[pacman-dev] [PATCH] Add support for the xz archive format

[Xavier]

On Wed, May 13, 2009 at 12:43 PM, Pierre Schmitz <pierre at archlinux.de> wrote:
> Am Mittwoch, 13. Mai 2009 10:00:55 schrieb Xavier:
>> To sum up the problems I expect :
>> * xdelta will be inefficient with xz packages since it does not recognize
>> it * when it recognizes it, the sync.c code will need to be updated.
>
> I did not have a closer look at pacman's code but can't we just uncompress the
> packages ourself and let xdelta handle plain tar files?
>

This was one of the available option. Maybe we didn't go for it
because it requires slightly more work.
But it may be the best option after all.

I first thought we would just have to change xdelta generation in
create-xdelta and xdelta patching in libalpm/sync.c , but I just
remembered I used the xdelta meta-info in repo-add :
http://projects.archlinux.org/?p=pacman.git;a=blob;f=scripts/repo-add.sh.in;h=2390a92ccfda3a7693a94a5459c023683325fd76;hb=HEAD#l142

So I use xdelta to get the original package file and destination
package file from a .delta file, to add this information to pacman
database.
However, if we do delta between .tar files, the origin and destination
will also be plain tar. But the packages in the file cache are not
plain tar but compressed tar.
So this requires more thinking and attention.