t8-mod/deps/winreg/WinReg/WinReg.hpp
2024-02-15 15:46:47 -05:00

2831 lines
81 KiB
C++

#ifndef GIOVANNI_DICANIO_WINREG_HPP_INCLUDED
#define GIOVANNI_DICANIO_WINREG_HPP_INCLUDED
////////////////////////////////////////////////////////////////////////////////
//
// *** Modern C++ Wrappers Around Windows Registry C API ***
//
// Copyright (C) by Giovanni Dicanio
//
// First version: 2017, January 22nd
// Last update: 2022, July 13th
//
// E-mail: <first name>.<last name> AT REMOVE_THIS gmail.com
//
// Registry key handles are safely and conveniently wrapped
// in the RegKey resource manager C++ class.
//
// Many methods are available in two forms:
//
// - One form that signals errors throwing exceptions
// of class RegException (e.g. RegKey::Open)
//
// - Another form that returns RegResult objects (e.g. RegKey::TryOpen)
//
// In addition, there are also some methods named like TryGet...Value
// (e.g. TryGetDwordValue), that _try_ to perform the given query,
// and return a RegExpected object. On success, that object contains
// the value read from the registry. On failure, the returned RegExpected object
// contains a RegResult storing the return code from the Windows Registry API call.
//
// Unicode UTF-16 strings are represented using the std::wstring class;
// ATL's CString is not used, to avoid dependencies from ATL or MFC.
//
// Compiler: Visual Studio 2019
// C++ Language Standard: C++17 (/std:c++17)
// Code compiles cleanly at warning level 4 (/W4) on both 32-bit and 64-bit builds.
//
// Requires building in Unicode mode (which has been the default since VS2005).
//
// ===========================================================================
//
// The MIT License(MIT)
//
// Copyright(c) 2017-2022 by Giovanni Dicanio
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files(the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions :
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// 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 AND NONINFRINGEMENT.IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//
////////////////////////////////////////////////////////////////////////////////
#include <Windows.h> // Windows Platform SDK
#include <crtdbg.h> // _ASSERTE
#include <memory> // std::unique_ptr, std::make_unique
#include <string> // std::wstring
#include <system_error> // std::system_error
#include <utility> // std::swap, std::pair, std::move
#include <variant> // std::variant
#include <vector> // std::vector
namespace winreg
{
//
// Forward Class Declarations
//
class RegException;
class RegResult;
template <typename T>
class RegExpected;
//
// Class Declarations
//
//------------------------------------------------------------------------------
//
// Safe, efficient and convenient C++ wrapper around HKEY registry key handles.
//
// This class is movable but not copyable.
//
// This class is designed to be very *efficient* and low-overhead, for example:
// non-throwing operations are carefully marked as noexcept, so the C++ compiler
// can emit optimized code.
//
// Moreover, this class just wraps a raw HKEY handle, without any
// shared-ownership overhead like in std::shared_ptr; you can think of this
// class kind of like a std::unique_ptr for HKEYs.
//
// The class is also swappable (defines a custom non-member swap);
// relational operators are properly overloaded as well.
//
//------------------------------------------------------------------------------
class RegKey
{
public:
//
// Construction/Destruction
//
// Initialize as an empty key handle
RegKey() noexcept = default;
// Take ownership of the input key handle
explicit RegKey(HKEY hKey) noexcept;
// Open the given registry key if it exists, else create a new key.
// Uses default KEY_READ|KEY_WRITE|KEY_WOW64_64KEY access.
// For finer grained control, call the Create() method overloads.
// Throw RegException on failure.
RegKey(HKEY hKeyParent, const std::wstring& subKey);
// Open the given registry key if it exists, else create a new key.
// Allow the caller to specify the desired access to the key
// (e.g. KEY_READ|KEY_WOW64_64KEY for read-only access).
// For finer grained control, call the Create() method overloads.
// Throw RegException on failure.
RegKey(HKEY hKeyParent, const std::wstring& subKey, REGSAM desiredAccess);
// Take ownership of the input key handle.
// The input key handle wrapper is reset to an empty state.
RegKey(RegKey&& other) noexcept;
// Move-assign from the input key handle.
// Properly check against self-move-assign (which is safe and does nothing).
RegKey& operator=(RegKey&& other) noexcept;
// Ban copy
RegKey(const RegKey&) = delete;
RegKey& operator=(const RegKey&) = delete;
// Safely close the wrapped key handle (if any)
~RegKey() noexcept;
//
// Properties
//
// Access the wrapped raw HKEY handle
[[nodiscard]] HKEY Get() const noexcept;
// Is the wrapped HKEY handle valid?
[[nodiscard]] bool IsValid() const noexcept;
// Same as IsValid(), but allow a short "if (regKey)" syntax
[[nodiscard]] explicit operator bool() const noexcept;
// Is the wrapped handle a predefined handle (e.g.HKEY_CURRENT_USER) ?
[[nodiscard]] bool IsPredefined() const noexcept;
//
// Operations
//
// Close current HKEY handle.
// If there's no valid handle, do nothing.
// This method doesn't close predefined HKEY handles (e.g. HKEY_CURRENT_USER).
void Close() noexcept;
// Transfer ownership of current HKEY to the caller.
// Note that the caller is responsible for closing the key handle!
[[nodiscard]] HKEY Detach() noexcept;
// Take ownership of the input HKEY handle.
// Safely close any previously open handle.
// Input key handle can be nullptr.
void Attach(HKEY hKey) noexcept;
// Non-throwing swap;
// Note: There's also a non-member swap overload
void SwapWith(RegKey& other) noexcept;
//
// Wrappers around Windows Registry APIs.
// See the official MSDN documentation for these APIs for detailed explanations
// of the wrapper method parameters.
//
//
// NOTE on the KEY_WOW64_64KEY flag
// ================================
//
// By default, a 32-bit application running on 64-bit Windows accesses the 32-bit registry view
// and a 64-bit application accesses the 64-bit registry view.
// Using this KEY_WOW64_64KEY flag, both 32-bit or 64-bit applications access the 64-bit
// registry view.
//
// MSDN documentation:
// https://docs.microsoft.com/en-us/windows/win32/winprog64/accessing-an-alternate-registry-view
//
// If you want to use the default Windows API behavior, don't OR (|) the KEY_WOW64_64KEY flag
// when specifying the desired access (e.g. just pass KEY_READ | KEY_WRITE as the desired
// access parameter).
//
// Wrapper around RegCreateKeyEx, that allows you to specify desired access
void Create(
HKEY hKeyParent,
const std::wstring& subKey,
REGSAM desiredAccess = KEY_READ | KEY_WRITE | KEY_WOW64_64KEY
);
// Wrapper around RegCreateKeyEx
void Create(
HKEY hKeyParent,
const std::wstring& subKey,
REGSAM desiredAccess,
DWORD options,
SECURITY_ATTRIBUTES* securityAttributes,
DWORD* disposition
);
// Wrapper around RegOpenKeyEx
void Open(
HKEY hKeyParent,
const std::wstring& subKey,
REGSAM desiredAccess = KEY_READ | KEY_WRITE | KEY_WOW64_64KEY
);
// Wrapper around RegCreateKeyEx, that allows you to specify desired access
[[nodiscard]] RegResult TryCreate(
HKEY hKeyParent,
const std::wstring& subKey,
REGSAM desiredAccess = KEY_READ | KEY_WRITE | KEY_WOW64_64KEY
) noexcept;
// Wrapper around RegCreateKeyEx
[[nodiscard]] RegResult TryCreate(
HKEY hKeyParent,
const std::wstring& subKey,
REGSAM desiredAccess,
DWORD options,
SECURITY_ATTRIBUTES* securityAttributes,
DWORD* disposition
) noexcept;
// Wrapper around RegOpenKeyEx
[[nodiscard]] RegResult TryOpen(
HKEY hKeyParent,
const std::wstring& subKey,
REGSAM desiredAccess = KEY_READ | KEY_WRITE | KEY_WOW64_64KEY
) noexcept;
//
// Registry Value Setters
//
void SetDwordValue(const std::wstring& valueName, DWORD data);
void SetQwordValue(const std::wstring& valueName, const ULONGLONG& data);
void SetStringValue(const std::wstring& valueName, const std::wstring& data);
void SetExpandStringValue(const std::wstring& valueName, const std::wstring& data);
void SetMultiStringValue(const std::wstring& valueName, const std::vector<std::wstring>& data);
void SetBinaryValue(const std::wstring& valueName, const std::vector<BYTE>& data);
void SetBinaryValue(const std::wstring& valueName, const void* data, DWORD dataSize);
//
// Registry Value Setters Returning RegResult
// (instead of throwing RegException on error)
//
[[nodiscard]] RegResult TrySetDwordValue(const std::wstring& valueName, DWORD data) noexcept;
[[nodiscard]] RegResult TrySetQwordValue(const std::wstring& valueName,
const ULONGLONG& data) noexcept;
[[nodiscard]] RegResult TrySetStringValue(const std::wstring& valueName,
const std::wstring& data) noexcept;
[[nodiscard]] RegResult TrySetExpandStringValue(const std::wstring& valueName,
const std::wstring& data) noexcept;
[[nodiscard]] RegResult TrySetMultiStringValue(const std::wstring& valueName,
const std::vector<std::wstring>& data);
// Note: The TrySetMultiStringValue method CANNOT be marked noexcept,
// because internally the method *dynamically allocates memory* for creating the multi-string
// that will be stored in the Registry.
