cleanup.hpp

Go to the documentation of this file.

//    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
//
 
#ifndef OPENVPN_COMMON_CLEANUP_H
#define OPENVPN_COMMON_CLEANUP_H
 
#include <utility>
#include <optional>
#include <concepts>
#include <functional>
#include <type_traits>
 
namespace openvpn {
 
template <typename F>
    requires std::invocable<F>
class CleanupType
{
  public:
    explicit CleanupType(F method) noexcept(std::is_nothrow_move_constructible_v<F>)
        : clean(std::move(method))
    {
    }
    CleanupType(const CleanupType &) = delete;
    CleanupType &operator=(const CleanupType &) = delete;
    CleanupType(CleanupType &&other) noexcept
        : clean(std::exchange(other.clean, std::nullopt))
    {
    }
    CleanupType &operator=(CleanupType &&other) noexcept
    {
        if (this != &other)
        {
            clean = std::exchange(other.clean, std::nullopt);
        }
        return *this;
    }
 
    ~CleanupType() noexcept
    {
        if (clean)
        {
            try
            {
                std::invoke(*clean);
            }
            catch (...)
            {
                // swallow exceptions to avoid throwing from destructor
            }
        }
    }
 
  public:
    void dismiss() noexcept
    {
        clean.reset();
    }
    std::optional<std::function<void()>> release() noexcept
    {
        if (clean)
        {
            std::function<void()> func = std::move(*clean);
            clean.reset();
            return func;
        }
        return std::nullopt;
    }
 
  private:
    std::optional<F> clean;
};
 
template <typename F>
    requires std::invocable<F>
inline CleanupType<F> Cleanup(F method) noexcept(std::is_nothrow_move_constructible_v<F>)
{
    return CleanupType<F>(std::move(method));
}
 
} // namespace openvpn
 
#endif