source: MondoRescue/branches/3.2/mindi-busybox/miscutils/microcom.c@ 3232

/* 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;
}