Experimental Physics and
Industrial Control System

Michael Davidsaver via Tech-talk <tech-talk at aps.anl.gov> · Sun, 8 Aug 2021 08:27:20 -0700

On 8/7/21 12:35 PM, Kasemir, Kay via Tech-talk wrote:
> Hi:
> 
>> I subsequently tried out on EPICS base version 7.0.3.1 ..
>> It works fine ..
>> I am suspecting the bug may be due to newer version of EPICS.
> 
> Looks like you found a problem in R7.0.6.

From a quick test, it looks like this call to dbPut() is erroneously taking
a code path intended for a scalar value even though nRequest==4.

https://github.com/epics-base/epics-base/blob/cb8c7998b62701a849a6fa9c299cc1613f66a627/modules/database/src/ioc/db/dbAccess.c#L1372

This change went into 7.0.5 as part of

https://code.launchpad.net/~dirk.zimoch/epics-base/+git/epics-base/+merge/386175

I guess the oversight was assuming that all array operations are on SPC_DBADDR fields,
while CALC is SPC_CALC.

> Take this example record, executed by softIoc:
> 
> record(calc, "test_calc")
> {
>     field(SCAN, "1 second")
>     field(CALC, "RNDM*100")
> }
> 
> $ caget -S test_calc.CALC$
> test_calc.CALC$ RNDM*100
> 
> $ caput -S test_calc.CALC$ "300"
> Old : test_calc.CALC$ RNDM*100
> CA.Client.Exception...............................................
>     Warning: "Channel write request failed"
>     Context: "op=1, channel=test_calc.CALC$, type=DBR_CHAR, count=4, ctx="test_calc""
>     Source File: ../oldChannelNotify.cpp line 159
>     Current Time: Sat Aug 07 2021 15:27:54.755166000
> ..................................................................
> New : test_calc.CALC$ 3NDM*100
> 
> .. and the softIoc shows this error:
> 
> Illegal field value PV: test_calc calc: Illegal CALC field
> test_calc.CALC: Syntax error, unknown operator/operand in expression "3NDM*100"
> 
> So the IOC didn't receive "300" as written, it only took "3" _and_ kept the rest of the previous CALC field value.
> 
> When instead using R7.0.4.1, all works fine.
> In fact the test also succeeds with softIoc from R7.0.4.1 and caget/caput from base-7.0.6.
> The issue starts when using the base-7.0.6 softIoc.
> 
> -Kay
> 

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System