#include <stdio.h>
#include <termios.h>
#include <unistd.h>
#include <stdlib.h>
#include <signal.h>
/*
 * getpw2.c: get a password with echo off
 * shows how to use signal to catch ^C and reset terminal before exit
 */

int  turn_off_echo(int);
int  turn_on_echo(int);
int  read_a_string(int , char [], int );
void intr_handler(int);
#define	SLEN	100

int main()
{
	char	str[SLEN];

	signal(SIGINT, intr_handler);
	if ( turn_off_echo(0) == -1 )		/* fd 0 is stdin */
		exit(1);
	if ( read_a_string(0, str, SLEN) == 0 )
		printf("You typed the string: %s\n", str);
	if ( turn_on_echo(0) == -1 )
		exit(1);
	return 0;
}
/* called when user presses Ctrl-C */
void intr_handler(int s)
{
	printf("interrupted! restoring echo state.\n");
	turn_on_echo(0);
	exit(1);
}
/*
 * read no more than len-1 chars into array, put a \0 at end
 * if last char is a \n, then remove that
 */
int read_a_string(int fd, char a[], int len)
{
	int	nread;

	nread = read(fd, a, len-1);
	if ( nread <= 0 )
		return -1;
	if ( a[nread-1] == '\n' )
		a[nread-1] = '\0';
	else
		a[nread] = '\0';
	return 0;
}
/*
 * get settings for fd, turn off the ECHO bit, set settings
 */
int turn_off_echo(int fd)
{
	struct termios settings;

	if ( tcgetattr(fd, &settings) == -1 )
		return -1;
	settings.c_lflag &= ~ECHO;		/* turn off echo bit */
	if ( tcsetattr(fd, TCSANOW, &settings) == -1 )
		return -1;
	return 0;
}
/*
 * get settings for fd, turn on the ECHO bit, set settings
 */
int turn_on_echo(int fd)
{
	struct termios settings;

	if ( tcgetattr(fd, &settings) == -1 )
		return -1;
	settings.c_lflag |= ECHO;		/* turn off echo bit */
	if ( tcsetattr(fd, TCSANOW, &settings) == -1 )
		return -1;
	return 0;
}