Re: [gentoo-portage-dev] [PATCH v2] Move INSTALL_MASK handling into merging

[Zac Medico]

On 06/12/2016 02:28 AM, Michał Górny wrote:
> Dnia 12 czerwca 2016 11:10:55 CEST, Zac Medico <zmedico@g.o> napisał(a):
>> On 05/22/2016 01:21 AM, Michał Górny wrote:
>>> Introduce a new logic for INSTALL_MASK handling in merging code,
>>> replacing the old code that removed matching files and directories
>>> from imagedir in bash. The new code actually ignores matching files
>>> on-the-fly while testing for file collisions and merging files.
>>> The files are still written to CONTENTS, and output using "###" zing
>>> to indicate being masked, yet are not actually merged to the
>> filesystem.
>>
>> Since collision-protect relies on existing files in its collision test,
>> install-masked files are no longer going to trigger collisions. Then,
>> since the install-masked files are still written to CONTENTS, it's
>> possible for the unmerge of one package to unmerge colliding files that
>> belong to another package!
>>
>> There are a number of ways to solve this problem. For example, we could
>> have the unmerge code ignore any files in CONTENTS that match the
>> INSTALL_MASK value that was used at merge time.
>
> Hmm, thinking about this more widely (i.e. actually thinking rather than mimicking the old behavior), I think it would be better to actually use the original file set for collision-protect. This will make it possible to detect collisions that would otherwise be hidden via INSTALL_MASK.

Even then, we have to carefully consider how the absence of installed
files affects the collision test. It's safest for the unmerge code to be
aware of the merge time INSTALL_MASK setting, and not try to unmerge the
install-masked files.
-- 
Thanks,
Zac