[Spice-devel] [PATCH] gstreamer-encoder: fix compiler warning with Fedora 30

[Frediano Ziglio]

> 
> Fedora 30 / gcc 9.1.1 20190503 (Red Hat 9.1.1-1) fails to build
> because of this error/warning:
> 
> > gstreamer-encoder.c: In function 'set_video_bit_rate':
> > gstreamer-encoder.c:518:17: error: taking the absolute value of unsigned
> > type 'uint64_t' {aka 'long unsigned int'} has no effect
> > [-Werror=absolute-value]
> >  518 |     } else  if (abs(bit_rate - encoder->video_bit_rate) >
> >  encoder->video_bit_rate * SPICE_GST_VIDEO_BITRATE_MARGIN) {
> >      |                 ^~~
> > gstreamer-encoder.c:518:17: error: absolute value function 'abs' given an
> > argument of type 'uint64_t' {aka 'long unsigned int'}
> 
> This patches solves these two warnings:
> 
> 1) cast the substraction to a signed type (int64_t instead of
> uint64_t) to preserve the operation meaning;
> 
> 2) use the long int labs() instead of the int version abs() to avoid
> data trunction.

Not working for all platform we support, maybe a

static inline int64_t i64abs(int64_t value)
{
    if (sizeof(int) == sizeof(value)) {
        return (int64_t) abs((int) value);
    }
    if (sizeof(long int) == sizeof(value)) {
        return (int64_t) labs((long int) value);
    }
    return (int64_t) llabs((long long int) value);
}

> ---
> 
> resending this patch with the comments addressed
> 
> ---
>  server/gstreamer-encoder.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/server/gstreamer-encoder.c b/server/gstreamer-encoder.c
> index 6416b688..da73c5ee 100644
> --- a/server/gstreamer-encoder.c
> +++ b/server/gstreamer-encoder.c
> @@ -515,7 +515,7 @@ static void set_video_bit_rate(SpiceGstEncoder *encoder,
> uint64_t bit_rate)
>          encoder->video_bit_rate = bit_rate;
>          set_gstenc_bitrate(encoder);
> 
> -    } else  if (abs(bit_rate - encoder->video_bit_rate) >
> encoder->video_bit_rate * SPICE_GST_VIDEO_BITRATE_MARGIN) {
> +    } else  if (labs((int64_t)(bit_rate - encoder->video_bit_rate)) >
> encoder->video_bit_rate * SPICE_GST_VIDEO_BITRATE_MARGIN) {
>          encoder->video_bit_rate = bit_rate;
>          set_pipeline_changes(encoder, SPICE_GST_VIDEO_PIPELINE_BITRATE);
>      }

Frediano