Re: Question about _Rreadn C function

["Charles Wilt" <charles.wilt@xxxxxxxxx>]

Ok another issue.

When I try to copy the data out of the buffer, I get garbage.

I think perhaps my RPG prototype isn't right or I'm not using it right.

here's part of the C structure definition for _RFILE:
volatile void  *const *const in_buf;
volatile void  *const *const out_buf;

Here's the RPG DS definition I'm using:
     D   in_buf                        *
     D   out_buf                       *

I was trying to use in_buf like so:
MemMove(fileFile.inbuf : myBuffer : 114)

Which apparently isn't right.

Is there a way to use _RFILE.in_buf in RPG?

Thanks!
Charles Wilt

On Wed, Sep 24, 2008 at 11:02 AM, Charles Wilt <charles.wilt@xxxxxxxxx> wrote:
> All,
>
> I'm calling the _Rread() C function from RPG (thus the cross-posting).
>
> _RIOFB_T *_Rreadn (_RFILE *fp, void *buf, size_t size, int opts)
>
> I'm trying to use the "locate mode" of the function by not passing the
> void *buf parameter as I want to move the buffer myself ( via
> fp->in_buf) in a later procedure.
>
> However, my question: how can I determine if an error occurred?
> According to the manual:
>
> "If attempts are made to read beyond the last record in the file, the
> num_bytes field is set to EOF. If it is unsuccessful, the num_bytes
> field is set to a value less than size, and errno is changed. If you
> are using device files and specify zero as the size, check errno to
> determine if the function was successful."
>
> But when in "locate mode" the manual says:
> "size Specifies the number of bytes that are to be read and stored in
> buf. If locate mode is used, this parameter is ignored."
>
> So I can still detect EOF, but what about other errors?
>
> Thanks!
> Charles Wilt