FmuToolsRuntimeLinking.h

// =============================================================================
// fmu-forge
//
// Copyright (c) 2024 Project Chrono (projectchrono.org)
// Copyright (c) 2024 Digital Dynamics Lab, University of Parma, Italy
// Copyright (c) 2024 Simulation Based Engineering Lab, University of Wisconsin-Madison, USA
// All rights reserved.
//
// Use of this source code is governed by a BSD-style license that can be found
// in the LICENSE file at the top level of the distribution.
//
// =============================================================================
// Utilities for run-time linking of shared libraries
// =============================================================================

#ifndef FMUTOOLS_RUNTIMELINKING_H
#define FMUTOOLS_RUNTIMELINKING_H

#include <string>
#include <stdexcept>
#include <iostream>
#include "filesystem.hpp"

#if defined(_MSC_VER) || defined(_WIN32) || defined(__MINGW32__)
    #define WIN32_LEAN_AND_MEAN
    #include <windows.h>
    #include <Errhandlingapi.h>
    #define DYNLIB_HANDLE HINSTANCE
    #define get_function_ptr GetProcAddress
    #include <system_error>
    #include <memory>
    #include <string>
#else
    #include <dlfcn.h>
    #include <limits.h>
    #define DYNLIB_HANDLE void*
    #define get_function_ptr dlsym
#endif

#include <iostream>

namespace fmu_forge {

/// @addtogroup fmu_forge
/// @{

/// Runtime/Dynamic linking of shared library.
/// @param dynlib_dir The directory where the shared library is located.
/// @param dynlib_name The name of the shared library.
DYNLIB_HANDLE RuntimeLinkLibrary(const std::string& dynlib_dir, const std::string& dynlib_name) {
#ifdef _WIN32
    if (!SetDllDirectory(dynlib_dir.c_str())) {
        std::cerr << "ERROR: Could not locate the DLL directory." << std::endl;
        throw std::runtime_error("Could not locate the DLL directory.");
    }

    DYNLIB_HANDLE dynlib_handle = LoadLibrary(dynlib_name.c_str());

    if (!dynlib_handle) {
        DWORD error = ::GetLastError();
        std::string message = std::system_category().message(error);

        std::cerr << "ERROR: DLL directory is found, but cannot load the library: " << dynlib_name << std::endl;
        std::cerr << "GetLastError returned: " << message << std::endl;

        throw std::runtime_error("Could not load the library.");
    }

    return dynlib_handle;
#else
    void* dlib = dlopen(dynlib_name.c_str(), RTLD_LAZY);
    if (dlib == NULL) {
        std::cerr << "ERROR: cannot load the shared object library: " << dynlib_name << std::endl;
        std::string message = dlerror();
        std::cerr << "dlerror returned: " << message << std::endl;
        throw std::runtime_error("Could not load the library.");
    }
    return dlib;
#endif
}

/// Get the location of the shared library.
std::string GetLibraryLocation() {
    fs::path library_path;
#ifdef _WIN32
    HMODULE hModule = nullptr;
    if (GetModuleHandleEx(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS | GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,
                          (LPCSTR)&GetLibraryLocation, &hModule)) {
        char library_pathc[MAX_PATH];
        DWORD result = GetModuleFileNameA(hModule, library_pathc, MAX_PATH);
        if (result != 0) {
            // std::cout << "The path of the FMU shared library is: " << library_pathc << std::endl;
            library_path = std::string(library_pathc);
        } else {
            std::cerr << "Error getting the FMU shared library name. Error code: " << GetLastError() << std::endl;
        }
    } else {
        std::cerr << "Error getting the FMU shared library handle. Error code: " << GetLastError() << std::endl;
    }
#else
    void* sym_ptr = nullptr;

    // Check first if FMI2 then if FMI3
    sym_ptr = dlsym(RTLD_DEFAULT, "fmi2DoStep");
    if (sym_ptr == nullptr) {
        sym_ptr = dlsym(RTLD_DEFAULT, "fmi3DoStep");
    }
    if (sym_ptr == nullptr) {
        std::cerr << "Error: FmuToolsRuntimeLinking: cannot find either fmi2DoStep nor fmi3DoStep" << std::endl;
    }

    Dl_info dl_info;
    if (dladdr(sym_ptr, &dl_info)) {
        char library_pathc[PATH_MAX];
        library_path = realpath(dl_info.dli_fname, library_pathc);
        // std::cout << "The path of the FMU shared library is: " << library_pathc << std::endl;
        library_path = std::string(library_pathc);
    } else {
        std::cerr << "Error getting the FMU shared library information." << std::endl;
    }
#endif

    fs::path library_folder = library_path.parent_path();
    return library_folder.string();
}

/// @} fmu_forge

}  // namespace fmu_forge

#endif