Win: Add ntstatus_error

Signed-off-by: Simon Rozman <simon@rozman.si>

include/WinStd/Win.h

@@ -1994,6 +1994,65 @@ namespace winstd
     };
 
     /// @}
+
+    /// \addtogroup WinStdExceptions
+    /// @{
+
+    ///
+    /// NTSTATUS error
+    ///
+    class ntstatus_error : public num_runtime_error<LONG>
+    {
+    public:
+        ///
+        /// Constructs an exception
+        ///
+        /// \param[in] num NTSTATUS error code
+        ///
+        ntstatus_error(_In_ error_type num) : num_runtime_error<LONG>(num, message(num))
+        {}
+
+        ///
+        /// Constructs an exception
+        ///
+        /// \param[in] num NTSTATUS error code
+        /// \param[in] msg Error message
+        ///
+        ntstatus_error(_In_ error_type num, _In_ const std::string& msg) : num_runtime_error<LONG>(num, msg + ": " + message(num))
+        {}
+
+        ///
+        /// Constructs an exception
+        ///
+        /// \param[in] num  NTSTATUS error code
+        /// \param[in] msg  Error message
+        ///
+        ntstatus_error(_In_ error_type num, _In_z_ const char *msg) : num_runtime_error<LONG>(num, std::string(msg) + ": " + message(num))
+        {}
+
+    protected:
+        ///
+        /// Returns a user-readable NTSTATUS error message.
+        /// As std::exception messages may only be char*, we use UTF-8 by convention.
+        ///
+        /// \sa [FormatMessage function](https://docs.microsoft.com/en-us/windows/desktop/api/winbase/nf-winbase-formatmessage)
+        ///
+        static std::string message(_In_ error_type num, _In_opt_ DWORD dwLanguageId = 0)
+        {
+            std::wstring wstr;
+            winstd::library ntdll(LoadLibraryW(L"NTDLL.DLL"));
+            if (ntdll && FormatMessageW(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_FROM_HMODULE | FORMAT_MESSAGE_IGNORE_INSERTS, (HMODULE)ntdll, num, dwLanguageId, wstr, NULL)) {
+                // Stock Windows error messages contain CRLF. Well... Trim all the trailing white space.
+                wstr.erase(wstr.find_last_not_of(L" \t\n\r\f\v") + 1);
+            } else
+                sprintf(wstr, num >= 0x10000 ? L"Error 0x%X" : L"Error %u", num);
+            std::string str;
+            WideCharToMultiByte(CP_UTF8, 0, wstr, str, NULL, NULL);
+            return str;
+        }
+    };
+
+    /// @}
 }
 
 /// \addtogroup WinStdWinAPI