/*

* tty2comport.c

*

* Direct tty to UART(COM) port

*

* Author: Soukthavy Sopha <soukthavy.sopha@yahoo.com>

*

* This file is licensed under the terms of the GNU General Public

* License version 2. This program is licensed "as is" without any

* warranty of any kind, whether express or implied.

*

*$Date: 2016-03-17 20:07:40 -0700 (Thu, 17 Mar 2016) $

*$Id: tty2comport.c 36 2016-03-18 03:07:40Z ssop $

*$Revision: 36 $

*/

#include <stdio.h>

#include <stdlib.h>

#include <termios.h>

#include <sys/time.h>

#include <sys/types.h>

#include <sys/ioctl.h>

#include <sys/syslog.h>

#include <unistd.h>

#include <fcntl.h>

#include <signal.h>

#include <linux/unistd.h>

#define TRANSFER_BUFFER_SIZE 1024*2

#define MAKE_TTY_RAW(fd, original)\

term = original;\

term.c_iflag &= ~(BRKINT | IGNCR | INLCR | ICRNL | IUCLC |\

IXANY | INPCK | ISTRIP);\

term.c_iflag |= (IGNBRK | IGNPAR);\

term.c_oflag &= ~(OPOST | ONLCR);\

term.c_lflag &= ~(XCASE | ECHONL | NOFLSH);\

term.c_lflag &= ~(ICANON | ISIG | ECHO | IEXTEN);\

term.c_cflag |= CREAD;\

term.c_cc[VTIME] = 5;\

term.c_cc[VMIN] = 1;\

tcsetattr(fd, TCSADRAIN, &term);

static int hndl;

static int tty_modified = 0;

static struct termios saved_termios;

static struct termios original_stdin,original_stdout,original_tty_stdx;

static void set_noecho(int fd) /* turn off echo (for slave pty) */

{

struct termios stermios;

if (tcgetattr(fd, &stermios) < 0)

fprintf(stderr,"tcgetattr error");

stermios.c_lflag &= ~(ECHO | ECHOE | ECHOK | ECHONL);

stermios.c_oflag &= ~(ONLCR);

/* also turn off NL to CR/NL mapping on output */

if (tcsetattr(fd, TCSANOW, &stermios) < 0)

fprintf(stderr,"tcsetattr error");

}

/*

clean up and close handle

*/

void cleanup()

{

if (tty_modified) {

tcsetattr(0,TCSADRAIN,&original_stdin);

tcsetattr(1,TCSADRAIN,&original_stdout);

tty_modified = 0;

}

close(hndl);

}

/*

signal catcher

*/

void sig_catcher(int sig)

{

tcsetattr(hndl,TCSANOW,&saved_termios);

printf("restored termios\n");

cleanup();

exit(1);

}

/*

detect keyboard hit

*/

int kbhit(void)

{

int cnt=0, error;

struct termios otty,otty_save;

tcgetattr(STDIN_FILENO,&otty_save);

otty=otty_save;

otty.c_iflag=0;

otty.c_oflag=0;

otty.c_lflag &= ~ICANON; /* set raw */

otty.c_cc[VMIN] = 1;

otty.c_cc[VTIME] = 1;

if ( !(error=tcsetattr(STDIN_FILENO,TCSANOW,&otty)) ) {

struct timeval tv;

error=ioctl(STDIN_FILENO,FIONREAD,&cnt);

error+=tcsetattr(STDIN_FILENO,TCSANOW,&otty_save);

tv.tv_sec=0;

tv.tv_usec=100;

select(STDIN_FILENO+1,NULL,NULL,NULL,&tv);

}

return ( error == 0 ? cnt: -1);

}

int getch(void)

{

int error;

struct termios otty,otty_save;

char ch;

fflush(stdout);

tcgetattr(STDIN_FILENO,&otty_save);

otty=otty_save;

otty.c_iflag=0;

otty.c_oflag=0;

otty.c_lflag &= ~(ICANON | ECHO); /* set raw, non echo*/

otty.c_cc[VMIN] = 1;

otty.c_cc[VTIME] = 1;

if ( !(error=tcsetattr(STDIN_FILENO,TCSANOW,&otty)) ) {

error = read(STDIN_FILENO,&ch,1);

error+= tcsetattr(STDIN_FILENO,TCSANOW,&otty_save);

}

return ( error == 1 ? (int)ch : -1);

}

/*

Open up UART port and begin redirect input/output from login shell.

