serial.c

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/****************************************************************************
** serial.c ****************************************************************
****************************************************************************
*
* common routines for hardware that uses the standard serial port driver
*
* Copyright (C) 1999 Christoph Bartelmus <lirc@bartelmus.de>
*
*/

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#ifndef LIRC_LOCKDIR
#define LIRC_LOCKDIR "/var/lock/lockdev"
#endif


#include <limits.h>
#include <poll.h>
#include <stdio.h>
#include <stdlib.h>
#include <termios.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <dirent.h>
#include <signal.h>
#include <stdlib.h>
#include <unistd.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>

#if defined __linux__
#include <linux/serial.h>       /* for 'struct serial_struct' to set custom
                                 * baudrates */
#endif

#include "lirc/lirc_log.h"
#include "lirc/curl_poll.h"


static const logchannel_t logchannel = LOG_LIB;

int tty_reset(int fd)
{
        struct termios options;

        if (tcgetattr(fd, &options) == -1) {
                log_trace("tty_reset(): tcgetattr() failed");
                log_perror_debug("tty_reset()");
                return 0;
        }
        cfmakeraw(&options);
        if (tcsetattr(fd, TCSAFLUSH, &options) == -1) {
                log_trace("tty_reset(): tcsetattr() failed");
                log_perror_debug("tty_reset()");
                return 0;
        }
        return 1;
}

int tty_setrtscts(int fd, int enable)
{
        struct termios options;

        if (tcgetattr(fd, &options) == -1) {
                log_trace("%s: tcgetattr() failed", __func__);
                log_perror_debug(__func__);
                return 0;
        }
        if (enable)
                options.c_cflag |= CRTSCTS;
        else
                options.c_cflag &= ~CRTSCTS;
        if (tcsetattr(fd, TCSAFLUSH, &options) == -1) {
                log_trace("%s: tcsetattr() failed", __func__);
                log_perror_debug(__func__);
                return 0;
        }
        return 1;
}

int tty_setdtr(int fd, int enable)
{
        int cmd, sts;

        if (ioctl(fd, TIOCMGET, &sts) < 0) {
                log_trace("%s: ioctl(TIOCMGET) failed", __func__);
                log_perror_debug(__func__);
                return 0;
        }
        if (((sts & TIOCM_DTR) == 0) && enable) {
                log_trace("%s: 0->1", __func__);
        } else if ((!enable) && (sts & TIOCM_DTR)) {
                log_trace("%s: 1->0", __func__);
        }
        if (enable)
                cmd = TIOCMBIS;
        else
                cmd = TIOCMBIC;
        sts = TIOCM_DTR;
        if (ioctl(fd, cmd, &sts) < 0) {
                log_trace("%s: ioctl(TIOCMBI(S|C)) failed", __func__);
                log_perror_debug(__func__);
                return 0;
        }
        return 1;
}

int tty_setbaud(int fd, int baud)
{
        struct termios options;
        int speed;

#if defined __linux__
        int use_custom_divisor = 0;
        struct serial_struct serinfo;
#endif

