Iterating over a binary file

[Derek]

Pardon the newbie question, but how can I iterate over blocks of data
from a binary file (i.e., I can't just iterate over lines, because
there may be no end-of-line delimiters at all).  Essentially I want to
to this:

f = file(filename, 'rb')
data = f.read(1024)
while len(data) > 0:
    someobj.update(data)
    data = f.read(1024)
f.close()

The above code works, but I don't like making two read() calls.  Any
way to avoid it, or a more elegant syntax?  Thanks.