ttynvt/ttynvt.c

/*
 * Copyright (c) 2018 Lars Thrane A/S
 * SPDX-License-Identifier: GPL-2.0
 */
#include "config.h"

#include <cuse_lowlevel.h>
#include <errno.h>
#include <fuse_opt.h>
#include <netdb.h>
#include <pthread.h>
#include <signal.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <asm/termbits.h>
#include <linux/sockios.h>
#include <linux/ppp-ioctl.h>
#include <netinet/in.h>
#include <sys/ioctl.h>
#include <sys/poll.h>
#include <sys/socket.h>
#include <sys/types.h>

#include "telnet.h"

#define NET_BUF_SIZE 1024
#define TMP_BUF_SIZE 1024

#define FD_NET     0
#define FD_MASTER  1
#define FD_SLAVE   2

#define _PRF_N_(no) __attribute__((__format__(__printf__, (no), (no) + 1)))
#define _PRF2_ _PRF_N_(2)


static struct ttynvt_param {
    unsigned int    major;
    unsigned int    minor;
    const char     *dev_name;
    char           *server;
    unsigned int    debug;
    int             logstd;
    /* Derived */
    char            host[64];
    unsigned int    port;
    /* Picked up */
    int             foreground;
} ttynvt_param;

typedef struct {
    pthread_mutex_t tty_lock;
    pthread_mutex_t poll_lock;
    pthread_t       ptid_poll;
    pthread_t       ptid_read;

    struct fuse_pollhandle *ph;

    volatile char   n_fds;
    struct pollfd   fds[3];

    char            net_buf[NET_BUF_SIZE];
    int             net_cnt;

    struct termios  tio;

    int             cmcr;
    volatile int    smcr;

    volatile int    pollin;
    volatile int    error;
    int             epipe;

    tn_ctx_t       *tn;
} ttynvt_t;

#include <sys/syscall.h>
#define gettid() (pid_t)syscall(__NR_gettid)

_PRF2_ static void _log(int prio, const char *fmt, ...)
{
    va_list         arg;
    char            buf[256];

    va_start(arg, fmt);
    vsnprintf(buf, sizeof(buf), fmt, arg);

    if (ttynvt_param.logstd)
        printf("[%d] %d: %s", gettid(), prio, buf);
    else
        syslog(prio, "[%d] %s", gettid(), buf);

    va_end(arg);
}

#define BPL 16                  /* Bytes per line */

void _log_buf(int prio, const char *txt, const void *ptr_, unsigned int len)
{
    unsigned int    ix, i, imax;
    int             l, n;
    char            buf[128];
    const unsigned char *ptr = ptr_;

    for (ix = 0; ix < len || (len == 0 && ix == 0); ix += BPL)
    {
        n = snprintf(buf, sizeof(buf), "%s: %04x:", txt, ix);
        if (n <= 0)
            return;             /* Just playing it safe */
        imax = (len - ix < BPL) ? len - ix : BPL;
        for (i = 0; i < imax; i++)
        {
            l = snprintf(buf + n, sizeof(buf) - n, " %02x", *ptr++);
            if (l <= 0)
                return;         /* Just playing it safe */
            n += l;
        }
        _log(prio, "%s\n", buf);
    }
}

#define DBG(...) \
    if (ttynvt_param.debug > 0) _log(LOG_DEBUG, __VA_ARGS__)
#define DBG2(...) \
    if (ttynvt_param.debug > 1) _log(LOG_DEBUG, __VA_ARGS__)
#define DBG2_BUF(txt, ptr, len) \
    if (ttynvt_param.debug > 1) _log_buf(LOG_DEBUG, txt, ptr, len)

static volatile char _is_interrupted = 0;

static void sig_handler(int sig)
{
    DBG("Interruped, signal = %d\n", sig);
    _is_interrupted = 1;
    if (sig != SIGUSR2)
        exit(0);
}

static void set_signal_handler(void)
{
    struct sigaction sa;

    memset(&sa, 0, sizeof(struct sigaction));
    sa.sa_handler = sig_handler;
    sigemptyset(&(sa.sa_mask));
    sa.sa_flags = 0;
    sigaction(SIGUSR2, &sa, NULL);
    sigaction(SIGTERM, &sa, NULL);
}

static void ttynvt_interrupted(fuse_req_t req, void *data)
{
    pthread_t       thread = (pthread_t) data;

    pthread_kill(thread, SIGUSR2);
}

static int _check_dev(void)
{
    int             rc;
    char            dev_nbuf[128];
    struct stat     st;

    snprintf(dev_nbuf, sizeof(dev_nbuf), "/dev/%s", ttynvt_param.dev_name);

    rc = stat(dev_nbuf, &st);

