sub bear_child {
   my $pid;
   my $sigset;

   # block signal for fork
   $sigset = POSIX::SigSet->new(SIGINT);
   sigprocmask( SIG_BLOCK, $sigset)
      or die "Can't block SIGINT for fork: $!\n";

   # fork a subprocess
   die "fork: $!" unless defined ($pid = fork);

   if ($pid) {
      # Parent records the child's birth and returns.
      sigprocmask( SIG_UNBLOCK, $sigset)
         or die "Can't unblock SIGINT for fork: $!\n";
      $children{$pid} = 1;
      $children++;
      return;
   } else {
      # Child process must *not* return from this subroutine.
      $SIG{INT} = 'DEFAULT';      # make SIGINT kill us as it did before
      # unblock signals
      sigprocmask( SIG_UNBLOCK, $sigset)
         or die "Can't unblock SIGINT for fork: $!\n";

      # do kid sutff
      # ...

      print "child $$ doing stuff\n";

      # cleanup

      print "child $$ is done processing\n";

      exit; # make sure sub never returns
   }
}