my $OPENFLAGS = O_CREAT | O_EXCL | O_RDWR;
my $LOCKFLAG;

unless ($^O eq 'MacOS') {
  for my $oflag (qw/ NOFOLLOW BINARY LARGEFILE NOINHERIT /) {
    my ($bit, $func) = (0, "Fcntl::O_" . $oflag);
    no strict 'refs';
    $OPENFLAGS |= $bit if eval {
      # Make sure that redefined die handlers do not cause problems
      # e.g. CGI::Carp
      local $SIG{__DIE__} = sub {};
      local $SIG{__WARN__} = sub {};     
      $bit = &$func();
      1;
    };
  }
  # Special case O_EXLOCK
  $LOCKFLAG = eval {
    local $SIG{__DIE__} = sub {};
    local $SIG{__WARN__} = sub {};
    &Fcntl::O_EXLOCK();
  };
}