need to modify file data before storing it on destination

[Kyle Jones]

I'd like to be able to store remote files compressed or encrypted
or both.  I think this could be supported in a general way by
having:

    1. an rsync option --remotefilter=command that specifies a
       remote command that rsync pushes file data through before
       storing it on disk.  This option would imply --whole-file.
    2. an rsync option --times-only so that rsync would consider
       only the modification time of the remote file when deciding
       whether to update it.  This is needed so that rsync would
       ignore the file size differences of compressed remote files.

I'm willing to contribute code to implement this.  I'd like to see
this functionality integrated in the standard rsync distribution in
some form.  I distribute a disk-to-disk backup tool that relies on
rsync (see http://freshmeat.net/projects/snapshot/ ) and I'd prefer
not to distribute patches to rsync to provide this functionality.