        switch (baud) {
        case 300:
                speed = B300;
                break;
        case 1200:
                speed = B1200;
                break;
        case 2400:
                speed = B2400;
                break;
        case 4800:
                speed = B4800;
                break;
        case 9600:
                speed = B9600;
                break;
        case 19200:
                speed = B19200;
                break;
        case 38400:
                speed = B38400;
                break;
        case 57600:
                speed = B57600;
                break;
        case 115200:
                speed = B115200;
                break;
#ifdef B230400
        case 230400:
                speed = B230400;
                break;
#endif
#ifdef B460800
        case 460800:
                speed = B460800;
                break;
#endif
#ifdef B500000
        case 500000:
                speed = B500000;
                break;
#endif
#ifdef B576000
        case 576000:
                speed = B576000;
                break;
#endif
#ifdef B921600
        case 921600:
                speed = B921600;
                break;
#endif
#ifdef B1000000
        case 1000000:
                speed = B1000000;
                break;
#endif
#ifdef B1152000
        case 1152000:
                speed = B1152000;
                break;
#endif
#ifdef B1500000
        case 1500000:
                speed = B1500000;
                break;
#endif
#ifdef B2000000
        case 2000000:
                speed = B2000000;
                break;
#endif
#ifdef B2500000
        case 2500000:
                speed = B2500000;
                break;
#endif
#ifdef B3000000
        case 3000000:
                speed = B3000000;
                break;
#endif
#ifdef B3500000
        case 3500000:
                speed = B3500000;
                break;
#endif
#ifdef B4000000
        case 4000000:
                speed = B4000000;
                break;
#endif
        default:
#if defined __linux__
                speed = B38400;
                use_custom_divisor = 1;
                break;
#else
                log_trace("tty_setbaud(): bad baud rate %d", baud);
                return 0;
#endif
        }
        if (tcgetattr(fd, &options) == -1) {
                log_trace("tty_setbaud(): tcgetattr() failed");
                log_perror_debug("tty_setbaud()");
                return 0;
        }
        (void)cfsetispeed(&options, speed);
        (void)cfsetospeed(&options, speed);
        if (tcsetattr(fd, TCSAFLUSH, &options) == -1) {
                log_trace("tty_setbaud(): tcsetattr() failed");
                log_perror_debug("tty_setbaud()");
                return 0;
        }
#if defined __linux__
        if (use_custom_divisor) {
                if (ioctl(fd, TIOCGSERIAL, &serinfo) < 0) {
                        log_trace("tty_setbaud(): TIOCGSERIAL failed");
                        log_perror_debug("tty_setbaud()");
                        return 0;
                }
                serinfo.flags &= ~ASYNC_SPD_MASK;
                serinfo.flags |= ASYNC_SPD_CUST;
                serinfo.custom_divisor = serinfo.baud_base / baud;
                if (ioctl(fd, TIOCSSERIAL, &serinfo) < 0) {
                        log_trace("tty_setbaud(): TIOCSSERIAL failed");
                        log_perror_debug("tty_setbaud()");
                        return 0;
                }
        }
#endif
        return 1;
}

int tty_setcsize(int fd, int csize)
{
        struct termios options;
        int size;

        switch (csize) {
        case 5:
                size = CS5;
                break;
        case 6:
                size = CS6;
                break;
        case 7:
                size = CS7;
                break;
        case 8:
                size = CS8;
                break;
        default:
                log_trace("tty_setcsize(): bad csize rate %d", csize);
                return 0;
        }
        if (tcgetattr(fd, &options) == -1) {
                log_trace("tty_setcsize(): tcgetattr() failed");
                log_perror_debug("tty_setcsize()");
                return 0;
        }
        options.c_cflag &= ~CSIZE;
        options.c_cflag |= size;
        if (tcsetattr(fd, TCSAFLUSH, &options) == -1) {
                log_trace("tty_setcsize(): tcsetattr() failed");
                log_perror_debug("tty_setcsize()");
                return 0;
        }
        return 1;
}

int tty_create_lock(const char* name)
{
        char filename[FILENAME_MAX + 1];
        char symlink[FILENAME_MAX + 1];
        char cwd[FILENAME_MAX + 1];
        const char* last;
        const char* s;
        char id[10 + 1 + 1];
        int lock;
        int len;

        strcpy(filename, LIRC_LOCKDIR "/LCK..");

        last = strrchr(name, '/');
        if (last != NULL)
                s = last + 1;
        else
                s = name;

        if (strlen(filename) + strlen(s) > FILENAME_MAX) {
                log_error("invalid filename \"%s%s\"", filename, s);
                return 0;
        }
        strcat(filename, s);

tty_create_lock_retry:
        len = snprintf(id, 10 + 1 + 1, "%10d\n", getpid());
        if (len == -1) {
                log_error("invalid pid \"%d\"", getpid());
                return 0;
        }
        lock = open(filename, O_CREAT | O_EXCL | O_WRONLY, 0644);
        if (lock == -1) {
                log_perror_err("could not create lock file \"%s\"", filename);
                lock = open(filename, O_RDONLY);
                if (lock != -1) {
                        pid_t otherpid;