[[nodiscard]] RegResult TrySetBinaryValue(const std::wstring& valueName,
const std::vector<BYTE>& data) noexcept;
[[nodiscard]] RegResult TrySetBinaryValue(const std::wstring& valueName,
const void* data,
DWORD dataSize) noexcept;
//
// Registry Value Getters
//
[[nodiscard]] DWORD GetDwordValue(const std::wstring& valueName) const;
[[nodiscard]] ULONGLONG GetQwordValue(const std::wstring& valueName) const;
[[nodiscard]] std::wstring GetStringValue(const std::wstring& valueName) const;
enum class ExpandStringOption
{
DontExpand,
Expand
};
[[nodiscard]] std::wstring GetExpandStringValue(
const std::wstring& valueName,
ExpandStringOption expandOption = ExpandStringOption::DontExpand
) const;
[[nodiscard]] std::vector<std::wstring> GetMultiStringValue(const std::wstring& valueName) const;
[[nodiscard]] std::vector<BYTE> GetBinaryValue(const std::wstring& valueName) const;
//
// Registry Value Getters Returning RegExpected<T>
// (instead of throwing RegException on error)
//
[[nodiscard]] RegExpected<DWORD> TryGetDwordValue(const std::wstring& valueName) const;
[[nodiscard]] RegExpected<ULONGLONG> TryGetQwordValue(const std::wstring& valueName) const;
[[nodiscard]] RegExpected<std::wstring> TryGetStringValue(const std::wstring& valueName) const;
[[nodiscard]] RegExpected<std::wstring> TryGetExpandStringValue(
const std::wstring& valueName,
ExpandStringOption expandOption = ExpandStringOption::DontExpand
) const;
[[nodiscard]] RegExpected<std::vector<std::wstring>>
TryGetMultiStringValue(const std::wstring& valueName) const;
[[nodiscard]] RegExpected<std::vector<BYTE>>
TryGetBinaryValue(const std::wstring& valueName) const;
//
// Query Operations
//
// Information about a registry key (retrieved by QueryInfoKey)
struct InfoKey
{
DWORD NumberOfSubKeys;
DWORD NumberOfValues;
FILETIME LastWriteTime;
// Clear the structure fields
InfoKey() noexcept
: NumberOfSubKeys{0}
, NumberOfValues{0}
{
LastWriteTime.dwHighDateTime = LastWriteTime.dwLowDateTime = 0;
}
InfoKey(DWORD numberOfSubKeys, DWORD numberOfValues, FILETIME lastWriteTime) noexcept
: NumberOfSubKeys{ numberOfSubKeys }
, NumberOfValues{ numberOfValues }
, LastWriteTime{ lastWriteTime }
{
}
};
// Retrieve information about the registry key
[[nodiscard]] InfoKey QueryInfoKey() const;
// Return the DWORD type ID for the input registry value
[[nodiscard]] DWORD QueryValueType(const std::wstring& valueName) const;
enum class KeyReflection
{
ReflectionEnabled,
ReflectionDisabled
};
// Determines whether reflection has been disabled or enabled for the specified key
[[nodiscard]] KeyReflection QueryReflectionKey() const;
// Enumerate the subkeys of the registry key, using RegEnumKeyEx
[[nodiscard]] std::vector<std::wstring> EnumSubKeys() const;
// Enumerate the values under the registry key, using RegEnumValue.
// Returns a vector of pairs: In each pair, the wstring is the value name,
// the DWORD is the value type.
[[nodiscard]] std::vector<std::pair<std::wstring, DWORD>> EnumValues() const;
//
// Query Operations Returning RegExpected
// (instead of throwing RegException on error)
//
// Retrieve information about the registry key
[[nodiscard]] RegExpected<InfoKey> TryQueryInfoKey() const;
// Return the DWORD type ID for the input registry value
[[nodiscard]] RegExpected<DWORD> TryQueryValueType(const std::wstring& valueName) const;
// Determines whether reflection has been disabled or enabled for the specified key
[[nodiscard]] RegExpected<KeyReflection> TryQueryReflectionKey() const;
// Enumerate the subkeys of the registry key, using RegEnumKeyEx
[[nodiscard]] RegExpected<std::vector<std::wstring>> TryEnumSubKeys() const;
// Enumerate the values under the registry key, using RegEnumValue.
// Returns a vector of pairs: In each pair, the wstring is the value name,
// the DWORD is the value type.
[[nodiscard]] RegExpected<std::vector<std::pair<std::wstring, DWORD>>> TryEnumValues() const;
//
// Misc Registry API Wrappers
//
void DeleteValue(const std::wstring& valueName);
void DeleteKey(const std::wstring& subKey, REGSAM desiredAccess);
void DeleteTree(const std::wstring& subKey);
void CopyTree(const std::wstring& sourceSubKey, const RegKey& destKey);
void FlushKey();
void LoadKey(const std::wstring& subKey, const std::wstring& filename);
void SaveKey(const std::wstring& filename, SECURITY_ATTRIBUTES* securityAttributes) const;
void EnableReflectionKey();
void DisableReflectionKey();
void ConnectRegistry(const std::wstring& machineName, HKEY hKeyPredefined);
//
// Misc Registry API Wrappers Returning RegResult Status
// (instead of throwing RegException on error)
//
[[nodiscard]] RegResult TryDeleteValue(const std::wstring& valueName) noexcept;
[[nodiscard]] RegResult TryDeleteKey(const std::wstring& subKey, REGSAM desiredAccess) noexcept;
[[nodiscard]] RegResult TryDeleteTree(const std::wstring& subKey) noexcept;
[[nodiscard]] RegResult TryCopyTree(const std::wstring& sourceSubKey,
const RegKey& destKey) noexcept;
[[nodiscard]] RegResult TryFlushKey() noexcept;
[[nodiscard]] RegResult TryLoadKey(const std::wstring& subKey,
const std::wstring& filename) noexcept;
[[nodiscard]] RegResult TrySaveKey(const std::wstring& filename,
SECURITY_ATTRIBUTES* securityAttributes) const noexcept;
[[nodiscard]] RegResult TryEnableReflectionKey() noexcept;
[[nodiscard]] RegResult TryDisableReflectionKey() noexcept;
[[nodiscard]] RegResult TryConnectRegistry(const std::wstring& machineName,
HKEY hKeyPredefined) noexcept;
// Return a string representation of Windows registry types
[[nodiscard]] static std::wstring RegTypeToString(DWORD regType);
//
// Relational comparison operators are overloaded as non-members
// ==, !=, <, <=, >, >=
//
//
// Private Implementation
//
private:
// The wrapped registry key handle
HKEY m_hKey{ nullptr };
};
//------------------------------------------------------------------------------
// An exception representing an error with the registry operations
//------------------------------------------------------------------------------
class RegException
: public std::system_error
{
public:
RegException(LSTATUS errorCode, const char* message);
RegException(LSTATUS errorCode, const std::string& message);
};
//------------------------------------------------------------------------------
// A tiny wrapper around LSTATUS return codes used by the Windows Registry API.
//------------------------------------------------------------------------------
class RegResult
{
public:
// Initialize to success code (ERROR_SUCCESS)
RegResult() noexcept = default;
// Initialize with specific Windows Registry API LSTATUS return code
explicit RegResult(LSTATUS result) noexcept;
// Is the wrapped code a success code?
[[nodiscard]] bool IsOk() const noexcept;
// Is the wrapped error code a failure code?
[[nodiscard]] bool Failed() const noexcept;
// Is the wrapped code a success code?
[[nodiscard]] explicit operator bool() const noexcept;
// Get the wrapped Win32 code
[[nodiscard]] LSTATUS Code() const noexcept;
// Return the system error message associated to the current error code
[[nodiscard]] std::wstring ErrorMessage() const;
// Return the system error message associated to the current error code,
// using the given input language identifier
[[nodiscard]] std::wstring ErrorMessage(DWORD languageId) const;
private:
// Error code returned by Windows Registry C API;
// default initialized to success code.
