/* con device */

#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <termios.h>
#include <unistd.h>

struct termios save;

void
host(int fd)
{
	int cc;
	char buf[128];

	for (;;) {
		cc = read(fd, buf, sizeof buf);
#ifdef HEX
		if (cc < 0)
			break;
		for (int i = 0; i < cc; ++i) {
			char hex[3];
			sprintf(hex, "%02X", (unsigned char) buf[i]);
			write(1, hex, 2);
		}
#else
		if (cc > 0)
			write(1, buf, cc);
		else if (cc < 0)
			break;
#endif
	}
}

void
hup(int signo)
{
	write(1, "HUP\n", 4);
	tcsetattr(0, TCSADRAIN, &save);
	_exit(0);
}

void
user(int fd)
{
	char c, last = '\r';

	signal(SIGHUP, hup);
	for (;;)
		while (read(0, &c, 1) > 0) {
			if (c == '~' && (last == '\n' || last == '\r'
					 || last == 4)) {
				read(0, &c, 1);
				if (c == '.')
					return;
			}
			write(fd, &c, 1);
			last = c;
		}
}

int
main(int argc, char *argv[])
{
	int fd;
	pid_t pid;
	struct termios t;

	if (argc != 2)
		exit(1);

	fd = open(argv[1], O_RDWR | O_NDELAY);
	if (fd < 0)
		exit(2);
	fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) & ~O_NDELAY);
	tcgetattr(fd, &t);
	t.c_cc[VMIN] = 1;
	t.c_cc[VTIME] = 0;
	tcsetattr(fd, TCSADRAIN, &t);

	tcgetattr(0, &t);
	save = t;
	t.c_iflag = 0;
	t.c_oflag = 0;
	t.c_lflag = 0;
	t.c_cc[VMIN] = 1;
	t.c_cc[VTIME] = 0;
	tcsetattr(0, TCSADRAIN, &t);

	if ((pid = fork()) > 0) {
		user(fd);
	} else if (pid == 0) {
		host(fd);
	} else {
		perror("fork");
		_exit(EXIT_FAILURE);
	}

	tcsetattr(0, TCSADRAIN, &save);
	kill(pid, SIGKILL);
	close(fd);
	_exit(EXIT_SUCCESS);
}