#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>

#include <signal.h>

int child();

void * kill_zombies( int n )
{
 int status;
 printf( "PARENT: Caught a SIGCHLD (%d). I'm trying to sleep!\n", n );
 waitpid( 0, &status, WNOHANG );

 /* some versions of Unix reset the signal handler to SIG_DFL */
 signal( SIGCHLD, kill_zombies );

 return (void *)NULL;
}

int main()
{
 int i, children = 8;   /* based on a true story .... */

 for ( i = 0 ; i < children ; i++ )
 {
   /* fork a child process */
   pid_t z = fork();

   if ( z < 0 ) {
     fprintf( stderr, "ERROR: fork() failed.\n" );
     exit( 1 );
   }

   if ( z == 0 ) {
     int rc = child();
     exit( rc );
   }
 }

 {
   int t = 40;
   printf( "PARENT: I don't care. I'm busy. Don't bother me.\n" );
   signal( SIGCHLD, kill_zombies );
   do {
     t = sleep( t );
   } while ( t > 0 );
 }

 return 0;
}

void * handle_sigint( int n )
{
 printf( "CHILD: Caught SIGINT (%d). Okay, I'm awake!\n", n );
 return (void *)NULL;
}

int child()
{
 int t;
 printf( "CHILD: I'm new. My pid is %d.\n", getpid() );

 signal( SIGINT, handle_sigint );

 srand( getpid() * getpid() );
 t = 10 + ( rand() % 21 );      /* in range [10,30] */
 printf( "CHILD: I'm gonna nap for %d seconds.\n", t );
 t -= sleep( t );
 return t;
}