[vlc-devel] [PATCH] vlc_es: add more documentation on es_format_Copy

[Rémi Denis-Courmont]

Le 13 juillet 2017 14:22:13 GMT+08:00, Steve Lhomme <robux4 at gmail.com> a écrit :
>On Wed, Jul 12, 2017 at 5:24 PM, Rémi Denis-Courmont <remi at remlab.net>
>wrote:
>> On mercredi 12 juillet 2017 16:51:19 EEST Steve Lhomme wrote:
>>> It must copy to an unitialized structure or one that was cleaned
>before.
>>>
>>> The result should always be checked as there are allocations that
>can fail
>>> but it's not safe for now given the state of the rest of the code.
>>> ---
>>>  include/vlc_es.h | 3 +++
>>>  1 file changed, 3 insertions(+)
>>>
>>> diff --git a/include/vlc_es.h b/include/vlc_es.h
>>> index e9d11d85a8..a428b561c2 100644
>>> --- a/include/vlc_es.h
>>> +++ b/include/vlc_es.h
>>> @@ -627,7 +627,10 @@ VLC_API void es_format_InitFromVideo(
>es_format_t *,
>>> const video_format_t * );
>>>
>>>  /**
>>>   * This functions will copy a es_format_t.
>>> + *
>>> + * The destination pointer must be uninitialized or not old any
>allocated
>
>Typo "hold"
>
>>> buffer. */
>>> +/* VLC_USED for now we're okay with losing strings and extradata */
>>>  VLC_API int es_format_Copy( es_format_t *p_dst, const es_format_t
>*p_src );
>>>
>>>  /**
>>
>> No. The error is impossible in some code paths (e.g. audio filters),
>and
>> totally harmless in others. Littering the code base with untested,
>buggy and
>> sometimes dead, error code does not make sense.
>>
>> You can't add VLC_USED then, since ignoring the result is not always
>a bug.
>
>OK
>
>> And video.p_palette should die. And language should be a small fixed
>size
>
>I think the reason to use a union was to save space. If we force
>psz_language and psz_description to fixed size buffers we lose that
>advantage and we gain strings that may not always fit the strings we
>want to store.
>
>> character array. That leaves only p_extra IIRC.
>
>There's also p_extra_languages, subs.psz_encoding and subs.p_style.
>
>So dynamically allocated memory in es_format_t is not going away
>anytime soon (if ever). We should make sure it's handled properly and
>make it harder to have leaks.
>
>> --
>> Rémi Denis-Courmont
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A language code is at most 8 bytes including nul. It is no more space than the pointer.
-- 
Rémi Denis-Courmont
Typed on an inconvenient virtual keyboard
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