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<== Date ==> <== Thread ==>
Subject: Re: PV save and restore tool sought
From: Andrew Johnson <[email protected]>
To: Kay-Uwe Kasemir <[email protected]>, EPICS tech-talk <[email protected]>
Date: Tue, 31 Jul 2007 15:47:29 -0500
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
References:
PV save and restore tool sought Rock, Judith E.
Re: PV save and restore tool sought Thomas Birke
Re: PV save and restore tool sought Emmanuel Mayssat
Re: PV save and restore tool sought Kay-Uwe Kasemir
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