[FFmpeg-devel] [PATCH] avformat: Add max_streams option

[Michael Niedermayer]

On Fri, Nov 18, 2016 at 06:22:06PM +0100, Alexander Strasser wrote:
> Hi Michael!
> 
> On 2016-11-18 17:03 +0100, Michael Niedermayer wrote:
> > This allows user apps to stop OOM due to excessive number of streams
> > TODO: bump & docs
> > 
> > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> > ---
> >  libavformat/avformat.h      | 7 +++++++
> >  libavformat/options_table.h | 1 +
> >  libavformat/utils.c         | 2 +-
> >  3 files changed, 9 insertions(+), 1 deletion(-)
> > 
> > diff --git a/libavformat/avformat.h b/libavformat/avformat.h
> > index f9f4d72..c81a916 100644
> > --- a/libavformat/avformat.h
> > +++ b/libavformat/avformat.h
> > @@ -1899,6 +1899,13 @@ typedef struct AVFormatContext {
> >       * - decoding: set by user through AVOptions (NO direct access)
> >       */
> >      char *protocol_blacklist;
> > +
> > +    /**
> > +     * The maximum number of streams.
> > +     * - encoding: unused
> > +     * - decoding: set by user through AVOptions (NO direct access)
> > +     */
> > +    int max_streams;
> >  } AVFormatContext;
> >  
> >  int av_format_get_probe_score(const AVFormatContext *s);
> > diff --git a/libavformat/options_table.h b/libavformat/options_table.h
> > index 9d61d5a..d5448e5 100644
> > --- a/libavformat/options_table.h
> > +++ b/libavformat/options_table.h
> > @@ -105,6 +105,7 @@ static const AVOption avformat_options[] = {
> >  {"format_whitelist", "List of demuxers that are allowed to be used", OFFSET(format_whitelist), AV_OPT_TYPE_STRING, { .str = NULL },  CHAR_MIN, CHAR_MAX, D },
> >  {"protocol_whitelist", "List of protocols that are allowed to be used", OFFSET(protocol_whitelist), AV_OPT_TYPE_STRING, { .str = NULL },  CHAR_MIN, CHAR_MAX, D },
> >  {"protocol_blacklist", "List of protocols that are not allowed to be used", OFFSET(protocol_blacklist), AV_OPT_TYPE_STRING, { .str = NULL },  CHAR_MIN, CHAR_MAX, D },
> > +{"max_streams", "maximum number of streams", OFFSET(max_streams), AV_OPT_TYPE_INT, { .i64 = INT_MAX }, 0, INT_MAX, D },
> >  {NULL},
> >  };
> >  
> > diff --git a/libavformat/utils.c b/libavformat/utils.c
> > index 5664646..ded0b52 100644
> > --- a/libavformat/utils.c
> > +++ b/libavformat/utils.c
> > @@ -4210,7 +4210,7 @@ AVStream *avformat_new_stream(AVFormatContext *s, const AVCodec *c)
> >      int i;
> >      AVStream **streams;
> >  
> > -    if (s->nb_streams >= INT_MAX/sizeof(*streams))
> > +    if (s->nb_streams >= s->max_streams/sizeof(*streams))
> >          return NULL;
> >      streams = av_realloc_array(s->streams, s->nb_streams + 1, sizeof(*streams));
> >      if (!streams)
> 
>   Maybe I am completely wrong, if so just tell me and sorry for the noise...
> 
>   You name the option max_streams, but you compare it to nb_streams after
> you divided it by size of a pointer.
> 
>   I guess you change it that way so the default stays the same. I hope that
> can be achieved in a different way.

changed to:
@@ -4210,7 +4210,7 @@ AVStream *avformat_new_stream(AVFormatContext *s, const AVCodec *c)
     int i;
     AVStream **streams;

-    if (s->nb_streams >= INT_MAX/sizeof(*streams))
+    if (s->nb_streams >= FFMIN(s->max_streams, INT_MAX/sizeof(*streams)))
         return NULL;
     streams = av_realloc_array(s->streams, s->nb_streams + 1, sizeof(*streams));
     if (!streams)

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

During times of universal deceit, telling the truth becomes a
revolutionary act. -- George Orwell
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