[FFmpeg-devel] [PATCH] avformat/mov: make compatible brands more readable

[James Almer]

On 9/9/2020 10:07 AM, quinkblack at foxmail.com wrote:
> From: Zhao Zhili <quinkblack at foxmail.com>
> 
> Use comma as separator between multiple compatible brands.

Wont this potentially break parsing of the output of ffmpeg/ffprobe, or
even of the compatible_brands key in c->fc->metadata when using the dict
API?

> ---
>  libavformat/mov.c | 24 +++++++++++++++---------
>  1 file changed, 15 insertions(+), 9 deletions(-)
> 
> diff --git a/libavformat/mov.c b/libavformat/mov.c
> index 690beb10ce..8f5341f925 100644
> --- a/libavformat/mov.c
> +++ b/libavformat/mov.c
> @@ -1093,7 +1093,7 @@ static int aax_filter(uint8_t *input, int size, MOVContext *c)
>  static int mov_read_ftyp(MOVContext *c, AVIOContext *pb, MOVAtom atom)
>  {
>      uint32_t minor_ver;
> -    int comp_brand_size;
> +    int comp_brand_count;
>      char* comp_brands_str;
>      uint8_t type[5] = {0};
>      int ret = ffio_read_size(pb, type, 4);
> @@ -1107,19 +1107,25 @@ static int mov_read_ftyp(MOVContext *c, AVIOContext *pb, MOVAtom atom)
>      minor_ver = avio_rb32(pb); /* minor version */
>      av_dict_set_int(&c->fc->metadata, "minor_version", minor_ver, 0);
>  
> -    comp_brand_size = atom.size - 8;
> -    if (comp_brand_size < 0 || comp_brand_size == INT_MAX)
> +    comp_brand_count = (atom.size - 8) / 4;
> +    if (!comp_brand_count)
> +        return 0;
> +    else if (comp_brand_count < 0 || comp_brand_count > INT_MAX / 5)
>          return AVERROR_INVALIDDATA;
> -    comp_brands_str = av_malloc(comp_brand_size + 1); /* Add null terminator */
> +    /* add separator between multiple brands, add null terminator */
> +    comp_brands_str = av_malloc(comp_brand_count * 5);
>      if (!comp_brands_str)
>          return AVERROR(ENOMEM);
>  
> -    ret = ffio_read_size(pb, comp_brands_str, comp_brand_size);
> -    if (ret < 0) {
> -        av_freep(&comp_brands_str);
> -        return ret;
> +    for (int i = 0; i < comp_brand_count; i++) {
> +        ret = ffio_read_size(pb, comp_brands_str + i * 5, 4);
> +        if (ret < 0) {
> +            av_freep(&comp_brands_str);
> +            return ret;
> +        }
> +        comp_brands_str[i * 5 + 4] = ',';
>      }
> -    comp_brands_str[comp_brand_size] = 0;
> +    comp_brands_str[comp_brand_count * 5 - 1] = '\0';
>      av_dict_set(&c->fc->metadata, "compatible_brands",
>                  comp_brands_str, AV_DICT_DONT_STRDUP_VAL);
>  
>