    DBG("Checking for %s: %d\n", dev_nbuf, rc);

    return rc;
}


static void ttynvt_release(fuse_req_t req, struct fuse_file_info *info)
{
    ttynvt_t       *tty = (ttynvt_t *) (uintptr_t) info->fh;

    _log(LOG_INFO, "connection closed\n");

    tty->n_fds = 0;
    close(tty->fds[FD_NET].fd);
    close(tty->fds[FD_MASTER].fd);
    close(tty->fds[FD_SLAVE].fd);

    pthread_cancel(tty->ptid_poll);
    pthread_join(tty->ptid_poll, NULL);
    pthread_mutex_destroy(&tty->tty_lock);
    pthread_mutex_destroy(&tty->poll_lock);

    if (tty->ph)
        fuse_pollhandle_destroy(tty->ph);

    free(tty->tn);
    free(tty);
    fuse_reply_err(req, 0);
}

static void _notify(ttynvt_t * tty)
{
    pthread_mutex_lock(&tty->poll_lock);
    if (tty->ph)
    {
        fuse_lowlevel_notify_poll(tty->ph);
        fuse_pollhandle_destroy(tty->ph);
        tty->ph = NULL;
    }
    pthread_mutex_unlock(&tty->poll_lock);
}

static void _update_notify(ttynvt_t * tty, struct fuse_pollhandle *ph)
{
    pthread_mutex_lock(&tty->poll_lock);
    struct fuse_pollhandle *tmp_ph = tty->ph;

    tty->ph = ph;
    pthread_mutex_unlock(&tty->poll_lock);
    if (tmp_ph)
        fuse_pollhandle_destroy(tmp_ph);
}

static void    *_read_net(void *arg)
{
    ttynvt_t       *tty = (ttynvt_t *) arg;
    char            buf[TMP_BUF_SIZE];
    int             res;

    pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
    DBG2("%s: net_cnt=%d\n", __func__, tty->net_cnt);

    while (tty->n_fds > 0)
    {
        tty->fds[FD_NET].revents = tty->fds[FD_MASTER].revents =
            tty->fds[FD_SLAVE].revents = 0;
        res = poll(tty->fds, tty->n_fds, -1);
        DBG2("%s: res=%d N=%d events-N/M/S=%#x/%#x/%#x\n", __func__,
             res, tty->n_fds,
             tty->fds[FD_NET].revents, tty->fds[FD_MASTER].revents,
             tty->fds[FD_SLAVE].revents);
        if (res < 0)
        {
            if (errno == EINTR)
                continue;
            break;
        }
        if (tty->n_fds == 0)
            break;

        if (tty->fds[FD_NET].revents & POLLIN)
        {
            res = read(tty->fds[FD_NET].fd, tty->net_buf + tty->net_cnt,
                       NET_BUF_SIZE - tty->net_cnt);
            if (res < 0)
            {
                _log(LOG_ERR, "net read error: %m\n");
                break;
            }
            if (res == 0)
            {
                _log(LOG_INFO, "Connection closed by remote host\n");
                break;
            }
            tty->net_cnt += res;
            DBG2_BUF("Serv in A", tty->net_buf, tty->net_cnt);
            res = telnet_rx(tty->tn, tty->net_buf, &tty->net_cnt);
            DBG2_BUF("Serv in B", tty->net_buf, tty->net_cnt);
            if (tty->net_cnt > 0 && res == 0)
            {
                DBG2_BUF("TtyM out ", tty->net_buf, tty->net_cnt);
                res =
                    write(tty->fds[FD_MASTER].fd, tty->net_buf, tty->net_cnt);
                if (res < 0)
                {
                    _log(LOG_ERR, "master write error: %m\n");
                    break;
                }
                tty->net_cnt = 0;
            }
        }

        if (tty->fds[FD_MASTER].revents & POLLIN)
        {
            res = read(tty->fds[FD_MASTER].fd, buf, TMP_BUF_SIZE);
            if (res < 0)
            {
                _log(LOG_ERR, "master read error: %m\n");
                break;
            }
            DBG2_BUF("TtyM in  ", buf, res);
            telnet_tx(tty->tn, buf, res);
        }

        if (tty->fds[FD_SLAVE].revents & POLLIN)
        {
            tty->pollin = 1;
            tty->n_fds = 2;     /* Disable polling of Slave */
            _notify(tty);
        }
    }

    DBG2("%s: done\n", __func__);
    if (tty->ptid_read)
        pthread_kill(tty->ptid_read, SIGUSR2);

    tty->error = 1;
    _notify(tty);

    return 0;
}

static int _srv_connect(const char *host, unsigned int port)
{
    struct sockaddr_in serveraddr;
    struct hostent *server;
    int             sockfd, err;