LSTATUS m_result{ ERROR_SUCCESS };
};
//------------------------------------------------------------------------------
// A class template that stores a value of type T (e.g. DWORD, std::wstring)
// on success, or a RegResult on error.
//
// Used as the return value of some Registry RegKey::TryGetXxxValue() methods
// as an alternative to exception-throwing methods.
//------------------------------------------------------------------------------
template <typename T>
class RegExpected
{
public:
// Initialize the object with an error code
explicit RegExpected(const RegResult& errorCode) noexcept;
// Initialize the object with a value (the success case)
explicit RegExpected(const T& value);
// Initialize the object with a value (the success case),
// optimized for move semantics
explicit RegExpected(T&& value);
// Does this object contain a valid value?
[[nodiscard]] explicit operator bool() const noexcept;
// Does this object contain a valid value?
[[nodiscard]] bool IsValid() const noexcept;
// Access the value (if the object contains a valid value).
// Throws an exception if the object is in invalid state.
[[nodiscard]] const T& GetValue() const;
// Access the error code (if the object contains an error status)
// Throws an exception if the object is in valid state.
[[nodiscard]] RegResult GetError() const;
private:
// Stores a value of type T on success,
// or RegResult on error
std::variant<RegResult, T> m_var;
};
//------------------------------------------------------------------------------
// Overloads of relational comparison operators for RegKey
//------------------------------------------------------------------------------
inline bool operator==(const RegKey& a, const RegKey& b) noexcept
{
return a.Get() == b.Get();
}
inline bool operator!=(const RegKey& a, const RegKey& b) noexcept
{
return a.Get() != b.Get();
}
inline bool operator<(const RegKey& a, const RegKey& b) noexcept
{
return a.Get() < b.Get();
}
inline bool operator<=(const RegKey& a, const RegKey& b) noexcept
{
return a.Get() <= b.Get();
}
inline bool operator>(const RegKey& a, const RegKey& b) noexcept
{
return a.Get() > b.Get();
}
inline bool operator>=(const RegKey& a, const RegKey& b) noexcept
{
return a.Get() >= b.Get();
}
//------------------------------------------------------------------------------
// Private Helper Classes and Functions
//------------------------------------------------------------------------------
namespace detail
{
//------------------------------------------------------------------------------
// Simple scoped-based RAII wrapper that *automatically* invokes LocalFree()
// in its destructor.
//------------------------------------------------------------------------------
template <typename T>
class ScopedLocalFree
{
public:
typedef T Type;
typedef T* TypePtr;
// Init wrapped pointer to nullptr
ScopedLocalFree() noexcept = default;
// Automatically and safely invoke ::LocalFree()
~ScopedLocalFree() noexcept
{
Free();
}
//
// Ban copy and move operations
//
ScopedLocalFree(const ScopedLocalFree&) = delete;
ScopedLocalFree(ScopedLocalFree&&) = delete;
ScopedLocalFree& operator=(const ScopedLocalFree&) = delete;
ScopedLocalFree& operator=(ScopedLocalFree&&) = delete;
// Read-only access to the wrapped pointer
[[nodiscard]] T* Get() const noexcept
{
return m_ptr;
}
// Writable access to the wrapped pointer
[[nodiscard]] T** AddressOf() noexcept
{
return &m_ptr;
}
// Explicit pointer conversion to bool
explicit operator bool() const noexcept
{
return (m_ptr != nullptr);
}
// Safely invoke ::LocalFree() on the wrapped pointer
void Free() noexcept
{
if (m_ptr != nullptr)
{
::LocalFree(m_ptr);
m_ptr = nullptr;
}
}
//
// IMPLEMENTATION
//
private:
T* m_ptr{ nullptr };
};
//------------------------------------------------------------------------------
// Helper function to build a multi-string from a vector<wstring>.
//
// A multi-string is a sequence of contiguous NUL-terminated strings,
// that terminates with an additional NUL.
// Basically, considered as a whole, the sequence is terminated by two NULs.
// E.g.:
// Hello\0World\0\0
//------------------------------------------------------------------------------
[[nodiscard]] inline std::vector<wchar_t> BuildMultiString(const std::vector<std::wstring>& data)
{
// Special case of the empty multi-string
if (data.empty())
{
// Build a vector containing just two NULs
return std::vector<wchar_t>(2, L'\0');
}
// Get the total length in wchar_ts of the multi-string
size_t totalLen = 0;
for (const auto& s : data)
{
// Add one to current string's length for the terminating NUL
totalLen += (s.length() + 1);
}
// Add one for the last NUL terminator (making the whole structure double-NUL terminated)
totalLen++;
// Allocate a buffer to store the multi-string
std::vector<wchar_t> multiString;
// Reserve room in the vector to speed up the following insertion loop
multiString.reserve(totalLen);
// Copy the single strings into the multi-string
for (const auto& s : data)
{
if (!s.empty())
{
// Copy current string's content
multiString.insert(multiString.end(), s.begin(), s.end());
}
// Don't forget to NUL-terminate the current string
// (or just insert L'\0' for empty strings)
multiString.emplace_back(L'\0');
}
// Add the last NUL-terminator
multiString.emplace_back(L'\0');
return multiString;
}
//------------------------------------------------------------------------------
// Return true if the wchar_t sequence stored in 'data' terminates
// with two null (L'\0') wchar_t's
//------------------------------------------------------------------------------
[[nodiscard]] inline bool IsDoubleNullTerminated(const std::vector<wchar_t>& data)
{
// First check that there's enough room for at least two nulls
if (data.size() < 2)
{
return false;
}
// Check that the sequence terminates with two nulls (L'\0', L'\0')
const size_t lastPosition = data.size() - 1;
return ((data[lastPosition] == L'\0') &&
(data[lastPosition - 1] == L'\0')) ? true : false;
}
//------------------------------------------------------------------------------
// Given a sequence of wchar_ts representing a double-null-terminated string,
// returns a vector of wstrings that represent the single strings.
//
// Also supports embedded empty strings in the sequence.
//------------------------------------------------------------------------------
[[nodiscard]] inline std::vector<std::wstring> ParseMultiString(const std::vector<wchar_t>& data)
{
// Make sure that there are two terminating L'\0's at the end of the sequence
if (!IsDoubleNullTerminated(data))
{
throw RegException{ ERROR_INVALID_DATA, "Not a double-null terminated string." };
}
// Parse the double-NUL-terminated string into a vector<wstring>,
// which will be returned to the caller
std::vector<std::wstring> result;
//
// Note on Embedded Empty Strings
// ==============================
//
// Below commented-out there is the previous parsing code,
// that assumes that an empty string *terminates* the sequence.
//
// In fact, according to the official Microsoft MSDN documentation,
// an empty string is treated as a sequence terminator,
// so you can't have empty strings inside the sequence.
//
// Source: https://docs.microsoft.com/en-us/windows/win32/sysinfo/registry-value-types
// "A REG_MULTI_SZ string ends with a string of length 0.
// Therefore, it is not possible to include a zero-length string
// in the sequence. An empty sequence would be defined as follows: \0."
//
// Unfortunately, it seems that Microsoft violates its own rule, for example
// in the PendingFileRenameOperations value under the
// "SYSTEM\CurrentControlSet\Control\Session Manager" key.
// This is a REG_MULTI_SZ value that does contain embedded empty strings.
//
// So, I changed the previous parsing code to support also embedded empty strings.
