/*
 * Sample program for ioctl system call - No.54
 *
 * ioctl - control device
 *
 * Synopsis
 *     #include <sys/ioctl.h>
 *
 *     int ioctl(int d, int request, ...);
 *
 *     [The "third" argument is traditionally char *argp, and
 *     will be so named for this discussion.]
 *
 * Description
 *     The ioctl function manipulates the underlying device
 *     parameters of special files. In particular, many operating
 *     characteristics of character special files (e.g. terminals)
 *     may be controlled with ioctl requests. The argument d
 *     must be an open file descriptor.
 *
 *     An ioctl request has encoded in it whether the argument is
 *     an in parameter or out parameter, and the size of the
 *     argument argp in bytes. Macros and defines used in specifying
 *     an ioctl request are located in the file <sys/ioctl.h>.
 *
 * Types - <sys/ioctl.h>
 *     struct termio
 *       {
 *         unsigned short int c_iflag;          
 *         unsigned short int c_oflag;          
 *         unsigned short int c_cflag;          
 *         unsigned short int c_lflag;          
 *         unsigned char c_line;                
 *         unsigned char c_cc[8 ];              
 *      };
 *
 * Macros - <asm/ioctl.h>
 *     #define __ARCH_I386_IOCTLS_H__
 *     #define TCGETS          0x5401
 *     #define TCSETS          0x5402
 *     #define TCSETSW         0x5403
 *     #define TCSETSF         0x5404
 *     #define TCGETA          0x5405	* set terminal attributes *
 *     #define TCSETA          0x5406
 *     #define TCSETAW         0x5407
 *     #define TCSETAF         0x5408	* set teminal attributes and flush the buffer *
 *     #define TCSBRK          0x5409
 *     #define TCXONC          0x540A
 *     #define TCFLSH          0x540B
 *     ..............................
 *
 *     <asm/termbits.h>
 *     #define ECHO    0000010	* 'enable echoing' bit of c_lflag *
 *
 *     see 'man ioctl_list' or 'man termios' for more information
 */

#include <stdio.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <unistd.h>
#include <asm/termbits.h>
#include <string.h>

#define BYTESIZE 8

void printbits(unsigned short int flag)
{
	int i;

	for (i = 0; i < BYTESIZE * sizeof(flag); ++i)
		printf("%d", (flag << i & 1 <<
			 BYTESIZE * sizeof(flag) -1) ? 1 : 0);
	putchar('\n');
}

print_termios(struct termio *tty)
{
	int i;

	printf("termio.c_iflag: "); printbits(tty->c_iflag);
	printf("termio.c_oflag: "); printbits(tty->c_oflag);
	printf("termio.c_cflag: "); printbits(tty->c_cflag);
	printf("termio.c_lflag: "); printbits(tty->c_lflag);
	printf("termio.c_line: %d\n", tty->c_line);
	for (i = 0; i < 8; i++) 
		printf("termio.c_cc[%d]: %d\n", i, tty->c_cc[i]);
}

main()
{
	int fd;
	char name[20];
	struct termio tty, tty_bak;

	/* The path /dev/pts/0 is a device file of the terminal emulator
        such as kterm. 0 is for the terminal opened fist, and 1 for the
        terminal opened second. So when you test this program, you need to
        open only one kterm on the desktop */

	fd = open("/dev/pts/0", O_RDWR);

	/* get terminal attributes */
	ioctl(fd, TCGETA, &tty);
	tty_bak = tty;

	print_termios(&tty);

	/* disable echoing by unsetting ECHO bit of c_lflag */
	tty.c_lflag &= ~ECHO;
	ioctl(fd, TCSETAF, &tty);

	printf("\nechoing disabled\n");
	printf("termio.c_lflag: "); printbits(tty.c_lflag);
	printf("name = ");
	fgets(name, sizeof name, stdin);
	name[strlen(name)-1] = '\0';
	printf("\nhello, %s.\n", name);

	/* recover the initial setting */
	ioctl(fd, TCSETAF, &tty_bak);

	exit(0);
}