I don't know if any of the previous responses satisfied your need. Another
approach would be to create a second DCB (PS, BSAM, RECFM=U, and
BLKSIZE=32760). Open the DCB, read the first block, and close the DCB.
Examine the data for whatever attributes you like (such as correct BDW and one
or more correct RDWs). Set some flags (such as "definitely not VB") and save
some values (such as length of first block). After opening your primary DCB,
check the fields that are filled in (such as DSORG, LRECL, BLKSIZE) for
consistency with your flags and saved values.
Not only will this let you catch the case you described (a PDS directory
would not pass the BDW/RDW check) but possibly other user mistakes such as
records larger than blocksize, FB blocksize (either DSCB or actual) not a
multiple of LRECL, F or FB blocks shorter than LRECL, etc
Thomas David Rivers <[EMAIL PROTECTED]> wrote:
Hi Bill...
Well - yes - you've hit the nail on the head - the routines are very
confused because they are expecting to see VB-type records (with a BDW
and RDW) and they are not.
The program uses BSAM I/O.
The issue here is that the program expects to not be directed to a PDS,
and when that accidently happens - things go, as you mention,
alarmingly wrong.
What I'm looking for is some way for the program to say "Hey! This
isn't a sequentional VB file at all." Instead of miserably blowing
up.
As I mentioned before, I tried looking the DSORG in the DCB, but that
indicates PS (because the PDS was opened with a PS DCB.)
So - is there another way to tell if the file I'm trying to read
with BSAM I/O (doing my own unblocking of the VB records) is at all
reasonable?
Someone else suggested using DYNALLOC to query the organization
of the file before the OPEN... is there a way to accomplish
this after the OPEN?
Then - when the user points the program to a PDS instead of a nice
sequential file (or PDS member), things don't just "blow up", but
can simply inform the user that is an invalid file.
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