如何与火鸟UDF中的char阵列一起工作

Question

ib_util.h

#ifndef _IB_UTIL_H
#define _IB_UTIL_H

#ifdef __cplusplus
extern "C"
{
#endif

    extern void *ib_util_malloc(long);

#ifdef __cplusplus
} /* extern "C" */
#endif

#endif /* _IB_UTIL_H */

test_udf.c

#include "ib_util.h"
#define MALLOC ib_util_malloc

typedef struct blob
{
    short (*blob_get_segment)();
    void *blob_handle;
    int blob_number_segments;
    int blob_max_segment;
    int blob_total_length;
    void (*blob_put_segment)();
} * BLOB;

char* fn_blob_echo(BLOB b)
{
    char *buffer = (char *)ib_util_malloc(256);
    return buffer;
}

编译为.so

FIREBIRD_UDF='/usr/lib/x86_64-linux-gnu/firebird/3.0/UDF/';
NameFile='test_udf';
gcc -c -O -fpic -Wwrite-strings $NameFile'.c'; ld -G $NameFile'.o' -lm -lc -o $NameFile'.so';  sudo cp $NameFile'.so' $FIREBIRD_UDF

在Firebird中

DECLARE EXTERNAL FUNCTION fn_blob_echo
BLOB
RETURNS CSTRING (256) FREE_IT 
ENTRY_POINT 'fn_blob_echo' MODULE_NAME 'test_udf';

使用

select fn_blob_echo(CAST('please run' AS blob)) from rdb$database;

错误

SQL Error [335544721] [08006]: Unable to complete network request to host "localhost". [SQLState:08006, ISC error code:335544721]

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