[Rpm-maint] [PATCH 08/19] Remove duplicates when preparing the policy set

[James Antill]

On Tue, 2010-02-02 at 15:25 -0500, Steve Lawrence wrote:
> There are cases where duplicates are expected, and we must be able to
> removed the older version of a duplicate. Unfortunately, policies are not
> versioned, so we must use the install time of a policy to determine which
> which is newer. Policies that have not yet been installed get a time of
> UINT_MAX so they are seen as the newest when compared to already installed
> policies. In the case of two policies having the same install time, we
> don't know which one to choose, so we error out.
> 
> Policies are only considered duplicates if they have the same name and
> their types overlay. For example, this would not be considered
> duplicates because their types do not overlap and could be installed at
> the same time (in different types) without a problem:
> 
> 	%policy package1
> 	%module modules/foo-targeted.pp
> 		Name: foo
> 		Types: targeted
> 
> 	%policy package2
> 	%module modules/foo-mls.pp
> 		Name: foo
> 		Types: mls
> 
> Whereas this would be considered a duplicate:
> 
> 	%policy package1
> 	%module modules/foo.pp
> 		Name: foo
> 		Types: targeted mls
> 
> 	%policy package2
> 	%module modules/foo-mls.pp
> 		Name: foo
> 		Types: mls
>
> Note: If 'targeted mls' were changed to 'default', that would still be
> considered a duplicate, because 'mls' is in the set of 'default'.

 This, along with the previous magic packages and the "obsoletes policy"
code ... all make me think policies should be in specific packages with
real nevr and prco information.

 For instance your "policy obsoletes" must need to reorder the
transaction, but obviously rpm isn't going to use it for that (where it
would use prco data).

 And the above looks like if "%policy pkg1" was in pkgA and "%policy
pkg2" was in pkgB this code will start doing really weird things (even
on downgrades! Because the uninstalled policy will be "newer").

-- 
James Antill - james at fedoraproject.org
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