//=====================================================
// Matt Kretchmar
// A second attempt at reaping zombie children.
// Problem: parent might miss future child signals while 
//  processing current signal.
//=====================================================

#include <unistd.h>      /* symbolic constants */
#include <sys/types.h>   /* system data types */
#include <errno.h>       /* Errors */
#include <stdio.h>       /* Input/Output */
#include <sys/wait.h>    /* Wait for Process Termination */
#include <stdlib.h>      /* General Utilities */
#include <string.h>
#include <stdlib.h>
#include <signal.h>
#include <stdarg.h>

void errExit(char * s)
{
  perror(s);
  exit(1);
}

void handler (int sig)
{
	pid_t pid;
    int status;
	if ( sig == SIGCHLD ) {
		printf("Parent receiving signal from child\n");
		pid = waitpid(-1,&status,0);
        printf("Parent waited for %d (status=%d)\n",pid,status);
        sleep(1);
    }
}

int main ( int argc, char *argv[] )
{
   pid_t  pid;          /* variable to hold process id */
   int i;
   int n = 3;

   if (signal(SIGCHLD,handler) == SIG_ERR)
      errExit("signal handler registration error");
  
   for (i = 0; i < n; i++ ) {
      pid = fork();
      if ( pid == 0 ) {
         printf("%d child spawned\n",getpid());
         sleep(1);
         exit(1);
      }
   }
   while(1);
   return 0;
}