#include <stdio.h>
#include <termios.h>
#include <unistd.h>
#include <stdlib.h>
#include <signal.h>
/*
 * getpw4.c: get a password with echo off and show stars for chars
 * shows how to use signal to catch ^C and reset terminal before exit
 * v3: restores terminal to original rather than always setting ECHO on
 * v4: shows how to use -ICANON (an lflag) and  c_cc[VMIN] = 1
 */

int  setup_terminal(int);
int  restore_terminal(int);
int  read_a_string_stars(int , char [], int );
void intr_handler(int);
#define	SLEN	100

int main()
{
	char	str[SLEN];

	signal(SIGINT, intr_handler);
	if ( setup_terminal(0) == -1 )		/* fd 0 is stdin */
		exit(1);
	if ( read_a_string_stars(0, str, SLEN) == 0 )
		printf("You typed the string: %s\n", str);
	if ( restore_terminal(0) == -1 )
		exit(1);
	return 0;
}
/* called when user presses Ctrl-C */
void intr_handler(int s)
{
	printf("interrupted! restoring echo state.\n");
	restore_terminal(0);
	exit(1);
}
/*
 * read no more than len-1 chars into array, put a \0 at end.  stop at \n or EOF
 * args: fd, array, space in array
 * rets: -1 for error or no data, 0 for success
 * does: class suggestions
 */
int read_a_string_stars(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;
}

static struct termios orig_settings;
static int            have_orig = 0;
/*
 * get settings for fd, turn off the ECHO bit, set settings
 */
int setup_terminal(int fd)
{
	struct termios settings;

	if ( tcgetattr(fd, &settings) == -1 )
		return -1;
	orig_settings = settings;
	have_orig     = 1;
	settings.c_lflag &= ~ECHO;		/* turn off echo bit */
	if ( tcsetattr(fd, TCSANOW, &settings) == -1 )
		return -1;
	return 0;
}
/*
 * restore terminal to original settings
 */
int restore_terminal(int fd)
{
	if ( have_orig )
		if ( tcsetattr(fd, TCSANOW, &orig_settings) == -1 )
			return -1;
	return 0;
}