[Rpm-maint] Filtering blues

[Panu Matilainen]

On 01/18/2013 01:15 AM, Alec Leamas wrote:

Hi, and apologies for the late reply...

> I'm somewhat unhappy with current filtering mechanisms, or perhaps just
> not clever enough to use them in the right way.
>
> In  a very normal usecase, I have  a private library from which I want
> to block the Provides: This is simple enough using
> __provides_exclude_from <some library.so>.  Here the story should end, I
> have filtered the Provides: the way I want..
>
> However, the package is now un-installable since the depsolver Requires:
> the symbols I just filtered. This  means that I have to filter the same
> symbols which I blocked using __provides_exclude_from from the Requires.
> But this is not a simple __requires_exclude_from, because  that will
> filter *all* dependencies from my library. So I have to use
> __requires_exclude, and enumerate each and every symbol catched by
> __provides_exclude_from in  a long list.

Yup, it is a bit tricky: when a another program/library links to a 
library, it'll show up in DT_NEEDED whether its internal or not. The 
linker doesn't really differentiate between the two, and thus rpm cannot 
automatically do it either.

> It definitely doable, but it feels clumsy and error-prone.  I miss an
> elegant way to do this, something like __provides_requires_exclude_from
> <file-match> which filters the symbols in <filematch> in both Requires:
> and Provides, or, perhaps better, a way to refer to the symbols in a
> <file-match> found by  __filter_provides_from so I can use them in
> __requires_exclude.

For filtering internal libraries from requires and provides, the easiest 
thing is to have an identical rule for both __filter_provides and 
__filter_requires and forget about the _from variants.

>
> But it might be that I just don't understand how to use those macros.
> It's not that intuitive, really.

Agreed, the filtering mechanism is not exactly intuitive or "nice" by 
any strech of imagination. Back when it got added, the idea was to first 
make it *possible* by providing a low-level mechanism, and later add 
some sugar on top to make it easier to use. Only the latter part hasn't 
gotten done :-/

	- Panu -