RE: Pointer or Parameter Error...

Cool...as long as it's me being crazy.. 


Thanks,
Tommy Holden


-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Scott Klement
Sent: Friday, April 14, 2006 2:22 PM
To: RPG programming on the AS400 / iSeries
Subject: RE: Pointer or Parameter Error...

Hi Tommy,

> The failing point was due to the GetOSInfo() procedure in the service
> program.  I restructed the procedure to return a varying field (in
this
> case the BasicInfo DS)

It's because you're writing blanks into 31434 bytes of memory that don't

belong to you.  As luck would have it, you seem to be accidentally
hitting 
the area of memory where the system stores the indicator that keeps
track 
of whether a file is open.

Who knows what else you're corrupting!

Here's where you're calling GetOsInfo():

          // Get OS/400 Information From The User's Profile

           GetOSInfo( BasicInfo
                    : %Size(BasicInfo)
                    : 'USRI0300'
                    : Kr_SxUser
                    : Successful);

The first parameter is BasicInfo, which is defined as a data structure 
that's 1333 bytes long.  Here's the PI for the GetOsInfo proc:

      pGetOSInfo        B                   Export
      d GetOSInfo       PI
      d  ReturnData                32767a   Options(*VarSize)
      d  ReturnLength                 10i 0 Const
      d  Format                        8a   Const
      d  UserProfile                  10a   Const
      d  Successful                     n

Note that in this place, you've defined the first parameter as 32767
bytes 
long.  Later in this procedure, you do the following:

          ReturnData = BasicInfo;

OOps...  now you've made a mess of things.  This statement doesn't just 
set the first 1333 bytes of ReturnData!   It sets the first 1333 bytes
to 
match what's in the BasicInfo data structure, and sets the other 31434 
bytes to blanks.

Unfortunately, ReturnData doesn't have any memory declared for it.  It's

using the memory of the BasicInfo data structure from the calling
module! 
And that's only 1333 bytes long.

That's, ostensibly, why you're passing the ReturnLength parameter.  So 
that you know how much space the caller has allocated to the ReturnData 
parameter -- but you're not using ReturnLength anywhere!

The fix should be to change that statement to read as follows:

          %subst(ReturnData:1:ReturnLength) = BasicInfo;

That will prevent it from corrupting memory.  Assuming you're not doing 
the same thing somewhere else, your problem should be solved.

Please remember to be very, very, very careful whenever you use 
OPTIONS(*VARSIZE).

> program KR0057EX & it works fine now.  Should this be reported to
IBM???
> What's your opinion??

No, this is clearly a bug in your code, not IBM's.