bug#7198: ls-misc failure with Oct 10 snapshot

[Jim Meyering]

Paul Eggert wrote:
> On 10/13/2010 12:37 AM, Jim Meyering wrote:
>
>> What is the server running?
>
> NetApp 6.5.6.  NFS is configured to be NFSv3, running over TCP.
>
>> First step for that one should be to avoid the warnings from perl,
>> e.g., via the patch I suggested.
>
> Yes, thanks, somehow I missed the patch to tests/misc/ls-misc
> that you suggested in
> <http://lists.gnu.org/archive/html/bug-coreutils/2010-10/msg00038.html>.
> I just tried it now, and it does fix the perl warnings.
>
> The problem goes away if I do the build on a local disk, so it does
> seem to be specific to NFS.
>
> I reproduced the problem with the standard RHEL tools, i.e., without
> using the newer versions of GCC etc. that I normally use.
>
> When I strace the make, the bug goes away.  This indicates that it's
> timing-related, and may be hard to debug.
>
> Ooo! Ooo!  The "timing-related" in the previous paragraph made the
> light bulb go on in my head.  It's clock skew.  The NFS server's
> clock is a tiny bit ahead of the NFS client's clock, and so the output
> of "ls -l" contains the date, not the time.

Good catch!

> I don't see how clock-skew could also explain the test-rename bug noted in
> <http://lists.gnu.org/archive/html/bug-coreutils/2010-10/msg00050.html>,
> though.  That part of NFS is not supposed to care about clock skew.
>
> Anyway, the following combined patch fixes the ls-misc failure:
...
> Subject: [PATCH] tests: work around portability and clock-skew problems
>
> * tests/misc/ls-misc (push_ls_colors): Don't assume LS_COLORS
> is set.  This part of the fix is by Jim Meyering.
> (sl-dangle2, sl-dangle3, sl-dangle4, sl-dangle5): Don't assume
> that newly-created files will have time stamps in the past.  They
> might not, due to clock skew, if the file systems are remote.

Thanks!
I've pushed that.