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Filename : win32_code.hpp
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/* Proposed SG14 status_code
(C) 2018-2020 Niall Douglas <http://www.nedproductions.biz/> (5 commits)
File Created: Feb 2018


Boost Software License - Version 1.0 - August 17th, 2003

Permission is hereby granted, free of charge, to any person or organization
obtaining a copy of the software and accompanying documentation covered by
this license (the "Software") to use, reproduce, display, distribute,
execute, and transmit the Software, and to prepare derivative works of the
Software, and to permit third-parties to whom the Software is furnished to
do so, all subject to the following:

The copyright notices in the Software and this entire statement, including
the above license grant, this restriction and the following disclaimer,
must be included in all copies of the Software, in whole or in part, and
all derivative works of the Software, unless such copies or derivative
works are solely in the form of machine-executable object code generated by
a source language processor.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.
*/

#ifndef BOOST_OUTCOME_SYSTEM_ERROR2_WIN32_CODE_HPP
#define BOOST_OUTCOME_SYSTEM_ERROR2_WIN32_CODE_HPP

#if !defined(_WIN32) && !defined(BOOST_OUTCOME_STANDARDESE_IS_IN_THE_HOUSE)
#error This file should only be included on Windows
#endif

#include "quick_status_code_from_enum.hpp"

BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_BEGIN

//! \exclude
namespace win32
{
  // A Win32 DWORD
  using DWORD = unsigned long;
  // Used to retrieve the current Win32 error code
  extern DWORD __stdcall GetLastError();
  // Used to retrieve a locale-specific message string for some error code
  extern DWORD __stdcall FormatMessageW(DWORD dwFlags, const void *lpSource, DWORD dwMessageId, DWORD dwLanguageId, wchar_t *lpBuffer, DWORD nSize, void /*va_list*/ *Arguments);
  // Converts UTF-16 message string to UTF-8
  extern int __stdcall WideCharToMultiByte(unsigned int CodePage, DWORD dwFlags, const wchar_t *lpWideCharStr, int cchWideChar, char *lpMultiByteStr, int cbMultiByte, const char *lpDefaultChar, int *lpUsedDefaultChar);
#pragma comment(lib, "kernel32.lib")
#if defined(_WIN64)
#pragma comment(linker, "/alternatename:?GetLastError@win32@system_error2@@YAKXZ=GetLastError")
#pragma comment(linker, "/alternatename:?FormatMessageW@win32@system_error2@@YAKKPEBXKKPEA_WKPEAX@Z=FormatMessageW")
#pragma comment(linker, "/alternatename:?WideCharToMultiByte@win32@system_error2@@YAHIKPEB_WHPEADHPEBDPEAH@Z=WideCharToMultiByte")
#else
#pragma comment(linker, "/alternatename:?GetLastError@win32@system_error2@@YGKXZ=__imp__GetLastError@0")
#pragma comment(linker, "/alternatename:?FormatMessageW@win32@system_error2@@YGKKPBXKKPA_WKPAX@Z=__imp__FormatMessageW@28")
#pragma comment(linker, "/alternatename:?WideCharToMultiByte@win32@system_error2@@YGHIKPB_WHPADHPBDPAH@Z=__imp__WideCharToMultiByte@32")
#endif
}  // namespace win32

class _win32_code_domain;
class _com_code_domain;
//! (Windows only) A Win32 error code, those returned by `GetLastError()`.
using win32_code = status_code<_win32_code_domain>;
//! (Windows only) A specialisation of `status_error` for the Win32 error code domain.
using win32_error = status_error<_win32_code_domain>;

namespace mixins
{
  template <class Base> struct mixin<Base, _win32_code_domain> : public Base
  {
    using Base::Base;

    //! Returns a `win32_code` for the current value of `GetLastError()`.
    static inline win32_code current() noexcept;
  };
}  // namespace mixins

