Created attachment 620170 [details]
My patch for the bug.

Description of problem:

The code in libvirt/stream.c registers the function Stream::recv as having two parameters while in reality it has just one. Thus, when you call it, you must supply a bogus second parameter:

stream = conn.stream
vol.download stream, 0, 0, 0
data = stream.recv(1024, 0)

while it should be just

data = stream.recv(1024)

Version-Release number of selected component (if applicable):

ruby-libvirt
commit a8d79e06419efadc86fc16e74b50bfc406f9746d
Date:   Thu Oct 13 16:23:28 2011 -0400