What's the correct way to use FunctionCallInvoke()?

Hi,

I have a problem calling a C function
from another C function - DirectFunctionCall*
cannot be used since some parameters may be NULL.
This dies:

FunctionCallInfoData fcinfo1;

InitFunctionCallInfoData(fcinfo1, NULL, 7, NULL, NULL);
/* arg[] and arnull[] are filled with correct values */
result = myfunc(&fcinfo1);

Also this also:

FunctionCallInfoData fcinfo1;
FmgrInfo flinfo1;

MemSet(&flinfo1, 0, sizeof(flinfo1));
flinfo1.fn_addr = myfunc;
flinfo1.fn_nargs = 7;
InitFunctionCallInfoData(fcinfo1, &flinfo1, 7, NULL, NULL);
/* arg[] and arnull[] are filled with correct values */
result = FunctionCallInvoke(&fcinfo1);

How to do it correctly? I am on PostgreSQL 8.1.9 currently.

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Zoltán Böszörményi
Cybertec Geschwinde & Schönig GmbH
http://www.postgresql.at/