1//
2// detail/winsock_init.hpp
3// ~~~~~~~~~~~~~~~~~~~~~~~
4//
5// Copyright (c) 2003-2015 Christopher M. Kohlhoff (chris at kohlhoff dot com)
6//
7// Distributed under the Boost Software License, Version 1.0. (See accompanying
8// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
9//
10
11#ifndef BOOST_ASIO_DETAIL_WINSOCK_INIT_HPP
12#define BOOST_ASIO_DETAIL_WINSOCK_INIT_HPP
13
14#if defined(_MSC_VER) && (_MSC_VER >= 1200)
15# pragma once
16#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
17
18#include <boost/asio/detail/config.hpp>
19
20#if defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
21
22#include <boost/asio/detail/push_options.hpp>
23
24namespace boost {
25namespace asio {
26namespace detail {
27
28class winsock_init_base
29{
30protected:
31 // Structure to track result of initialisation and number of uses. POD is used
32 // to ensure that the values are zero-initialised prior to any code being run.
33 struct data
34 {
35 long init_count_;
36 long result_;
37 };
38
39 BOOST_ASIO_DECL static void startup(data& d,
40 unsigned char major, unsigned char minor);
41
42 BOOST_ASIO_DECL static void manual_startup(data& d);
43
44 BOOST_ASIO_DECL static void cleanup(data& d);
45
46 BOOST_ASIO_DECL static void manual_cleanup(data& d);
47
48 BOOST_ASIO_DECL static void throw_on_error(data& d);
49};
50
51template <int Major = 2, int Minor = 0>
52class winsock_init : private winsock_init_base
53{
54public:
55 winsock_init(bool allow_throw = true)
56 {
57 startup(data_, Major, Minor);
58 if (allow_throw)
59 throw_on_error(data_);
60 }
61
62 winsock_init(const winsock_init&)
63 {
64 startup(data_, Major, Minor);
65 throw_on_error(data_);
66 }
67
68 ~winsock_init()
69 {
70 cleanup(data_);
71 }
72
73 // This class may be used to indicate that user code will manage Winsock
74 // initialisation and cleanup. This may be required in the case of a DLL, for
75 // example, where it is not safe to initialise Winsock from global object
76 // constructors.
77 //
78 // To prevent asio from initialising Winsock, the object must be constructed
79 // before any Asio's own global objects. With MSVC, this may be accomplished
80 // by adding the following code to the DLL:
81 //
82 // #pragma warning(push)
83 // #pragma warning(disable:4073)
84 // #pragma init_seg(lib)
85 // boost::asio::detail::winsock_init<>::manual manual_winsock_init;
86 // #pragma warning(pop)
87 class manual
88 {
89 public:
90 manual()
91 {
92 manual_startup(data_);
93 }
94
95 manual(const manual&)
96 {
97 manual_startup(data_);
98 }
99
100 ~manual()
101 {
102 manual_cleanup(data_);
103 }
104 };
105
106private:
107 friend class manual;
108 static data data_;
109};
110
111template <int Major, int Minor>
112winsock_init_base::data winsock_init<Major, Minor>::data_;
113
114// Static variable to ensure that winsock is initialised before main, and
115// therefore before any other threads can get started.
116static const winsock_init<>& winsock_init_instance = winsock_init<>(false);
117
118} // namespace detail
119} // namespace asio
120} // namespace boost
121
122#include <boost/asio/detail/pop_options.hpp>
123
124#if defined(BOOST_ASIO_HEADER_ONLY)
125# include <boost/asio/detail/impl/winsock_init.ipp>
126#endif // defined(BOOST_ASIO_HEADER_ONLY)
127
128#endif // defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
129
130#endif // BOOST_ASIO_DETAIL_WINSOCK_INIT_HPP
131