[libav-devel] [PATCH] png: Be more informative regarding signature errors

Janne Grunau janne-libav at jannau.net
Sun Aug 2 10:07:41 CEST 2015


On 2015-07-31 14:24:08 +0200, Luca Barbato wrote:
> ---
>  libavcodec/pngdec.c | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
> index 4ca919b..006cb90 100644
> --- a/libavcodec/pngdec.c
> +++ b/libavcodec/pngdec.c
> @@ -414,9 +414,18 @@ static int decode_frame(AVCodecContext *avctx,
>      int ret;
>  
>      /* check signature */
> -    if (buf_size < 8 ||
> -        (memcmp(buf, ff_pngsig, 8) != 0 && memcmp(buf, ff_mngsig, 8) != 0)) {
> -        av_log(avctx, AV_LOG_ERROR, "Invalid PNG signature (%d).\n", buf_size);
> +    if (buf_size < 8) {
> +        av_log(avctx, AV_LOG_ERROR, "Not enough data %d\n",
> +               buf_size);
> +        return AVERROR_INVALIDDATA;
> +    }
> +    if (memcmp(buf, ff_pngsig, 8) != 0 &&
> +        memcmp(buf, ff_mngsig, 8) != 0) {
> +        int i;
> +        av_log(avctx, AV_LOG_ERROR, "Invalid PNG signature");
> +        for (i = 0; i < 8; i++)
> +            av_log(avctx, AV_LOG_ERROR, " 0x%02x", buf[0]);
> +        av_log(avctx, AV_LOG_ERROR, "\n");
>          return AVERROR_INVALIDDATA;

a single av_log() call and snprintf'ing the header to a buffer would be 
preferred, otherwise ok

Janne


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