[PATCH wayland] wayland-egl: Ignore underscored symbols in ABI check

Derek Foreman derekf at osg.samsung.com
Tue Mar 20 14:50:11 UTC 2018

On 2018-03-20 07:11 AM, Daniel Stone wrote:
> On 20 March 2018 at 11:55, Emil Velikov <emil.l.velikov at gmail.com> wrote:
>> On 20 March 2018 at 11:46, Daniel Stone <daniel at fooishbar.org> wrote:
>>> Sure. As on IRC though, we definitely need to add at least _ftext for
>>> MIPS anyway:
>>> https://gitlab.gnome.org/GNOME/glib/commit/ad12142943e0f20ed9583c9d6bf50f6262110c74
>>> And probably some more for ARM toolchains using other linkers:
>>> http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0474k/pge1362066045758.html
>>> Doing a quick check across all the architectures on Debian shows that
>>> your updated list is also missing _fbss, _fdata, and _ftext. So we'd
>>> need to respin for those as well, but I think at this point the
>>> inconvenience of maintaining a list of every linker's implementation
>>> detail on every platform, outweighs the risk of an exported
>>> underscore-prefixed symbol slipping through review.
>> I think you're preemptively worried about this. Plus there's no need
>> to add every symbol a search could find.
>> Even then, ask yourself the question:
>> Which is better - updating an ugly looking list once in a blue moon or
>> having apps use internal API?
>> As said above: _if_ it turns out to be labour intensive - fine remove it.
>> We've already spend more time researching than what the [expected]
>> maintenance for 1 year would be ;-)
> It all depends on how you view scope and probability.
> I don't agree my concern is preemptive: we've just shipped a beta
> where 'make check' fails on a few architectures, and the proposed fix
> (adding several symbols to the platform list) will still fail on
> architectures Debian ships on, until it also adds _fbss, _fdata and
> _ftext. I think my suggestion is reasonable: it fixes the very real
> problem, in a way which avoids expanding the scope of our ABI checker
> to include the implementation details of every linker/architecture
> pair that people use Wayland on. The cost of this is the probability
> that someone manages to add a new underscored symbol marked with
> WL_EXPORT into a library which is currently 105 LoC, and have no-one
> notice that in review. I think that's a reasonable tradeoff.

I'm inclined to agree with Daniel here.

Someone managing to sneak a WL_EXPORT on a symbol starting with a _ past
review seems reasonably unlikely.

And after reading this thread I'm still not entirely sure we have a
complete list of what should be on that whitelist, and there are only a
limited number of systems I can test build on right now.

Reviewed-by: Derek Foreman <derekf at osg.samsung.com>

> Cheers,
> Daniel
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