CREATE FUNCTION and LANGUAGE 'C'

Hello,

I'm trying to call a C function (C++ in fact but I think, it's not a problem) from a
stored procedure (using CREATE FUNCTION).

-------------------------------------------------------
This is the creation of my stored procedure:

CREATE FUNCTION Get_Length(TEXT)
RETURNS INTEGER
AS
'/home/ncxusers/criviere/TOOLS/lib/tools.so', 'Get_Length'
LANGUAGE 'C';

This is the C implementation of GetLength :

#include <stdio.h>
#include "postgres.h"
#include "fmgr.h"

PG_FUNCTION_INFO_V1(file_open);

extern "C" Datum file_open (PG_FUNCTION_ARGS)
{
char *szName = PG_GETARG_CSTRING(0);
long lgLength = strlen(szName);
PG_RETURN_UINT32(lgLength);
}

This is the result of the execution :

TestVersioning=# select file_open('abcdefgh') as v_result;
v_result
----------
2
(1 row)

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Why does it return 2 and not 8 (length of 'abcdef') ?

Thanks for your help.

Céline

PS:
I think I have a problem with string manipulation.
Because I also have a 2nd issue when trying to return a variable of type TEXT (or VARCHAR).
The following error occurs :

pqReadData() -- backend closed the channel unexpectedly.
This probably means the backend terminated abnormally
before or while processing the request.
The connection to the server was lost. Attempting reset: Failed.