[PATCH-0.9.33] common/pread_write.c: unbreak on archs without __NR_pread64

[Anthony G. Basile]

On 11/21/2013 06:41 PM, Peter Korsgaard wrote:
>>>>>> "Khem" == Khem Raj <raj.khem at gmail.com> writes:
>
> Hi,
>
>   >>>> The code nicely checks for it, but then ends up hard coding the
>   >>>> syscall to use __NR_pread64 afterwards, rendering the check
>   >>>> useless. Fix it by using the result of the test instead.
>   >>
>   Mike> i think you should look at all the pread/pwrite changes in
>   Mike> master.  afaik, all issues are addressed there.
>   >>
>   >> Yes, possible. I'm trying to test the 0.9.33 branch to hopefully speed
>   >> up the 0.9.33.3 release as there's quite some fixes pending, but it
>   >> looks like some more stuff should get backported.
>   >>
>   >> Anybody else testing the branch?
>
>   > I would be interested if you try out latest master.
>
> Sorry for the slow response - I only now found time to do so. I'm happy
> to say that the pread issue ISN'T present on todays snapshot of master.
>
> So these pread/pwrite changes imho should get backported to to the
> 0.9.33 branch if we ever plan on doing a bugfix release from it.
>

I hit a nasty race condition in git 1.8 because pread/pwrite are not 
atomic in 0.9.33.2 [1].  I've been meaning to backport Mike's fixes for 
Gentoo, but really we should push out another release.  The linux kernel 
has provided pread/pwrite for a long time now, no need to simulate them 
with lseek().

Ref
[1] https://bugs.gentoo.org/show_bug.cgi?id=475920

-- 
Anthony G. Basile, Ph. D.
Chair of Information Technology
D'Youville College
Buffalo, NY 14201
(716) 829-8197