[FFmpeg-devel] [PATCH v2 2/3] avformat/hashenc: use an array of hashes

[James Almer]

On 9/11/2019 10:53 AM, Moritz Barsnick wrote:
> On Wed, Sep 11, 2019 at 10:39:40 -0300, James Almer wrote:
>> On 9/11/2019 10:34 AM, Moritz Barsnick wrote:
>>> +static void hash_free(struct AVFormatContext *s)
>>> +{
>>> +    struct HashContext *c = s->priv_data;
>>> +    av_hash_freep(&c->hashes[0]);
>>
>> AVOutputFormat.deinit() is called when AVOutputFormat.init() fails, so
>> c->hashes can be NULL. same with the framehash muxer.
>>
>>> +    av_freep(&c->hashes);
>>> +}
> 
> Does this mean there should just be a check for "if (c->hashes)" here,
> or can the suggestion in
> http://ffmpeg.org/pipermail/ffmpeg-devel/2019-August/248014.html
> actually not be implemented? No common freeing function?

av_freep() can be used with NULL variables without issues. The problem
is that you're dereferencing c->hashes for the av_hash_freep() call. If
it's NULL, you'll get a segfault. So just do

if (c->hashes)
    av_hash_freep(&c->hashes[0]);
av_freep(&c->hashes);

In both muxers. Then adapt it in PATCH 3/3 for the streamhash muxer
addition.

> 
> Thanks,
> Moritz
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