text: //
  // impl/error_code.ipp
  // ~~~~~~~~~~~~~~~~~~~
  //
  // Copyright (c) 2003-2015 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_IMPL_ERROR_CODE_IPP
  #define ASIO_IMPL_ERROR_CODE_IPP
  
  #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 <winerror.h>
  #elif defined(ASIO_WINDOWS_RUNTIME)
  # include <windows.h>
  #else
  # include <cerrno>
  # include <cstring>
  # include <string>
  #endif
  #include "asio/detail/local_free_on_block_exit.hpp"
  #include "asio/detail/socket_types.hpp"
  #include "asio/error_code.hpp"
  
  #include "asio/detail/push_options.hpp"
  
  namespace asio {
  namespace detail {
  
  class system_category : public error_category
  {
  public:
    const char* name() const ASIO_ERROR_CATEGORY_NOEXCEPT
    {
      return "asio.system";
    }
  
    std::string message(int value) const
    {
  #if defined(ASIO_WINDOWS) || defined(__CYGWIN__)
      char* msg = 0;
      DWORD length = ::FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER
          | FORMAT_MESSAGE_FROM_SYSTEM
          | FORMAT_MESSAGE_IGNORE_INSERTS, 0, value,
          MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (char*)&msg, 0, 0);
      detail::local_free_on_block_exit local_free_obj(msg);
      if (length && msg[length - 1] == '\n')
        msg[--length] = '\0';
      if (length && msg[length - 1] == '\r')
        msg[--length] = '\0';
      if (length)
        return msg;
      else
        return "asio.system error";
  #elif defined(ASIO_WINDOWS_RUNTIME)
      std::wstring wmsg(128, wchar_t());
      for (;;)
      {
        DWORD wlength = ::FormatMessageW(FORMAT_MESSAGE_FROM_SYSTEM
            | FORMAT_MESSAGE_IGNORE_INSERTS, 0, value,
            MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), &wmsg[0], wmsg.size(), 0);
        if (wlength == 0 && ::GetLastError() == ERROR_INSUFFICIENT_BUFFER)
        {
          wmsg.resize(wmsg.size() + wmsg.size() / 2);
          continue;
        }
        if (wlength && wmsg[wlength - 1] == '\n')
          --wlength;
        if (wlength && wmsg[wlength - 1] == '\r')
          --wlength;
        if (wlength)
        {
          std::string msg(wlength * 2, char());
          int length = ::WideCharToMultiByte(CP_ACP, 0,
              wmsg.c_str(), static_cast<int>(wlength),
              &msg[0], static_cast<int>(wlength * 2), 0, 0);
          if (length <= 0)
            return "asio.system error";
          msg.resize(static_cast<std::size_t>(length));
          return msg;
        }
        else
          return "asio.system error";
      }
  #else // defined(ASIO_WINDOWS)
  #if !defined(__sun)
      if (value == ECANCELED)
        return "Operation aborted.";
  #endif // !defined(__sun)
  #if defined(__sun) || defined(__QNX__) || defined(__SYMBIAN32__)
      using namespace std;
      return strerror(value);
  #elif defined(__MACH__) && defined(__APPLE__) \
    || defined(__NetBSD__) || defined(__FreeBSD__) || defined(__OpenBSD__) \
    || defined(_AIX) || defined(__hpux) || defined(__osf__) \
    || defined(__ANDROID__)
      char buf[256] = "";
      using namespace std;
      strerror_r(value, buf, sizeof(buf));
      return buf;
  #else
      char buf[256] = "";
      strerror_r(value, buf, sizeof(buf));
  	return buf;
  #endif
  #endif // defined(ASIO_WINDOWS)
    }
  
  #if defined(ASIO_HAS_STD_ERROR_CODE)
    std::error_condition default_error_condition(
        int ev) const ASIO_ERROR_CATEGORY_NOEXCEPT
    {
      switch (ev)
      {
      case access_denied:
        return std::errc::permission_denied;
      case address_family_not_supported:
        return std::errc::address_family_not_supported;
      case address_in_use:
        return std::errc::address_in_use;
      case already_connected:
        return std::errc::already_connected;
      case already_started:
        return std::errc::connection_already_in_progress;
      case broken_pipe:
        return std::errc::broken_pipe;
      case connection_aborted:
        return std::errc::connection_aborted;
      case connection_refused:
        return std::errc::connection_refused;
      case connection_reset:
        return std::errc::connection_reset;
      case bad_descriptor:
        return std::errc::bad_file_descriptor;
      case fault:
        return std::errc::bad_address;
      case host_unreachable:
        return std::errc::host_unreachable;
      case in_progress:
        return std::errc::operation_in_progress;
      case interrupted:
        return std::errc::interrupted;
      case invalid_argument:
        return std::errc::invalid_argument;
      case message_size:
        return std::errc::message_size;
      case name_too_long:
        return std::errc::filename_too_long;
      case network_down:
        return std::errc::network_down;
      case network_reset:
        return std::errc::network_reset;
      case network_unreachable:
        return std::errc::network_unreachable;
      case no_descriptors:
        return std::errc::too_many_files_open;
      case no_buffer_space:
        return std::errc::no_buffer_space;
      case no_memory:
        return std::errc::not_enough_memory;
      case no_permission:
        return std::errc::operation_not_permitted;
      case no_protocol_option:
        return std::errc::no_protocol_option;
      case no_such_device:
        return std::errc::no_such_device;
      case not_connected:
        return std::errc::not_connected;
      case not_socket:
        return std::errc::not_a_socket;
      case operation_aborted:
        return std::errc::operation_canceled;
      case operation_not_supported:
        return std::errc::operation_not_supported;
      case shut_down:
        return std::make_error_condition(ev, *this);
      case timed_out:
        return std::errc::timed_out;
      case try_again:
        return std::errc::resource_unavailable_try_again;
      case would_block:
        return std::errc::operation_would_block;
      default:
        return std::make_error_condition(ev, *this);
    }
  #endif // defined(ASIO_HAS_STD_ERROR_CODE)
  };
  
  } // namespace detail
  
  const error_category& system_category()
  {
    static detail::system_category instance;
    return instance;
  }
  
  } // namespace asio
  
  #include "asio/detail/pop_options.hpp"
  
  #endif // ASIO_IMPL_ERROR_CODE_IPP
  