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

[Alexander Strasser]

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.


  Alexander