[libvirt] FreeBSD, no gcc present libvirt build issue

[Jason Helfman]

On Thu, Aug 29, 2013 at 9:42 AM, Eric Blake <eblake at redhat.com> wrote:

> On 08/29/2013 10:33 AM, Eric Blake wrote:
> >> Since gnulib has a working random_r() function can we just make
> >> gnulib replace the boneheaded freebsd impl ?
> >
> > Huh - the glibc man pages state that random_r returns RAND_MAX bits.
> > random_r is a glibc extension: POSIX only requires rand(), rand_r(), and
> > random(); but even with random(), POSIX has no requirements that it be
> > related to RAND_MAX - so the fact that glibc equates random()/random_r()
> > with RAND_MAX is also a glibc extension.
> >
> > I guess that means we should't be worrying about RAND_MAX in the first
> > place, as it is tied to the (potentially algorithmically weaker) rand(),
> > and need not have any bearing on the fact that we already use gnulib's
> > random_r().
> >
> > I'll play around with a patch.
>
> As it is, POSIX recommends the use of drand48() and friends for
> multithreaded apps, not random() (where lrand48() would match precisely
> with a RAND_MAX of 0x7fffffff); but that's because POSIX lacks
> random_r().  But since gnulib lacks [dl]rand48(), I still think libvirt
> is still better off sticking with random_r(), and just avoiding the red
> herring of a potentially unrelated RAND_MAX.
>
> --
> Eric Blake   eblake redhat com    +1-919-301-3266
> Libvirt virtualization library http://libvirt.org
>
>
This is outside of my expertise at this point, but here is the discussion
thread regarding this on a FreeBSD mailing list:

http://lists.freebsd.org/pipermail/freebsd-current/2013-August/044084.html

Thanks!

-jgh

-- 
Jason Helfman          | FreeBSD Committer
jgh at FreeBSD.org     | http://people.freebsd.org/~jgh  | The Power to Serve
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