 | // t->c_cc[VTIME] = 0; |
34 | } |
35 | |
36 | static int xset1(int fd, struct termios *tio, const char *device) |
37 | { |
38 | int ret = tcsetattr(fd, TCSAFLUSH, tio); |
39 | |
40 | if (ret) { |
41 | bb_perror_msg("can't tcsetattr for %s", device); |
42 | } |
43 | return ret; |
44 | } |
45 | |
46 | int microcom_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
47 | int microcom_main(int argc UNUSED_PARAM, char **argv) |
48 | { |
49 | int sfd; |
50 | int nfd; |
51 | struct pollfd pfd[2]; |
52 | struct termios tio0, tiosfd, tio; |
53 | char *device_lock_file; |
54 | enum { |
55 | OPT_X = 1 << 0, // do not respect Ctrl-X, Ctrl-@ |
56 | OPT_s = 1 << 1, // baudrate |
57 | OPT_d = 1 << 2, // wait for device response, ms |
58 | OPT_t = 1 << 3, // timeout, ms |
59 | }; |
60 | speed_t speed = 9600; |
61 | int delay = -1; |
62 | int timeout = -1; |
63 | unsigned opts; |
64 | |
65 | // fetch options |
66 | opt_complementary = "=1:s+:d+:t+"; // exactly one arg, numeric options |
67 | opts = getopt32(argv, "Xs:d:t:", &speed, &delay, &timeout); |
68 | // argc -= optind; |
69 | argv += optind; |
70 | |
71 | // try to create lock file in /var/lock |
72 | device_lock_file = (char *)bb_basename(argv[0]); |
73 | device_lock_file = xasprintf("/var/lock/LCK..%s", device_lock_file); |
74 | sfd = open(device_lock_file, O_CREAT | O_WRONLY | O_TRUNC | O_EXCL, 0644); |
75 | if (sfd < 0) { |
76 | // device already locked -> bail out |
77 | if (errno == EEXIST) |
78 | bb_perror_msg_and_die("can't create '%s'", device_lock_file); |
79 | // can't create lock -> don't care |
80 | if (ENABLE_FEATURE_CLEAN_UP) |
81 | free(device_lock_file); |
82 | device_lock_file = NULL; |
83 | } else { |
84 | // %4d to make concurrent mgetty (if any) happy. |
85 | // Mgetty treats 4-bytes lock files as binary, |
86 | // not text, PID. Making 5+ char file. Brrr... |
87 | fdprintf(sfd, "%4d\n", getpid()); |
88 | close(sfd); |
89 | } |
90 | |
91 | // setup signals |
92 | bb_signals(0 |
93 | + (1 << SIGHUP) |
94 | + (1 << SIGINT) |
95 | + (1 << SIGTERM) |
96 | + (1 << SIGPIPE) |
97 | , record_signo); |
98 | |
99 | // error exit code if we fail to open the device |
100 | bb_got_signal = 1; |
101 | |
102 | // open device |
103 | sfd = open_or_warn(argv[0], O_RDWR | O_NOCTTY | O_NONBLOCK); |
104 | if (sfd < 0) |
105 | goto done; |
106 | fcntl(sfd, F_SETFL, O_RDWR); |
107 | |
108 | // put device to "raw mode" |
109 | xget1(sfd, &tio, &tiosfd); |
110 | // set device speed |
111 | cfsetspeed(&tio, tty_value_to_baud(speed)); |
112 | if (xset1(sfd, &tio, argv[0])) |
113 | goto done; |
114 | |
115 | // put stdin to "raw mode" (if stdin is a TTY), |
116 | // handle one character at a time |
117 | if (isatty(STDIN_FILENO)) { |
118 | xget1(STDIN_FILENO, &tio, &tio0); |
119 | if (xset1(STDIN_FILENO, &tio, "stdin")) |
120 | goto done; |
121 | } |
122 | |
123 | // main loop: check with poll(), then read/write bytes across |
124 | pfd[0].fd = sfd; |
125 | pfd[0].events = POLLIN; |
126 | pfd[1].fd = STDIN_FILENO; |
127 | pfd[1].events = POLLIN; |
128 | |
129 | bb_got_signal = 0; |
130 | nfd = 2; |
131 | // Not safe_poll: we want to exit on signal |
132 | while (!bb_got_signal && poll(pfd, nfd, timeout) > 0) { |
133 | if (nfd > 1 && pfd[1].revents) { |
134 | char c; |
135 | // read from stdin -> write to device |
136 | if (safe_read(STDIN_FILENO, &c, 1) < 1) { |
137 | // don't poll stdin anymore if we got EOF/error |
138 | nfd--; |
139 | goto skip_write; |
140 | } |
141 | // do we need special processing? |
142 | if (!(opts & OPT_X)) { |
143 | // ^@ sends Break |
144 | if (VINTR == c) { |
145 | tcsendbreak(sfd, 0); |
146 | goto skip_write; |
147 | } |
148 | // ^X exits |
149 | if (24 == c) |
150 | break; |
151 | } |
152 | write(sfd, &c, 1); |
153 | if (delay >= 0) |
154 | safe_poll(pfd, 1, delay); |
155 | skip_write: ; |
156 | } |
157 | if (pfd[0].revents) { |
158 | #define iobuf bb_common_bufsiz1 |
159 | ssize_t len; |
160 | // read from device -> write to stdout |
161 | len = safe_read(sfd, iobuf, sizeof(iobuf)); |
162 | if (len > 0) |
163 | full_write(STDOUT_FILENO, iobuf, len); |
164 | else { |
165 | // EOF/error -> bail out |
166 | bb_got_signal = SIGHUP; |
167 | break; |
168 | } |
169 | } |
170 | } |
171 | |
172 | // restore device mode |
173 | tcsetattr(sfd, TCSAFLUSH, &tiosfd); |
174 | |
175 | if (isatty(STDIN_FILENO)) |
176 | tcsetattr(STDIN_FILENO, TCSAFLUSH, &tio0); |
177 | |
178 | done: |
179 | if (device_lock_file) |
180 | unlink(device_lock_file); |
181 | |
182 | return bb_got_signal; |
183 | } |
184 |