[vlc-devel] [vlc-commits] decoder: add Destroy helper function for decoder owners

[Steve Lhomme]

There cannot be any double-free occurring in my implementation. That's 
the class of bugs it removes.

It will of course not solve use after free issues. And I don't see how 
it makes it easier/harder to track such issues.

On 19/02/2019 09:02, Rémi Denis-Courmont wrote:
> This does not remove any class of bug. If there is a use-after-free, 
> it still fails or hides the bug (depending if the use checks for NULL 
> or not). If there is a double free race, it hides the bug in most 
> cases making it very hard to reproduce, all the while not actually 
> fixing it.
>
> Le 19 février 2019 09:13:36 GMT+02:00, Steve Lhomme <robux4 at ycbcr.xyz> 
> a écrit :
>
>     On 19/02/2019 08:03, Jean-Baptiste Kempf wrote:
>
>         Hello, On Tue, 19 Feb 2019, at 08:01, Steve Lhomme wrote:
>
>                 I really prefer having a crash (via assert/ASAN) when
>                 a client is 
>
>             misusing an API (calling Destroy with a freed pointer)
>             instead of ignoring it. This is true when calling Destroy
>             twice is a bug. It isn't with this 
>
>         Then assert() it. 
>
>
>     I'm not sure I'm following. Would you assert when calling
>     decoder_Destroy() with a NULL decoder (meaning it doesn't exist at all,
>     not even been through decoder_Init) ? Or in the solution I removed where
>     you'd call decoder_Destroy() with a holder than has been emptied, which
>     is not a bug at all.
>
>     Or you mean assert when decoder_Destroy() is passed an already freed
>     pointer ? In which case no assert will help detect a double free.
>
>     As a more general remark, I think it's odd that rather than removing a
>     class of bugs, we prefer to keep it and rely on tools to find them for
>     us, when they eventually occur.
>
>     >
>
>         This is not a libVLC API, where you need to deal with invalid
>         input, and where assert is not enough. -- Jean-Baptiste Kempf
>         - President +33 672 704 734
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