#include <iostream>
#include <signal.h>
#include <sys/types.h>
#include <unistd.h>
#include <string.h>
#include <stdio.h>

using namespace std;

const int NAP_TIME = 20;

void CheckAndReport(sigset_t set, int signal) {
   if (sigismember(&set, signal)) {
      cout << "\tI ignored a " << strsignal(signal) << endl;
   }
   return;
}

void ReportOut() {
   sigset_t set1;

   sigpending(&set1);

   CheckAndReport(set1, SIGHUP);
   CheckAndReport(set1, SIGUSR1);
   CheckAndReport(set1, SIGUSR2);

   return;
}

void BetterHandler(int signal, siginfo_t * info, void * doNotUse) {
    cout << "I just handeled a " << signal  << endl;
    return;
}


int main() {
   sigset_t set1, set2, set3;
   struct sigaction action;

   cout << "This is pid " << getpid() << endl;
   cout << endl;

   // set up a handler for sigusr1
   sigemptyset(&set3);
   sigaddset(&set3, SIGUSR2);

   action.sa_sigaction = BetterHandler;
   action.sa_flags = SA_SIGINFO;
   action.sa_mask = set3;

   if (0 != sigaction(SIGUSR1, &action, nullptr)) {
      perror("sigaction");
   }
 
   // put everything into one set.
   sigfillset(&set1);

   cout << "Blocking all signals (that I can)" << endl;
   cout << "Sleeping for so you can kill at will " << endl;
   sigprocmask(SIG_BLOCK, &set1, &set2);

   sleep(NAP_TIME);

   ReportOut();

   cout << endl;
   cout << "Unblocking USR1 and USR2 " << endl;

   sigemptyset(&set3);
   sigaddset(&set3, SIGUSR1);
   sigaddset(&set3, SIGUSR2);
   sigprocmask(SIG_UNBLOCK, &set3, &set1);
   sleep(NAP_TIME);

   ReportOut();

   cout << endl;
   cout << "Restoring the previous signanal mask " << endl;

   sigprocmask(SIG_SETMASK, &set2, &set1);
   sleep(NAP_TIME);

   ReportOut();

   cout << "ALl Done " << endl;
   return 0;
}