libdebian-installer Packages support proposal

[Bastian Blank <waldi@debian.org>]

Hi folks

I got a request from Colin if it is possible to add udeb selection per
frontend. I had to decline this as it will break the ABI.

As I have some pending changes which does that also, I hereby propose
the following which will make it possible to change the ABI of the
Packages reading part of libd-i without affecting all packages.

* Split the whole thing into another shared library (adds 8KiB on i386
  for the SO startup code).
* Either don't change the SONAME of libdebian-installer and provide the
  old symbols until the next beta as the removal will break existing
  images,
* or change the SONAME once.

With this, the following changes can be done easily.

* Support for udebs per frontend.
* Removal of hashmap usage. Replace them with a binary tree.
* Support for more than one version of a package.
  There are two possible solutions:
  - The package struct get a list of versions.
  - The parser is allowed to replace the information of an older version
    of a package with a newer.
* Support for reading more than on Packages files.

Bastian

-- 
What kind of love is that?  Not to be loved; never to have shown love.
		-- Commissioner Nancy Hedford, "Metamorphosis",
		   stardate 3219.8