/*! (Windows only) The implementation of the domain for Win32 error codes, those returned by `GetLastError()`.
 */
class _win32_code_domain : public status_code_domain
{
  template <class DomainType> friend class status_code;
  template <class StatusCode> friend class detail::indirecting_domain;
  friend class _com_code_domain;
  using _base = status_code_domain;
  static int _win32_code_to_errno(win32::DWORD c)
  {
    switch(c)
    {
    case 0:
      return 0;
#include "detail/win32_code_to_generic_code.ipp"
    }
    return -1;
  }
  //! Construct from a Win32 error code
  static _base::string_ref _make_string_ref(win32::DWORD c) noexcept
  {
    wchar_t buffer[32768];
    win32::DWORD wlen = win32::FormatMessageW(0x00001000 /*FORMAT_MESSAGE_FROM_SYSTEM*/ | 0x00000200 /*FORMAT_MESSAGE_IGNORE_INSERTS*/, nullptr, c, 0, buffer, 32768, nullptr);
    size_t allocation = wlen + (wlen >> 1);
    win32::DWORD bytes;
    if(wlen == 0)
    {
      return _base::string_ref("failed to get message from system");
    }
    for(;;)
    {
      auto *p = static_cast<char *>(malloc(allocation));  // NOLINT
      if(p == nullptr)
      {
        return _base::string_ref("failed to get message from system");
      }
      bytes = win32::WideCharToMultiByte(65001 /*CP_UTF8*/, 0, buffer, (int) (wlen + 1), p, (int) allocation, nullptr, nullptr);
      if(bytes != 0)
      {
        char *end = strchr(p, 0);
        while(end[-1] == 10 || end[-1] == 13)
        {
          --end;
        }
        *end = 0;  // NOLINT
        return _base::atomic_refcounted_string_ref(p, end - p);
      }
      free(p);  // NOLINT
      if(win32::GetLastError() == 0x7a /*ERROR_INSUFFICIENT_BUFFER*/)
      {
        allocation += allocation >> 2;
        continue;
      }
      return _base::string_ref("failed to get message from system");
    }
  }

public:
  //! The value type of the win32 code, which is a `win32::DWORD`
  using value_type = win32::DWORD;
  using _base::string_ref;

public:
  //! Default constructor
  constexpr explicit _win32_code_domain(typename _base::unique_id_type id = 0x8cd18ee72d680f1b) noexcept
      : _base(id)
  {
  }
  _win32_code_domain(const _win32_code_domain &) = default;
  _win32_code_domain(_win32_code_domain &&) = default;
  _win32_code_domain &operator=(const _win32_code_domain &) = default;
  _win32_code_domain &operator=(_win32_code_domain &&) = default;
  ~_win32_code_domain() = default;

  //! Constexpr singleton getter. Returns the constexpr win32_code_domain variable.
  static inline constexpr const _win32_code_domain &get();

  virtual string_ref name() const noexcept override { return string_ref("win32 domain"); }  // NOLINT
protected:
  virtual bool _do_failure(const status_code<void> &code) const noexcept override  // NOLINT
  {
    assert(code.domain() == *this);
    return static_cast<const win32_code &>(code).value() != 0;  // NOLINT
  }
  virtual bool _do_equivalent(const status_code<void> &code1, const status_code<void> &code2) const noexcept override  // NOLINT
  {
    assert(code1.domain() == *this);
    const auto &c1 = static_cast<const win32_code &>(code1);  // NOLINT
    if(code2.domain() == *this)
    {
      const auto &c2 = static_cast<const win32_code &>(code2);  // NOLINT
      return c1.value() == c2.value();
    }
    if(code2.domain() == generic_code_domain)
    {
      const auto &c2 = static_cast<const generic_code &>(code2);  // NOLINT
      if(static_cast<int>(c2.value()) == _win32_code_to_errno(c1.value()))
      {
        return true;
      }
    }
    return false;
  }
  virtual generic_code _generic_code(const status_code<void> &code) const noexcept override  // NOLINT
  {
    assert(code.domain() == *this);
    const auto &c = static_cast<const win32_code &>(code);  // NOLINT
    return generic_code(static_cast<errc>(_win32_code_to_errno(c.value())));
  }
  virtual string_ref _do_message(const status_code<void> &code) const noexcept override  // NOLINT
  {
    assert(code.domain() == *this);
    const auto &c = static_cast<const win32_code &>(code);  // NOLINT
    return _make_string_ref(c.value());
  }
#if defined(_CPPUNWIND) || defined(__EXCEPTIONS) || defined(BOOST_OUTCOME_STANDARDESE_IS_IN_THE_HOUSE)
  BOOST_OUTCOME_SYSTEM_ERROR2_NORETURN virtual void _do_throw_exception(const status_code<void> &code) const override  // NOLINT
  {
    assert(code.domain() == *this);
    const auto &c = static_cast<const win32_code &>(code);  // NOLINT
    throw status_error<_win32_code_domain>(c);
  }
#endif
};
//! (Windows only) A constexpr source variable for the win32 code domain, which is that of `GetLastError()` (Windows). Returned by `_win32_code_domain::get()`.
constexpr _win32_code_domain win32_code_domain;
inline constexpr const _win32_code_domain &_win32_code_domain::get()
{
  return win32_code_domain;
}

namespace mixins
{
  template <class Base> inline win32_code mixin<Base, _win32_code_domain>::current() noexcept { return win32_code(win32::GetLastError()); }
}  // namespace mixins

BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_END

#endif