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/* microcom.c
*
* bare bones 'talk to modem' program - similar to 'cu -l $device'
* inspired by mgetty's microcom
*
*/
#include "busybox.h"
int microcom_main(int argc, char **argv);
int microcom_main(int argc, char **argv)
{
struct pollfd pfd[2];
#define sfd (pfd[1].fd)
char *device_lock_file = NULL;
const char *s;
const char *opt_s = "9600";
unsigned speed;
int len;
int exitcode = 1;
struct termios tio0, tiosfd, tio;
getopt32(argv, "s:", &opt_s);
argc -= optind;
argv += optind;
if (!argv[0])
bb_show_usage();
speed = xatou(opt_s);
// try to create lock file in /var/lock
s = bb_basename(argv[0]);
if (!s[0]) {
errno = ENODEV;
bb_perror_msg_and_die("can't lock device");
}
device_lock_file = xasprintf("/var/lock/LCK..%s", s);
sfd = open(device_lock_file, O_CREAT | O_WRONLY | O_TRUNC | O_EXCL, 0644);
if (sfd < 0) {
if (ENABLE_FEATURE_CLEAN_UP)
free(device_lock_file);
device_lock_file = NULL;
if (errno == EEXIST)
bb_perror_msg_and_die("can't lock device");
// We don't abort on other errors: /var/lock can be
// non-writable or non-existent
} else {
// %4d to make mgetty happy. It treats 4-bytes lock files as binary,
// not text, PID. Making 5+ char file. Brrr...
s = xasprintf("%4d\n", getpid());
write(sfd, s, strlen(s));
if (ENABLE_FEATURE_CLEAN_UP)
free((char*)s);
close(sfd);
}
// open device
sfd = open(argv[0], O_RDWR | O_NDELAY);
if (sfd < 0) {
bb_perror_msg("can't open device");
goto unlock_and_exit;
}
fcntl(sfd, F_SETFL, O_RDWR); // why?
// put stdin to "raw mode", handle one character at a time
tcgetattr(STDIN_FILENO, &tio0);
tio = tio0;
tio.c_lflag &= ~(ICANON|ECHO);
tio.c_iflag &= ~(IXON|ICRNL);
tio.c_oflag &= ~(ONLCR);
tio.c_cc[VMIN] = 1;
tio.c_cc[VTIME] = 0;
if (tcsetattr(STDIN_FILENO, TCSANOW, &tio)) {
bb_perror_msg("can't tcsetattr for %s", "stdin");
goto unlock_and_exit;
}
/* same thing for modem (plus: set baud rate) - TODO: make CLI option */
tcgetattr(sfd, &tiosfd);
tio = tiosfd;
tio.c_lflag &= ~(ICANON|ECHO);
tio.c_iflag &= ~(IXON|ICRNL);
tio.c_oflag &= ~(ONLCR);
tio.c_cc[VMIN] = 1;
tio.c_cc[VTIME] = 0;
cfsetispeed(&tio, tty_value_to_baud(speed));
cfsetospeed(&tio, tty_value_to_baud(speed));
if (tcsetattr(sfd, TCSANOW, &tio)) {
bb_perror_msg("can't tcsetattr for %s", "device");
goto unlock_and_exit;
}
// disable SIGINT
signal(SIGINT, SIG_IGN);
// drain stdin
tcflush(STDIN_FILENO, TCIFLUSH);
printf("connected to '%s' (%d bps), exit with ctrl-X...\r\n", argv[0], speed);
// main loop: check with poll(), then read/write bytes across
pfd[0].fd = STDIN_FILENO;
pfd[0].events = POLLIN;
/*pfd[1].fd = sfd;*/
pfd[1].events = POLLIN;
while (1) {
int i;
while (-1 == poll(pfd, 2, -1) && EINTR == errno)
continue;
for (i = 0; i < 2; ++i) {
if (pfd[i].revents & POLLIN) {
len = read(pfd[i].fd, bb_common_bufsiz1, COMMON_BUFSIZE);
if (len > 0) {
if (!i && 24 == bb_common_bufsiz1[0])
goto done; // ^X exits
write(pfd[1-i].fd, bb_common_bufsiz1, len);
}
}
}
}
done:
tcsetattr(sfd, TCSANOW, &tiosfd);
tcsetattr(STDIN_FILENO, TCSANOW, &tio0);
tcflush(STDIN_FILENO, TCIFLUSH);
if (ENABLE_FEATURE_CLEAN_UP)
close(sfd);
exitcode = 0;
unlock_and_exit:
// delete lock file
if (device_lock_file) {
unlink(device_lock_file);
if (ENABLE_FEATURE_CLEAN_UP)
free(device_lock_file);
}
return exitcode;
}
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