Re: [FFmpeg-devel] [PATCH v2 1/2] avcodec: Fix warnings with signed/unsigned compare in bitstream.h

[Andreas Rheinhardt <andreas.rheinhardt@outlook.com>]

Devin Heitmueller:
> When including the header in decklink_enc.cpp it would be fed
> through the C++ compiler rather than the C compiler, which has
> more strict warnings when comparing signed/unsigned values.
> 
> Make the local variables unsigned to match the arguments they are
> being passed for those functions.
> 
> Signed-off-by: Devin Heitmueller <dheitmueller@ltnglobal.com>
> ---
>  libavcodec/bytestream.h | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/libavcodec/bytestream.h b/libavcodec/bytestream.h
> index d0033f14f3..67080604b9 100644
> --- a/libavcodec/bytestream.h
> +++ b/libavcodec/bytestream.h
> @@ -180,7 +180,7 @@ static av_always_inline void bytestream2_skipu(GetByteContext *g,
>  static av_always_inline void bytestream2_skip_p(PutByteContext *p,
>                                                  unsigned int size)
>  {
> -    int size2;
> +    unsigned int size2;
>      if (p->eof)
>          return;
>      size2 = FFMIN(p->buffer_end - p->buffer, size);
> @@ -268,7 +268,7 @@ static av_always_inline unsigned int bytestream2_get_buffer(GetByteContext *g,
>                                                              uint8_t *dst,
>                                                              unsigned int size)
>  {
> -    int size2 = FFMIN(g->buffer_end - g->buffer, size);
> +    unsigned int size2 = FFMIN(g->buffer_end - g->buffer, size);
>      memcpy(dst, g->buffer, size2);
>      g->buffer += size2;
>      return size2;
> @@ -287,7 +287,7 @@ static av_always_inline unsigned int bytestream2_put_buffer(PutByteContext *p,
>                                                              const uint8_t *src,
>                                                              unsigned int size)
>  {
> -    int size2;
> +    unsigned int size2;
>      if (p->eof)
>          return 0;
>      size2 = FFMIN(p->buffer_end - p->buffer, size);
> @@ -311,7 +311,7 @@ static av_always_inline void bytestream2_set_buffer(PutByteContext *p,
>                                                      const uint8_t c,
>                                                      unsigned int size)
>  {
> -    int size2;
> +    unsigned int size2;
>      if (p->eof)
>          return;
>      size2 = FFMIN(p->buffer_end - p->buffer, size);
> @@ -348,7 +348,7 @@ static av_always_inline unsigned int bytestream2_copy_buffer(PutByteContext *p,
>                                                               GetByteContext *g,
>                                                               unsigned int size)
>  {
> -    int size2;
> +    unsigned int size2;
>  
>      if (p->eof)
>          return 0;

The bytestream APIs are allowed to overread if the buffer is padded and
the user manages this himself. So you are not allowed to presume that
g->buffer_end - g->buffer is positive.

- Andreas

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