Factor out .rsyncsums logic into a separate checksum-caching library?

Wayne Davison wayned at samba.org
Sat Jun 30 19:20:47 GMT 2007

On Sun, Jun 24, 2007 at 01:03:03PM -0400, Matt McCutchen wrote:
> The git index has been heavily used and tested, so you might find it
> helpful when implementing a checksum cache for rsync.

The problem with this is that the git cache is SHA1, and rsync needs
both MD4 and MD5, depending on what protocol version is in effect.
It should be possible to adapt their code for rsync's purpose, but it's
probably overkill.  The idea behind the new checksum patch is mainly to
allow servers to provide cached checksums for their files, especially
servers whose content is slow to change.

> Specifically, it has protection against being fooled when a file's
> checksum is cached and the file is modified again in the same second;
> .rsyncsums could use this.

I tried to find a description for this algorithm, but didn't see it
mentioned in any of the web searches I made.  Is the algorithm described
anywhere?  Or is my only choice to dig into the source and try to find


More information about the rsync mailing list