File over 2GB using Cygwin

Ville Herva vherva at
Sun Feb 24 04:21:11 EST 2002

On Fri, Feb 22, 2002 at 04:56:49PM -0500, you [David Bolen] wrote:
> Martin Pool [mbp at] writes:
> > It could be an interesting project to try to build rsync under MSVC++.
> > Presumably it can handle large files.  I don't think there's anything
> > impossible in principle about it.
> Not in principle, but unless you're also going to handle the same fork
> emulation and Unix semantics that Cygwin is doing, it's unlikely to be
> a weekend project :-)
At first glance it would seem more productive to create a large file capable
file io library (open()/close()/read()/write() etc) with MSVC, and link
rsync against that. Trying to make its API as much unix-like as possible
would propable be sensible. Then you could even think of integrating that
part to Cygwin as a long term plan.

> In theory a native port might use threads and overlapping I/O very
> effectively, but I think it would be fairly tough to do without some
> significant changes to the existing code.

You could gain some performance with the library as well.

(Of course I know nothing about how Cygwin file io is implemented and what
are the bottlenecks and problems.)

-- v --

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