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/*************
bridg.dll
************/
//sharedobject.h

#ifndef SHAREDOBJECT
#define SHAREDOBJECT

class ISharedObject {
public:
 virtual void set(int data) = 0;
 virtual int get() const = 0;
 virtual ~ISharedObject() {}
};

class SharedObject : public ISharedObject {

public:
 SharedObject() : data(-1) {}

 void set(int data) { this->data = data; }
 int get() const { return data; }

private:
 int data;
};

#endif //SHAREDOBJECT

//main

#include <QSharedMemory>
#include "sharedobject.h"
#include "SLogger.h"

static QSharedMemory* sharedMemory = NULL;

const char* slogger::fileName = "bridg.log";

extern "C" __declspec(dllexport) bool createSharedMemory(const char* key)
{
 DEBUG() << "Key is: " << key;
 sharedMemory = new QSharedMemory(key);

 if ( !sharedMemory->create(sizeof(SharedObject)) ) return false;

 SharedObject *obj = new SharedObject();
 SharedObject *sharedObj = (SharedObject*) sharedMemory->data();
 DEBUG() << "Shared instance pointer: " << std::hex << obj;
 DEBUG() << "Data pointer: " << std::hex << sharedObj;

 memcpy(sharedObj, obj, sizeof(SharedObject));

 return true; //все нормально!
}

extern "C" __declspec(dllexport) bool destroySharedMemory()
{
 if ( sharedMemory->detach() )
 {
  delete sharedMemory;
  return true;
 }

 return false;
}

extern "C" __declspec(dllexport) ISharedObject* getSharedObject(const char* key)
{
 DEBUG() << "Key is: " << key; //key is valid

 QSharedMemory sm(key); 

 if ( !sm.attach() ) return NULL; //attach is ok

 ISharedObject *obj = (ISharedObject*)sm.data(); //<--- локальная sharedmemory возвращает невалидный(другой!!, но не NULL) поинтер
 //ISharedObject *obj = (ISharedObject*)sharedMemory->data(); //<--- с глобальным все ок!
 DEBUG() << "Shared instance " << std::hex << obj;

 return obj;
}

/*************
wincons.exe //my test
*************/
#include <windows.h>
#include <iostream>

class ISharedObject {
public:
 virtual void set(int data) = 0;
 virtual int get() const = 0;
 virtual ~ISharedObject() {}
};

typedef bool (*FCreate)(const char*);
typedef bool (*FDestroy)();
typedef ISharedObject* (*FGet)(const char*);

static const char* key = "test";

int main()
{
 HINSTANCE dll =  LoadLibrary(L"bridg.dll");

 if ( dll )
 {
  FCreate  _create  = (FCreate)GetProcAddress(dll, "createSharedMemory");
  FDestroy _destroy = (FDestroy)GetProcAddress(dll, "destroySharedMemory");
  FGet     _get     = (FGet) GetProcAddress(dll, "getSharedObject");

  if ( _create )
  {
   bool ret =  _create(key);

   if ( ret )
   {
    ISharedObject* obj = _get(key);

    if ( obj ) // <---не валиден (!!но не NULL)
    {
     //obj->set(42);
     //std::cout << "Data: " << obj->get() << std::endl;
    } else std::cout << "Can not get shared instance." << std::endl;
   }
   else std::cout << "Can not get create shared memory. Error: " << GetLastError() << std::endl;
  }
  else std::cout << "Can not get create function pointer. Error: " << GetLastError() << std::endl;

  FreeLibrary(dll);
 }
 else std::cout << "Can not load library. Error: " << GetLastError() << std::endl;

 std::getchar();
 return 0;
}

class Manager {
    typedef void (*FFoo)();

public:
   FFoo foo;

   bool initialize()
   {
        dll_instance = LoadLibrary("some.dll");
         
        if ( !dll_instance ) return false;
        foo = (FFoo)GetProccessAdress(dll_instance, "foo");
        
        if ( !foo ) return false;

        return true;
   }

  ~Manager()
   {
      FreeLibrary(dll_instance);
   }

private:
    HMODULE dll_instance;
};