//
// -------------------------------------------------------------------------
//// *** Previous parsing code - Assumes an empty string terminates the sequence ***
//
//const wchar_t* currStringPtr = data.data();
//while (*currStringPtr != L'\0')
//{
// // Current string is NUL-terminated, so get its length calling wcslen
// const size_t currStringLength = wcslen(currStringPtr);
//
// // Add current string to the result vector
// result.emplace_back(currStringPtr, currStringLength);
//
// // Move to the next string
// currStringPtr += currStringLength + 1;
//}
// -------------------------------------------------------------------------
//
const wchar_t* currStringPtr = data.data();
const wchar_t* const endPtr = data.data() + data.size() - 1;
while (currStringPtr < endPtr)
{
// Current string is NUL-terminated, so get its length calling wcslen
const size_t currStringLength = wcslen(currStringPtr);
// Add current string to the result vector
if (currStringLength > 0)
{
result.emplace_back(currStringPtr, currStringLength);
}
else
{
// Insert empty strings, as well
result.emplace_back(std::wstring{});
}
// Move to the next string, skipping the terminating NUL
currStringPtr += currStringLength + 1;
}
return result;
}
//------------------------------------------------------------------------------
// Builds a RegExpected object that stores an error code
//------------------------------------------------------------------------------
template <typename T>
[[nodiscard]] inline RegExpected<T> MakeRegExpectedWithError(const LSTATUS retCode)
{
return RegExpected<T>{ RegResult{ retCode } };
}
} // namespace detail
//------------------------------------------------------------------------------
// RegKey Inline Methods
//------------------------------------------------------------------------------
inline RegKey::RegKey(const HKEY hKey) noexcept
: m_hKey{ hKey }
{
}
inline RegKey::RegKey(const HKEY hKeyParent, const std::wstring& subKey)
{
Create(hKeyParent, subKey);
}
inline RegKey::RegKey(const HKEY hKeyParent, const std::wstring& subKey, const REGSAM desiredAccess)
{
Create(hKeyParent, subKey, desiredAccess);
}
inline RegKey::RegKey(RegKey&& other) noexcept
: m_hKey{ other.m_hKey }
{
// Other doesn't own the handle anymore
other.m_hKey = nullptr;
}
inline RegKey& RegKey::operator=(RegKey&& other) noexcept
{
// Prevent self-move-assign
if ((this != &other) && (m_hKey != other.m_hKey))
{
// Close current
Close();
// Move from other (i.e. take ownership of other's raw handle)
m_hKey = other.m_hKey;
other.m_hKey = nullptr;
}
return *this;
}
inline RegKey::~RegKey() noexcept
{
// Release the owned handle (if any)
Close();
}
inline HKEY RegKey::Get() const noexcept
{
return m_hKey;
}
inline void RegKey::Close() noexcept
{
if (IsValid())
{
// Do not call RegCloseKey on predefined keys
if (! IsPredefined())
{
::RegCloseKey(m_hKey);
}
// Avoid dangling references
m_hKey = nullptr;
}
}
inline bool RegKey::IsValid() const noexcept
{
return m_hKey != nullptr;
}
inline RegKey::operator bool() const noexcept
{
return IsValid();
}
inline bool RegKey::IsPredefined() const noexcept
{
// Predefined keys
// https://msdn.microsoft.com/en-us/library/windows/desktop/ms724836(v=vs.85).aspx
if ( (m_hKey == HKEY_CURRENT_USER)
|| (m_hKey == HKEY_LOCAL_MACHINE)
|| (m_hKey == HKEY_CLASSES_ROOT)
|| (m_hKey == HKEY_CURRENT_CONFIG)
|| (m_hKey == HKEY_CURRENT_USER_LOCAL_SETTINGS)
|| (m_hKey == HKEY_PERFORMANCE_DATA)
|| (m_hKey == HKEY_PERFORMANCE_NLSTEXT)
|| (m_hKey == HKEY_PERFORMANCE_TEXT)
|| (m_hKey == HKEY_USERS))
{
return true;
}
return false;
}
inline HKEY RegKey::Detach() noexcept
{
HKEY hKey = m_hKey;
// We don't own the HKEY handle anymore
m_hKey = nullptr;
// Transfer ownership to the caller
return hKey;
}
inline void RegKey::Attach(const HKEY hKey) noexcept
{
// Prevent self-attach
if (m_hKey != hKey)
{
// Close any open registry handle
Close();
// Take ownership of the input hKey
m_hKey = hKey;
}
}
inline void RegKey::SwapWith(RegKey& other) noexcept
{
// Enable ADL (not necessary in this case, but good practice)
using std::swap;
// Swap the raw handle members
swap(m_hKey, other.m_hKey);
}
inline void swap(RegKey& a, RegKey& b) noexcept
{
a.SwapWith(b);
}
inline void RegKey::Create(
const HKEY hKeyParent,
const std::wstring& subKey,
const REGSAM desiredAccess
)
{
constexpr DWORD kDefaultOptions = REG_OPTION_NON_VOLATILE;
Create(hKeyParent, subKey, desiredAccess, kDefaultOptions,
nullptr, // no security attributes,
nullptr // no disposition
);
}
inline void RegKey::Create(
const HKEY hKeyParent,
const std::wstring& subKey,
const REGSAM desiredAccess,
const DWORD options,
SECURITY_ATTRIBUTES* const securityAttributes,
DWORD* const disposition
)
{
HKEY hKey = nullptr;
LSTATUS retCode = ::RegCreateKeyExW(
hKeyParent,
subKey.c_str(),
0, // reserved
REG_NONE, // user-defined class type parameter not supported
options,
desiredAccess,
securityAttributes,
&hKey,
disposition
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "RegCreateKeyExW failed." };
}
// Safely close any previously opened key
Close();
// Take ownership of the newly created key
m_hKey = hKey;
}
inline void RegKey::Open(
const HKEY hKeyParent,
const std::wstring& subKey,
const REGSAM desiredAccess
)
{
HKEY hKey = nullptr;
LSTATUS retCode = ::RegOpenKeyExW(
hKeyParent,
subKey.c_str(),
REG_NONE, // default options
desiredAccess,
&hKey
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "RegOpenKeyExW failed." };
}
// Safely close any previously opened key
Close();
// Take ownership of the newly created key
m_hKey = hKey;
}
inline RegResult RegKey::TryCreate(
const HKEY hKeyParent,
const std::wstring& subKey,
const REGSAM desiredAccess
) noexcept
{
constexpr DWORD kDefaultOptions = REG_OPTION_NON_VOLATILE;
return TryCreate(hKeyParent, subKey, desiredAccess, kDefaultOptions,
nullptr, // no security attributes,
nullptr // no disposition
);
}
inline RegResult RegKey::TryCreate(
const HKEY hKeyParent,
const std::wstring& subKey,
const REGSAM desiredAccess,
const DWORD options,
SECURITY_ATTRIBUTES* const securityAttributes,
DWORD* const disposition
) noexcept
{
HKEY hKey = nullptr;
RegResult retCode{ ::RegCreateKeyExW(
hKeyParent,
subKey.c_str(),
0, // reserved
REG_NONE, // user-defined class type parameter not supported
options,
desiredAccess,
securityAttributes,
&hKey,
disposition
) };
if (retCode.Failed())
{
return retCode;
}
// Safely close any previously opened key
Close();
// Take ownership of the newly created key
m_hKey = hKey;
_ASSERTE(retCode.IsOk());
return retCode;
}
inline RegResult RegKey::TryOpen(
const HKEY hKeyParent,
const std::wstring& subKey,
const REGSAM desiredAccess
) noexcept
{
HKEY hKey = nullptr;
RegResult retCode{ ::RegOpenKeyExW(
hKeyParent,
subKey.c_str(),
REG_NONE, // default options
desiredAccess,
&hKey
) };
if (retCode.Failed())
{
return retCode;
}
// Safely close any previously opened key
Close();
// Take ownership of the newly created key
m_hKey = hKey;
_ASSERTE(retCode.IsOk());
return retCode;
}
inline void RegKey::SetDwordValue(const std::wstring& valueName, const DWORD data)
{
_ASSERTE(IsValid());
LSTATUS retCode = ::RegSetValueExW(
m_hKey,
valueName.c_str(),
0, // reserved
REG_DWORD,
reinterpret_cast<const BYTE*>(&data),
sizeof(data)
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "Cannot write DWORD value: RegSetValueExW failed." };
}
}
inline void RegKey::SetQwordValue(const std::wstring& valueName, const ULONGLONG& data)
{
_ASSERTE(IsValid());
LSTATUS retCode = ::RegSetValueExW(
m_hKey,
valueName.c_str(),
0, // reserved
REG_QWORD,
reinterpret_cast<const BYTE*>(&data),
sizeof(data)
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "Cannot write QWORD value: RegSetValueExW failed." };
}
}
inline void RegKey::SetStringValue(const std::wstring& valueName, const std::wstring& data)
{
_ASSERTE(IsValid());
// String size including the terminating NUL, in bytes
const DWORD dataSize = static_cast<DWORD>((data.length() + 1) * sizeof(wchar_t));
LSTATUS retCode = ::RegSetValueExW(
m_hKey,
valueName.c_str(),
0, // reserved
REG_SZ,
reinterpret_cast<const BYTE*>(data.c_str()),
