#include <iostream>
#include <string>
#include <termios.h>
#include <unistd.h>
#include <fcntl.h>

void setEcho(bool echo);
void setBlocking(bool block);
bool hasInput();
void clearStdin();

using namespace std;

int main(void) {
  int i;
  char c;
  //turn off blocking
  fcntl(STDIN_FILENO, O_NONBLOCK, O_ASYNC);
  setBlocking(false);
  setEcho(false);
  

  cout << "set  your password: ";
  cout.flush();
  do {
    if(hasInput()) {
      c = cin.get();
      c++;
      cout.put(c+1);
      cout.flush();
    }
    usleep(1000);
  } while(c!='\n');


  setEcho(true);
  clearStdin();
  return 0;
}

void
setEcho(bool echo) {
  struct termios t;

  //get the current settings
  tcgetattr(STDIN_FILENO, &t);

  //toggle echo
  if(echo)
    t.c_lflag = t.c_lflag | ECHO;
  else
    t.c_lflag = t.c_lflag & ~ECHO;

  //set the settings
  tcsetattr(STDIN_FILENO, TCSANOW, &t);
}


void
setBlocking(bool block) {
  struct termios t;

  //get the current settings
  tcgetattr(STDIN_FILENO, &t);

  //toggle blocking
  if(block)
    t.c_lflag = t.c_lflag | ICANON;
  else
    t.c_lflag = t.c_lflag & ~ICANON;

  //set the settings
  tcsetattr(STDIN_FILENO, TCSANOW, &t);
}


bool
hasInput() {
  fd_set fs;
  timeval tv;
  int i;
  
  //set up the fd set
  FD_SET(STDIN_FILENO, &fs);

  //set up the timespec
  tv.tv_sec = 0;
  tv.tv_usec = 1;

  //select
  i=select(STDIN_FILENO + 1, &fs, NULL, NULL, &tv);

  //0 no input  available
  //-1  error
  if(i==0 || i==-1) {
    return false;
  }

  //there is input
  return true;
  
}


void
clearStdin()  {
  while(hasInput())
    cin.get();
}