[Spice-devel] [PATCH v2 spice-server] 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 a custom version of abs() to avoid data truncation and/or
> platform-dependent type lengths (abs/labs/llabs)
> ---
>  server/gstreamer-encoder.c | 2 +-
>  server/utils.h             | 5 +++++
>  2 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/server/gstreamer-encoder.c b/server/gstreamer-encoder.c
> index 6416b688..54aa1963 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 (i64abs((int64_t)(bit_rate - encoder->video_bit_rate)) >
> encoder->video_bit_rate * SPICE_GST_VIDEO_BITRATE_MARGIN) {

Is it fine for you if I split the line at 100 characters (after " >") ?

>          encoder->video_bit_rate = bit_rate;
>          set_pipeline_changes(encoder, SPICE_GST_VIDEO_PIPELINE_BITRATE);
>      }
> diff --git a/server/utils.h b/server/utils.h
> index 54bc9d49..a54d5433 100644
> --- a/server/utils.h
> +++ b/server/utils.h
> @@ -75,4 +75,9 @@ int red_channel_name_to_type(const char *name);
> 
>  void red_dump_openssl_errors(void);
> 
> +static inline int64_t i64abs(int64_t value)
> +{
> +    return (value >= 0) ? value : -value;
> +}
> +
>  #endif /* UTILS_H_ */

Otherwise patch is fine for me.

Frediano