[erlang-questions] Blocking send to port

[tsuraan]

I have a program that wants to receive a constant stream of bytes on
stdin so that it can forward them to an icecast server.  Is there any
way that the erlang process sending the data to that port program can
block on writes (port_command calls), allowing me to write a really
simple process that just gets data from its source and sends it to the
port program at exactly the same rate that the port program consumes
the data?