Hi Mirela,
thank you for the update. Just two issues below:
On Tue, 2020-12-15 at 13:18 +0200, Mirela Rabulea (OSS) wrote:
> From: Mirela Rabulea <mirela.rabulea@xxxxxxx>
>
> According to Rec. ITU-T T.872 (06/2012) 6.5.3
> APP14 segment is for color encoding, it contains a transform flag, which
> may have values of 0, 1 and 2 and are interpreted as follows:
> 0 - CMYK for images that are encoded with four components
> - RGB for images that are encoded with three components
> 1 - An image encoded with three components using YCbCr colour encoding.
> 2 - An image encoded with four components using YCCK colour encoding.
>
> This is used in imx-jpeg decoder, to distinguish between
> YUV444 and RGB24.
>
> Signed-off-by: Mirela Rabulea <mirela.rabulea@xxxxxxx>
> ---
> Changes in v6:
> Switch variable to lowercase Lp->lp
> Check for "Adobe\0" in Ap1..6
> Make the transform flag an enum
> Removed a change in comment section, a leftover from a previous version
> Thanks Philipp for feedback.
>
> drivers/media/v4l2-core/v4l2-jpeg.c | 43 +++++++++++++++++++++++++++--
> include/media/v4l2-jpeg.h | 18 ++++++++++++
> 2 files changed, 59 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/v4l2-core/v4l2-jpeg.c b/drivers/media/v4l2-core/v4l2-jpeg.c
> index 8947fd95c6f1..d1483e7a775c 100644
> --- a/drivers/media/v4l2-core/v4l2-jpeg.c
> +++ b/drivers/media/v4l2-core/v4l2-jpeg.c
> @@ -45,6 +45,7 @@ MODULE_LICENSE("GPL");
> #define DHP 0xffde /* hierarchical progression */
> #define EXP 0xffdf /* expand reference */
> #define APP0 0xffe0 /* application data */
> +#define APP14 0xffee /* application data for colour encoding */
> #define APP15 0xffef
> #define JPG0 0xfff0 /* extensions */
> #define JPG13 0xfffd
> @@ -444,8 +445,41 @@ static int jpeg_skip_segment(struct jpeg_stream *stream)
> return jpeg_skip(stream, len - 2);
> }
>
> +/* Rec. ITU-T T.872 (06/2012) 6.5.3 */
> +static int jpeg_parse_app14_data(struct jpeg_stream *stream)
> +{
> + int ret;
> + int lp;
> + int skip;
> + int tf;
> +
> + lp = jpeg_get_word_be(stream);
> + if (lp < 0)
> + return lp;
Here we should check that there are still 6 bytes available to compare:
if (stream->curr + 6 > stream->end)
return -EINVAL;
> + /* Check for "Adobe\0" in Ap1..6 */
> + if (strncmp(stream->curr, "Adobe\0", 6))
> + return -EINVAL;
> +
> + /* get to Ap12 */
> + ret = jpeg_skip(stream, 11);
> + if (ret < 0)
> + return -EINVAL;
> +
> + tf = jpeg_get_byte(stream);
> + if (tf < 0)
> + return tf;
> +
> + skip = lp - 2 - 11;
> + ret = jpeg_skip(stream, skip);
> + if (ret < 0)
> + return -EINVAL;
> + else
> + return tf;
> +}
> +
> /**
> - * jpeg_parse_header - locate marker segments and optionally parse headers
> + * v4l2_jpeg_parse_header - locate marker segments and optionally parse headers
> * @buf: address of the JPEG buffer, should start with a SOI marker
> * @len: length of the JPEG buffer
> * @out: returns marker segment positions and optionally parsed headers
> @@ -476,6 +510,9 @@ int v4l2_jpeg_parse_header(void *buf, size_t len, struct v4l2_jpeg_header *out)
> if (marker != SOI)
> return -EINVAL;
>
> + /* init value to signal if this marker is not present */
> + out->app14_tf = -EINVAL;
> +
Here we set app14_tf to a value that is not part of the enum.
You could define a value V4L2_JPEG_APP14_TF_UNKNOWN for the
uninitialized / error state.
> /* loop through marker segments */
> while ((marker = jpeg_next_marker(&stream)) >= 0) {
> switch (marker) {
> @@ -519,7 +556,9 @@ int v4l2_jpeg_parse_header(void *buf, size_t len, struct v4l2_jpeg_header *out)
> ret = jpeg_parse_restart_interval(&stream,
> &out->restart_interval);
> break;
> -
> + case APP14:
> + out->app14_tf = jpeg_parse_app14_data(&stream);
Same as above in case of -EINVAL return. Apart from this,
Reviewed-by: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
regards
Philipp
