[FFmpeg-devel] [PATCH] Add SUP/PGS subtitle demuxer

[Reimar Döffinger]

On 30.08.2014, at 15:38, wm4 <nfxjfg at googlemail.com> wrote:
> +    // The packet-size is stored as part of the packet.
> +    if ((ret = avio_read(s->pb, tmp, 3)) < 0)
> +        return ret;
> +
> +    len = AV_RB16(tmp + 1);
> +
> +    if ((ret = av_new_packet(pkt, len + 3)) < 0)
> +        return ret;
> +
> +    memcpy(pkt->data, tmp, 3);
> +
> +    if ((ret = avio_read(s->pb, pkt->data + 3, len)) < 0) {
> +        av_free_packet(pkt);
> +        return ret;
> +    }

I think this will not handle short reads correctly, retuning uninitialised data.
My suggestion would be to read the length, then seek back (buffering should ensure this is no issue even if we read from stdin) and then use the functions to read the full packet with all the proper error handling.