Re: [Vala] Creating bindings for Oracle OCI

[Jiří Zárevúcky <zarevucky jiri gmail com>]

Well, I don't know how the API you're binding works, but in Vala,
string is usually understood as an immutable nul-terminated UTF-8
encoded text. Maybe you're using something the wrong way?

I suppose it would be easier for you if you actually learned C better
first, then learned exactly how Vala translates to C.

Maybe you can attach your work so far along with a link to the C
documentation. That way someone could figure out what exactly is going
wrong. I suppose it could be me, but I'm not really that experienced
with Vala myself, yet.

2009/6/17 Shawn Ferris <shawn ferris gmail com>:
> I'm sorry to keep pestering.. but if I omit the asterick, nothing
> changes.. it still aborts.. What I did get to work, sorta, was to omit
> the 'out'.. initially I got the error 'error: use of possibly unassigned
> local variable `errbuf'' which I got around by declaring errbuf as
> 'string errbuf = ""'.. now, the buffer is filled, but with only 7
> characters of the error:
>
> ORA-121
>
> which should be:
>
> ORA-12154: TNS:could not resolve the connect identifier specified
>
> Which I can get if I change the bufsiz arg from '(int)sizeof(string)' to
> 512.. but I then it's worse as I also get:
>
> *** glibc detected *** ./x: free(): invalid next size (fast):
> 0x0000000000688510 ***
>
> Which I presume is because I'm freeing more memory than the string
> actually occupies? (I assume this is true, because if I change it to 16,
> I get more of the message returned, without the error.. but I can't go
> anywhere near the 66 chars needed.. not even 33)
>
> The thing I don't understand is that the docs say if buffsiz isn't big
> enough, OCIErrorGet will return null.. so, I'm lead to believe that
> oracle is getting a big enough buffer, but somehow string is truncating
> it? Should I not be using string?
>
>
> On Wed, 2009-06-17 at 13:24 +0200, Jiří Zárevúcky wrote:
> > You have problem with pointers, again. ;) Once you add "out", it's not
> > a pointer anymore as far as Vala is concerned, so you have to omit the
> > asterisk. You are essentially replacing it.
> >
> > 2009/6/17 Shawn Ferris <shawn ferris gmail com>:
> > > Ooops.. Resending, didn't realize this didn't go to the list.. my
> > > apologies.
> > >
> > > On Tue, 2009-06-16 at 21:44 -0600, Shawn Ferris wrote:
> > > > Man.. I'm so close I can smell it.. I actually have the bindings working
> > > > to the point were I am fetching a value from a table. Unfortunately, the
> > > > way it sits, I'm stuck with ints alone.. as soon as I try to return a
> > > > string, the code aborts.. there's actually two cases where the results
> > > > are the same and I'm assuming the fix for one will fix the other, so
> > > > I'll ask for help on the easier one. In this case, it's the ErrorGet
> > > > function defined as:
> > > >
> > > > sword OCIErrorGet ( void      *hndlp,
> > > >                   ub4        recordno,
> > > >                   OraText       *sqlstate,
> > > >                   ub4        *errcodep,
> > > >                   OraText       *bufp,
> > > >                   ub4        bufsiz,
> > > >                   ub4        type );
> > > >
> > > > My vapi definition:
> > > >
> > > >   [CCode (cname = "OCIErrorGet")]
> > > >   public int ErrorGet (
> > > >     Error*       error,
> > > >     int          record,
> > > >     out string*  sqlstate,
> > > >     out int*     errcode,
> > > >     out string*  buffer,
> > > >     int          buffersz,
> > > >     HType        type
> > > >   );
> > > >
> > > > And a C example:
> > > >
> > > >   text errbuf[512];
> > > >   OCIErrorGet ((dvoid *) errhp, (ub4) 1, (text *) NULL, &errcode,
> > > >             errbuf, (ub4) sizeof(errbuf), (ub4) OCI_HTYPE_ERROR);
> > > >
> > > > If I leave off errbuf (which should be the physical message string
> > > > assoctiate to errcode) everything works fine. EG:
> > > >
> > > >     int*    errno;
> > > >     OCI.ErrorGet ( err, 1, null, out errno, null, 0, HType.ERROR);
> > > >     stdout.printf("Error - ORA-%5.5d (%s)\n", (int)errno, action);
> > > >
> > > > I absolutely get the right error code (i can force which error I gen)
> > > > but as soon as I try to touch errbuf the program aborts.. I can not for
> > > > the life of me find the correct way to do this. Can someone point me in
> > > > the right direction? And then, I'll warn you that I'll have at least one
> > > > more email.. but more critique and style.. I'm assuming I haven't
> > > > followed the vala way, but I'm more interested in getting it to work and
> > > > addressing style later.
> > > >
> > > > Thanks for the help!
> > > > SMF
> > >
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