lewaimai_pos_windows/include/boost/outcome/experimental/status-code/win32_code.hpp

/* Proposed SG14 status_code
(C) 2018-2019 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
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the above license grant, this restriction and the following disclaimer,
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
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*/

#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 "generic_code.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 "C" DWORD __stdcall GetLastError();
  // Used to retrieve a locale-specific message string for some error code
  extern "C" 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 "C" 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")
}  // 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>;

/*! (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;
}

BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_END

#endif