                        id[10 + 1] = 0;
                        if (read(lock, id, 10 + 1) == 10 + 1 && read(lock, id, 1) == 0
                            && sscanf(id, "%d\n", &otherpid) > 0) {
                                if (kill(otherpid, 0) == -1 && errno == ESRCH) {
                                        log_warn("detected stale lockfile %s", filename);
                                        close(lock);
                                        if (unlink(filename) != -1) {
                                                log_warn("stale lockfile removed");
                                                goto tty_create_lock_retry;
                                        } else {
                                                log_perror_err(
                                                          "could not remove stale lockfile");
                                        }
                                        return 0;
                                }
                                log_error("%s is locked by PID %d", name, otherpid);
                        } else {
                                log_error("invalid lockfile %s encountered", filename);
                        }
                        close(lock);
                }
                return 0;
        }
        if (write(lock, id, len) != len) {
                log_perror_err("could not write pid to lock file");
                close(lock);
                if (unlink(filename) == -1)
                        log_perror_err("could not delete file \"%s\"", filename);
                /* FALLTHROUGH */
                return 0;
        }
        if (close(lock) == -1) {
                log_perror_err("could not close lock file");
                if (unlink(filename) == -1)
                        log_perror_err("could not delete file \"%s\"", filename);
                /* FALLTHROUGH */
                return 0;
        }

        len = readlink(name, symlink, FILENAME_MAX);
        if (len == -1) {
                if (errno != EINVAL) {  /* symlink */
                        log_perror_err("readlink() failed for \"%s\"", name);
                        if (unlink(filename) == -1) {
                                log_perror_err("could not delete file \"%s\"",
                                               filename);
                                /* FALLTHROUGH */
                        }
                        return 0;
                }
        } else {
                symlink[len] = 0;

                if (last) {
                        char dirname[FILENAME_MAX + 1];

                        if (getcwd(cwd, FILENAME_MAX) == NULL) {
                                log_perror_err("getcwd() failed");
                                if (unlink(filename) == -1) {
                                        log_perror_err(
                                                  "could not delete file \"%s\"",
                                                  filename);
                                        /* FALLTHROUGH */
                                }
                                return 0;
                        }

                        strcpy(dirname, name);
                        dirname[strlen(name) - strlen(last)] = 0;
                        if (chdir(dirname) == -1) {
                                log_perror_err(
                                          "chdir() to \"%s\" failed", dirname);
                                if (unlink(filename) == -1) {
                                        log_perror_err(
                                                  "could not delete file \"%s\"",
                                                  filename);
                                        /* FALLTHROUGH */
                                }
                                return 0;
                        }
                }
                if (tty_create_lock(symlink) == -1) {
                        if (unlink(filename) == -1) {
                                log_perror_err(
                                          "could not delete file \"%s\"", filename);
                                /* FALLTHROUGH */
                        }
                        return 0;
                }
                if (last) {
                        if (chdir(cwd) == -1) {
                                log_perror_err("chdir() to \"%s\" failed", cwd);
                                if (unlink(filename) == -1) {
                                        log_perror_err(
                                                  "could not delete file \"%s\"",
                                                  filename);
                                        /* FALLTHROUGH */
                                }
                                return 0;
                        }
                }
        }
        return 1;
}

int tty_delete_lock(void)
{
        DIR* dp;
        struct dirent* ep;
        int lock;
        int len;
        char id[20] = { '\0' };
        char filename[FILENAME_MAX + 1];
        long pid;
        int retval = 1;

