RE: errno (is no longer: VIRUS ALERT!)

["Joe Pluta" <joepluta@xxxxxxxxxxxxxxxxx>]

The topic is changed <laughing>.

Seriously, I suspect this thread will die a natural death soon, so no major
problem.  I've gotten errno to work now, using Rolf's original prototype.  I
now have a called subprogram that (almost) writes intelligently to a stream
file in EBCDIC.  I'm still getting used to the BIFs - %TRIMR trims a string
before I store it in a variable, but %SIZE returns the whole size of the
variable.  I'm unsure whether to use varying on the variable, or if there's
a BIF that returns the length of the trimmed string.  But I'm learning, and
learning quickly.

Joe


> -----Original Message-----
> From: owner-midrange-l@midrange.com
> [mailto:owner-midrange-l@midrange.com]On Behalf Of Sion Coulter
> Sent: Wednesday, June 06, 2001 9:54 PM
> To: MIDRANGE-L@midrange.com
> Subject: errno (was: VIRUS ALERT!)
>
>
>
> Hello Joe,
>
> Change the bloody topic!
>
> You wrote:
> >Does anybod have the ILE C pieces needed to allow me to retrieve the
> >"errno" parameter when using the Unix APIs?  According to the manuals, I
> >need a C module because the error is exported as "errno", which is lower
> >case and cannot be accessed by ILE RPG.
>
> Not strictly true.  RPG IV can access lower case exports.  For example
>
>  * Errno in C style - imported from QC2UTIL1 service program
> D errno           S                   LIKE(int_t) IMPORT('errno')
>
> however, although that is syntactically correct it won't work because the
> errno variable exported from the QC2UTIL1 service program is
> always zero.
> Bastards!  Read on ....
>
> >And rather than provide a "geterrno()" method in the Unix APIs,
> evidently
> >I'm expected to make my own.  Since I don't have the ILE C compiler,
> >that's sort of difficult, so I was wondering if anybody else had gone
> >through this step.
>
> You are expected to create your own because the conventional
> wisdom is that
> you should be using C for this stuff.  However, you don't need to
> create it
> completely because the C runtime (which is on every system) already
> provides it.  Read on ...
>
> You do have the C compiler.  It is on your installation CD-ROM.  You can
> install it and run it for 70 days before it dies.  It is probably worth
> installing simply so you can examine the C header files whenever you need
> to convert an include to RPG IV.  If you look at the errno.h include you
> will see that errno in C on the AS/400 is actually a function call.
>
>       extern int *__errno(void);
>       #define errno (*__errno())
>
> You can prototype the function call and use it from RPG IV.  It is not as
> transparent as the C version but it works.  Here is an excerpt from my
> version of errno.h for RPG IV.  Note that you only need to address the
> errno variable once in the program so put the
>                        EVAL      @errno = getErrno
> in the *INZSR and then errno is always available.
>
>  *************************************************************************
>  * Definition of errno :  Slightly different from C language invocation  *
>  *                        due to language semantics.  Invoke like:       *
>  * CL0N01Factor1+++++++Opcode&ExtExtended-factor2+++++++++++++++++++++++ *
>  *                     EVAL      @errno = getErrno                       *
>  * and then test like:                                                   *
>  *                     IF        errno = $EWOULDBLOCK                    *
>  *                        do something about it                          *
>  *                     ENDIF                                             *
>  *************************************************************************
>
>  * Error number returned
> D errno           S                   LIKE(int_t) BASED(@errno)
> D @errno          S               *
>
> D getErrno        PR              *   Extproc('__errno')
>  /endif
>
> Regards,
> Simon Coulter.
>
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