[FFmpeg-devel] [PATCH 3/4] avutil/detection_bbox: simplify code for better readability

[Andreas Rheinhardt]

lance.lmwang at gmail.com:
> From: Limin Wang <lance.lmwang at gmail.com>
> 
> Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
> ---
>  libavutil/detection_bbox.c | 24 +++++++++++++-----------
>  1 file changed, 13 insertions(+), 11 deletions(-)
> 
> diff --git a/libavutil/detection_bbox.c b/libavutil/detection_bbox.c
> index 8bfdff7..3de66ce 100644
> --- a/libavutil/detection_bbox.c
> +++ b/libavutil/detection_bbox.c
> @@ -23,27 +23,29 @@ AVDetectionBBoxHeader *av_detection_bbox_alloc(uint32_t nb_bboxes, size_t *out_s
>      size_t size;
>      struct BBoxContext {
>          AVDetectionBBoxHeader header;
> -        AVDetectionBBox boxes[1];
> -    } *ret;
> +        AVDetectionBBox boxes;
> +    };
>      const size_t bboxes_offset = offsetof(struct BBoxContext, boxes);
> +    const size_t bbox_size = sizeof(AVDetectionBBox);
> +    AVDetectionBBoxHeader *header;
>  
> -    size = sizeof(*ret);
> -    if (nb_bboxes - 1 > (SIZE_MAX - size) / sizeof(*ret->boxes))

This here is actually not a simplification, but a patch: The old code
would not really work if nb_bboxes == 0.

> +    size = bboxes_offset;
> +    if (nb_bboxes > (SIZE_MAX - size) / bbox_size)
>          return NULL;
> -    size += sizeof(*ret->boxes) * (nb_bboxes - 1);
> +    size += bbox_size * nb_bboxes;
>  
> -    ret = av_mallocz(size);
> -    if (!ret)
> +    header = av_mallocz(size);
> +    if (!header)
>          return NULL;
>  
> -    ret->header.nb_bboxes = nb_bboxes;
> -    ret->header.bbox_size = sizeof(*ret->boxes);
> -    ret->header.bboxes_offset = bboxes_offset;
> +    header->nb_bboxes     = nb_bboxes;
> +    header->bbox_size     = bbox_size;
> +    header->bboxes_offset = bboxes_offset;
>  
>      if (out_size)
>          *out_size = size;
>  
> -    return &ret->header;
> +    return header;
>  }
>  
>  AVDetectionBBoxHeader *av_detection_bbox_create_side_data(AVFrame *frame, uint32_t nb_bboxes)
>