This library makes the classic error, it returns the first file descriptor that is sent then finishes. You can then DoS the process by sending it huge numbers

This library makes the classic error, it returns the first file descriptor that is sent then finishes. You can then DoS the process by sending it huge numbers of fds instead of just one, which it will omit to close, and thus run out of file descriptors. So to be safe you need to iterate over all the fds and close them.