misc/tst-preadvwritev2 incorrect test of [BZ #23579"]

[Sergey Kolosov]

On Fri, 2019-01-25 at 14:40 +0100, Florian Weimer wrote:
> * Sergey Kolosov:
> 
> > glibc misc/tst-preadvwritev2 and misc/tst-preadvwritev64v2 tests
> > are
> > always passing even on unpatched glibc. I've found out that added
> > test
> > case function do_test_with_invalid_fd() checks preadv2 (-1, &iov,
> > 1, 0,
> > RWF_HIPRI) result with TEST_VERIFY (errno == EBADF || errno ==
> > ENOTSUP), that means both values(correct EBADF and incorrect
> > ENOTSUP)
> > are considered valid, so the test is always passing.
> 
> I think we need to probe first if there is emulation or not, and skip
> the test if there is kernel support.
> 
> Do you want to work on a patch?
> 
> Thanks,
> Florian

Sure, I would like to work on a patch.

Thanks,
Sergey