> On Dec 22, 2021, at 7:30 PM, Gyan Doshi <ffm...@gyani.pro> wrote:
>
> Helper function to check if stored box size is correct and looks
> to be fully available.
> ---
> libavformat/mov.c | 32 ++++++++++++++++++++++++++++++++
> 1 file changed, 32 insertions(+)
>
> diff --git a/libavformat/mov.c b/libavformat/mov.c
> index 2aed6e80ef..2cc9e699de 100644
> --- a/libavformat/mov.c
> +++ b/libavformat/mov.c
> @@ -80,6 +80,38 @@ static int mov_read_mfra(MOVContext *c, AVIOContext *f);
> static int64_t add_ctts_entry(MOVCtts** ctts_data, unsigned int* ctts_count,
> unsigned int* allocated_size,
> int count, int duration);
>
> +/** Check if the box size meets the requirements passed in limit and
> constraint_type.
> + * If input avio_size is valid, it checks if box size appears to be
> available.
> + *
> + * constraint_type may be
> + * 0 if the box size has to be exactly equal to limit
> + * -1 if the box size has to be at most limit
> + * 1 if the box size has to be at least limit
> + *
> + * Returns 0 if size meets requirements.
> + */
> +static int validate_box_size(MOVContext *c, MOVAtom atom, AVIOContext *pb,
> + int64_t pos, int64_t limit, int constraint_type)
> +{
> + int size_fit;
> + int64_t input_size = avio_size(pb);
> +
> + if (input_size > 0 &&
> + input_size - pos < atom.size) {
> + av_log(c->fc, AV_LOG_ERROR, "Box %s is truncated\n",
> av_fourcc2str(atom.type));
> + return AVERROR_INVALIDDATA;
> + }
> +
> + switch(constraint_type) {
> + case 0: size_fit = atom.size == limit; break;
> + case -1: size_fit = atom.size <= limit; break;
> + case 1: size_fit = atom.size >= limit; break;
> + default: return AVERROR_INVALIDDATA;
The default case doesn’t come from invalid data, I prefer assert and
return AVERROR(EINVAL) or AVERROR_BUG.
> + }
> +
> + return !size_fit;
> +}
> +
> static int mov_metadata_track_or_disc_number(MOVContext *c, AVIOContext *pb,
> unsigned len, const char *key)
> {
> --
> 2.33.0
>
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