Re: getting errno and its text description

["Simon Coulter" <shc@xxxxxxxxxxxxxxxxx>]

Hello Steve,

You wrote:
>The return value I am getting from a call to open( ) is -1.  My non ibm
>documentation of the C standard says that -1 indicates an error and to look
>to the "errno" global variable for the error code.

That is generally how C and Unix functions behave (but in typical Unix 
fashion you can't presume that is how they will work).

>Am I going too far if I write a CPP routine to retrieve the value of errno?

Yes --- way too far, unless you need to access errno from CL.

>Is there an ile/rpg way to retrieve errno?

Yes.  See example code below.

>Also, is there a function that can be called that converts the errno to 
>text form?

Prototype the strerror() and perror() functions. You can also use DSPMSGD 
CPEnnnn where nnnn is the errno value.

Accessing errno from RPG
=========================

Include the following definitions in your code

 * Error number returned                                         
D errno           S                   LIKE(int_t) BASED(@errno)  
D @errno          S               *                              
                                                                 
D getErrno        PR              *   Extproc('__errno')         

Somewhere in your initialisation code do:

C                       EVAL      @errno = getErrno

Then whenever you need to test errno you can do:

C                       IF        errno = $EWOULDBLOCK
 *                         do something about it      
C                       ENDIF                         

presuming that you have defined constants for each of the various errno 
values.

Regards,
Simon Coulter.
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