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Re: [Qemu-devel] [PATCH] osdep: Deal with TIME_MAX and OpenBSD 64-bit ti
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] [PATCH] osdep: Deal with TIME_MAX and OpenBSD 64-bit time_t |
Date: |
Thu, 23 Nov 2017 15:31:14 +0000 |
On 6 November 2017 at 17:41, Paolo Bonzini <address@hidden> wrote:
> 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.
GCC doesn't like this phrasing, it complains
qmp.c: In function ‘qmp_expire_password’:
qmp.c:334:89: error: integer overflow in expression [-Werror=overflow]
because of the shift into the sign bit. Instead we can borrow the
TYPE_MAXIMUM macro from gnulib, which uses basically the same
approach but avoids the UB and the compiler warning. I'll send
a patch in a bit.
thanks
-- PMM