Binary diffs for deb files

[Matt Zimmerman]

On Tue, May 02, 2006 at 11:10:08PM +0100, Colin Watson wrote:
> On Tue, May 02, 2006 at 02:50:50PM -0700, Matt Zimmerman wrote:
> > On Tue, May 02, 2006 at 10:14:50PM +0100, James Hall wrote:
> > > Some other issues I have with zsync are:
> > > 
> > > 1. How easy would it be to recompress all the packages with the gzip
> > > --rsync flag?
> > 
> > Trivial.  At the appropriate time, we enable this flag by default for
> > dpkg-deb, and all builds from that point forward produce rsyncable debs.
> 
> 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, and would require some moderately
> complex porting work.

Good point; it wouldn't quite be trivial.  We could recompress the debs
using gzip after the build, I suppose, but is there any particular reason
why dpkg needs to use zlib?  It already relies on external tools of similar
ubiquity (e.g., GNU tar), and forking gzip is typically faster on
multiprocessor machines like our buildds.

-- 
 - mdz