[FFmpeg-devel] [PATCH] avformat/dhav: Fix incorrect non-DHAV chunk skipping logic

[Idan Freiberg]

Oh i didn't notice that. Thanks.

On Mon, Jan 18, 2021 at 8:22 PM Paul B Mahol <onemda at gmail.com> wrote:

> Isn't this applied already?
>
> On Mon, Jan 18, 2021 at 6:46 PM Idan Freiberg <speidy at gmail.com> wrote:
>
> > Can one of the maintainers review the patch please?
> >
> > בתאריך יום ד׳, 13 בינו׳ 2021 ב-14:35 מאת Idan Freiberg <speidy at gmail.com
> >:
> >
> > > DAV files may contain a variable length padding in between chunks
> > > filled with 0xff bytes. The current skipping logic is incorrect as it
> > > may skip over DHAV chunks not appearing sequentially in the file.
> > >
> > > We now look for the 'DHAV' tag using a byte-by-byte search in order
> > > to handle such situations. Also the dhav->last_good_pos field will
> > > not be updated while skipping unrecognized data.
> > > ---
> > >  libavformat/dhav.c | 15 +++------------
> > >  1 file changed, 3 insertions(+), 12 deletions(-)
> > >
> > > diff --git a/libavformat/dhav.c b/libavformat/dhav.c
> > > index 00e0d8476e..6a6c235e65 100644
> > > --- a/libavformat/dhav.c
> > > +++ b/libavformat/dhav.c
> > > @@ -173,18 +173,9 @@ static int read_chunk(AVFormatContext *s)
> > >      if (avio_feof(s->pb))
> > >          return AVERROR_EOF;
> > >
> > > -    if (avio_rl32(s->pb) != MKTAG('D','H','A','V') &&
> > dhav->last_good_pos
> > > < INT64_MAX - 0x8000) {
> > > -        dhav->last_good_pos += 0x8000;
> > > -        avio_seek(s->pb, dhav->last_good_pos, SEEK_SET);
> > > -
> > > -        while (avio_rl32(s->pb) != MKTAG('D','H','A','V')) {
> > > -            if (avio_feof(s->pb) || dhav->last_good_pos >= INT64_MAX -
> > > 0x8000)
> > > -                return AVERROR_EOF;
> > > -            dhav->last_good_pos += 0x8000;
> > > -            ret = avio_skip(s->pb, 0x8000 - 4);
> > > -            if (ret < 0)
> > > -                return ret;
> > > -        }
> > > +    while (avio_r8(s->pb) != 'D' || avio_r8(s->pb) != 'H' ||
> > > avio_r8(s->pb) != 'A' || avio_r8(s->pb) != 'V') {
> > > +        if (avio_feof(s->pb))
> > > +            return AVERROR_EOF;
> > >      }
> > >
> > >      start = avio_tell(s->pb) - 4;
> > > --
> > > 2.30.0
> > >
> > > --
> > Idan Freiberg Mobile: +972-52-2925213
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-- 
Idan Freiberg
Mobile: +972-52-2925213