dataSize
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "Cannot write string value: RegSetValueExW failed." };
}
}
inline void RegKey::SetExpandStringValue(const std::wstring& valueName, const std::wstring& data)
{
_ASSERTE(IsValid());
// String size including the terminating NUL, in bytes
const DWORD dataSize = static_cast<DWORD>((data.length() + 1) * sizeof(wchar_t));
LSTATUS retCode = ::RegSetValueExW(
m_hKey,
valueName.c_str(),
0, // reserved
REG_EXPAND_SZ,
reinterpret_cast<const BYTE*>(data.c_str()),
dataSize
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "Cannot write expand string value: RegSetValueExW failed." };
}
}
inline void RegKey::SetMultiStringValue(
const std::wstring& valueName,
const std::vector<std::wstring>& data
)
{
_ASSERTE(IsValid());
// First, we have to build a double-NUL-terminated multi-string from the input data
const std::vector<wchar_t> multiString = detail::BuildMultiString(data);
// Total size, in bytes, of the whole multi-string structure
const DWORD dataSize = static_cast<DWORD>(multiString.size() * sizeof(wchar_t));
LSTATUS retCode = ::RegSetValueExW(
m_hKey,
valueName.c_str(),
0, // reserved
REG_MULTI_SZ,
reinterpret_cast<const BYTE*>(multiString.data()),
dataSize
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "Cannot write multi-string value: RegSetValueExW failed." };
}
}
inline void RegKey::SetBinaryValue(const std::wstring& valueName, const std::vector<BYTE>& data)
{
_ASSERTE(IsValid());
// Total data size, in bytes
const DWORD dataSize = static_cast<DWORD>(data.size());
LSTATUS retCode = ::RegSetValueExW(
m_hKey,
valueName.c_str(),
0, // reserved
REG_BINARY,
data.data(),
dataSize
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "Cannot write binary data value: RegSetValueExW failed." };
}
}
inline void RegKey::SetBinaryValue(
const std::wstring& valueName,
const void* const data,
const DWORD dataSize
)
{
_ASSERTE(IsValid());
LSTATUS retCode = ::RegSetValueExW(
m_hKey,
valueName.c_str(),
0, // reserved
REG_BINARY,
static_cast<const BYTE*>(data),
dataSize
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "Cannot write binary data value: RegSetValueExW failed." };
}
}
inline RegResult RegKey::TrySetDwordValue(const std::wstring& valueName, const DWORD data) noexcept
{
_ASSERTE(IsValid());
return RegResult{ ::RegSetValueExW(
m_hKey,
valueName.c_str(),
0, // reserved
REG_DWORD,
reinterpret_cast<const BYTE*>(&data),
sizeof(data)
) };
}
inline RegResult RegKey::TrySetQwordValue(const std::wstring& valueName,
const ULONGLONG& data) noexcept
{
_ASSERTE(IsValid());
return RegResult{ ::RegSetValueExW(
m_hKey,
valueName.c_str(),
0, // reserved
REG_QWORD,
reinterpret_cast<const BYTE*>(&data),
sizeof(data)
) };
}
inline RegResult RegKey::TrySetStringValue(const std::wstring& valueName,
const std::wstring& data) noexcept
{
_ASSERTE(IsValid());
// String size including the terminating NUL, in bytes
const DWORD dataSize = static_cast<DWORD>((data.length() + 1) * sizeof(wchar_t));
return RegResult{ ::RegSetValueExW(
m_hKey,
valueName.c_str(),
0, // reserved
REG_SZ,
reinterpret_cast<const BYTE*>(data.c_str()),
dataSize
) };
}
inline RegResult RegKey::TrySetExpandStringValue(const std::wstring& valueName,
const std::wstring& data) noexcept
{
_ASSERTE(IsValid());
// String size including the terminating NUL, in bytes
const DWORD dataSize = static_cast<DWORD>((data.length() + 1) * sizeof(wchar_t));
return RegResult{ ::RegSetValueExW(
m_hKey,
valueName.c_str(),
0, // reserved
REG_EXPAND_SZ,
reinterpret_cast<const BYTE*>(data.c_str()),
dataSize
) };
}
inline RegResult RegKey::TrySetMultiStringValue(const std::wstring& valueName,
const std::vector<std::wstring>& data)
{
_ASSERTE(IsValid());
// First, we have to build a double-NUL-terminated multi-string from the input data.
//
// NOTE: This is the reason why I *cannot* mark this method noexcept,
// since a *dynamic allocation* happens for creating the std::vector in BuildMultiString.
// And, if dynamic memory allocations fail, an exception is thrown.
//
const std::vector<wchar_t> multiString = detail::BuildMultiString(data);
// Total size, in bytes, of the whole multi-string structure
const DWORD dataSize = static_cast<DWORD>(multiString.size() * sizeof(wchar_t));
return RegResult{ ::RegSetValueExW(
m_hKey,
valueName.c_str(),
0, // reserved
REG_MULTI_SZ,
reinterpret_cast<const BYTE*>(multiString.data()),
dataSize
) };
}
inline RegResult RegKey::TrySetBinaryValue(const std::wstring& valueName,
const std::vector<BYTE>& data) noexcept
{
_ASSERTE(IsValid());
// Total data size, in bytes
const DWORD dataSize = static_cast<DWORD>(data.size());
return RegResult{ ::RegSetValueExW(
m_hKey,
valueName.c_str(),
0, // reserved
REG_BINARY,
data.data(),
dataSize
) };
}
inline RegResult RegKey::TrySetBinaryValue(const std::wstring& valueName,
const void* const data,
const DWORD dataSize) noexcept
{
_ASSERTE(IsValid());
return RegResult{ ::RegSetValueExW(
m_hKey,
valueName.c_str(),
0, // reserved
REG_BINARY,
static_cast<const BYTE*>(data),
dataSize
) };
}
inline DWORD RegKey::GetDwordValue(const std::wstring& valueName) const
{
_ASSERTE(IsValid());
DWORD data = 0; // to be read from the registry
DWORD dataSize = sizeof(data); // size of data, in bytes
constexpr DWORD flags = RRF_RT_REG_DWORD;
LSTATUS retCode = ::RegGetValueW(
m_hKey,
nullptr, // no subkey
valueName.c_str(),
flags,
nullptr, // type not required
&data,
&dataSize
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "Cannot get DWORD value: RegGetValueW failed." };
}
return data;
}
inline ULONGLONG RegKey::GetQwordValue(const std::wstring& valueName) const
{
_ASSERTE(IsValid());
ULONGLONG data = 0; // to be read from the registry
DWORD dataSize = sizeof(data); // size of data, in bytes
constexpr DWORD flags = RRF_RT_REG_QWORD;
LSTATUS retCode = ::RegGetValueW(
m_hKey,
nullptr, // no subkey
valueName.c_str(),
flags,
nullptr, // type not required
&data,
&dataSize
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "Cannot get QWORD value: RegGetValueW failed." };
}
return data;
}
inline std::wstring RegKey::GetStringValue(const std::wstring& valueName) const
{
_ASSERTE(IsValid());
// Get the size of the result string
DWORD dataSize = 0; // size of data, in bytes
constexpr DWORD flags = RRF_RT_REG_SZ;
LSTATUS retCode = ::RegGetValueW(
m_hKey,
nullptr, // no subkey
valueName.c_str(),
flags,
nullptr, // type not required
nullptr, // output buffer not needed now
&dataSize
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "Cannot get size of string value: RegGetValueW failed." };
}
// Allocate a string of proper size.
// Note that dataSize is in bytes and includes the terminating NUL;
// we have to convert the size from bytes to wchar_ts for wstring::resize.
std::wstring result(dataSize / sizeof(wchar_t), L' ');
// Call RegGetValue for the second time to read the string's content
retCode = ::RegGetValueW(
m_hKey,
nullptr, // no subkey
valueName.c_str(),
flags,
nullptr, // type not required
result.data(), // output buffer
&dataSize
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "Cannot get string value: RegGetValueW failed." };
}
// Remove the NUL terminator scribbled by RegGetValue from the wstring
result.resize((dataSize / sizeof(wchar_t)) - 1);
return result;
}
inline std::wstring RegKey::GetExpandStringValue(
const std::wstring& valueName,
const ExpandStringOption expandOption
) const
{
_ASSERTE(IsValid());
DWORD flags = RRF_RT_REG_EXPAND_SZ;
// Adjust the flag for RegGetValue considering the expand string option specified by the caller
if (expandOption == ExpandStringOption::DontExpand)
{
flags |= RRF_NOEXPAND;
}
// Get the size of the result string
DWORD dataSize = 0; // size of data, in bytes
LSTATUS retCode = ::RegGetValueW(
m_hKey,
nullptr, // no subkey
valueName.c_str(),
flags,
nullptr, // type not required
nullptr, // output buffer not needed now
&dataSize
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "Cannot get size of expand string value: RegGetValueW failed." };
}
// Allocate a string of proper size.
// Note that dataSize is in bytes and includes the terminating NUL.
