#include <stdlib.h>
#include <stdio.h>
#include <signal.h>
#include <unistd.h>
#include <assert.h>

volatile sig_atomic_t sig_int_flag = 0;
volatile sig_atomic_t sig_term_flag = 0;

typedef void (*SigHandler)(int);

void EstablishSignal(int sig, SigHandler handler)
{
   SigHandler res;
      
   res = signal(sig, handler);
   if(res == SIG_ERR)
   {
      perror("Could not establish signal handler");
      exit(EXIT_FAILURE);
   }   
}

void sig_int_handler(int sig)
{
   EstablishSignal(SIGINT, sig_int_handler);

   assert(sig == SIGINT);
   printf("Caught SIGINT!\n"); /* Risky - preferably we should not
                                  call any library function that is
                                  not explicitely marked as reentrant!
                                  (the signal may arrive while we are
                                  already executing this function) */
   sig_int_flag = 1;
}

void sig_term_handler(int sig)
{
   EstablishSignal(SIGTERM, sig_term_handler);
   assert(sig == SIGTERM);
   printf("Caught SIGTERM!\n"); /* Risky! */
   sig_term_flag = 1;
}

int main(int argc, char* argv[])
{
   int i;
   int int_counter = 0;
   
   EstablishSignal(SIGTERM, sig_term_handler);
   EstablishSignal(SIGINT, sig_int_handler);

   for(i=0; i<1000 && !sig_term_flag; i++)
   {
      printf("Going to sleep!\n");
      sleep(30);
      if(sig_int_flag)
      {
	 sig_int_flag = 0;
	 int_counter++;
      }
   }
   printf("SIGINTs: %d  Iterations:%d\n", int_counter, i);
   
   return EXIT_SUCCESS;
}