Re: [FFmpeg-devel] [PATCH 01/12] fftools/textformat/avtextformat: Simplify avtext_print_rational()

[Andreas Rheinhardt <andreas.rheinhardt@outlook.com>]

softworkz .:
> 
> 
>> -----Original Message-----
>> From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf Of
>> Andreas Rheinhardt
>> Sent: Mittwoch, 16. April 2025 07:37
>> To: ffmpeg-devel@ffmpeg.org
>> Subject: Re: [FFmpeg-devel] [PATCH 01/12]
>> fftools/textformat/avtextformat: Simplify avtext_print_rational()
>>
>> softworkz .:
>>>
>>>
>>>> -----Original Message-----
>>>> From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf Of
>>>> Andreas Rheinhardt
>>>> Sent: Mittwoch, 16. April 2025 06:28
>>>> To: ffmpeg-devel@ffmpeg.org
>>>> Subject: Re: [FFmpeg-devel] [PATCH 01/12]
>>>> fftools/textformat/avtextformat: Simplify avtext_print_rational()
>>>>
>>>> softworkz .:
>>>>>
>>>>>
>>>>>> -----Original Message-----
>>>>>> From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf Of
>>>>>> Andreas Rheinhardt
>>>>>> Sent: Dienstag, 15. April 2025 10:36
>>>>>> To: ffmpeg-devel@ffmpeg.org
>>>>>> Subject: Re: [FFmpeg-devel] [PATCH 01/12]
>>>>>> fftools/textformat/avtextformat: Simplify avtext_print_rational()
>>>>>>
>>>>>> softworkz .:
>>>>>>>
>>>>>>>
>>>>>>>> -----Original Message-----
>>>>>>>> From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf
>> Of
>>>>>>>> Andreas Rheinhardt
>>>>>>>> Sent: Dienstag, 15. April 2025 03:00
>>>>>>>> To: FFmpeg development discussions and patches <ffmpeg-
>>>>>>>> devel@ffmpeg.org>
>>>>>>>> Subject: [FFmpeg-devel] [PATCH 01/12]
>>>>>> fftools/textformat/avtextformat:
>>>>>>>> Simplify avtext_print_rational()
>>>>>>>>
>>>>>>>> Patches attached.
>>>>>>>>
>>>>>>>> - Andreas
>>>>>>>
>>>>>>>
>>>>>>> Hi Andreas,
>>>>>>>
>>>>>>> thanks a lot for working through this. I'll go over it tomorrow.
>>>>>>>
>>>>>>> As to not waste your time, it's probably best when we get those
>>>>>>> changes applied in a timely manner so that I can rebase the new
>>>>>>> patchset on top of it.
>>>>>>>
>>>>>>> Since you're sending the patches as attachments:
>>>>>>> How do you want me to reply with code context? Whole files or
>>>>>>> just snippets? And quoted?
>>>>>>>
>>>>>>
>>>>>> Snippets is better. So is quoted.
>>>>>>
>>>>>> - Andreas
>>>>>>
>>>>>
>>>>> Hi Andreas,
>>>>>
>>>>> thanks again for the well-spotted improvements. Just two notes:
>>>>>
>>>>>
>>>>> 0007-fftools-textformat-Use-av_default_item_name.patch
>>>>>
>>>>> In the new patchset, those macros are removed from the individual
>>>>> files. There's now a single macro in tf_internal.h and I've
>> applied
>>>>> this change there.
>>>>
>>>> So you use a move/deduplicate commit to change something? Not good.
>>>
>>> No. The patchset has a deduplication commit. That's what I've
>> submitted
>>> to the ML already.
>>> Now I made another commit locally (on top of that) which makes this
>> change.
>>>
>>>
>>>>> 0008-fftools-textformat-avtextformat-Fix-segfault-upon-al.patch
>>>>> 0009-fftools-textformat-avtextformat-Fix-segfault-upon-al.patch
>>>>>
>>>>> Can this happen?
>>>>
>>>> Of course it can. All allocations can fail. That's why we check
>> them.
>>>> Have you been coding with the assumption that allocations never
>> fail?
>>>> (You can use av_max_alloc(1); to simulate allocation failures.)
>>>
>>> Allocations can fail, but statically initialized global const
>> values?
>>
>> The pointers to said static objects are only set after having
>> allocated
>> the private context. So the issue can happen (not with current master)
> 
> Current master is on top of which I had applied your patches and 
> there's no possible way for those pointers to be null.
> 
> That you are submitting a patch that is fixing a flaw in an
> unmerged future patch is pretty cool, but was also beyond my range
> of consideration. 😊
> 
> Thanks for the clarification.
> 

You completely misunderstand (or you try to be trolling me as your 😊
indicates). "The issue" that can no longer happen with current master is
the segfault after allocation failure. This could really happen before
my fixes. The pointers to writer/formatter can still be NULL even on
master (namely after allocation failure), therefore the checks need to
be there.

- Andreas

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