dll.cc

#include <iostream>
#include "./dll.hh"

using namespace std;

//Implementation for WINNT
#if     defined(_WIN32)
#include <Windows.h>

//Copy std::string to wstring
static void string_to_wstring(const string &source, wstring &destination)
{
    destination.clear();
    for(size_t i = 0; i < source.size(); i++) {
        destination += source[i];
    }
}

//Constructor
dll::dll(const string &filename) : m_Handle(nullptr)
{
    wstring w_filename;
    string_to_wstring(filename, w_filename);

    m_Handle = (void *)LoadLibrary(w_filename.c_str());
    if(m_Handle == nullptr) {
        int error = GetLastError();
        fprintf(stderr, "Couldn't load DLL through WINAPI.\nError code: %d\n", error);
    }
}

//Destructor
dll::~dll()
{
    if(m_Handle != nullptr) {
        FreeLibrary((HMODULE)m_Handle);
    }
}

//Get symbol
void * dll::get_sym(const string &sym)
{
    if(m_Handle) {
        void * data = GetProcAddress((HMODULE)m_Handle, sym.c_str());
        return data;
    }

    return nullptr;
}

//Implementation for POSIX
#elif   defined(__unix__)
#include <dlfcn.h>

//Constructor
dll::dll(const string &filename) : m_Handle(nullptr)
{
    m_Handle = dlopen(filename.c_str(), RTLD_LAZY);
    if(m_Handle == nullptr) {
        fprintf(stderr, "Couldn't load SO through POSIX API.\n%s\n", dlerror());
    }
}

//Destructor
dll::~dll()
{
    if(m_Handle != nullptr) {
        dlclose(m_Handle);
    }
}

//Get symbol
void * dll::get_sym(const string &sym)
{
    if(m_Handle) {
        void * data = dlsym(m_Handle, sym.c_str());
        return data;
    }

    return nullptr;
}

#endif

dll.hh

#ifndef _DLL_HH
#define _DLL_HH

#include <string>

//A DLL
class dll {
private:
    void *m_Handle;

public:
    dll(const std::string &filename);
    ~dll();
    void * get_sym(const std::string &sym);
};

#endif