[FFmpeg-devel] [PATCH v1 1/4] avformat/dashenc: remove unused check of avformat_free_context

[Steven Liu]

> 在 2019年11月29日，13:40，Andreas Rheinhardt <andreas.rheinhardt at gmail.com> 写道：
> 
> Jeyapal, Karthick:
>> 
>> On 11/29/19 10:45 AM, Steven Liu wrote:
>>> Signed-off-by: Steven Liu <lq at chinaffmpeg.org>
>>> ---
>>> libavformat/dashenc.c | 3 +--
>>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>> 
>>> diff --git a/libavformat/dashenc.c b/libavformat/dashenc.c
>>> index a462876c13..8c28fb6b6e 100644
>>> --- a/libavformat/dashenc.c
>>> +++ b/libavformat/dashenc.c
>>> @@ -588,8 +588,7 @@ static void dash_free(AVFormatContext *s)
>>>                 avio_close(os->ctx->pb);
>>>         }
>>>         ff_format_io_close(s, &os->out);
>>> -        if (os->ctx)
>>> -            avformat_free_context(os->ctx);
>>> +        avformat_free_context(os->ctx);
>> This 'if' condition is a safety net against double frees caused due to any corner case and/or wrong usage.
>> Unless this is absolutely required for some reason, this 'if' condition should not be removed.
> 
> This 'if' doesn't help against double-frees at all:
> avformat_free_context() itself checks against its argument being NULL
> and returns immediately if it is. (But double frees are still possible
> given that avformat_free_context can't reset the pointer to NULL due
> to its signature. Resetting is something the callers have to do for
> themselves.)
What about add reset pointer to NULL into the avformat_free_context?
> 
> - Andreas
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Thanks
Steven