Hi Mirela,
On Thu, 2020-11-12 at 05:05 +0200, Mirela Rabulea (OSS) wrote:
> From: Mirela Rabulea <mirela.rabulea@xxxxxxx>
>
> These are optional in struct v4l2_jpeg_header, so do not parse if
> not requested, save some time.
>
> Signed-off-by: Mirela Rabulea <mirela.rabulea@xxxxxxx>
> ---
> drivers/media/v4l2-core/v4l2-jpeg.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/media/v4l2-core/v4l2-jpeg.c b/drivers/media/v4l2-core/v4l2-jpeg.c
> index d77e04083d57..7576cd0ce6b9 100644
> --- a/drivers/media/v4l2-core/v4l2-jpeg.c
> +++ b/drivers/media/v4l2-core/v4l2-jpeg.c
> @@ -307,6 +307,9 @@ static int jpeg_parse_quantization_tables(struct jpeg_stream *stream,
> {
> int len = jpeg_get_word_be(stream);
>
> + if (!tables)
> + return 0;
> +
> if (len < 0)
> return len;
> /* Lq = 2 + n * 65 (for baseline DCT), n >= 1 */
> @@ -361,6 +364,9 @@ static int jpeg_parse_huffman_tables(struct jpeg_stream *stream,
> int mt;
> int len = jpeg_get_word_be(stream);
>
> + if (!tables)
> + return 0;
> +
> if (len < 0)
> return len;
> /* Table B.5 - Huffman table specification parameter sizes and values */
I don't understand this. jpeg_parse_quantization_tables() is only called
if v4l2_jpeg_parse_header() finds a DQT marker. The entire quantization
table-specification parameter block is optional, but when a DQT marker
is present, IIUC the block must contain at least one table (see B.2.4.1,
specifically figure B.6).
regards
Philipp
