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//
// detail/winsock_init.hpp
// ~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2018 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 ASIO_DETAIL_WINSOCK_INIT_HPP
#define ASIO_DETAIL_WINSOCK_INIT_HPP
#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
#include "asio/detail/config.hpp"
#if defined(ASIO_WINDOWS) || defined(__CYGWIN__)
#include "asio/detail/push_options.hpp"
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_;
};
ASIO_DECL static void startup(data& d,
unsigned char major, unsigned char minor);
ASIO_DECL static void manual_startup(data& d);
ASIO_DECL static void cleanup(data& d);
ASIO_DECL static void manual_cleanup(data& d);
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)
// 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
#include "asio/detail/pop_options.hpp"
#if defined(ASIO_HEADER_ONLY)
# include "asio/detail/impl/winsock_init.ipp"
#endif // defined(ASIO_HEADER_ONLY)
#endif // defined(ASIO_WINDOWS) || defined(__CYGWIN__)
#endif // ASIO_DETAIL_WINSOCK_INIT_HPP
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