/***************************************************************/
/*                                                             */
/* File:  sigTalk.c                                            */
/* Purpose: Demonstrate signals and communicating processes.   */
/*   Fork a process and parent sends signals to child using    */
/*   the kill() system call.  Child catches signals using      */
/*   signal() system call.                                     */
/*                                                             */
/***************************************************************/

#include <stdio.h>
#include <signal.h>

// Signal handlers
void sighup(); 
void sigint();
void sigquit();

int main()
{ 
  int pid;


  // fork process
  if ((pid = fork()) < 0) {
    perror("fork");
    exit(1);
  }
    
  if (pid == 0)  {   // Child process
    // set signal handlers
    signal(SIGHUP,sighup); 
    signal(SIGINT,sigint);
    signal(SIGQUIT, sigquit);
    for(;;); 
  }
  else  {   // Parent process
    printf("\nPARENT: sending SIGHUP\n\n");
    kill(pid,SIGHUP);
    sleep(3); /* pause for 3 secs */
    printf("\nPARENT: sending SIGINT\n\n");
    kill(pid,SIGINT);
    sleep(3); /* pause for 3 secs */
    printf("\nPARENT: sending SIGQUIT\n\n");
    kill(pid,SIGQUIT);
    sleep(3);
  }
}  // end function main


void sighup() {
  signal(SIGHUP,sighup); /* reset signal */
  printf("CHILD: I have received a SIGHUP\n");
}

void sigint() {
  signal(SIGINT,sigint); /* reset signal */
  printf("CHILD: I have received a SIGINT\n");
}

void sigquit() {
  printf("My parent process has killed me!!!\n");
  exit(0);
}