local -> local file copy question

[Linda Walsh]

In looking at source, I started at fileio and found
write routines but no read routines.

I found a 'WRITE_SIZE' (32K), but no 'READ_SIZE' --
is that' what the MAX_MAP_SIZE (256K)?

I would like to make so that rsync can use larger I/O sizes if
(maybe a command line option?)....

The map routine led me to receiver -- where it looks like it
is responsible for reading the file.

A comment says:
"Receiver process runs on the same host as the generator process.".

I am thinking that is the case where you are not sending to a
a remote machine? I.e. that routine is for local copying only?

But is that right? Generator generates sums and sends lists of sums
to the receiving process before sending the data -- but if it is
on the same machine, are any sum's needed?

Then it looks like it sends all of the data through a pipe line -- even
if it is on the same machine...

i.e. it looks like there are no optimizations for local-to-local file
copy?

Is that the case?