- Write a length prefix instead of a trailing null for the name that

- Write a length prefix instead of a trailing null for the name that
  goes down the pipe from the generator to the receiver.
- Use the helper functions in io.c to read/write the pipe data (now
  that they have been improved to properly support non-main-socket
  fds).
- Make the generator side of the pipe non-blocking so that we can
  (and now do) monitor the incoming messages from the receiver while
  we're trying to send them the next name.