Binary diffs for deb files

[Paul Sladen]

On Tue, 2 May 2006, Colin Watson wrote:
> dpkg-deb uses zlib for compression, not gzip. Last time I talked to
> Scott about this, I seem to remember that he said that it was
> non-trivial to enable rsyncability because the gzip --rsyncable patch
> was done in gzip rather than in zlib,

Gzip uses a statically included copy of zlib (aka "cp -a") and this is what
has been patched.  The actual change is fairly trivial, it being:

  1) Add together the last 4096 bytes in the stream.
  2) If that sum, modulo 65536, equals zero.  Restart the stream.

This does not actually have to be done in zlib itself...  It is however
mostly irrelevant if we have a zsync-style job working for Edgy.

	-Paul
-- 
High on a Spanish mountain, surrounded by howling dogs.  Southampton, GB