Re: 'cp: .snapshot/xxx and xxx are identical'

[Jim Meyering]

Paul Eggert <address@hidden> wrote:
> Jim Meyering <address@hidden> writes:
>
>> Can someone make sure this patch works and let me know?
>> Just apply it, build cp, and then run a command like
>>
>>   ./cp .snapshot/F F
>>
>> for some file F, on a NetApp-backed file system.
>> The above command should succeed, while using an
>> unpatched `cp' should fail.
>
> I just tried it on a Solaris 8 host with a remote NetApp filesystem,
> and it sort of worked, but it had problems.

Thanks for the quick work!

> 1.  Patched GNU "cp .snapshot/weekly.1/F F" fails if F has not been
>     changed since the snapshot.  It succeeds only if F has changed.
>     This is pretty weird, especially if you do "cp
>     .snapshot/weekly.1/* ."  and get a bunch of error messages for
>     your unchanged files.
>
> 2.  Solaris 8 "cp .snapshot/weekly.1/F F" fails regardless of whether
>     F has changed, with these symptoms:
>
>     $ /bin/cp -p .snapshot/weekly.1/rcs-5.7.tar.gz rcs-5.7.tar.gz
>     cp: .snapshot/weekly.1/rcs-5.7.tar.gz and rcs-5.7.tar.gz are identical
>
>     So if we make this change to GNU "cp", it won't be compatible with
>     Solaris "cp".

If you are motivated, you might be able to find a solution yourself.
You could try comparing the entire `struct stat's of two file/snapshot
pairs, one where the snapshot is the same, the other where it differs,
in the hopes that there will be something obvious that distinguishes
the two cases.