    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0)
    {
        _log(LOG_ERR, "Socket open failed: %m\n");
        return sockfd;
    }

    server = gethostbyname(host);
    if (server == NULL)
    {
        _log(LOG_ERR, "Cannot resolve host name: %m\n");
        close(sockfd);
        return -1;
    }

    bzero((char *)&serveraddr, sizeof(serveraddr));
    serveraddr.sin_family = AF_INET;
    bcopy((char *)server->h_addr, (char *)&serveraddr.sin_addr.s_addr,
          server->h_length);
    serveraddr.sin_port = htons(port);

    err = connect(sockfd, (struct sockaddr *)&serveraddr, sizeof(serveraddr));
    if (err < 0)
    {
        _log(LOG_ERR, "Failed to connect to: %s:%u: %m\n", host, port);
        close(sockfd);
        return -1;
    }

    return sockfd;
}

static int _srv_write(void *cctx, const void *buf, int len)
{
    ttynvt_t       *tty = cctx;
    int             res;

    DBG2_BUF("Serv out ", buf, len);

    res = write(tty->fds[FD_NET].fd, buf, len);

    DBG2("%s: fd=%d: len=%u: res=%d\n", __func__,
         tty->fds[FD_NET].fd, len, res);

    return res;
}

static int _srv_read(void *cctx, int timeout)
{
    ttynvt_t       *tty = cctx;
    int             res;

    DBG2("%s: net_cnt=%d\n", __func__, tty->net_cnt);
    while (1)
    {
        res = poll(&tty->fds[FD_NET], 1, timeout);
        DBG("%s: res=%d events-N=%#x\n",
            __func__, res, tty->fds[FD_NET].revents);
        if (res <= 0)
            return res;

        if (tty->fds[FD_NET].revents & POLLIN)
        {
            res = read(tty->fds[FD_NET].fd, tty->net_buf + tty->net_cnt,
                       NET_BUF_SIZE - tty->net_cnt);
            DBG2("%s: fd=%d: res=%d net_cnt=%d\n", __func__,
                 tty->fds[FD_NET].fd, res, tty->net_cnt);
            if (res <= 0)
                return res;
            tty->net_cnt += res;
            DBG2_BUF("Serv in a", tty->net_buf, tty->net_cnt);
            res = telnet_rx(tty->tn, tty->net_buf, &tty->net_cnt);
            DBG2_BUF("Serv in b", tty->net_buf, tty->net_cnt);
            DBG2("%s: res=%d net_cnt=%d\n", __func__, res, tty->net_cnt);
            if (res == 0)
                break;
        }
    }
    return 1;
}

static void _modem_status_cb(void *cctx, int status)
{
    ttynvt_t       *tty = cctx;
    int             mcr = 0;

    DBG("MCR: DSR=%c CTS=%c RI=%c CD=%c\n",
        status & TNS_STATE_DSR ? '1' : '0',
        status & TNS_STATE_CTS ? '1' : '0',
        status & TNS_STATE_RI ? '1' : '0', status & TNS_STATE_CD ? '1' : '0');

    if (status & TNS_STATE_CD)
        mcr |= TIOCM_CD;
    if (status & TNS_STATE_RI)
        mcr |= TIOCM_RI;
    if (status & TNS_STATE_CTS)
        mcr |= TIOCM_CTS;
    if (status & TNS_STATE_DSR)
        mcr |= TIOCM_DSR;

    pthread_mutex_lock(&tty->tty_lock);
    tty->smcr = mcr;
    pthread_mutex_unlock(&tty->tty_lock);
}

static void ttynvt_init(void *userdata, struct fuse_conn_info *conn)
{
    set_signal_handler();
}

static void ttynvt_open(fuse_req_t req, struct fuse_file_info *info)
{
    ttynvt_t       *tty;
    char           *slave_name;
    struct termios  ios;
    int             sockfd;
    int             fd;
    int             res;
    int             n;

    DBG("%s\n", __func__);

    tty = calloc(1, sizeof(*tty));
    if (!tty)
    {
        fuse_reply_err(req, ENOMEM);
        return;
    }
    for (n = 0; n < 3; n++)
        tty->fds[n].fd = -1;

    tty->tn = telnet_ctx_init(tty, _srv_write, _srv_read, _modem_status_cb);
    if (!tty->tn)
    {
        free(tty);
        fuse_reply_err(req, ENOMEM);
        return;
    }

    sockfd = _srv_connect(ttynvt_param.host, ttynvt_param.port);
    if (sockfd < 0)
    {
        free(tty->tn);
        free(tty);
        fuse_reply_err(req, EHOSTUNREACH);
        return;
    }

    tty->fds[FD_NET].fd = sockfd;
    tty->fds[FD_NET].events = POLLIN;
    tty->net_cnt = 0;

    if ((fd = open("/dev/ptmx", O_RDWR)) < 0)   /* open master */
        goto open_err;

