Fix for #130376

[Jonathan Yu]

All:

I have been talking with Evan about this on IRC. I think subclassing
everything as ::Debian modules is a bit ridiculous, however, he did
propose a simple fix for modules like dpkg:

13:59:58 < EvanCarroll> jawnsy: so then make that the official debian
repsonse, all things such as dpkg, and update-perl-sax-parsers should
be prefixed with BEGIN { @INC = grep { !/local/ } @INC }

I think this is a fair point. Our system-installed tools which are
coded in Perl should be designed to safeguard against using packages
in /local/ since they are unsupported in Debian.

This provides users a bit of defense against totally borking their
system when they unwittingly install packages via CPAN. If they mess
up other (unpatched) apps, at least they don't break dpkg (which is
pretty darn important).

On the other hand I think we should also patch the CPAN Shell to
notify users upon execution that packages installed via the CPAN Shell
are *not* supported by Debian, and that they can really break their
systems by doing so.

Cheers,

Jonathan

On Thu, Jun 18, 2009 at 1:17 PM, Evan Carroll<me at evancarroll.com> wrote:
> I'm looking to solve a long standing bug, here is a brief overview.
>
> DESCRIPTION:
> * BUG ID: 130376
> * LINK: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=130376
> * PROBLEM: Prevents using cpanp and cpan to update system
>
> The real issue here is this was done **totally** wrong. Someone forked
> over a module from cpan by polluting the namespace with
> save_parsers_debian {} and breaking upstreams save_parsers {}. This
> results in an update of XML::SAX (which will install to /usr/local)
> holding higher precedence than /usr in the perl load sequence and
> totally breaking the debian added functionality (including dpkg which
> relies on it).
>
> My fix for this problem is fairly simple:
> 1) Move Debian-specific changes into XML::SAX::Debian a subclass of
> upstream XML::SAX
> 3) Update the /usr/bin/update-perl-sax-parsers to use XML::SAX::Debian
> 2) Package both separately. (libxml-sax-perl, libxml-sax-debian-perl)
>
> Any input is appreciated, I'm not exactly sure on how to package perl
> modules for debian, but I can do the subclassing of XML::SAX and
> submit a tarball to CPAN (my pause id is ECARROLL) or the list. I can
> also supply a patch to /usr/bin/update-perl-sax-parsers
>
> --
> Evan Carroll
> System Lord of the Internets
>
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