Re: [RFA] off by one array reference in i386-low.c/i386_show_dr

Jan Kratochvil
2011-02-27T21:36:14Z

On Sun, 27 Feb 2011 22:27:31 +0100, Michael Snyder wrote:
> Jan Kratochvil wrote:
> >Hi Michael,
> >On Sat, 26 Feb 2011 23:52:23 +0100, Michael Snyder wrote:
> >>--- i386-low.c 1 Jan 2011 15:33:24 -0000 1.5
> >>+++ i386-low.c 26 Feb 2011 22:48:38 -0000
> >/* A macro to loop over all debug registers. */
> >#define ALL_DEBUG_REGISTERS(i) for (i = 0; i < DR_NADDR; i++)
> >>@@ -195,7 +195,7 @@ i386_show_dr (struct i386_debug_reg_stat
> > ALL_DEBUG_REGISTERS(i)
> > {
> > printf_unfiltered ("\
> >> \tDR%d: addr=0x%s, ref.count=%d DR%d: addr=0x%s, ref.count=%d\n",
> >> i, paddress (state->dr_mirror[i]),
> >> state->dr_ref_count[i],
> >>- i + 1, paddress (state->dr_mirror[i + 1]),
> >>+ i + 1, paddress (state->dr_mirror[i]),
> >> state->dr_ref_count[i + 1]);
> >> i++;
> >> }
> >
> >->
> > CONTROL (DR7): 0000000000090101 STATUS (DR6): 0000000000004000
> > DR0: addr=0x0000000001c31f30, ref.count=1 DR1: addr=0x0000000000000000, ref.count=0
> > DR2: addr=0x0000000000000000, ref.count=0 DR3: addr=0x0000000000000000, ref.count=0
> >
> >I do not see a bug there; still it could be better commented.
>
> The bug is that when "i" is 3, "i + 1" is 4, and the array only runs
> from 0 to 3.

But "i" is never 3. "i" is 0 during the first cycle and 2 during the second
cycle. And then the for cycle ends. There is no 1 and there is no 3.

Regards,
Jan