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Re: About the GPL

Rob Browning <rlb@cs.utexas.edu> writes:

> gsstark@mit.edu (Gregory S. Stark) writes:
> > Actually Xdelta is cool it deals with this problem, and it has
> > native support for .deb files. One of these days I'll go play with
> > it and figure out how to set up our archives so that people can
> > download xdelta patches instead of complete packages. This will
> > really help people track those large packages that keep changing
> > packaging details (hi Branden:).

> I doubt that xdelta will actually give you any space savings with .deb
> files.  .deb files are compressed, so even a minor change to one file
> in the package will be likely to make the package incomparable to the
> previous version on a binary level.

"Native support for .deb files" probably means that it knows a .deb
file is an ar archive of two .tar.gz files.  (It can successfully diff
RPM files, because it finds the cpio file and decompresses it before
doing the diff.)

Nonetheless, the last time I checked out xdelta, it took a lot of
memory to take a diff of big files (where big is circa 4MB, and a lot
of memory is over 20MB), which would make taking diffs of Branden's
packages rather difficult.

A different approach, which wouldn't require the user have the
original package would be to develop "patch packages" which contain:

 * A list of files to delete.
 * A .tar.gz of new files.
 * A .tar.gz of xdeltas of changed files
 * A normal control.tar.gz file


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