    tty->fds[FD_MASTER].fd = fd;
    tty->fds[FD_MASTER].events = POLLIN;

    memset(&ios, 0, sizeof(ios));

    ios.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP
                     | INLCR | IGNCR | ICRNL | IXON);
    ios.c_oflag &= ~OPOST;
    ios.c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
    ios.c_cflag &= ~(CSIZE | PARENB);
    ios.c_cflag |= CS8;

    if (ioctl(fd, TCSETS, &ios) < 0)
        goto open_err;

    grantpt(fd);                /* change permission of slave */
    unlockpt(fd);               /* unlock slave */
    slave_name = ptsname(fd);   /* get name of slave */

    if ((fd = open(slave_name, O_RDWR | O_NOCTTY)) < 0) /* open slave */
        goto open_err;

    ioctl(fd, TCGETS, &tty->tio);
    tty->tio.c_cflag &= ~(CSIZE | PARENB);
    tty->tio.c_cflag |= B115200 | CS8 | CREAD | CLOCAL;
    ioctl(fd, TCSETS, &tty->tio);

    tty->fds[FD_SLAVE].fd = fd;
    tty->fds[FD_SLAVE].events = POLLIN;

    res = telnet_open(tty->tn);
    if (res < 0)
    {
        errno = EPROTO;
        goto open_err;
    }
    if ((res = pthread_mutex_init(&tty->tty_lock, NULL) < 0) ||
        (res = pthread_mutex_init(&tty->poll_lock, NULL) < 0) ||
        (res = pthread_create(&tty->ptid_poll, NULL, &_read_net, tty)))
    {
        errno = res;
        goto open_err;
    }

    tty->n_fds = 3;             /* Initially poll Net, Master, and Slave */

    info->fh = (uintptr_t) tty;
    info->nonseekable = 1;
    info->direct_io = 1;

    _log(LOG_INFO, "Connected to server: %s:%d\n",
         ttynvt_param.host, ttynvt_param.port);

    fuse_reply_open(req, info);

    return;

  open_err:

    _log(LOG_INFO, "Connection to server: %s:%d failed: %m\n",
         ttynvt_param.host, ttynvt_param.port);

    for (n = 0; n < 3; n++)
        if (tty->fds[n].fd >= 0)
            close(tty->fds[n].fd);

    free(tty->tn);
    free(tty);
    fuse_reply_err(req, errno);
}

static void
ttynvt_read(fuse_req_t req, size_t size, off_t off,
            struct fuse_file_info *info)
{
    ttynvt_t       *tty = (ttynvt_t *) (uintptr_t) info->fh;
    char            buf[TMP_BUF_SIZE];
    int             res;

    DBG2("%s\n", __func__);

    if (tty->error)
    {
        DBG2("%s: tty->error=%d\n", __func__, tty->error);
        if (tty->epipe == 0)
        {
            _log(LOG_WARNING, "Rx EPIPE\n");
            tty->epipe = 1;
            fuse_reply_buf(req, NULL, 0);
        }
        else
            fuse_reply_err(req, EBADFD);

        return;
    }

    if (size > TMP_BUF_SIZE)
        size = TMP_BUF_SIZE;

    tty->ptid_read = pthread_self();
    fuse_req_interrupt_func(req, ttynvt_interrupted, (void *)tty->ptid_read);
    res = _is_interrupted ? -2 : read(tty->fds[FD_SLAVE].fd, buf, size);
    _is_interrupted = 0;
    tty->ptid_read = 0;
    tty->n_fds = 3;             /* Enable polling of Slave */
    fuse_req_interrupt_func(req, NULL, NULL);
    if (res < 0)
    {
        DBG2("%s: error: %m\n", __func__);
        fuse_reply_err(req, errno);
        return;
    }

    DBG2("%s: fd=%d: sz=%u/%u: '%.*s'\n", __func__,
         tty->fds[FD_SLAVE].fd, res, (int)size, res, buf);

    fuse_reply_buf(req, buf, res);
}

static void
ttynvt_write(fuse_req_t req, const char *data, size_t size, off_t off,
             struct fuse_file_info *info)
{
    ttynvt_t       *tty = (ttynvt_t *) (uintptr_t) info->fh;
    int             res;

