[alsa-devel] [PATCH 4/4] aplay: Limit VUMeter progress bar to 100 for negative as well

[Rosen Penev]

On Tue, Nov 19, 2019 at 10:48 PM Takashi Iwai <tiwai at suse.de> wrote:
>
> On Wed, 20 Nov 2019 07:36:19 +0100,
> Rosen Penev wrote:
> >
> > On Tue, Nov 19, 2019 at 10:26 PM Takashi Iwai <tiwai at suse.de> wrote:
> > >
> > > On Wed, 20 Nov 2019 05:28:56 +0100,
> > > Rosen Penev wrote:
> > > >
> > > > If the progress bar somehow becomes negative, it ends up overwritting
> > > > tmp. Fixes this GCC warning:
> > > >
> > > > aplay.c:1747:18: warning: '%02d' directive writing between 2 and 11 bytes
> > > >  into a region of size 4 [-Wformat-overflow=]
> > > >  1747 |    sprintf(tmp, "%02d%%", maxperc[c]);
> > >
> > > This is false-positive.  The value passed there is guaranteed to be a
> > > positive integer at the calculation time.
> > Sure. But best to silence GCC. It probably optimizes better this way.
>
> I guess this adds more code in binary.  Comparing with 99U would work?
I tried that. Here are some results:

134348 for this patch
134832 if changed to U. Also tried casting lhs to unnsigned int, same size.
135125 originally

I understand this is an exercise in micro-optimization, but still.

Sizes are in bytes. It's the size of a compressed OpenWrt archive.

>
>
> Takashi
>
>
> > >
> > >
> > > thanks,
> > >
> > > Takashi
> > >
> > > >
> > > > Signed-off-by: Rosen Penev <rosenp at gmail.com>
> > > > ---
> > > >  aplay/aplay.c | 4 +++-
> > > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/aplay/aplay.c b/aplay/aplay.c
> > > > index 72fa567..9c5a11b 100644
> > > > --- a/aplay/aplay.c
> > > > +++ b/aplay/aplay.c
> > > > @@ -54,6 +54,8 @@
> > > >  #include "formats.h"
> > > >  #include "version.h"
> > > >
> > > > +#define ABS(a)  (a) < 0 ? -(a) : (a)
> > > > +
> > > >  #ifdef SND_CHMAP_API_VERSION
> > > >  #define CONFIG_SUPPORT_CHMAP 1
> > > >  #endif
> > > > @@ -1741,7 +1743,7 @@ static void print_vu_meter_stereo(int *perc, int *maxperc)
> > > >                       line[bar_length + 6 + 1 + p] = '+';
> > > >               else
> > > >                       line[bar_length - p - 1] = '+';
> > > > -             if (maxperc[c] > 99)
> > > > +             if (ABS(maxperc[c]) > 99)
> > > >                       sprintf(tmp, "MAX");
> > > >               else
> > > >                       sprintf(tmp, "%02d%%", maxperc[c]);
> > > > --
> > > > 2.23.0
> > > >
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> > > >
> >