On Wed, 1 Sep 2010, John Baldwin wrote:
On Wednesday, September 01, 2010 6:50:03 am Andriy Gapon wrote:
The following reply was made to PR amd64/150170; it has been noted by GNATS.
From: Andriy Gapon <a...@icyb.net.ua>
To: Gerald Pfeifer <pfei...@sputnik1.dbai.tuwien.ac.at>
Cc: Gerald Pfeifer <ger...@pfeifer.com>, freebsd-gnats-sub...@freebsd.org
Subject: Re: amd64/150170: SIG_ATOMIC_MIN/SIG_ATOMIC_MAX 32-bit when
sig_atomic_t
is 64-bit
Date: Wed, 01 Sep 2010 13:26:36 +0300
on 01/09/2010 01:32 Gerald Pfeifer said the following:
...
>> Description:
> On a 9.0-CURRENT machine, amd64, we have:
>
> /usr/include/machine/signal.h:typedef long sig_atomic_t;
>
> This is 32-bit. At the same time we have:
>
> /usr/include/machine/_stdint.h:#define SIG_ATOMIC_MIN INT32_MIN
> /usr/include/machine/_stdint.h:#define SIG_ATOMIC_MAX INT32_MAX
>
> Which is 64-bit.
32-bit vs 64-bit seems to be reversed here...
Yes, but we should still fix this one way or another. I was surprised
recently when I found that sig_atomic_t was long on amd64. Perhaps Bruce
(cc'd) knows which way it should be fixed?
Not really. It is weird that sig_atomic_t is long on all 64-bit arches,
but long on only 1 32-bit (also 64-bit?) arch (arm). I would have
used the smallest type that works (usually signed char), but a case
can be made for using the largest type that works. C99 only requires
the range of the type to be at least that of an 8-bit signed char if
the type is signed or at least that of an 8-bit unsigned char if the
type is unsigned. Portable programs would have problems using more than
the intersection of these ranges, even (or especially) if they have ifdefs
using SIG_ATOMIC_MAX/MIN. Now there might be ABI problems for changing
the type, or perhaps even with changing SIG_ATOMIC_MAX/MIN since these
are specified as the limits of a sig_atomic_t and ifdef tangles using them
might trust this.
Bruce
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