Re: Check existence of data area in ILE C -- C400-L

Also my thanks to Chuck for _CTLA_HANDLE_NO_MSG.
I had no idea about this option. Of course a piece I shared was
written by someone here in the previous millenium.
And the fact that _CTLA_HANDLE does generate error message into the
log in our particular case was rather useful....

Jevgeni.

On Wed, Mar 11, 2015 at 9:56 AM, Zvi Kave <zvi.kave@xxxxxxxxxx> wrote:

Hi Chris,

I shall try it later because I need a quick solution.
In the meantime I need only to replace _CTLA_HANDLE with
_CTLA_HANDLE_NO_MSG
in the exception handler.
Do I save CPU in your solution or it is the same, but without exception
handler ?

Thanks,

Zvi

On 10/03/2015 20:10, [1]chrish@xxxxxxxxxxxxxxxxx wrote:

Here is a quick sample for a data area which is a decimal data area (cannot
be retrieved using the QXX API's)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <qusec.h>
#include <decimal.h>
#include <qwcrdtaa.h>

typedef _Packed struct DA_content_x {
Qwc_Rdtaa_Data_Returned_t hdr;
char data[10];
} DA_content_t;

int main(int argc, char **argv) {
int rcvr_count = 0;
DA_content_t Dta_Content; /* data area content */
decimal(5,0) *d_ptr;
char DA_Name[20] = "NBROFRCV CHLIB "; /* Name */
Qus_EC_t Error_Code = {0}; /* error code struct */

Error_Code.Bytes_Provided = sizeof(Error_Code);

QWCRDTAA(&Dta_Content,
sizeof(Dta_Content),
DA_Name,
1,
5,
&Error_Code);
if(Error_Code.Bytes_Available > 0) {
// do something about the error
printf("Error received %.7s\n",Error_Code.Exception_Id);
return -1;
}
printf("Available = %d\n",Dta_Content.hdr.Bytes_Available);
printf("Returned = %d\n",Dta_Content.hdr.Bytes_Returned);
printf("Type = %.10s\n",Dta_Content.hdr.Type_Value_Returned);
printf("Length = %.10s\n",Dta_Content.hdr.Length_Value_Returned);
printf("Decimal pos = %d\n",Dta_Content.hdr.Number_Decimal_Positions);
d_ptr = (decimal(5,0)*)Dta_Content.data; printf("Content =
%D(5,0)\n",*d_ptr); return 1;
}

It's simple and easy to understand and does not require you to build in your
own error handler. Write it up as a generic handler for retrieving any data
area content.

Chris...

-----Original Message-----
From: C400-L [[2]mailto:c400-l-bounces@xxxxxxxxxxxx] On Behalf Of Zvi Kave
Sent: March 10, 2015 12:04 PM
To: [3]c400-l@xxxxxxxxxxxx
Subject: Re: [C400-L] Check existence of data area in ILE C

Very nice.
_CTLA_HANDLE_NO_MSG made the trick!!

Many thanks,

Zvi

On 10/03/2015 17:36, CRPence wrote:

On 10-Mar-2015 10:20 -0500, Zvi Kave wrote:

Sorry. It is too much complicated for me.
Waiting for simpler solution.
Perhaps a change in the exception handler?:
#pragma exception_handler(ERROR_OCCURED, ca, 0, _C2_MH_ESCAPE, \
_CTLA_HANDLE, "MCH3401")

Of course that would not resolve the issue of concurrency introduced
by performing a separate /check for existence/ test prior to invoking
the request to /Retrieve Data Area/ that itself performs the same
existence check. Nevertheless...

I was unaware that the capability to suppress the messaging was
exposed externally in any of the HLLs, but a quick search of the
KnowledgeCenter revealed that there are both of the Exception Control
Actions available to the C language, "_CTLA_IGNORE_NO_MSG" and
"_CTLA_HANDLE_NO_MSG", which apparently provide the equivalent effect
of
the message suppression:

[1][4]<http://www.ibm.com/support/knowledgecenter/ssw_ibm_i_71/rzarf/prag_excep
tion_handler.htm%23prag_exception_handler>
"...
ctl_action

Specifies an integer constant to indicate what action should take
place for this exception handler. If handler is a function, the default
value is _CTLA_INVOKE. If handler is a label, the default value is
_CTLA_HANDLE. This parameter is optional.

The following are valid exception control actions that are defined
in the <except.h> header file:

#define name Defined value and action
...
_CTLA_HANDLE_NO_MSG Defined to 3. The exception is handled but
messages are not logged before calling the handler. The exception will
no longer be active when the handler gets control. Exception messages
are not logged. Msg_Ref_Key in the typedef _INTRPT_Hndlr_Parms_T is set
to zero. Exception processing ends when the exception handler returns.
This is valid for functions and labels.
...
_CTLA_IGNORE_NO_MSG Defined to 132. The exception is handled and
messages are not logged. Control is not passed to the handler function
named on the directive and exception will no longer be active.
Execution
resumes at the instruction immediately following the instruction that
caused the exception. This is valid for functions only.
..."

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