[FFmpeg-devel] [PATCH v4] vaapi_encode_mjpeg: fix bad component id bug

[Reimar Döffinger]

On 07.06.2019, at 23:45, "U. Artie Eoff" <ullysses.a.eoff at intel.com> wrote:

> The compound literals assigned to "components"
> only exist within the scope of the if/else
> block (thanks Mark Thompson for the better
> explanation).
> 
> Thus, after this if/else block, "components"
> ends up pointing to an arbitrary/undefined
> array.  With some compilers and depending on
> optimization settings, these arbitrary values
> may end up being the same value (i.e. 0 with
> GNU GCC 9.x).  Unfortunately, the GNU GCC
> compiler, at least, never prints any warnings
> about this.
> 
> This patch fixes this issue by assigning the
> constant arrays to local variables at function
> scope and then pointing "components" to those
> as necessary.
> 
> Fixes #7915
> 
> Signed-off-by: U. Artie Eoff <ullysses.a.eoff at intel.com>
> ---
> libavcodec/vaapi_encode_mjpeg.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/libavcodec/vaapi_encode_mjpeg.c b/libavcodec/vaapi_encode_mjpeg.c
> index 4dcdc3d16bb0..bd029cc90315 100644
> --- a/libavcodec/vaapi_encode_mjpeg.c
> +++ b/libavcodec/vaapi_encode_mjpeg.c
> @@ -227,6 +227,8 @@ static int vaapi_encode_mjpeg_init_picture_params(AVCodecContext *avctx,
>     JPEGRawScanHeader                 *sh = &priv->scan.header;
>     VAEncPictureParameterBufferJPEG *vpic = pic->codec_picture_params;
>     const AVPixFmtDescriptor *desc;
> +    const uint8_t components_rgb[3] = { 'R', 'G', 'B' };
> +    const uint8_t components_yuv[3] = {  1,   2,   3  };

Not sure what the necessary scope is for these, but maybe safest to go for "static const"?