*/

void *ttyS(char *port)

{

struct termios term,stdIn,stdOut;

fd_set rset;

int fd, maxfd,selectval,nbytes;

int sd=STDIN_FILENO;

char buf[TRANSFER_BUFFER_SIZE];

char devname[40];

int ch,lastchar;

/* connect to tty device write port */

sprintf(devname,"/dev/tty%s",port);

if( (fd=open(devname,O_RDWR | O_NOCTTY |O_NDELAY)) < 0 ){

fprintf(stderr,"can't open device %s\n",devname);

return NULL;

}

#ifdef DEBUG

fprintf(stderr,"%s opened, fd=%d\n",devname,fd);

#endif

hndl =fd;

fcntl(fd,F_SETFL,O_NONBLOCK); /* set non-blocking mode */

if (tcgetattr(fd,&term) ){

fprintf(stderr,"Can't get device attr.\n");

close(fd);

return NULL;

}

saved_termios = term; //save original termios

if(signal(SIGINT,sig_catcher) == SIG_ERR) {

fprintf(stderr,"Can't install signal SIGINT handler\n");

close(fd);

return NULL;

}

if(signal(SIGTERM,sig_catcher) == SIG_ERR) {

fprintf(stderr,"Can't install signal SIGTERM handler\n");

close(fd);

return NULL;

}

if(signal(SIGHUP,sig_catcher) == SIG_ERR) {

fprintf(stderr,"Can't install signal SIGHUP handler\n");

close(fd);

return NULL;

}

/* make the following file descriptors raw */

if (isatty (0)) {

tcgetattr(0, &original_stdin);

tcgetattr(1, &original_stdout);

tty_modified = 1;

stdIn = original_stdin;

stdOut = original_stdout;

MAKE_TTY_RAW(0, original_stdin);

MAKE_TTY_RAW(1, original_stdout);

}

cfmakeraw(&term); /* raw mode */

atexit(cleanup);

cfsetispeed(&term,B115200); //B9600);

cfsetospeed(&term,B115200); //B9600);

tcsetattr(fd,TCSANOW,&term);

#ifdef DEBUG

if (!tcgetattr(fd,&term) ){

fprintf(stderr,"tty: ispeed=%d, ospeed = %d\n",\

cfgetispeed(&term),cfgetospeed(&term));

}

#endif

set_noecho(fd);

set_noecho(STDOUT_FILENO);

#ifdef DEBUG

if (!tcgetattr(STDIN_FILENO,&stdIn) ){

fprintf(stderr,"STDIN: ispeed=%d, ospeed = %d\n",\

cfgetispeed(&stdIn),cfgetospeed(&stdIn));

}

#endif

tcflush(fd,TCIOFLUSH);

maxfd = ((sd > fd) ? sd:fd)+1;

/*

* Loop to read/write between remote client and host until 'esc q' is received.

*/

for (;;)

{

FD_ZERO(&rset);

FD_SET (STDIN_FILENO, &rset);

FD_SET (fd, &rset);

selectval = select (maxfd, &rset, NULL, NULL, NULL);

if (selectval == -1)

{

syslog (LOG_ERR, "select(): %m");

break;

}

/*

* if client is readable, read from client, write to destination

*/

if (FD_ISSET (STDIN_FILENO, &rset))

{

ch = getch();

if ((lastchar==0x1b) && (ch=='q')) {

#ifdef DEBUG

fprintf(stderr,"Esc-q received\n");

#endif

break;

}

write(fd,&ch,1);

lastchar = ch;

#ifdef DEBUG

if(lastchar == 0x1b)fprintf(stderr,"0x1b char received\n");

#endif

}

/*

* If destination is readable, read from destination, write to client.

*/

if (FD_ISSET (fd, &rset))

{

nbytes = read(fd, &buf, TRANSFER_BUFFER_SIZE);

if (nbytes <= 0)

{

fprintf(stderr,"server close connection\n");

break;

}

if (write (STDOUT_FILENO, &buf, nbytes) != nbytes)

syslog(LOG_ERR, "Error on write %m");

nbytes -= nbytes;

}

}

cleanup();

#ifdef DEBUG

fprintf(stderr,"thread exit\n");

#endif

tcsetattr(hndl,TCSANOW,&saved_termios);

return NULL;

}

/* Main */

int main (int argc, char *argv[])

{

if (argc > 1)

ttyS(argv[1]);

}