#include <iostream>

#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();
}