    DBG2("%s: fd=%d: sz=%u: '%.*s'\n", __func__,
         tty->fds[FD_SLAVE].fd, (int)size, (int)size, data);

    if (size == 0)
    {
        fuse_reply_write(req, 0);
        return;
    }

    if (tty->error)
    {
        DBG2("%s: tty->error=%d\n", __func__, tty->error);
        fuse_reply_err(req, EPIPE);
        return;
    }

    res = write(tty->fds[FD_SLAVE].fd, data, size);
    if (res < 0)
    {
        DBG2("%s: error: %m\n", __func__);
        tty->error = 1;
        fuse_reply_err(req, errno);
        return;
    }

    fuse_reply_write(req, res);
}

static int baudrate(speed_t speed)
{
    return speed == B50 ? 50 :
        speed == B75 ? 75 :
        speed == B110 ? 110 :
        speed == B300 ? 300 :
        speed == B600 ? 600 :
        speed == B1200 ? 1200 :
        speed == B1800 ? 1800 :
        speed == B2400 ? 2400 :
        speed == B4800 ? 4800 :
        speed == B9600 ? 9600 :
        speed == B19200 ? 19200 :
        speed == B38400 ? 38400 :
        speed == B57600 ? 57600 :
        speed == B115200 ? 115200 : speed == B230400 ? 230400 : 0;
}

static const char pstr[] = { ' ', 'N', 'O', 'E', 'M', 'S' };

#define CASE(name) case name: return #name

static const char *_ioctl_name(int cmd)
{
    static char     buf[16];

    switch (cmd)
    {
    default:
        snprintf(buf, sizeof(buf), "0x%x", cmd);
        return buf;
        CASE(TCSETSF);
        CASE(TCSETSW);
        CASE(TCSETS);
        CASE(TCGETS);
        CASE(TIOCINQ);
        CASE(TIOCOUTQ);
        CASE(TCFLSH);
        CASE(TCIFLUSH);
        CASE(TCOFLUSH);
        CASE(TCIOFLUSH);
        CASE(TIOCMGET);
        CASE(TIOCMBIS);
        CASE(TIOCMBIC);
        CASE(TIOCMSET);
        CASE(TCSBRK);
        CASE(TIOCGWINSZ);
        CASE(TIOCSWINSZ);
        /* Controlling terminal */
        CASE(TIOCSCTTY);
        CASE(TIOCNOTTY);
        /* Exclusive mode */
        CASE(TIOCEXCL);
        CASE(TIOCGEXCL);
        CASE(TIOCNXCL);
        /* Line discipline */
        CASE(TIOCGETD);
        CASE(TIOCSETD);
        /*PPP support */
        CASE(PPPIOCGCHAN);
    }
}

#define CHECK_BUF_IN(sz) \
    if (in_bufsz < sz)  do { in_bufsz  = sz; goto retry_in;  } while(0)
#define CHECK_BUF_OUT(sz) \
    if (out_bufsz < sz) do { out_bufsz = sz; goto retry_out; } while(0)

static void
ttynvt_ioctl(fuse_req_t req, int cmd, void *arg,
             struct fuse_file_info *info, unsigned int flags,
             const void *in_buf, size_t in_bufsz, size_t out_bufsz)
{
    ttynvt_t       *tty = (ttynvt_t *) (uintptr_t) info->fh;
    struct termios *tio = &tty->tio;
    struct winsize  ws;
    unsigned int    tiocm = 0;
    int             mcr;
    int             val;
    int             res;

    DBG("%s: cmd=%s arg=%p ibuf=%p:%u obuf=:%u\n", __func__,
        _ioctl_name(cmd), arg, in_buf,
        (unsigned int)in_bufsz, (unsigned int)out_bufsz);

    switch (cmd)
    {
    case TCSETSF:
    case TCSETSW:
    case TCSETS:
        CHECK_BUF_IN(sizeof(struct termios));
        {
            speed_t         speed;
            int             csize, par, sb;

            memcpy(tio, in_buf, in_bufsz);

            speed = tio->c_cflag & (CBAUD | CBAUDEX);
            val = htonl(baudrate(speed));
            telnet_rfc2217_cfg(tty->tn, TNS_SET_BAUDRATE, &val, 4);

            if ((tio->c_cflag & CSIZE) == CS5)
                csize = 5;
            else if ((tio->c_cflag & CSIZE) == CS6)
                csize = 6;
            else if ((tio->c_cflag & CSIZE) == CS7)
                csize = 7;
            else
                csize = 8;
            telnet_rfc2217_cfg(tty->tn, TNS_SET_DATASIZE, &csize, 1);

            if (tio->c_cflag & PARENB && tio->c_iflag & IGNPAR)
                par = 1;
#ifdef CMSPAR
            else if (tio->c_cflag & PARENB && tio->c_iflag & CMSPAR)
            {
                if (tio->c_cflag & PARODD)
                    par = 4;
                else
                    par = 5;
            }
#endif
            else if (tio->c_cflag & PARENB)
                par = 3;
            else
                par = 1;
            telnet_rfc2217_cfg(tty->tn, TNS_SET_PARITY, &par, 1);

            if (tio->c_cflag & CSTOPB)
                sb = 2;
            else
                sb = 1;
            telnet_rfc2217_cfg(tty->tn, TNS_SET_STOPSIZE, &sb, 1);

            if (tio->c_cflag & CRTSCTS)
            {
                tty->cmcr |= TIOCM_RTS;
                telnet_rfc2217_ctl(tty->tn, TNS_CTL_CTSRTS);
            }

            if (!(tty->cmcr & TIOCM_DTR) && speed != B0)
            {
                tty->cmcr |= TIOCM_DTR;
                telnet_rfc2217_ctl(tty->tn, TNS_CTL_DTR_ON);
            }