        dp = opendir(LIRC_LOCKDIR);
        if (dp != NULL) {
                while ((ep = readdir(dp))) {
                        if (strcmp(ep->d_name, ".") == 0 || strcmp(ep->d_name, "..") == 0) {
                                retval = 0;
                                continue;
                        }
                        strcpy(filename, LIRC_LOCKDIR "/");
                        if (strlen(filename) + strlen(ep->d_name) > FILENAME_MAX) {
                                retval = 0;
                                continue;
                        }
                        strcat(filename, ep->d_name);
                        if (strstr(filename, "LCK..") == NULL) {
                                log_debug("Ignoring non-LCK.. logfile %s",
                                          filename);
                                retval = 0;
                                continue;
                        }
                        lock = open(filename, O_RDONLY);
                        if (lock == -1) {
                                retval = 0;
                                continue;
                        }
                        len = read(lock, id, sizeof(id) - 1);
                        close(lock);
                        if (len <= 0) {
                                retval = 0;
                                continue;
                        }
                        pid = strtol(id, NULL, 10);
                        if (pid == LONG_MIN || pid == LONG_MAX || pid == 0) {
                                log_debug("Can't parse lockfile %s (ignored)",
                                          filename);
                                retval = 0;
                                continue;
                        }
                        if (pid == getpid()) {
                                if (unlink(filename) == -1) {
                                        log_perror_err(
                                                  "could not delete file \"%s\"",
                                                  filename);
                                        retval = 0;
                                        continue;
                                }
                        }
                }
                closedir(dp);
        } else {
                log_error("could not open directory \"" LIRC_LOCKDIR "\"");
                return 0;
        }
        return retval;
}

int tty_set(int fd, int rts, int dtr)
{
        int mask;

        mask = rts ? TIOCM_RTS : 0;
        mask |= dtr ? TIOCM_DTR : 0;
        if (ioctl(fd, TIOCMBIS, &mask) == -1) {
                log_trace("tty_set(): ioctl() failed");
                log_perror_warn("tty_set()");
                return 0;
        }
        return 1;
}

int tty_clear(int fd, int rts, int dtr)
{
        int mask;

        mask = rts ? TIOCM_RTS : 0;
        mask |= dtr ? TIOCM_DTR : 0;
        if (ioctl(fd, TIOCMBIC, &mask) == -1) {
                log_perror_debug("tty_clear()");
                log_trace("tty_clear(): ioctl() failed");
                return 0;
        }
        return 1;
}

int tty_write(int fd, char byte)
{
        if (write(fd, &byte, 1) != 1) {
                log_trace("tty_write(): write() failed");
                log_perror_debug("tty_write()");
                return -1;
        }
        /* wait until the stop bit of Control Byte is sent
         * (for 9600 baud rate, it takes about 100 msec */
        usleep(100 * 1000);

        /* we don't wait because tcdrain() does this for us */
        /* tcdrain(fd); */
        /* FIXME! but unfortunately this does not seem to be
         * implemented in 2.0.x kernels ... */
        return 1;
}

int tty_read(int fd, char* byte)
{
        struct pollfd pfd = {.fd = fd, .events = POLLIN, .revents = 0};
        int ret;

        ret = curl_poll(&pfd, 1, 1000); /* 1 second timeout. */
        if (ret == 0) {
                log_error("tty_read(): timeout");
                return -1;      /* received nothing, bad */
        } else if (ret != 1) {
                log_perror_debug("tty_read(): curl_poll() failed");
                return -1;
        }
        if (read(fd, byte, 1) != 1) {
                log_perror_debug("tty_read(): read() failed");
                return -1;
        }
        return 1;
}

int tty_write_echo(int fd, char byte)
{
        char reply;

        if (tty_write(fd, byte) == -1)
                return -1;
        if (tty_read(fd, &reply) == -1)
                return -1;
        log_trace("sent: A%u D%01x reply: A%u D%01x", (((unsigned int)(unsigned char)byte) & 0xf0) >> 4,
                  ((unsigned int)(unsigned char)byte) & 0x0f, (((unsigned int)(unsigned char)reply) & 0xf0) >> 4,
                  ((unsigned int)(unsigned char)reply) & 0x0f);
        if (byte != reply)
                log_error("Command mismatch.");
        return 1;
}