Initial Commit

include/asio/detail/winsock_init.hpp

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+//
+// detail/winsock_init.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2025 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 = 2>
+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