            DBG("termios: %u%c%u%u %cCTSRTS %cCREAD %cHUPCL %cCLOCAL\n",
                baudrate(speed), pstr[par], csize, sb,
                tio->c_cflag & CRTSCTS ? '+' : '-',
                tio->c_cflag & CREAD ? '+' : '-',
                tio->c_cflag & HUPCL ? '+' : '-',
                tio->c_cflag & CLOCAL ? '+' : '-');

            ioctl(tty->fds[FD_SLAVE].fd, cmd, tio);

            fuse_reply_ioctl(req, 0, 0, 0);
        }
        break;
    case TCGETS:
        CHECK_BUF_OUT(sizeof(struct termios));
        fuse_reply_ioctl(req, 0, tio, sizeof(struct termios));
        break;
    case TIOCINQ:              /* Get the number of bytes in the input
                                 * buffer */
        CHECK_BUF_OUT(sizeof(int));
        ioctl(tty->fds[FD_SLAVE].fd, TIOCINQ, &val);
        fuse_reply_ioctl(req, 0, &val, sizeof(int));
        break;
    case TIOCOUTQ:             /* Get the number of bytes in the output
                                 * buffer */
        CHECK_BUF_OUT(sizeof(int));
        ioctl(tty->fds[FD_SLAVE].fd, TIOCOUTQ, &val);
        fuse_reply_ioctl(req, 0, &val, sizeof(int));
        break;
    case TCFLSH:
        if (arg == TCIFLUSH)
        {
            /*todo */
        }
        else if ((size_t) arg == TCOFLUSH)
        {
            /*todo */
        }
        else if ((size_t) arg == TCIOFLUSH)
        {
            /*todo */
        }
        fuse_reply_ioctl(req, 0, 0, 0);
        break;
    case TCIFLUSH:
        val = 1;
        telnet_rfc2217_cfg(tty->tn, TNS_SET_PURGE, &val, 1);
        fuse_reply_ioctl(req, 0, 0, 0);
        break;
    case TCOFLUSH:
        val = 2;
        telnet_rfc2217_cfg(tty->tn, TNS_SET_PURGE, &val, 1);
        fuse_reply_ioctl(req, 0, 0, 0);
        break;
    case TCIOFLUSH:
        val = 3;
        telnet_rfc2217_cfg(tty->tn, TNS_SET_PURGE, &val, 1);
        fuse_reply_ioctl(req, 0, 0, 0);
        break;
    case TIOCMGET:
        CHECK_BUF_OUT(sizeof(int));
        pthread_mutex_lock(&tty->tty_lock);
        mcr = tty->cmcr | tty->smcr;
        pthread_mutex_unlock(&tty->tty_lock);
        fuse_reply_ioctl(req, 0, &mcr, sizeof(int));
        break;
    case TIOCMBIS:
        CHECK_BUF_IN(sizeof(int));
        tiocm = *(unsigned int *)in_buf;
        fuse_reply_ioctl(req, 0, 0, 0);
        DBG("%s: cmd=%s tiocm=%#x\n", __func__, _ioctl_name(cmd), tiocm);
        if (tiocm & TIOCM_RTS)
        {
            tty->cmcr |= TIOCM_RTS;
            telnet_rfc2217_ctl(tty->tn, TNS_CTL_RTS_ON);
        }
        if (tiocm & TIOCM_DTR)
        {
            tty->cmcr |= TIOCM_DTR;
            telnet_rfc2217_ctl(tty->tn, TNS_CTL_DTR_ON);
        }
        goto show_mctl;
    case TIOCMBIC:
        CHECK_BUF_IN(sizeof(int));
        tiocm = *(unsigned int *)in_buf;
        fuse_reply_ioctl(req, 0, 0, 0);
        DBG("%s: cmd=%s tiocm=%#x\n", __func__, _ioctl_name(cmd), tiocm);
        if (tiocm & TIOCM_RTS)
        {
            tty->cmcr &= ~TIOCM_RTS;
