Обсуждение: C-function, don't load external dll file

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C-function, don't load external dll file

От

Przemek Lisowski

Дата:

20 ноября 2012 г., 15:54:07

I write my dll files in visual studio 2010.

The dll file (name fservice.dll), which has an external function, code write in c++ (VS2010, I have dll and lib files)

char * convert(char *)

I tested my fservice.dll in console application which called function in this dll. It was work fine. I have a problem when a write and tests in Postgrsql.

Dll file witch has c-function, who exports and imports to postgresql:

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

typedef char* (__cdecl *MYPROC)(char * value); 

__declspec( dllexport ) PG_FUNCTION_INFO_V1(transform); 

__declspec( dllexport ) Datum transform (PG_FUNCTION_ARGS) 
{ 
HINSTANCE hinstLib= LoadLibrary("fservice.dll"); 

char * pointer; text *t = PG_GETARG_TEXT_P(0);

if (hinstLib != NULL)
{ 
 ProcAdd = (MYPROC) GetProcAddress(hinstLib, "convert"); 
 pointer=ProcAdd("text"); FreeLibrary(hinstLib); 
}
else
 PG_RETRUN_NULL();


 /* * code */ 


PG_RETURN_TEXT_P(new_t); 
}

I have a problem because, mod is doesn't exists. Path to dll file I check before write. Compile this c-function, and when i debug i saw it HINSTANCE hinstLib it wasn't created. It wasn't NULL or any value, It wasn't exist. Finally my c-function doesn't use my function form external dll.

How load dll and use my external function ?

My external function form dll and LoadLibrary() is not called by dll program with called by Postgresql, Why?

Przemek

1 down vote favorite

I write my dll files in visual studio 2010.

The dll file (name fservice.dll), which has an external function, code write in c++ (VS2010, I have dll and lib files)

char * convert(char *)

Dll file witch has c-function, who exports and imports to postgresql:

typedef char* (__cdecl *MYPROC)(char * value); PG_FUNCTION_INFO_V1(transform); Datum transform (PG_FUNCTION_ARGS) { HINSTANCE hinstLib= LoadLibrary("fservice.dll"); char * pointer; text *t = PG_GETARG_TEXT_P(0); if (hinstLib != NULL) { ProcAdd = (MYPROC) GetProcAddress(hinstLib, "convert"); pointer=ProcAdd("text"); FreeLibrary(hinstLib); } /* * code */ PG_RETURN_TEXT_P(new_t); }

How load dll and use my external function ?

My external function form dll and LoadLibrary() is not called by dll program with called by Postgresql, Why?

Re: C-function, don't load external dll file

От

Dimitri Fontaine

Дата:

21 ноября 2012 г., 14:58:35

Hi,

Przemek Lisowski <przemek@lisnet.info> writes:
> HOW LOAD DLL AND USE MY EXTERNAL
> FUNCTION ? 

You need to declare it in SQL, maybe like this:
 create function public.transform(text) returns text as '$libdir/fservice', 'transform' language C;

See also the LOAD command and the CREATE EXTENSION documentation for how
to organise testing and shipping of your code.

Regards,
-- 
Dimitri Fontaine
http://2ndQuadrant.fr     PostgreSQL : Expertise, Formation et Support

Re: C-function, don't load external dll file

От

pl65

Дата:

22 ноября 2012 г., 12:17:43

Dimitri Fontaine-7 wrote
You need to declare it in SQL, maybe like this: create function public.transform(text) returns text as '$libdir/fservice', 'transform' language C;

I'm afraid that I won't do it becouse fservice.dll is writen in c++, but dll file which contains function transform (this function export to Postgresql) was wrote in ANSI C. Secondly, LOAD function in posttgresql libraries that are use of my all dependent dll? I think i should use: LOAD 'fservice.dll' But I don't know which dll load to use function or makros which called from windows.h (HINSTANCE, LoadLibray(), GetProcAddress())?

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Обсуждение: C-function, don't load external dll file

C-function, don't load external dll file

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Re: C-function, don't load external dll file