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- //
- // detail/winsock_init.hpp
- // ~~~~~~~~~~~~~~~~~~~~~~~
- //
- // Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
- //
- // Distributed under the Boost Software License, Version 1.0. (See accompanying
- // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- //
- #ifndef BOOST_ASIO_DETAIL_WINSOCK_INIT_HPP
- #define BOOST_ASIO_DETAIL_WINSOCK_INIT_HPP
- #if defined(_MSC_VER) && (_MSC_VER >= 1200)
- # pragma once
- #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
- #include <boost/asio/detail/config.hpp>
- #if defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
- #include <boost/asio/detail/push_options.hpp>
- namespace boost {
- namespace asio {
- namespace detail {
- class winsock_init_base
- {
- protected:
- // Structure to track result of initialisation and number of uses. POD is used
- // to ensure that the values are zero-initialised prior to any code being run.
- struct data
- {
- long init_count_;
- long result_;
- };
- BOOST_ASIO_DECL static void startup(data& d,
- unsigned char major, unsigned char minor);
- BOOST_ASIO_DECL static void manual_startup(data& d);
- BOOST_ASIO_DECL static void cleanup(data& d);
- BOOST_ASIO_DECL static void manual_cleanup(data& d);
- BOOST_ASIO_DECL static void throw_on_error(data& d);
- };
- template <int Major = 2, int Minor = 0>
- class winsock_init : private winsock_init_base
- {
- public:
- winsock_init(bool allow_throw = true)
- {
- startup(data_, Major, Minor);
- if (allow_throw)
- throw_on_error(data_);
- }
- winsock_init(const winsock_init&)
- {
- startup(data_, Major, Minor);
- throw_on_error(data_);
- }
- ~winsock_init()
- {
- cleanup(data_);
- }
- // This class may be used to indicate that user code will manage Winsock
- // initialisation and cleanup. This may be required in the case of a DLL, for
- // example, where it is not safe to initialise Winsock from global object
- // constructors.
- //
- // To prevent asio from initialising Winsock, the object must be constructed
- // before any Asio's own global objects. With MSVC, this may be accomplished
- // by adding the following code to the DLL:
- //
- // #pragma warning(push)
- // #pragma warning(disable:4073)
- // #pragma init_seg(lib)
- // boost::asio::detail::winsock_init<>::manual manual_winsock_init;
- // #pragma warning(pop)
- class manual
- {
- public:
- manual()
- {
- manual_startup(data_);
- }
- manual(const manual&)
- {
- manual_startup(data_);
- }
- ~manual()
- {
- manual_cleanup(data_);
- }
- };
- private:
- friend class manual;
- static data data_;
- };
- template <int Major, int Minor>
- winsock_init_base::data winsock_init<Major, Minor>::data_;
- // Static variable to ensure that winsock is initialised before main, and
- // therefore before any other threads can get started.
- static const winsock_init<>& winsock_init_instance = winsock_init<>(false);
- } // namespace detail
- } // namespace asio
- } // namespace boost
- #include <boost/asio/detail/pop_options.hpp>
- #if defined(BOOST_ASIO_HEADER_ONLY)
- # include <boost/asio/detail/impl/winsock_init.ipp>
- #endif // defined(BOOST_ASIO_HEADER_ONLY)
- #endif // defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
- #endif // BOOST_ASIO_DETAIL_WINSOCK_INIT_HPP
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