[FFmpeg-devel] [PATCH 1/3] avcodec/cllc: Don't unnecessarily free VLC

[Andreas Rheinhardt]

Andreas Rheinhardt:
> The Canopus Lossless decoder uses several VLCs and if initializing the
> ith VLC fails, all the VLCs 0..i have been freed; the ith VLC's table is
> initialized to NULL for this purpose. Yet it is totally unnecessary to
> free the ith VLC table at all: ff_init_vlc_sparse() cleans up after
> itself on error and if an error happens before ff_init_vlc_sparse(),
> the ith VLC hasn't been touched yet and doesn't need freeing.
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
> ---
>  libavcodec/cllc.c | 11 +++--------
>  1 file changed, 3 insertions(+), 8 deletions(-)
> 
> diff --git a/libavcodec/cllc.c b/libavcodec/cllc.c
> index 1f2c98ef73..8b1bc75faa 100644
> --- a/libavcodec/cllc.c
> +++ b/libavcodec/cllc.c
> @@ -57,8 +57,6 @@ static int read_code_table(CLLCContext *ctx, GetBitContext *gb, VLC *vlc)
>      num_lens = get_bits(gb, 5);
>  
>      if (num_lens > VLC_BITS * VLC_DEPTH) {
> -        vlc->table = NULL;
> -
>          av_log(ctx->avctx, AV_LOG_ERROR, "To long VLCs %d\n", num_lens);
>          return AVERROR_INVALIDDATA;
>      }
> @@ -68,8 +66,6 @@ static int read_code_table(CLLCContext *ctx, GetBitContext *gb, VLC *vlc)
>          num_codes_sum += num_codes;
>  
>          if (num_codes_sum > 256) {
> -            vlc->table = NULL;
> -
>              av_log(ctx->avctx, AV_LOG_ERROR,
>                     "Too many VLCs (%d) to be read.\n", num_codes_sum);
>              return AVERROR_INVALIDDATA;
> @@ -83,7 +79,6 @@ static int read_code_table(CLLCContext *ctx, GetBitContext *gb, VLC *vlc)
>              count++;
>          }
>          if (prefix > (65535 - 256)/2) {
> -            vlc->table = NULL;
>              return AVERROR_INVALIDDATA;
>          }
>  
> @@ -247,7 +242,7 @@ static int decode_argb_frame(CLLCContext *ctx, GetBitContext *gb, AVFrame *pic)
>      for (i = 0; i < 4; i++) {
>          ret = read_code_table(ctx, gb, &vlc[i]);
>          if (ret < 0) {
> -            for (j = 0; j <= i; j++)
> +            for (j = 0; j < i; j++)
>                  ff_free_vlc(&vlc[j]);
>  
>              av_log(ctx->avctx, AV_LOG_ERROR,
> @@ -290,7 +285,7 @@ static int decode_rgb24_frame(CLLCContext *ctx, GetBitContext *gb, AVFrame *pic)
>      for (i = 0; i < 3; i++) {
>          ret = read_code_table(ctx, gb, &vlc[i]);
>          if (ret < 0) {
> -            for (j = 0; j <= i; j++)
> +            for (j = 0; j < i; j++)
>                  ff_free_vlc(&vlc[j]);
>  
>              av_log(ctx->avctx, AV_LOG_ERROR,
> @@ -343,7 +338,7 @@ static int decode_yuv_frame(CLLCContext *ctx, GetBitContext *gb, AVFrame *pic)
>      for (i = 0; i < 2; i++) {
>          ret = read_code_table(ctx, gb, &vlc[i]);
>          if (ret < 0) {
> -            for (j = 0; j <= i; j++)
> +            for (j = 0; j < i; j++)
>                  ff_free_vlc(&vlc[j]);
>  
>              av_log(ctx->avctx, AV_LOG_ERROR,
> 
Will apply the rest of this patchset tomorrow unless there are objections.

- Andreas