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WEBUTIL_C_API does not work with generic C pointers (Doc ID 298388.1)

Last updated on OCTOBER 09, 2023

Applies to:

Oracle Forms - Version 10.1.2.0.2 and later
Information in this document applies to any platform.
Symptoms
========

When using WEBUTIL_C_API.INVOKE_PTR, an ORA-302000 exception is raised.

Cause
=====

The value of a pointer as returned by the Java part of C_API is of the format
oracle.forms.webutil.cApi.CPtr@fd764a0, and not just a number as one would
expect.


Fix
===

From the PL/SQL interface in C_API, access the pointer as if it were a c_long.

1) Use WEBUTIL_C_API.INVOKE_LONG rather than WEBUTIL_C_API.INVOKE_PTR to call
a C function that returns a pointer.

So for
int * getptr()
use
myptr := WEBUTIL_C_API.INVOKE_PTR ('mydll.dll', 'getptr', NULL);

2) Use WEBUTIL_C_API.ADD_PARAMETER (plist, WEBUTIL_C_API.C_LONG,...) rather
than WEBUTIL_C_API.ADD_PARAMETER (plist, WEBUTIL_C_API.C_PTR, ...)

Also be sure to specify WEBUTIL_C_API.PARAM_IN and *not* PARAM_INOUT, as
this would cause attempted pointer dereferencing in C.

So for
void useptr (int *ip)
use
plist := WEBUTIL_C_API.CREATE_PARAMETER_LIST;
mypar := WEBUTIL_C_API.ADD_PARAMETER (plist,
WEBUTIL_C_API.C_LONG,
WEBUTIL_C_API.PARAM_IN,
myptr);
WEBUTIL_C_API.INVOKE ('mydll.dll', 'useptr', plist);
WEBUTIL_C_API.DESTROY_PARAMETER_LIST (plist);





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Symptoms

 When using WEBUTIL_C_API.INVOKE_PTR, an ORA-302000 exception is raised.

Cause

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