RE: *varying vs varchar -- RPG400-L

I'd also remove all OPTIONS(*VARSIZE) if CONST is specified.

The called procedure has no way to detect the lengths of these fields

For an in/out parameter the called procedure can determine the length of the passed variable with the CEEDOD API (assumed the OPDESC keyword is specified within the Prototype of the called procedure);
https://www.ibm.com/docs/en/i/7.4?topic=ssw_ibm_i_74/apis/CEEDOD.htm

Then you can substring exactly the passed data from the parameter.
When returning data, you also have to return the data in the length of the passed variable (determined with the CEEDOD API).

Mit freundlichen Grüßen / Best regards

Birgitta Hauser
Modernization – Education – Consulting on IBM i

"Shoot for the moon, even if you miss, you'll land among the stars." (Les Brown)
"If you think education is expensive, try ignorance." (Derek Bok)
"What is worse than training your staff and losing them? Not training them and keeping them!"
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-----Original Message-----
From: RPG400-L <rpg400-l-bounces@xxxxxxxxxxxxxxxxxx> On Behalf Of Scott Klement
Sent: Freitag, 29. April 2022 19:39
To: rpg400-l@xxxxxxxxxxxxxxxxxx
Subject: Re: *varying vs varchar

I would remove all of those options(*varsize) keywords.

The way this is coded is dangerous. The called procedure has no way to detect the lengths of these fields, so if you pass something shorter than indicated on the prototype, you will end up overwriting random memory.

Whomever wrote this did not understand how options(*varsize) works.

On 4/29/2022 12:22 PM, Greg Wilburn wrote:

So just to clarify...

This is the actual prototype:

dcl-pr Eml_Stmf int(10) ExtProc('Eml_Stmf');
pcom# char(6) const options(*varsize);
psubject char(100) const options(*varsize);
pstmf char(1024) const options(*varsize);
ptoaddr char(50) const options(*varsize);
pccaddr char(50) const options(*nopass:*varsize);
pmessage char(1024) const options(*nopass:*varsize);
pbdyct char(80) const options(*nopass:*varsize);
end-pr;

What I observed:
I passed in a CHAR(3) variable for PCOM# when I called EML_STMF from
another program. The calling program passed (as the first two positions) COM_NBR='070'
SUBJECT='Invoice #40064611'

Inside EML_STMF, the PCOM# variable contained '070 I '. It looks like the "I" from "Invoice"

Based on your last sentence below, PCOM# should have contained blanks for the 3 trailing positions. Or am I still misunderstanding?

-----Original Message-----
From: RPG400-L <rpg400-l-bounces@xxxxxxxxxxxxxxxxxx> On Behalf Of Jon
Paris
Sent: Friday, April 29, 2022 11:58 AM
To: RPG programming on IBM i <rpg400-l@xxxxxxxxxxxxxxxxxx>
Subject: Re: *varying vs varchar

Correct - but the assumption is that you will detect the actual length and process accordingly.

Remember - when you pass a parm (other that by value) you are only passing a pointer. So unless your called routine restricts itself to the length passed you will "see" whatever data is in the 6 bytes addressed by the pointer. That extra stuff could be blanks or just rubbish left around by a previous user of that storage.

The important thing is NOT to use the combination you used - it has no value. CONST was enough by itself and will always supply blanks for the training positions.

Jon P

On Apr 29, 2022, at 11:18 AM, Greg Wilburn <gwilburn@xxxxxxxxxxxxxxxxxxxxxxx> wrote:

Sorry... my fault, Charles is right. It was not real code, and the
option is *varsize

So back to my example... if I call this procedure, where the first parameter is CHAR(6) *VARSIZE passing only '123', why does it contain "other" data?

My understanding is that I can pass it something smaller?

-----Original Message-----
From: RPG400-L <rpg400-l-bounces@xxxxxxxxxxxxxxxxxx> On Behalf Of Jon
Paris
Sent: Friday, April 29, 2022 11:12 AM
To: RPG programming on IBM i <rpg400-l@xxxxxxxxxxxxxxxxxx>
Subject: Re: *varying vs varchar

Thanks Charles - I knew there was something wrong with Options(*varchar) but since it _appeared_ to be from real code ...

Jon P.

On Apr 29, 2022, at 11:05 AM, Charles Wilt <charles.wilt@xxxxxxxxx> wrote:

There is no options(*varchar)

I assume from the title you mean options(*varsize)

options(*varsize) and varchar()/varying are two very different
things

...and Jon beat me to the details... :)

Charles

On Fri, Apr 29, 2022 at 8:37 AM Greg Wilburn <
gwilburn@xxxxxxxxxxxxxxxxxxxxxxx> wrote:

I have an older procedure interface defined like this:

dcl-pr myProc;
myfield char(6) const options(*varchar);
myfield2 char(100) const options(*varchar);
end-pr;

If I call this procedure like this:

Callp myProc('123':'This is myfield2');

The value of myfield in the procedure is not just "123"...

What am I missing?
Should I change the Procedure Interface to be VARCHAR instead? And
what are the ramifications of that?

I apologize for asking as I have a strange sense of déjà vu.

[Logo]<https://www.totalbizfulfillment.com/> Greg Wilburn
Director of IT
301.895.3792 ext. 1231
301.895.3895 direct
gwilburn@xxxxxxxxxxxxxxxxxxxxxxx<mailto:gwilburn@totalbizfulfillmen
t.com>
1 Corporate Dr
Grantsville, MD 21536
www.totalbizfulfillment.com<http://www.totalbizfulfillment.com>
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