On Thu, Aug 29, 2013 at 9:42 AM, Eric Blake <ebl...@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 j...@freebsd.org | http://people.freebsd.org/~jgh | The Power to Serve
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