Re: Find control boundary with a machine interface instruction

Hi Jon,

In 2010, Junlei Li published an article explaining how to traverse the call
stack using MI. Very fast and efficient, no need to load the entire call
stack. That utility provided a lot of information about the call stack
entry, but not the ‘control boundary’.

I have been using a self-developed tool for exception handling in RPG for
several years, in which I use the Junlei utility. Now I need to find out
the 'control boundaries', at least the nearest one, for some procedures
responsible for sending messages.

My idea is to simulate the new %target(*CTLBDY...) built-in in my exception
handling tool.

As a challenge I find it very interesting. If there is no other choice, I
will use the QWVRCSTK API.
Best regards,

Javier Mora

El lun, 10 feb 2025 a las 18:46, Jon Paris (<jon.paris@xxxxxxxxxxxxxx>)
escribió:

Perhaps if you told us _why_ you want this and what you plan on using it
for we might be able to offer some alternative suggestions.


Jon Paris
Jon.Paris@xxxxxxxxxxxxxx

On Feb 10, 2025, at 12:44 PM, datil400 <datil400@xxxxxxxxx> wrote:

Thanks Marco for your help.


With the instructions FNDRINVN, MATINVAT and MATPTRIF, I am trying to get
whether any stack entry is a control boundary or not. I am not finding

this

information when materializing the corresponding pointers.

I think I could deduce it from the activation group mark by comparing it
with the previous entry.

I don't know if I'm on the right track.
Javier Mora

El lun, 10 feb 2025 a las 17:38, Marco Facchinetti (<
marco.facchinetti@xxxxxxxxx>) escribió:

https://www.ibm.com/docs/en/i/7.5?topic=execution-materialize-invocation-stack-matinvs

But don't forget:

Warning
The following information is subject to change from release to release.

Use

it with caution and be prepared to adjust for changes with each new
release.

Note
It is recommended that you use Materialize Invocation Attributes

(MATINVAT)

or Materialize Invocation Entry (MATINVE) to materialize an 8-byte
invocation mark. 4-byte marks can wrap and produce unexpected results.

--
Marco Facchinetti

Mr S.r.l.

Tel. 035 962885
Cel. 393 9620498

Skype: facchinettimarco


Il giorno lun 10 feb 2025 alle ore 17:06 datil400 <datil400@xxxxxxxxx>

ha

scritto:

Hi guys,

QWVRCSTK API and STACK_INFO table function return information about the
control boundary of each entry in the call stack.

I have been investigating to find out if it is possible to obtain this

data

through the machine interface. I have not found anything that helps me.

Is this possible?
Best regards

--
Javier Mora
https://github.com/datil400
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