Infinite loop...!!! -- SYSTEM21

We found a problem with program OSLPCP3/PC155 in a unique circumstance with
Work Orders that had created detail records in MSTEXT (MSP02) but had
somehow had their Status set back to a '1'...  When users chose to create
details again the segment of text shown below was executed and caused an
infinite loop on our system that wrote 98 MILLION records on our disk
before the problem was discovered...!!!   I got woken up at 3:30 AM by a
user who found this problem because the AMDAYEND routine locks the users
out of the system...  I was upset when they called, when I finally realized
what was going on I was glad they called...  It took us two days and a
trigger program over MSP02 later to finally find the source (excuse the
pun) of the problem...  PS - The problem still exists in V3.5.2B SP3
too...!!!

Here is the segment of code from PC155 that causes the infinite loop...:
0805.00      C           K02       SETLLMSTEXT
891016
0806.00      C           K02       READEMSTEXT                   96
891016
0807.00B01C           *IN96     DOWEQ'0'
891016
0808.00      C                     Z-ADDL#IDAT    TXDT02
891016
0809.00      C                     WRITEMSR02
920702            (Time Bomb from July 2, 1992)
0810.00      C           TXLN02    ADD  1         EXTLIN  40
891016
0811.00      C           K02       READEMSTEXT                   96
891016
0812.00E01C                     END
891016
(This code segment is like the train track scene from "The Wrong Trousers"
with Wallace and Gromit when they are chasing the penguin around the house
on the model train...  Gromit is laying down new track sections as fast as
he can just before the train runs over them...)  Each record that is
written is the next one read in the loop so this loop will run until either
the file is full or the disk is full (if the file is set to MAXRCDS(*NOMAX)
which in our case it was...Ooooo)...!!!

The line numbers are different in 3.5.2B so I'll include that code segment
here as well...:
0847.00      C           K02       SETLLMSTEXT
891016
0848.00      C           K02       READEMSTEXT                   96
891016
0849.00B01C           *IN96     DOWEQ'0'
891016
0850.00      C                     Z-ADDL#IDAT    TXDT02
891016
0851.00      C                     WRITEMSR02
920702
0852.00      C           TXLN02    ADD  1         EXTLIN  40
891016
0853.00      C           K02       READEMSTEXT                   96
891016
0854.00E01C                     END
891016

We have purged our system of duplicate records in file MSP02 but wanted to
report this obvious logic flaw in the hopes that it could be removed from
the system in order to prevent someone else's system from having their disk
get filled up without them knowing about it...!!!

I have another question related to this...  There is a program that runs in
the AMDAYEND routine - MS902 - Utilities - Clear redundant text records.
Why does this program even exist...?  Could it be because of the logic
error in PC155 that I have reported above...?  We would never have found
the problem unless either the disk got full or the MS902 program held up
our night job trying to delete 98 MILLION records...!!!  MS902 was deleting
records from MSP02 as fast as PC155 was writing them...  A real comedy of
errors...!

This is a real flaw and if you have a programmer look closely at the logic
you will easily see the logic flaw I'm referring to...  If you cannot see
it then call me and I'll be happy to explain it to you...  Thank you.


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