// We must convert from bytes to wchar_ts for wstring::resize.
std::wstring result(dataSize / sizeof(wchar_t), L' ');
// Call RegGetValue for the second time to read the string's content
retCode = ::RegGetValueW(
m_hKey,
nullptr, // no subkey
valueName.c_str(),
flags,
nullptr, // type not required
result.data(), // output buffer
&dataSize
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "Cannot get expand string value: RegGetValueW failed." };
}
// Remove the NUL terminator scribbled by RegGetValue from the wstring
result.resize((dataSize / sizeof(wchar_t)) - 1);
return result;
}
inline std::vector<std::wstring> RegKey::GetMultiStringValue(const std::wstring& valueName) const
{
_ASSERTE(IsValid());
// Request the size of the multi-string, in bytes
DWORD dataSize = 0;
constexpr DWORD flags = RRF_RT_REG_MULTI_SZ;
LSTATUS retCode = ::RegGetValueW(
m_hKey,
nullptr, // no subkey
valueName.c_str(),
flags,
nullptr, // type not required
nullptr, // output buffer not needed now
&dataSize
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode,
"Cannot get size of multi-string value: RegGetValueW failed." };
}
// Allocate room for the result multi-string.
// Note that dataSize is in bytes, but our vector<wchar_t>::resize method requires size
// to be expressed in wchar_ts.
std::vector<wchar_t> data(dataSize / sizeof(wchar_t), L' ');
// Read the multi-string from the registry into the vector object
retCode = ::RegGetValueW(
m_hKey,
nullptr, // no subkey
valueName.c_str(),
flags,
nullptr, // no type required
data.data(), // output buffer
&dataSize
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "Cannot get multi-string value: RegGetValueW failed." };
}
// Resize vector to the actual size returned by GetRegValue.
// Note that the vector is a vector of wchar_ts, instead the size returned by GetRegValue
// is in bytes, so we have to scale from bytes to wchar_t count.
data.resize(dataSize / sizeof(wchar_t));
// Convert the double-null-terminated string structure to a vector<wstring>,
// and return that back to the caller
return detail::ParseMultiString(data);
}
inline std::vector<BYTE> RegKey::GetBinaryValue(const std::wstring& valueName) const
{
_ASSERTE(IsValid());
// Get the size of the binary data
DWORD dataSize = 0; // size of data, in bytes
constexpr DWORD flags = RRF_RT_REG_BINARY;
LSTATUS retCode = ::RegGetValueW(
m_hKey,
nullptr, // no subkey
valueName.c_str(),
flags,
nullptr, // type not required
nullptr, // output buffer not needed now
&dataSize
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "Cannot get size of binary data: RegGetValueW failed." };
}
// Allocate a buffer of proper size to store the binary data
std::vector<BYTE> data(dataSize);
// Handle the special case of zero-length binary data:
// If the binary data value in the registry is empty, just return
if (dataSize == 0)
{
_ASSERTE(data.empty());
return data;
}
// Call RegGetValue for the second time to read the data content
retCode = ::RegGetValueW(
m_hKey,
nullptr, // no subkey
valueName.c_str(),
flags,
nullptr, // type not required
data.data(), // output buffer
&dataSize
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "Cannot get binary data: RegGetValueW failed." };
}
return data;
}
inline RegExpected<DWORD> RegKey::TryGetDwordValue(const std::wstring& valueName) const
{
_ASSERTE(IsValid());
using RegValueType = DWORD;
DWORD data = 0; // to be read from the registry
DWORD dataSize = sizeof(data); // size of data, in bytes
constexpr DWORD flags = RRF_RT_REG_DWORD;
LSTATUS retCode = ::RegGetValueW(
m_hKey,
nullptr, // no subkey
valueName.c_str(),
flags,
nullptr, // type not required
&data,
&dataSize
);
if (retCode != ERROR_SUCCESS)
{
return detail::MakeRegExpectedWithError<RegValueType>(retCode);
}
return RegExpected<RegValueType>{ data };
}
inline RegExpected<ULONGLONG> RegKey::TryGetQwordValue(const std::wstring& valueName) const
{
_ASSERTE(IsValid());
using RegValueType = ULONGLONG;
ULONGLONG data = 0; // to be read from the registry
DWORD dataSize = sizeof(data); // size of data, in bytes
constexpr DWORD flags = RRF_RT_REG_QWORD;
LSTATUS retCode = ::RegGetValueW(
m_hKey,
nullptr, // no subkey
valueName.c_str(),
flags,
nullptr, // type not required
&data,
&dataSize
);
if (retCode != ERROR_SUCCESS)
{
return detail::MakeRegExpectedWithError<RegValueType>(retCode);
}
return RegExpected<RegValueType>{ data };
}
inline RegExpected<std::wstring> RegKey::TryGetStringValue(const std::wstring& valueName) const
{
_ASSERTE(IsValid());
using RegValueType = std::wstring;
// Get the size of the result string
DWORD dataSize = 0; // size of data, in bytes
constexpr DWORD flags = RRF_RT_REG_SZ;
LSTATUS retCode = ::RegGetValueW(
m_hKey,
nullptr, // no subkey
valueName.c_str(),
flags,
nullptr, // type not required
nullptr, // output buffer not needed now
&dataSize
);
if (retCode != ERROR_SUCCESS)
{
return detail::MakeRegExpectedWithError<RegValueType>(retCode);
}
// Allocate a string of proper size.
// Note that dataSize is in bytes and includes the terminating NUL;
// we have to convert the size from bytes to wchar_ts for wstring::resize.
std::wstring result(dataSize / sizeof(wchar_t), L' ');
// Call RegGetValue for the second time to read the string's content
retCode = ::RegGetValueW(
m_hKey,
nullptr, // no subkey
valueName.c_str(),
flags,
nullptr, // type not required
result.data(), // output buffer
&dataSize
);
if (retCode != ERROR_SUCCESS)
{
return detail::MakeRegExpectedWithError<RegValueType>(retCode);
}
// Remove the NUL terminator scribbled by RegGetValue from the wstring
result.resize((dataSize / sizeof(wchar_t)) - 1);
return RegExpected<RegValueType>{ result };
}
inline RegExpected<std::wstring> RegKey::TryGetExpandStringValue(
const std::wstring& valueName,
const ExpandStringOption expandOption
) const
{
_ASSERTE(IsValid());
using RegValueType = std::wstring;
DWORD flags = RRF_RT_REG_EXPAND_SZ;
// Adjust the flag for RegGetValue considering the expand string option specified by the caller
if (expandOption == ExpandStringOption::DontExpand)
{
flags |= RRF_NOEXPAND;
}
// Get the size of the result string
DWORD dataSize = 0; // size of data, in bytes
LSTATUS retCode = ::RegGetValueW(
m_hKey,
nullptr, // no subkey
valueName.c_str(),
flags,
nullptr, // type not required
nullptr, // output buffer not needed now
&dataSize
);
if (retCode != ERROR_SUCCESS)
{
return detail::MakeRegExpectedWithError<RegValueType>(retCode);
}
// Allocate a string of proper size.
// Note that dataSize is in bytes and includes the terminating NUL.
// We must convert from bytes to wchar_ts for wstring::resize.
std::wstring result(dataSize / sizeof(wchar_t), L' ');
// Call RegGetValue for the second time to read the string's content
retCode = ::RegGetValueW(
m_hKey,
nullptr, // no subkey
valueName.c_str(),
flags,
nullptr, // type not required
result.data(), // output buffer
&dataSize
);
if (retCode != ERROR_SUCCESS)
{
return detail::MakeRegExpectedWithError<RegValueType>(retCode);
}
// Remove the NUL terminator scribbled by RegGetValue from the wstring
result.resize((dataSize / sizeof(wchar_t)) - 1);
return RegExpected<RegValueType>{ result };
}
inline RegExpected<std::vector<std::wstring>>
RegKey::TryGetMultiStringValue(const std::wstring& valueName) const
{
_ASSERTE(IsValid());
using RegValueType = std::vector<std::wstring>;
// Request the size of the multi-string, in bytes
DWORD dataSize = 0;
constexpr DWORD flags = RRF_RT_REG_MULTI_SZ;
LSTATUS retCode = ::RegGetValueW(
m_hKey,
nullptr, // no subkey
valueName.c_str(),
flags,
nullptr, // type not required
nullptr, // output buffer not needed now
&dataSize
);
if (retCode != ERROR_SUCCESS)
{
return detail::MakeRegExpectedWithError<RegValueType>(retCode);
}
// Allocate room for the result multi-string.
// Note that dataSize is in bytes, but our vector<wchar_t>::resize method requires size
// to be expressed in wchar_ts.
std::vector<wchar_t> data(dataSize / sizeof(wchar_t), L' ');
// Read the multi-string from the registry into the vector object
retCode = ::RegGetValueW(
m_hKey,
nullptr, // no subkey
valueName.c_str(),
flags,
nullptr, // no type required
data.data(), // output buffer
&dataSize
);
if (retCode != ERROR_SUCCESS)
{
return detail::MakeRegExpectedWithError<RegValueType>(retCode);
}
// Resize vector to the actual size returned by GetRegValue.
