Re: Check existence of data area in ILE C

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 [mailto:c400-l-bounces-Zwy7GipZuJhWk0Htik3J/[email protected]] On Behalf Of Zvi Kave
Sent: March 10, 2015 12:04 PM
To: c400-l-Zwy7GipZuJhWk0Htik3J/[email protected]
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]<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.
      ..."

References

   Visible links
   1.
http://www.ibm.com/support/knowledgecenter/ssw_ibm_i_71/rzarf/prag_exception
_handler.htm%23prag_exception_handler
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