Re: PV save and restore tool sought

[Andrew Johnson <anj@aps.anl.gov>]

Hello Kay,

Kay-Uwe Kasemir wrote:
> It works, but there's something fishy with the errno handling.
> Probably more of a vxWorks and network setup error than autosave:
> For us, errno is usually set during write runs,
> indicating some error, even though all is fine
> when looking at the generated files.
> The reaction to most errno errors is just a printf anyway,
> and we #ifdef'ed those printfs away, since we otherwise
> get them all the time,

In vxWorks, errno may be set even when no errors have been returned to 
application-level code.  No vxWorks library routine ever clears the 
errno variable, thus you should only ever look at its value after some 
library routine has returned an ERROR status.  Some library routines are 
capable of recovering from errors returned to them by lower level code 
or may even expect such errors, so just because errno has been set 
doesn't necessarily mean that anything bad happened.

Now it is entirely possible that some code in autosave is not properly 
looking at some returned status value and is thus missing an error, but 
if you're looking at errno without explicitly being told to do so (if 
the above "something fishy" report comes from looking at the ERRNO 
values output by the 'i' routine for example), you're wasting your time 
worrying about it.

- Andrew
--
When a distinguished but elderly scientist states that something is
possible, he is almost certainly right.  When he states that something
is impossible, he is very probably wrong.  -- Arthur C. Clarke