On 06/11/2017 12:26, Daniel P. Berrange wrote:
> On Mon, Nov 06, 2017 at 10:51:16AM +0000, Peter Maydell wrote:
>> On 6 November 2017 at 00:56, Brad Smith <b...@comstyle.com> wrote:
>>> Define TIME_MAX to LLONG_MAX for OpenBSD since OpenBSD uses 64-bit time_t.
>>>
>>> Signed-off-by: Brad Smith <b...@comstyle.com>
>>>
>>>
>>> diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
>>> index 6855b94bbf..824714049b 100644
>>> --- a/include/qemu/osdep.h
>>> +++ b/include/qemu/osdep.h
>>> @@ -132,8 +132,12 @@ extern int daemon(int, int);
>>> #define ESHUTDOWN 4099
>>> #endif
>>> #ifndef TIME_MAX
>>> +#ifdef __OpenBSD__
>>> +#define TIME_MAX LLONG_MAX
>>> +#else
>>> #define TIME_MAX LONG_MAX
>>> #endif
>>> +#endif
>>
>> I'm not really a fan of adding new OS-specific #ifdefs --
>> what if one of the other BSDs uses or switches to 64-bit
>> time_t for 32-bit platforms? Is there some way we can detect
>> this generically at compile time (possibly in configure) ?
>
> You could use a pair of compile time asserts to figure it out.
>
> Would need one compile test to check 32 vs 64 bit:
>
> #include <time.h>
> char time_t_64bit[sizeof(time_t) == 8 ? 1 : -1];
>
> and a second to check signed vs unsigned:
>
> #include <time.h>
> char time_t_signed[(time_t) -1 < 0 ? 1 : -1];
>
>
> Save each of these programs to the file $TMPC, and then run 'compile_object'
> from configure. You then have a decision matrix for 4 different TIME_MAX
> values to write into config-host.h.
What about
#define type_max(t) \
((t) -1 > 0 \
? (t)~0 \
: (((t)1) << \
(sizeof(t) * 8 - 1)) - 1) \
#define TIME_MAX type_max(time_t)
? We don't need it to be a cpp constant, do we? Or if we did, we could
assume it to be signed, it's enough for the three users.
Thanks,
Paolo
