diff options
| -rw-r--r-- | util-linux/microcom.c | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/util-linux/microcom.c b/util-linux/microcom.c new file mode 100644 index 000000000..f6f8e07f6 --- /dev/null +++ b/util-linux/microcom.c @@ -0,0 +1,135 @@ +/* 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; +} |