use constant {
  DARWIN_SYS_getsockopt => 118, # from bsd/kern/syscalls.master
  GETSOCKOPT_MAXLEN => 512, # enough for now I guess...
};

sub darwin_getsockopt {
  my $optval = "\0" x GETSOCKOPT_MAXLEN;
  my $optlen=pack('i',GETSOCKOPT_MAXLEN);
  my $rv=syscall(DARWIN_SYS_getsockopt,fileno($_[0]),$_[1],$_[2],$optval,$optlen);
  return $rv < 0 ? undef : substr($optval,0,unpack('i',$optlen));
}