Generate import library for exported function of the main executable file

There is a statement in your project home page:

Windows DLL cannot refer to symbols defined in the main application or in previously loaded DLLs.

Some usual solutions exist, but they are not very flexible. A notable exception is the edll library (its homepage also describes the usual solutions), which follows a rather drastic approach; indeed, edll implements a new dynamic linker which can directly load object files (without creating a Windows DLL).

While, it looks like I can do this with the tool gendef and dlltool.

The method I was using is like:

For example, the exe_export.exe has some code like:

#include <Windows.h>
#include <stdio.h>

#define MYDLL_EXPORTS

#include "interface_exe.h"

void appli_printf7777(void)
{
   printf("7777");
   return;
}

void appli_printf8888(void)
{
   printf("8888");
   return;
}


int main(void)
{
   HMODULE hModule = LoadLibrary("dll.dll");
   FARPROC pFunc = GetProcAddress(hModule, "dllFunction");

   ((DLL_FUNC)pFunc)();

   return 0;
}

The content of the interface_exe.h is like below:

#ifndef INTERFACE_EXE_H_INCLUDED
#define INTERFACE_EXE_H_INCLUDED


 #ifdef  MYDLL_EXPORTS
    /*Enabled as "export" while compiling the dll project*/
    #define DLLEXPORT __declspec(dllexport)
 #else
    /*Enabled as "import" in the Client side for using already created dll file*/
    #define DLLEXPORT __declspec(dllimport)
 #endif

#ifdef __cplusplus
extern "C"
{
#endif

typedef void(*DLL_FUNC)(void);

DLLEXPORT void appli_printf7777(void);

DLLEXPORT void appli_printf8888(void);


#ifdef __cplusplus
}
#endif

#endif // INTERFACE_EXE_H_INCLUDED

And I have another dll.cpp file which is used to generate the dll.

#include <Windows.h>
#include <stdio.h>

#include "interface_exe.h"


#ifdef __cplusplus
extern "C"
{
#endif

__declspec (dllexport) void dllFunction(void);

#ifdef __cplusplus
}
#endif




typedef void(*APPLI_PRINTF7)(void);

__declspec(dllexport) void dllFunction(void)
{
   //HMODULE hModule = LoadLibrary("exe_export.exe");
   FARPROC pFunc = GetProcAddress(0, "appli_printf7777");

   if(pFunc)
      ((APPLI_PRINTF7)pFunc)();
   else
      printf("error = %d\n", GetLastError());

   appli_printf7777();
   appli_printf8888();

   return;
}

I first build the exe_export.exe file, and later I use the commands below to generate the import .a file:

gendef exe_export.exe
dlltool --dllname exe_export.exe --def exe_export.def --output-lib libexe_export.a

Then later, I link the libexe_export.a file to generate the dll.

Now, when I run the exe file, I have two methods to call the methods in the dll.

One is using the GetProcAddress method.

   //HMODULE hModule = LoadLibrary("exe_export.exe");
   FARPROC pFunc = GetProcAddress(0, "appli_printf7777");

   if(pFunc)
      ((APPLI_PRINTF7)pFunc)();
   else
      printf("error = %d\n", GetLastError());

The other is using the imported method, which I can directly call

   appli_printf7777();
   appli_printf8888();

All works fine.

Here are some reference:
1, the method I use is described as the .def and .a method, see this discussion:
Enhanced DLL / Discussion / Help and FAQ: The .def and .a method mentioned in the home page

2, https://www.codeproject.com/Articles/17697/Plugin-System-an-alternative-to-GetProcAddress-and
The method mentioned in this link is using MSVC, and I think it is similar with the gendef and dlltool method.

3, my demo code was changed from the sample code in this discussion:
Exporting symbols in a .exe for external DLLs

Hope the above method can help others.

No files, tests, or entry points are named in the report. Start by locating flexdll's Windows dynamic-linking and build entry points, then compare current behavior with the gendef/dlltool workflow described here. Done should be a clearly defined, supported way to generate and use an import library for exported executable functions, with coverage or documentation showing the result.