initprocess.hpp

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//    OpenVPN -- An application to securely tunnel IP networks
//               over a single port, with support for SSL/TLS-based
//               session authentication and key exchange,
//               packet encryption, packet authentication, and
//               packet compression.
//
//    Copyright (C) 2012- OpenVPN Inc.
//
//    SPDX-License-Identifier: MPL-2.0 OR AGPL-3.0-only WITH openvpn3-openssl-exception
//
 
// Process-wide static initialization
 
#pragma once
 
#include <thread>
#include <mutex>
 
#include <openvpn/common/size.hpp>
#include <openvpn/common/base64.hpp>
#include <openvpn/time/time.hpp>
#include <openvpn/compress/compress.hpp>
#include <openvpn/init/engineinit.hpp>
 
namespace openvpn::InitProcess {
class Init
{
  private:
    class InitImpl
    {
      public:
        InitImpl()
        {
            // initialize time base
            Time::reset_base();
 
            // initialize compression
            CompressContext::init_static();
 
            // init OpenSSL if included
            init_openssl("auto");
 
            base64_init_static();
        }
 
        ~InitImpl()
        {
            base64_uninit_static();
            uninit_openssl();
        }
    };
 
    // process-wide singular instance
    inline static std::weak_ptr<InitImpl> init_instance; // GLOBAL
    inline static std::mutex the_instance_mutex;         // GLOBAL
 
    // istance of this class to refcount
    std::shared_ptr<InitImpl> initptr;
 
  public:
    Init()
    {
        const std::lock_guard<std::mutex> lock(the_instance_mutex);
 
        initptr = init_instance.lock();
        if (!initptr)
        {
            initptr = std::make_shared<InitImpl>();
            init_instance = initptr;
        }
    }
 
    ~Init()
    {
        // explicitly reset smart pointer to make the destructor run under the lock_guard
        const std::lock_guard<std::mutex> lock(the_instance_mutex);
        initptr.reset();
    }
};
 
} // namespace openvpn::InitProcess