            telnet_rfc2217_ctl(tty->tn, TNS_CTL_RTS_OFF);
        }
        if (tiocm & TIOCM_DTR)
        {
            tty->cmcr &= ~TIOCM_DTR;
            telnet_rfc2217_ctl(tty->tn, TNS_CTL_DTR_OFF);
        }
        goto show_mctl;
    case TIOCMSET:
        CHECK_BUF_IN(sizeof(int));
        tiocm = *(unsigned int *)in_buf;
        fuse_reply_ioctl(req, 0, 0, 0);
        DBG("%s: cmd=%s tiocm=%#x\n", __func__, _ioctl_name(cmd), tiocm);
        tty->cmcr &= ~(TIOCM_RTS | TIOCM_DTR);
        tty->cmcr |= tiocm & (TIOCM_RTS | TIOCM_DTR);
        telnet_rfc2217_ctl(tty->tn, (tiocm & TIOCM_DTR) ?
                           TNS_CTL_DTR_ON : TNS_CTL_DTR_OFF);
        telnet_rfc2217_ctl(tty->tn, (tiocm & TIOCM_RTS) ?
                           TNS_CTL_RTS_ON : TNS_CTL_RTS_OFF);
        goto show_mctl;
      show_mctl:
        DBG("MCR: DTR=%c RTS=%c\n",
            tty->cmcr & TIOCM_DTR ? '1' : '0',
            tty->cmcr & TIOCM_RTS ? '1' : '0');
        break;
    case TCSBRK:
        fuse_reply_ioctl(req, 0, 0, 0);
        break;
    case TIOCGWINSZ:
        CHECK_BUF_OUT(sizeof(struct winsize));
        res = ioctl(tty->fds[FD_SLAVE].fd, TIOCGWINSZ, &ws);
        if (res < 0)
        {
            fuse_reply_err(req, errno);
            return;
        }
        fuse_reply_ioctl(req, 0, &ws, sizeof(struct winsize));
        break;
    case TIOCSWINSZ:
        CHECK_BUF_IN(sizeof(struct winsize));
        ws = *(struct winsize *)in_buf;
        res = ioctl(tty->fds[FD_SLAVE].fd, TIOCSWINSZ, &ws);
        if (res < 0)
        {
            fuse_reply_err(req, errno);
            return;
        }
        fuse_reply_ioctl(req, 0, &ws, sizeof(struct winsize));
        break;
    case TIOCEXCL:
        ioctl(tty->fds[FD_SLAVE].fd, TIOCEXCL, NULL);
        fuse_reply_ioctl(req, 0, 0, 0);
        break;
    case TIOCGEXCL:
        CHECK_BUF_OUT(sizeof(int));
        ioctl(tty->fds[FD_SLAVE].fd, TIOCGEXCL, &val);
        fuse_reply_ioctl(req, 0, &val, sizeof(int));
        break;
    case TIOCNXCL:
        ioctl(tty->fds[FD_SLAVE].fd, TIOCNXCL, NULL);
        fuse_reply_ioctl(req, 0, 0, 0);
        break;
    case TIOCSETD:
        CHECK_BUF_IN(sizeof(int));
        val = *(int *)in_buf;
        res = ioctl(tty->fds[FD_SLAVE].fd, TIOCSETD, &val);
        if (res < 0)
            fuse_reply_err(req, errno);
        else
            fuse_reply_ioctl(req, 0, 0, 0);
        break;
    case TIOCGETD:
        CHECK_BUF_OUT(sizeof(int));
        res = ioctl(tty->fds[FD_SLAVE].fd, TIOCGETD, &val);
        if (res < 0)
            fuse_reply_err(req, errno);
        else
            fuse_reply_ioctl(req, 0, &val, sizeof(int));
        break;
    case PPPIOCGCHAN:
        CHECK_BUF_OUT(sizeof(int));
        res = ioctl(tty->fds[FD_SLAVE].fd, PPPIOCGCHAN, &val);
        if (res < 0)
            fuse_reply_err(req, errno);
        else
            fuse_reply_ioctl(req, 0, &val, sizeof(int));
        break;
    default:
        fuse_reply_err(req, ENOSYS);
        break;

