Shared Library Manager

library.cpp

#include "library.h"
#ifdef BUILD_LINUX
#include <dlfcn.h>
#endif
#ifdef BUILD_WIN
#include <windows.h>
#endif
#include <map>

struct Handle
{
    void* value;
    int counter;
};

std::map< std::string, Handle > g_handles;

void* loadLibrary( const std::string& path )
{
    if( g_handles.count( path ) )
    {
        auto& h = g_handles[ path ];
        ++h.counter;
        return h.value;
    }
    void* handle = nullptr;
    #ifdef BUILD_LINUX
    handle = dlopen( (path + ".so").c_str(), RTLD_LAZY );
    if( !handle )
        handle = dlopen( path.c_str(), RTLD_LAZY );
    #endif
    #ifdef BUILD_WIN
    handle = LoadLibrary( (path + ".dll").c_str() );
    if( !handle )
        handle = LoadLibrary( path.c_str() );
    #endif
    if( handle )
    {
        auto& h = g_handles[ path ];
        h.counter = 1;
        h.value = handle;
    }
    return handle;
}

void* getFunction( void* handle, const std::string& name )
{
    #ifdef BUILD_LINUX
    return dlsym( handle, name.c_str() );
    #endif
    #ifdef BUILD_WIN
    return (void*)GetProcAddress( (HINSTANCE)handle, name.c_str() );
    #endif
}

int closeLibrary( void* handle )
{
    for( auto& kv : g_handles )
    {
        if( kv.second.value == handle )
        {
            if( --kv.second.counter > 0 )
                return 0;
            else
            {
                g_handles.erase( kv.first );
                #ifdef BUILD_LINUX
                return dlclose( handle );
                #endif
                #ifdef BUILD_WIN
                return FreeLibrary( (HINSTANCE)handle );
                #endif
            }
        }
    }
    return -1;
}

library.h

#ifndef __LIBRARY_H__
#define __LIBRARY_H__

#include <string>

void* loadLibrary( const std::string& path );
void* getFunction( void* handle, const std::string& name );
int closeLibrary( void* handle );

#endif