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Date: Thu, 18 Jun 2015 05:58:56 -0400 (EDT)
From: Frediano Ziglio <fziglio@redhat.com>
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Subject: Re: [Qemu-devel] [Qemu-trivial] [PATCH 2/2] Check value for
	invalid	negative values
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To: Michael Tokarev <mjt@tls.msk.ru>
Cc: qemu-trivial@nongnu.org, Gerd Hoffmann <kraxel@redhat.com>, qemu-devel@nongnu.org

For the same reason there is the v >= l test.
The v >= l test state that the value can be out of range so it not always a constant in the range.
Adding the v < 0 check for every invalid value. As these are executed only for logging should not be a performance penalty.
I also hope the compiler is able to optimize

if (v < 0 || v >= l)

with 

if ((unsigned) v >= l)

Frediano

> 
> 11.06.2015 16:17, Frediano Ziglio wrote:
> > In qxl_v2n check that value is not negative.
> 
> Why do you think it is necessary?
> 
> Thanks,
> 
> /mjt
> 
> > Signed-off-by: Frediano Ziglio <fziglio@redhat.com>
> > ---
> >  hw/display/qxl-logger.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/hw/display/qxl-logger.c b/hw/display/qxl-logger.c
> > index d944d3f..faed869 100644
> > --- a/hw/display/qxl-logger.c
> > +++ b/hw/display/qxl-logger.c
> > @@ -93,7 +93,7 @@ static const char *const spice_cursor_type[] = {
> >  
> >  static const char *qxl_v2n(const char *const n[], size_t l, int v)
> >  {
> > -    if (v >= l || !n[v]) {
> > +    if (v < 0 || v >= l || !n[v]) {
> >          return "???";
> >      }
> >      return n[v];
> 
> 
> 
>