[PATCH v1] libcamera: controls: Check size of enum

[Barnabás Pőcze]

Hi

2025. 03. 19. 11:48 keltezéssel, Kieran Bingham írta:
> Quoting Kieran Bingham (2025-03-17 17:56:43)
>> Quoting Barnabás Pőcze (2025-03-10 17:02:54)
>>> Only enums whose sizes match that of `int32_t` can be directly
>>> supported. Otherwise the expected size and the real size would
>>> disagree, leading to an assertion failure in `ControlValue::set()`.
>>>
>>> Signed-off-by: Barnabás Pőcze <barnabas.pocze at ideasonboard.com>
>>
>> Has this happened? I assume if we try to make a control from an enum
>> where we override the type it would now produce a compile failure (which
>> I'm fine with for now).
>>
>> I assume we could make similar mappings of other enum sizes if we needed
>> to at that point, but I don't see that as a requirement at the moment.
>>
>> This looks positively defensive so:
>>
>> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
>>
>> We're in a public header, but I don't think this is an API breaking
>> change at all is it ? If this changed anything we'd see a compile
>> failure already...
>>
> 
> gitlab.freedesktop.org is starting to come back online \o/
> 
> but alas CI picked something up on this patch...
> 
> https://gitlab.freedesktop.org/camera/libcamera/-/jobs/73022971
> 
> Could you check please? (it could be false positive still or something
> with the CI)

I am fairly sure that is unrelated.


Regards,
Barnabás Pőcze


> 
> --
> Kieran
> 
>>
>>> ---
>>>   include/libcamera/controls.h | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/include/libcamera/controls.h b/include/libcamera/controls.h
>>> index 7c7828ae5..4bfe9615c 100644
>>> --- a/include/libcamera/controls.h
>>> +++ b/include/libcamera/controls.h
>>> @@ -125,7 +125,7 @@ struct control_type<Span<T, N>> : public control_type<std::remove_cv_t<T>> {
>>>   };
>>>   
>>>   template<typename T>
>>> -struct control_type<T, std::enable_if_t<std::is_enum_v<T>>> : public control_type<int32_t> {
>>> +struct control_type<T, std::enable_if_t<std::is_enum_v<T> && sizeof(T) == sizeof(int32_t)>> : public control_type<int32_t> {
>>>   };
>>>   
>>>   } /* namespace details */
>>> -- 
>>> 2.48.1
>>>