[FFmpeg-devel] [PATCH v6 4/4] lavf/utils: Normalize AVPacket.data to native endian

[Mats Peterson]

On 03/04/2016 03:41 AM, Mats Peterson wrote:
> On 03/04/2016 03:30 AM, Michael Niedermayer wrote:
>>>
>>> -    if (!*palette && ret == CONTAINS_PAL)
>>> -        *palette = pkt->data + pkt->size - AVPALETTE_SIZE;
>>> +    if (!*palette && ret == CONTAINS_PAL) {
>>> +        uint8_t *pkt_pal = pkt->data + pkt->size - AVPALETTE_SIZE;
>>> +        int i;
>>> +        for (i = 0; i < AVPALETTE_COUNT; i++) {
>>> +            uint8_t *p8 = pkt_pal + 4*i;
>>
>>> +            uint32_t *p32 = (uint32_t *)p8;
>>
>> undefined behavior, violating alignment requirements, and possibly
>> aliassing violation
>>
>
> Really? It works just fine, so please elaborate.
>
>>
>>> +            *p32 = AV_RL32(p8);
>>
>> corrupting potenially shared or read only input packet
>>
>> [...]
>
> That one I do understand.
>
> _______________________________________________

Forget this version then, and use version 5. Just as long as it gets 
applied in a foreseeable future.

Mats