// Note that the vector is a vector of wchar_ts, instead the size returned by GetRegValue
// is in bytes, so we have to scale from bytes to wchar_t count.
data.resize(dataSize / sizeof(wchar_t));
// Convert the double-null-terminated string structure to a vector<wstring>,
// and return that back to the caller
return RegExpected<RegValueType>{ detail::ParseMultiString(data) };
}
inline RegExpected<std::vector<BYTE>>
RegKey::TryGetBinaryValue(const std::wstring& valueName) const
{
_ASSERTE(IsValid());
using RegValueType = std::vector<BYTE>;
// Get the size of the binary data
DWORD dataSize = 0; // size of data, in bytes
constexpr DWORD flags = RRF_RT_REG_BINARY;
LSTATUS retCode = ::RegGetValueW(
m_hKey,
nullptr, // no subkey
valueName.c_str(),
flags,
nullptr, // type not required
nullptr, // output buffer not needed now
&dataSize
);
if (retCode != ERROR_SUCCESS)
{
return detail::MakeRegExpectedWithError<RegValueType>(retCode);
}
// Allocate a buffer of proper size to store the binary data
std::vector<BYTE> data(dataSize);
// Handle the special case of zero-length binary data:
// If the binary data value in the registry is empty, just return
if (dataSize == 0)
{
_ASSERTE(data.empty());
return RegExpected<RegValueType>{ data };
}
// Call RegGetValue for the second time to read the data content
retCode = ::RegGetValueW(
m_hKey,
nullptr, // no subkey
valueName.c_str(),
flags,
nullptr, // type not required
data.data(), // output buffer
&dataSize
);
if (retCode != ERROR_SUCCESS)
{
return detail::MakeRegExpectedWithError<RegValueType>(retCode);
}
return RegExpected<RegValueType>{ data };
}
inline std::vector<std::wstring> RegKey::EnumSubKeys() const
{
_ASSERTE(IsValid());
// Get some useful enumeration info, like the total number of subkeys
// and the maximum length of the subkey names
DWORD subKeyCount = 0;
DWORD maxSubKeyNameLen = 0;
LSTATUS retCode = ::RegQueryInfoKeyW(
m_hKey,
nullptr, // no user-defined class
nullptr, // no user-defined class size
nullptr, // reserved
&subKeyCount,
&maxSubKeyNameLen,
nullptr, // no subkey class length
nullptr, // no value count
nullptr, // no value name max length
nullptr, // no max value length
nullptr, // no security descriptor
nullptr // no last write time
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{
retCode,
"RegQueryInfoKeyW failed while preparing for subkey enumeration."
};
}
// NOTE: According to the MSDN documentation, the size returned for subkey name max length
// does *not* include the terminating NUL, so let's add +1 to take it into account
// when I allocate the buffer for reading subkey names.
maxSubKeyNameLen++;
// Preallocate a buffer for the subkey names
auto nameBuffer = std::make_unique<wchar_t[]>(maxSubKeyNameLen);
// The result subkey names will be stored here
std::vector<std::wstring> subkeyNames;
// Reserve room in the vector to speed up the following insertion loop
subkeyNames.reserve(subKeyCount);
// Enumerate all the subkeys
for (DWORD index = 0; index < subKeyCount; index++)
{
// Get the name of the current subkey
DWORD subKeyNameLen = maxSubKeyNameLen;
retCode = ::RegEnumKeyExW(
m_hKey,
index,
nameBuffer.get(),
&subKeyNameLen,
nullptr, // reserved
nullptr, // no class
nullptr, // no class
nullptr // no last write time
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "Cannot enumerate subkeys: RegEnumKeyExW failed." };
}
// On success, the ::RegEnumKeyEx API writes the length of the
// subkey name in the subKeyNameLen output parameter
// (not including the terminating NUL).
// So I can build a wstring based on that length.
subkeyNames.emplace_back(nameBuffer.get(), subKeyNameLen);
}
return subkeyNames;
}
inline std::vector<std::pair<std::wstring, DWORD>> RegKey::EnumValues() const
{
_ASSERTE(IsValid());
// Get useful enumeration info, like the total number of values
// and the maximum length of the value names
DWORD valueCount = 0;
DWORD maxValueNameLen = 0;
LSTATUS retCode = ::RegQueryInfoKeyW(
m_hKey,
nullptr, // no user-defined class
nullptr, // no user-defined class size
nullptr, // reserved
nullptr, // no subkey count
nullptr, // no subkey max length
nullptr, // no subkey class length
&valueCount,
&maxValueNameLen,
nullptr, // no max value length
nullptr, // no security descriptor
nullptr // no last write time
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{
retCode,
"RegQueryInfoKeyW failed while preparing for value enumeration."
};
}
// NOTE: According to the MSDN documentation, the size returned for value name max length
// does *not* include the terminating NUL, so let's add +1 to take it into account
// when I allocate the buffer for reading value names.
maxValueNameLen++;
// Preallocate a buffer for the value names
auto nameBuffer = std::make_unique<wchar_t[]>(maxValueNameLen);
// The value names and types will be stored here
std::vector<std::pair<std::wstring, DWORD>> valueInfo;
// Reserve room in the vector to speed up the following insertion loop
valueInfo.reserve(valueCount);
// Enumerate all the values
for (DWORD index = 0; index < valueCount; index++)
{
// Get the name and the type of the current value
DWORD valueNameLen = maxValueNameLen;
DWORD valueType = 0;
retCode = ::RegEnumValueW(
m_hKey,
index,
nameBuffer.get(),
&valueNameLen,
nullptr, // reserved
&valueType,
nullptr, // no data
nullptr // no data size
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "Cannot enumerate values: RegEnumValueW failed." };
}
// On success, the RegEnumValue API writes the length of the
// value name in the valueNameLen output parameter
// (not including the terminating NUL).
// So we can build a wstring based on that.
valueInfo.emplace_back(
std::wstring{ nameBuffer.get(), valueNameLen },
valueType
);
}
return valueInfo;
}
inline RegExpected<std::vector<std::wstring>> RegKey::TryEnumSubKeys() const
{
_ASSERTE(IsValid());
using ReturnType = std::vector<std::wstring>;
// Get some useful enumeration info, like the total number of subkeys
// and the maximum length of the subkey names
DWORD subKeyCount = 0;
DWORD maxSubKeyNameLen = 0;
LSTATUS retCode = ::RegQueryInfoKeyW(
m_hKey,
nullptr, // no user-defined class
nullptr, // no user-defined class size
nullptr, // reserved
&subKeyCount,
&maxSubKeyNameLen,
nullptr, // no subkey class length
nullptr, // no value count
nullptr, // no value name max length
nullptr, // no max value length
nullptr, // no security descriptor
nullptr // no last write time
);
if (retCode != ERROR_SUCCESS)
{
return detail::MakeRegExpectedWithError<ReturnType>(retCode);
}
// NOTE: According to the MSDN documentation, the size returned for subkey name max length
// does *not* include the terminating NUL, so let's add +1 to take it into account
// when I allocate the buffer for reading subkey names.
maxSubKeyNameLen++;
// Preallocate a buffer for the subkey names
auto nameBuffer = std::make_unique<wchar_t[]>(maxSubKeyNameLen);
// The result subkey names will be stored here
std::vector<std::wstring> subkeyNames;
// Reserve room in the vector to speed up the following insertion loop
subkeyNames.reserve(subKeyCount);
// Enumerate all the subkeys
for (DWORD index = 0; index < subKeyCount; index++)
{
// Get the name of the current subkey
DWORD subKeyNameLen = maxSubKeyNameLen;
retCode = ::RegEnumKeyExW(
m_hKey,
index,
nameBuffer.get(),
&subKeyNameLen,
nullptr, // reserved
nullptr, // no class
nullptr, // no class
nullptr // no last write time
);
if (retCode != ERROR_SUCCESS)
{
return detail::MakeRegExpectedWithError<ReturnType>(retCode);
}
// On success, the ::RegEnumKeyEx API writes the length of the
// subkey name in the subKeyNameLen output parameter
// (not including the terminating NUL).
