[FFmpeg-devel] [PATCH 1/3] avformat/aviobuf: read till the very end of the IO buffer

[Marton Balint]

On Sun, 20 Sep 2020, Marton Balint wrote:

>
>
> On Sun, 20 Sep 2020, Paul B Mahol wrote:
>
>> On Sun, Sep 20, 2020 at 10:52:51AM +0200, Marton Balint wrote:
>>> There was an off-by-one error when checking if the IO buffer still has 
> enough
>>> space till the end.
>>
>> How to reproduce such error(s)?
>
> It is not something you will notice, only the buffer is flushed when it
> does not necessarily need to be.
>
> But I guess you can reproduce it by using an buffer size of 66852 and try
> receiving an MPEGTS UDP stream. Without the patch fill_buffer always
> flushes, with the patch fill_buffer only flushes in every second
> call, as it needs to, because a single UDP TS packet (1316 bytes) and
> the potential maximum sized UDP packet (65536 bytes) simultaneously fit in
> the buffer.

Ping.

Thanks,
Marton

>
> Regards,
> Marton
>
>
>>
>>> 
>>> Signed-off-by: Marton Balint <cus at passwd.hu>
>>> ---
>>>  libavformat/aviobuf.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>> 
>>> diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c
>>> index a77517d712..9675425349 100644
>>> --- a/libavformat/aviobuf.c
>>> +++ b/libavformat/aviobuf.c
>>> @@ -540,7 +540,7 @@ static void fill_buffer(AVIOContext *s)
>>>  {
>>>      int max_buffer_size = s->max_packet_size ?
>>>                            s->max_packet_size : IO_BUFFER_SIZE;
>>> -    uint8_t *dst        = s->buf_end - s->buffer + max_buffer_size < 
> s->buffer_size ?
>>> +    uint8_t *dst        = s->buf_end - s->buffer + max_buffer_size <= 
> s->buffer_size ?
>>>                            s->buf_end : s->buffer;
>>>      int len             = s->buffer_size - (dst - s->buffer);
>>> 
>>> -- 
>>> 2.26.2
>>> 
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