#include<stdio.h>
#include<signal.h>
#include<sys/types.h>
#include<unistd.h>
#include<sys/wait.h>
#include<limits.h>
#include<fcntl.h>

volatile int flag1 = 0, flag2 = 0;
volatile char abc = 0;
volatile int k = 0;
volatile pid_t p1, p2, pp;

void dadhandler(int signo) {
    if (signo == SIGIO) {
        wait(NULL);
        wait(NULL);
        _exit(0);
    } else {
        kill(p2, SIGALRM);      
    }
}

void flg(int signo) {
    flag1 = 1;
}

void handler(int signo)
{
    //printf("sig : %d %d\n", k, abc); 
    if(signo == SIGUSR1) {
        if(k == CHAR_BIT - 1) {
            abc <<= 1;
            printf("%c", abc);
            abc = 0;
            k = 0;
        } else {
            k++;
            abc <<= 1;
        } 
    } else if(signo == SIGUSR2) {
        if(k == CHAR_BIT - 1) {
            abc = (abc << 1) + 1;
            printf("%c", abc);
            abc = 0;
            k = 0;
        } else {
            k++;
            abc = (abc << 1) + 1;
        }
    } else if(signo == SIGIO) {
        kill(pp, SIGIO); 
        printf("\n");
        _exit(0);
    }
    flag2 = 1;
    fflush(stdout);
}

int main(int argc, char *argv[])
{
    pp = getpid();
    
    struct sigaction ppsa;
    sigemptyset(&ppsa.sa_mask);
    ppsa.sa_handler = dadhandler;
    ppsa.sa_flags = SA_RESTART;
    sigaction(SIGALRM, &ppsa, NULL);
    sigaction(SIGIO, &ppsa, NULL);
    
    sigset_t pps;
    sigaddset(&pps, SIGUSR1);
    sigaddset(&pps, SIGUSR2);
    sigaddset(&pps, SIGIO);
    sigaddset(&pps, SIGALRM);
    sigprocmask(SIG_BLOCK, &pps, NULL);
    
    p1 = fork();
    if(!p1) {
        
        struct sigaction sa;
        sigemptyset(&sa.sa_mask);
        sa.sa_flags = SA_RESTART;
        sa.sa_handler = handler;
        sigaction(SIGUSR1, &sa, NULL);
        sigaction(SIGUSR2, &sa, NULL);
        sigaction(SIGIO, &sa, NULL);
      
        sigprocmask(SIG_UNBLOCK, &pps, NULL);
        while(1) {
            while(!flag2);
            flag2 = 0;
            kill(pp, SIGALRM);
        }
        _exit(0);
    }
    
    p2 = fork();
    if(!p2) {
        int fd = open(argv[1], O_RDONLY);
        char c;

        struct sigaction alr;
        sigemptyset(&alr.sa_mask);
        alr.sa_handler = flg;
        alr.sa_flags = SA_RESTART;
        sigaction(SIGALRM, &alr, NULL);

        sigprocmask(SIG_UNBLOCK, &pps, NULL);
        while(read(fd, &c, sizeof(c) == sizeof(c))) {
            for(int i = CHAR_BIT - 1; i >= 0; --i) {
                if(c >> i & 1) {
                    kill(p1, SIGUSR2);
                } else {
                    kill(p1, SIGUSR1);
                }
                while(!flag1);
                flag1 = 0;
            }
        }
        close(fd);
        kill(p1, SIGIO);
        _exit(0);
    }

    sigprocmask(SIG_UNBLOCK, &pps, NULL);
    while(1) {
        pause();
    }
    return 0;
}