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/* vi: set sw=4 ts=4: */
/*
* bare bones 'talk to modem' program - similar to 'cu -l $device'
* inspired by mgetty's microcom
*
* Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com>
*
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
//usage:#define microcom_trivial_usage
//usage: "[-d DELAY] [-t TIMEOUT] [-s SPEED] [-X] TTY"
//usage:#define microcom_full_usage "\n\n"
//usage: "Copy bytes for stdin to TTY and from TTY to stdout\n"
//usage: "\n -d Wait up to DELAY ms for TTY output before sending every"
//usage: "\n next byte to it"
//usage: "\n -t Exit if both stdin and TTY are silent for TIMEOUT ms"
//usage: "\n -s Set serial line to SPEED"
//usage: "\n -X Disable special meaning of NUL and Ctrl-X from stdin"
#include "libbb.h"
// 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 UNUSED_PARAM, 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, ms
OPT_t = 1 << 3, // timeout, ms
};
speed_t speed = 9600;
int delay = -1;
int timeout = -1;
unsigned opts;
// fetch options
opt_complementary = "=1:s+:d+:t+"; // exactly one arg, numeric options
opts = getopt32(argv, "Xs:d:t:", &speed, &delay, &timeout);
// 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) {
// device already locked -> bail out
if (errno == EEXIST)
bb_perror_msg_and_die("can't create '%s'", device_lock_file);
// can't create lock -> don't care
if (ENABLE_FEATURE_CLEAN_UP)
free(device_lock_file);
device_lock_file = NULL;
} else {
// %4d to make concurrent mgetty (if any) happy.
// Mgetty treats 4-bytes lock files as binary,
// not text, PID. Making 5+ char file. Brrr...
fdprintf(sfd, "%4d\n", getpid());
close(sfd);
}
// setup signals
bb_signals(0
+ (1 << SIGHUP)
+ (1 << SIGINT)
+ (1 << SIGTERM)
+ (1 << SIGPIPE)
, record_signo);
// error exit code if we fail to open the device
bb_got_signal = 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);
// put device to "raw mode"
xget1(sfd, &tio, &tiosfd);
// set device speed
cfsetspeed(&tio, tty_value_to_baud(speed));
if (xset1(sfd, &tio, argv[0]))
goto done;
// 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;
}
// 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;
bb_got_signal = 0;
nfd = 2;
// Not safe_poll: we want to exit on signal
while (!bb_got_signal && poll(pfd, nfd, timeout) > 0) {
if (nfd > 1 && pfd[1].revents) {
char c;
// 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--;
goto skip_write;
}
// do we need special processing?
if (!(opts & OPT_X)) {
// ^@ sends Break
if (VINTR == c) {
tcsendbreak(sfd, 0);
goto skip_write;
}
// ^X exits
if (24 == c)
break;
}
write(sfd, &c, 1);
if (delay >= 0)
safe_poll(pfd, 1, delay);
skip_write: ;
}
if (pfd[0].revents) {
#define iobuf bb_common_bufsiz1
ssize_t len;
// read from device -> write to stdout
len = safe_read(sfd, iobuf, sizeof(iobuf));
if (len > 0)
full_write(STDOUT_FILENO, iobuf, len);
else {
// EOF/error -> bail out
bb_got_signal = SIGHUP;
break;
}
}
}
// restore device mode
tcsetattr(sfd, TCSAFLUSH, &tiosfd);
if (isatty(STDIN_FILENO))
tcsetattr(STDIN_FILENO, TCSAFLUSH, &tio0);
done:
if (device_lock_file)
unlink(device_lock_file);
return bb_got_signal;
}
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