      retry_in:
        {
            struct iovec    iov = { arg, in_bufsz };
            fuse_reply_ioctl_retry(req, &iov, 1, NULL, 0);
        }
        break;

      retry_out:
        {
            struct iovec    iov = { arg, out_bufsz };
            fuse_reply_ioctl_retry(req, NULL, 0, &iov, 1);
        }
        break;
    }
}

static void
ttynvt_poll(fuse_req_t req, struct fuse_file_info *info,
            struct fuse_pollhandle *ph)
{
    ttynvt_t       *tty = (ttynvt_t *) (uintptr_t) info->fh;
    int             revents;

    DBG2("%s: tty->pollin=%d tty->error/epipe=%d/%d\n",
         __func__, tty->pollin, tty->error, tty->epipe);

    _update_notify(tty, ph);

    revents = POLLOUT;

    if (tty->pollin)
    {
        tty->pollin = 0;
        revents |= POLLIN;
    }
    if (tty->error)
    {
        if (tty->epipe == 0)
            revents |= POLLHUP | POLLIN;
        else
            revents = 0;
    }

    DBG2("%s: revents=%#x\n", __func__, revents);

    fuse_reply_poll(req, revents);
}

static const struct cuse_lowlevel_ops ttynvt_op = {
    .init = ttynvt_init,
    .open = ttynvt_open,
    .read = ttynvt_read,
    .write = ttynvt_write,
    .ioctl = ttynvt_ioctl,
    .poll = ttynvt_poll,
    .release = ttynvt_release,
};

#define TTYNET_OPT(t, p, v) { t, offsetof(struct ttynvt_param, p), v }

static const struct fuse_opt ttynvt_opts[] = {
    TTYNET_OPT("-D %d", debug, 1),
    TTYNET_OPT("-E", logstd, 1),
    TTYNET_OPT("-M %u", major, 1),
    TTYNET_OPT("--maj=%u", major, 1),
    TTYNET_OPT("-m %u", minor, 1),
    TTYNET_OPT("--min=%u", minor, 1),
    TTYNET_OPT("-n %s", dev_name, 0),
    TTYNET_OPT("--name=%s", dev_name, 0),
    TTYNET_OPT("-S %s", server, 0),
    TTYNET_OPT("--server=%s", server, 0),
    FUSE_OPT_KEY("-h", 0),
    FUSE_OPT_KEY("--help", 0),
    FUSE_OPT_END
};

static void print_help(void)
{
    fprintf(stderr, "ttynvt Usage:\n"
            "\t-D level\tEnable debug\n"
            "\t-E\t\tPrint debug to stdout (default is syslog)\n"
            "\t-M major, --maj=major\n"
            "\t-m minor, --min=minor\n"
            "\t-n name, --name=name (default: ttyNVT0)\n"
            "\t\tDevice will be created in /dev/$name.\n"
            "\t-S server, --server=host:port\n");
}

static int
process_arg(void *data, const char *arg, int key, struct fuse_args *outargs)
{
    switch (key)
    {
    case 0:
        print_help();
        return fuse_opt_add_arg(outargs, "-ho");
    default:
        if (strcmp(arg, "-d") == 0 || strcmp(arg, "-f") == 0)
            ttynvt_param.foreground = 1;
        return 1;
    }
}

int main(int argc, char *argv[])
{
    int             rc;
    struct fuse_args args = FUSE_ARGS_INIT(argc, argv);

    char            dev_name[128];
    const char     *dev_info_argv[] = { dev_name };
    pid_t           cpid;

    openlog("ttynvt", LOG_PID, LOG_DAEMON);

    if (fuse_opt_parse(&args, &ttynvt_param, ttynvt_opts, process_arg))
    {
        fprintf(stderr, "Failed to parse arguments\n");
        return 1;
    }

    if (!ttynvt_param.dev_name)
        ttynvt_param.dev_name = "ttyNVT0";

    if (!ttynvt_param.server)
    {
        fprintf(stderr, "Server must be specified\n");
        return 1;
    }

    rc = sscanf(ttynvt_param.server, "%63[^:]:%u", ttynvt_param.host,
                &ttynvt_param.port);
    if (rc <= 1)
    {
        fprintf(stderr, "Bad server specification: '%s'\n",
                ttynvt_param.server);
        return 1;
    }
    if (ttynvt_param.port == 0)
    {
        fprintf(stderr, "Bad server port: %u\n", ttynvt_param.port);
        return 1;
    }

    snprintf(dev_name, sizeof(dev_name), "DEVNAME=%s", ttynvt_param.dev_name);

    struct cuse_info ci = {
        .dev_major = ttynvt_param.major,
        .dev_minor = ttynvt_param.minor,
        .dev_info_argc = sizeof(dev_info_argv) / sizeof(char *),
        .dev_info_argv = dev_info_argv,
        .flags = CUSE_UNRESTRICTED_IOCTL,
    };

    if (ttynvt_param.foreground)
    {
        return cuse_lowlevel_main(args.argc, args.argv, &ci, &ttynvt_op, NULL);
    }

    cpid = fork();
    switch (cpid)
    {
    case -1:
        _log(LOG_ERR, "fork(): %m\n");
        return -1;

    case 0:                    /* Child */
        DBG("Child proceeding...\n");
        rc = cuse_lowlevel_main(args.argc, args.argv, &ci, &ttynvt_op, NULL);
        if (rc != 0)
            _log(LOG_ERR, "ttynvt failed rc=%d\n", rc);
        else
            DBG("Child exited\n");
        return rc;

    default:                   /* Parent */
        break;
    }

    DBG("Parent proceeding (child=%d)...\n", cpid);

    for (rc = 0; rc < 10; rc++)
    {
        if (_check_dev() == 0)
            break;
        usleep(500000);
    }

    DBG("Parent exiting\n");

    return 0;
}