[PATCH 4/5] io: Add io/tst-lchmod covering lchmod and fchmodat

[Florian Weimer]

* Adhemerval Zanella:

> On 11/02/2020 12:27, Florian Weimer wrote:
>> * Florian Weimer:
>> 
>>> +     /* Without AT_SYMLINK_NOFOLLOW, changing the permissions should
>>> +        work as before.  */
>>> +     arg = select_path (do_relative_path, path_file, "file");
>>> +     TEST_COMPARE (chmod_func (fd, arg, 3, 0), 0);
>>> +     xstat (path_file, &st);
>>> +     TEST_COMPARE (st.st_mode & 0777, 3);
>>> +     /* But with AT_SYMLINK_NOFOLLOW, even if we originally had
>>> +        support, we may have lost it.  */
>>> +     ret = chmod_func (fd, arg, 2, 0);
>> 
>> The last line misses AT_SYMLINK_NOFOLLOW.  The version below (which I'm
>> going to commit) fixes this and adds another check.
>
> I am seeing the following failures on ext2/ext3 on both powerpc64le
> (4.18.0-80.7.2.el7.ppc64le) and aarch64 (4.12.13).

Yeah, please see this thread:

  <https://sourceware.org/ml/libc-alpha/2020-02/msg00467.html>

It affects more than XFS, but apparently not tmpfs (which is what I
happened to use during development of the emulation).

I'll patch this up tomorrow.  It'll considerably simplify the test
case, too.