futimens and utimensat vs birthtime

[John Baldwin]

On Friday, August 14, 2015 10:46:10 PM Julian Elischer wrote:
> I would like to implement this call. but would like input as to it's 
> nature.
> The code inside the system would already appear to support handling 
> three elements, though it needs some scrutiny,
> so all that is needed is a system call with the ability to set the 
> birthtime directly.
> 
> Whether it should take the form of the existing calls but expecting 
> three items is up for discussion.
> Maybe teh addition of a flags argument to specify which items are 
> present and which to set.
> 
> ideas?

I believe these should be new calls.  Only utimensat() provides a flag
argument, but it is reserved for AT_* flags.  I would be fine with
something like futimens3() and utimensat3() (where 3 means "three
timespecs").  Jilles implemented futimens() and utimensat(), so he
might have ideas as well.  I would probably stick the birth time in
the third (final) timespec slot to make it easier to update new code
(you can use an #ifdef just around ts[2] without having to #ifdef the
entire block).

-- 
John Baldwin