1 /* Proposed SG14 status_code
2 (C) 2018-2019 Niall Douglas <http://www.nedproductions.biz/> (5 commits)
6 Boost Software License - Version 1.0 - August 17th, 2003
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31 #ifndef BOOST_OUTCOME_SYSTEM_ERROR2_WIN32_CODE_HPP
32 #define BOOST_OUTCOME_SYSTEM_ERROR2_WIN32_CODE_HPP
34 #if !defined(_WIN32) && !defined(BOOST_OUTCOME_STANDARDESE_IS_IN_THE_HOUSE)
35 #error This file should only be included on Windows
38 #include "generic_code.hpp"
40 BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_BEGIN
46 using DWORD = unsigned long;
47 // Used to retrieve the current Win32 error code
48 extern DWORD __stdcall GetLastError();
49 // Used to retrieve a locale-specific message string for some error code
50 extern DWORD __stdcall FormatMessageW(DWORD dwFlags, const void *lpSource, DWORD dwMessageId, DWORD dwLanguageId, wchar_t *lpBuffer, DWORD nSize, void /*va_list*/ *Arguments);
51 // Converts UTF-16 message string to UTF-8
52 extern int __stdcall WideCharToMultiByte(unsigned int CodePage, DWORD dwFlags, const wchar_t *lpWideCharStr, int cchWideChar, char *lpMultiByteStr, int cbMultiByte, const char *lpDefaultChar, int *lpUsedDefaultChar);
53 #pragma comment(lib, "kernel32.lib")
54 #pragma comment(linker, "/alternatename:?GetLastError@win32@system_error2@@YAKXZ=GetLastError")
55 #pragma comment(linker, "/alternatename:?FormatMessageW@win32@system_error2@@YAKKPEBXKKPEA_WKPEAX@Z=FormatMessageW")
56 #pragma comment(linker, "/alternatename:?WideCharToMultiByte@win32@system_error2@@YAHIKPEB_WHPEADHPEBDPEAH@Z=WideCharToMultiByte")
59 class _win32_code_domain;
60 class _com_code_domain;
61 //! (Windows only) A Win32 error code, those returned by `GetLastError()`.
62 using win32_code = status_code<_win32_code_domain>;
63 //! (Windows only) A specialisation of `status_error` for the Win32 error code domain.
64 using win32_error = status_error<_win32_code_domain>;
66 /*! (Windows only) The implementation of the domain for Win32 error codes, those returned by `GetLastError()`.
68 class _win32_code_domain : public status_code_domain
70 template <class DomainType> friend class status_code;
71 template <class StatusCode> friend class detail::indirecting_domain;
72 friend class _com_code_domain;
73 using _base = status_code_domain;
74 static int _win32_code_to_errno(win32::DWORD c)
80 #include "detail/win32_code_to_generic_code.ipp"
84 //! Construct from a Win32 error code
85 static _base::string_ref _make_string_ref(win32::DWORD c) noexcept
87 wchar_t buffer[32768];
88 win32::DWORD wlen = win32::FormatMessageW(0x00001000 /*FORMAT_MESSAGE_FROM_SYSTEM*/ | 0x00000200 /*FORMAT_MESSAGE_IGNORE_INSERTS*/, nullptr, c, 0, buffer, 32768, nullptr);
89 size_t allocation = wlen + (wlen >> 1);
93 return _base::string_ref("failed to get message from system");
97 auto *p = static_cast<char *>(malloc(allocation)); // NOLINT
100 return _base::string_ref("failed to get message from system");
102 bytes = win32::WideCharToMultiByte(65001 /*CP_UTF8*/, 0, buffer, (int) (wlen + 1), p, (int) allocation, nullptr, nullptr);
105 char *end = strchr(p, 0);
106 while(end[-1] == 10 || end[-1] == 13)
111 return _base::atomic_refcounted_string_ref(p, end - p);
114 if(win32::GetLastError() == 0x7a /*ERROR_INSUFFICIENT_BUFFER*/)
116 allocation += allocation >> 2;
119 return _base::string_ref("failed to get message from system");
124 //! The value type of the win32 code, which is a `win32::DWORD`
125 using value_type = win32::DWORD;
126 using _base::string_ref;
129 //! Default constructor
130 constexpr explicit _win32_code_domain(typename _base::unique_id_type id = 0x8cd18ee72d680f1b) noexcept : _base(id) {}
131 _win32_code_domain(const _win32_code_domain &) = default;
132 _win32_code_domain(_win32_code_domain &&) = default;
133 _win32_code_domain &operator=(const _win32_code_domain &) = default;
134 _win32_code_domain &operator=(_win32_code_domain &&) = default;
135 ~_win32_code_domain() = default;
137 //! Constexpr singleton getter. Returns the constexpr win32_code_domain variable.
138 static inline constexpr const _win32_code_domain &get();
140 virtual string_ref name() const noexcept override { return string_ref("win32 domain"); } // NOLINT
142 virtual bool _do_failure(const status_code<void> &code) const noexcept override // NOLINT
144 assert(code.domain() == *this);
145 return static_cast<const win32_code &>(code).value() != 0; // NOLINT
147 virtual bool _do_equivalent(const status_code<void> &code1, const status_code<void> &code2) const noexcept override // NOLINT
149 assert(code1.domain() == *this);
150 const auto &c1 = static_cast<const win32_code &>(code1); // NOLINT
151 if(code2.domain() == *this)
153 const auto &c2 = static_cast<const win32_code &>(code2); // NOLINT
154 return c1.value() == c2.value();
156 if(code2.domain() == generic_code_domain)
158 const auto &c2 = static_cast<const generic_code &>(code2); // NOLINT
159 if(static_cast<int>(c2.value()) == _win32_code_to_errno(c1.value()))
166 virtual generic_code _generic_code(const status_code<void> &code) const noexcept override // NOLINT
168 assert(code.domain() == *this);
169 const auto &c = static_cast<const win32_code &>(code); // NOLINT
170 return generic_code(static_cast<errc>(_win32_code_to_errno(c.value())));
172 virtual string_ref _do_message(const status_code<void> &code) const noexcept override // NOLINT
174 assert(code.domain() == *this);
175 const auto &c = static_cast<const win32_code &>(code); // NOLINT
176 return _make_string_ref(c.value());
178 #if defined(_CPPUNWIND) || defined(__EXCEPTIONS) || defined(BOOST_OUTCOME_STANDARDESE_IS_IN_THE_HOUSE)
179 BOOST_OUTCOME_SYSTEM_ERROR2_NORETURN virtual void _do_throw_exception(const status_code<void> &code) const override // NOLINT
181 assert(code.domain() == *this);
182 const auto &c = static_cast<const win32_code &>(code); // NOLINT
183 throw status_error<_win32_code_domain>(c);
187 //! (Windows only) A constexpr source variable for the win32 code domain, which is that of `GetLastError()` (Windows). Returned by `_win32_code_domain::get()`.
188 constexpr _win32_code_domain win32_code_domain;
189 inline constexpr const _win32_code_domain &_win32_code_domain::get()
191 return win32_code_domain;
194 BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_END