my strftime func doesn't work. please help.

hello!

I tried to make a function, like strftime in C
called pstrtime( format, date )

here's the source... but when I compile it and create the function
under 6.3.2 first time it gives back an emty string.. after the backend
stops ;(

please correct my faults,
----------------------------------------------------------------------
#include <stdio.h>                              /* for sprintf() */
#include <string.h>
#include <limits.h>
#include "postgres.h"
#include "miscadmin.h"
#include "utils/builtins.h"
#include "utils/nabstime.h"
#include "utils/datetime.h"
#include "access/xact.h"

#define JDATE_2000      2451545

char       *pstrtime(char *format, DateADT val);


char *
pstrtime( char *format , DateADT val)
{
        int                     year,
                                month,
                                day;
        struct tm * time1;
        char *sometext;
        sometext = malloc(100);
        time1 = malloc(sizeof(struct tm));

        j2date(val + JDATE_2000, &year, &month, &day);

        time1->tm_year=year;
        time1->tm_mon=month-1;
        time1->tm_mday=day;

        strftime(sometext,90,format,time1 );
        free(time1);
        return( sometext );
}


anyway how to create this function under psql ?
C type               postgres type
-----------------------------------
DateADT            date
char *             ???????????

thanks,

    Best regards,
        Redax
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