[FFmpeg-cvslog] png: Be more informative regarding signature errors

[Clément Bœsch]

On Wed, Aug 05, 2015 at 12:10:56PM +0200, Luca Barbato wrote:
> ffmpeg | branch: master | Luca Barbato <lu_zero at gentoo.org> | Fri Jul 31 14:24:08 2015 +0200| [4fee11ab05fc8569ef35c0ce86a60375c903eefb] | committer: Luca Barbato
> 
> png: Be more informative regarding signature errors
> 
> Signed-off-by: Luca Barbato <lu_zero at gentoo.org>
> 
> > http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=4fee11ab05fc8569ef35c0ce86a60375c903eefb
> ---
> 
>  libavcodec/pngdec.c |   20 +++++++++++++++++---
>  1 file changed, 17 insertions(+), 3 deletions(-)
> 
> diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
> index 4ca919b..5fa7a2d 100644
> --- a/libavcodec/pngdec.c
> +++ b/libavcodec/pngdec.c
> @@ -18,6 +18,8 @@
>   * License along with Libav; if not, write to the Free Software
>   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
>   */
> +
> +#include "libavutil/avstring.h"
>  #include "libavutil/imgutils.h"
>  #include "avcodec.h"
>  #include "bytestream.h"
> @@ -414,9 +416,21 @@ 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) {
> +        char signature[5 * 8 + 1] = { 0 };
> +        int i;
> +        for (i = 0; i < 8; i++) {

> +            av_strlcatf(signature + i * 5, sizeof(signature) - i * 5,
> +                        " 0x%02x", buf[i]);

Unless I'm mistaken you want to either use snprintf, or strlcatf but
without the redundant +i*5 -i*5

> +        }
> +        av_log(avctx, AV_LOG_ERROR, "Invalid PNG signature %s\n",
> +               signature);
>          return AVERROR_INVALIDDATA;
>      }
>  

-- 
Clément B.
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