/*
 * term-enq
 * 2002-01-15 Fredrik Roubert <roubert@df.lth.se>
 *
 * Send ENQ (0x05) to the terminal, and print the returned string to stdout.
 *
 */

#include <sys/time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <termios.h>


#if DEBUG

# include <stdio.h>
# include <string.h>
# include <errno.h>

# define PERROR(s) \
        fprintf(stderr, __FILE__ ": line %i: %s(): %s\n", \
		__LINE__, #s, strerror(errno))
#else

# define PERROR(s)

#endif


int main(int argc, char *argv[])
{
	static const char	tty[] = "/dev/tty", enq = 5;
	int			fd;
	struct termios		term_std, term_raw;
	fd_set			rfds;
	struct timeval		tv;
	unsigned char		buf[255];
	ssize_t			size;

	if (-1 == (fd = open(tty, O_RDWR)))
	{
		PERROR(open);
		return EXIT_FAILURE;
	}

	if (0 != tcgetattr(fd, &term_std))
	{
		PERROR(tcgetattr);
		return EXIT_FAILURE;
	}

	term_raw = term_std;
	term_raw.c_lflag &= ~(ECHO | ICANON);
	term_raw.c_cc[VTIME] = 5;
	term_raw.c_cc[VMIN] = 1;

	if (0 != tcsetattr(fd, TCSANOW, &term_raw))
	{
		PERROR(tcsetattr);
		return EXIT_FAILURE;
	}

	if (1 != write(fd, &enq, 1))
	{
		PERROR(write);
		goto exit_failure;
	}

	if (0 != usleep(250000))
	{
		PERROR(usleep);
		goto exit_failure;
	}

	FD_ZERO(&rfds);
	FD_SET(fd, &rfds);

	tv.tv_sec = 0;
	tv.tv_usec = 500000;

	switch (select(fd + 1, &rfds, NULL, NULL, &tv))
	{
		case 0:
			goto exit_success;

		case 1:
			break;

		default:
			PERROR(select);
			goto exit_failure;
	}

	if (-1 == (size = read(fd, buf, sizeof buf)))
	{
		PERROR(read);
		goto exit_failure;
	}

	if (size > 0)
	{
		if (size >= sizeof buf)
		{
			goto exit_failure;
		}

		buf[size ++] = '\n';

		if (size != write(STDOUT_FILENO, buf, size))
		{
			PERROR(write);
			goto exit_failure;
		}
	}

exit_success:

	if (0 != tcsetattr(fd, TCSANOW, &term_std))
	{
		PERROR(tcsetattr);
		return EXIT_FAILURE;
	}

	return EXIT_SUCCESS;

exit_failure:

	if (0 != tcsetattr(fd, TCSANOW, &term_std))
	{
		PERROR(tcsetattr);
	}

	return EXIT_FAILURE;
}