// So I can build a wstring based on that length.
subkeyNames.emplace_back(nameBuffer.get(), subKeyNameLen);
}
return RegExpected<ReturnType>{ subkeyNames };
}
inline RegExpected<std::vector<std::pair<std::wstring, DWORD>>> RegKey::TryEnumValues() const
{
_ASSERTE(IsValid());
using ReturnType = std::vector<std::pair<std::wstring, DWORD>>;
// Get useful enumeration info, like the total number of values
// and the maximum length of the value names
DWORD valueCount = 0;
DWORD maxValueNameLen = 0;
LSTATUS retCode = ::RegQueryInfoKeyW(
m_hKey,
nullptr, // no user-defined class
nullptr, // no user-defined class size
nullptr, // reserved
nullptr, // no subkey count
nullptr, // no subkey max length
nullptr, // no subkey class length
&valueCount,
&maxValueNameLen,
nullptr, // no max value length
nullptr, // no security descriptor
nullptr // no last write time
);
if (retCode != ERROR_SUCCESS)
{
return detail::MakeRegExpectedWithError<ReturnType>(retCode);
}
// NOTE: According to the MSDN documentation, the size returned for value name max length
// does *not* include the terminating NUL, so let's add +1 to take it into account
// when I allocate the buffer for reading value names.
maxValueNameLen++;
// Preallocate a buffer for the value names
auto nameBuffer = std::make_unique<wchar_t[]>(maxValueNameLen);
// The value names and types will be stored here
std::vector<std::pair<std::wstring, DWORD>> valueInfo;
// Reserve room in the vector to speed up the following insertion loop
valueInfo.reserve(valueCount);
// Enumerate all the values
for (DWORD index = 0; index < valueCount; index++)
{
// Get the name and the type of the current value
DWORD valueNameLen = maxValueNameLen;
DWORD valueType = 0;
retCode = ::RegEnumValueW(
m_hKey,
index,
nameBuffer.get(),
&valueNameLen,
nullptr, // reserved
&valueType,
nullptr, // no data
nullptr // no data size
);
if (retCode != ERROR_SUCCESS)
{
return detail::MakeRegExpectedWithError<ReturnType>(retCode);
}
// On success, the RegEnumValue API writes the length of the
// value name in the valueNameLen output parameter
// (not including the terminating NUL).
// So we can build a wstring based on that.
valueInfo.emplace_back(
std::wstring{ nameBuffer.get(), valueNameLen },
valueType
);
}
return RegExpected<ReturnType>{ valueInfo };
}
inline DWORD RegKey::QueryValueType(const std::wstring& valueName) const
{
_ASSERTE(IsValid());
DWORD typeId = 0; // will be returned by RegQueryValueEx
LSTATUS retCode = ::RegQueryValueExW(
m_hKey,
valueName.c_str(),
nullptr, // reserved
&typeId,
nullptr, // not interested
nullptr // not interested
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "Cannot get the value type: RegQueryValueExW failed." };
}
return typeId;
}
inline RegExpected<DWORD> RegKey::TryQueryValueType(const std::wstring& valueName) const
{
_ASSERTE(IsValid());
using ReturnType = DWORD;
DWORD typeId = 0; // will be returned by RegQueryValueEx
LSTATUS retCode = ::RegQueryValueExW(
m_hKey,
valueName.c_str(),
nullptr, // reserved
&typeId,
nullptr, // not interested
nullptr // not interested
);
if (retCode != ERROR_SUCCESS)
{
return detail::MakeRegExpectedWithError<ReturnType>(retCode);
}
return RegExpected<ReturnType>{ typeId };
}
inline RegKey::InfoKey RegKey::QueryInfoKey() const
{
_ASSERTE(IsValid());
InfoKey infoKey{};
LSTATUS retCode = ::RegQueryInfoKeyW(
m_hKey,
nullptr,
nullptr,
nullptr,
&(infoKey.NumberOfSubKeys),
nullptr,
nullptr,
&(infoKey.NumberOfValues),
nullptr,
nullptr,
nullptr,
&(infoKey.LastWriteTime)
);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "RegQueryInfoKeyW failed." };
}
return infoKey;
}
inline RegExpected<RegKey::InfoKey> RegKey::TryQueryInfoKey() const
{
_ASSERTE(IsValid());
using ReturnType = RegKey::InfoKey;
InfoKey infoKey{};
LSTATUS retCode = ::RegQueryInfoKeyW(
m_hKey,
nullptr,
nullptr,
nullptr,
&(infoKey.NumberOfSubKeys),
nullptr,
nullptr,
&(infoKey.NumberOfValues),
nullptr,
nullptr,
nullptr,
&(infoKey.LastWriteTime)
);
if (retCode != ERROR_SUCCESS)
{
return detail::MakeRegExpectedWithError<ReturnType>(retCode);
}
return RegExpected<ReturnType>{ infoKey };
}
inline RegKey::KeyReflection RegKey::QueryReflectionKey() const
{
BOOL isReflectionDisabled = FALSE;
LSTATUS retCode = ::RegQueryReflectionKey(m_hKey, &isReflectionDisabled);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "RegQueryReflectionKey failed." };
}
return (isReflectionDisabled ? KeyReflection::ReflectionDisabled
: KeyReflection::ReflectionEnabled);
}
inline RegExpected<RegKey::KeyReflection> RegKey::TryQueryReflectionKey() const
{
using ReturnType = RegKey::KeyReflection;
BOOL isReflectionDisabled = FALSE;
LSTATUS retCode = ::RegQueryReflectionKey(m_hKey, &isReflectionDisabled);
if (retCode != ERROR_SUCCESS)
{
return detail::MakeRegExpectedWithError<ReturnType>(retCode);
}
KeyReflection keyReflection = isReflectionDisabled ? KeyReflection::ReflectionDisabled
: KeyReflection::ReflectionEnabled;
return RegExpected<ReturnType>{ keyReflection };
}
inline void RegKey::DeleteValue(const std::wstring& valueName)
{
_ASSERTE(IsValid());
LSTATUS retCode = ::RegDeleteValueW(m_hKey, valueName.c_str());
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "RegDeleteValueW failed." };
}
}
inline RegResult RegKey::TryDeleteValue(const std::wstring& valueName) noexcept
{
_ASSERTE(IsValid());
return RegResult{ ::RegDeleteValueW(m_hKey, valueName.c_str()) };
}
inline void RegKey::DeleteKey(const std::wstring& subKey, const REGSAM desiredAccess)
{
_ASSERTE(IsValid());
LSTATUS retCode = ::RegDeleteKeyExW(m_hKey, subKey.c_str(), desiredAccess, 0);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "RegDeleteKeyExW failed." };
}
}
inline RegResult RegKey::TryDeleteKey(const std::wstring& subKey,
const REGSAM desiredAccess) noexcept
{
_ASSERTE(IsValid());
return RegResult{ ::RegDeleteKeyExW(m_hKey, subKey.c_str(), desiredAccess, 0) };
}
inline void RegKey::DeleteTree(const std::wstring& subKey)
{
_ASSERTE(IsValid());
LSTATUS retCode = ::RegDeleteTreeW(m_hKey, subKey.c_str());
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "RegDeleteTreeW failed." };
}
}
inline RegResult RegKey::TryDeleteTree(const std::wstring& subKey) noexcept
{
_ASSERTE(IsValid());
return RegResult{ ::RegDeleteTreeW(m_hKey, subKey.c_str()) };
}
inline void RegKey::CopyTree(const std::wstring& sourceSubKey, const RegKey& destKey)
{
_ASSERTE(IsValid());
LSTATUS retCode = ::RegCopyTreeW(m_hKey, sourceSubKey.c_str(), destKey.Get());
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "RegCopyTreeW failed." };
}
}
inline RegResult RegKey::TryCopyTree(const std::wstring& sourceSubKey,
const RegKey& destKey) noexcept
{
_ASSERTE(IsValid());
return RegResult{ ::RegCopyTreeW(m_hKey, sourceSubKey.c_str(), destKey.Get()) };
}
inline void RegKey::FlushKey()
{
_ASSERTE(IsValid());
LSTATUS retCode = ::RegFlushKey(m_hKey);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "RegFlushKey failed." };
}
}
inline RegResult RegKey::TryFlushKey() noexcept
{
_ASSERTE(IsValid());
return RegResult{ ::RegFlushKey(m_hKey) };
}
inline void RegKey::LoadKey(const std::wstring& subKey, const std::wstring& filename)
{
Close();
LSTATUS retCode = ::RegLoadKeyW(m_hKey, subKey.c_str(), filename.c_str());
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "RegLoadKeyW failed." };
}
}
inline RegResult RegKey::TryLoadKey(const std::wstring& subKey,
const std::wstring& filename) noexcept
{
Close();
return RegResult{ ::RegLoadKeyW(m_hKey, subKey.c_str(), filename.c_str()) };
}
inline void RegKey::SaveKey(
const std::wstring& filename,
SECURITY_ATTRIBUTES* const securityAttributes
) const
{
_ASSERTE(IsValid());
LSTATUS retCode = ::RegSaveKeyW(m_hKey, filename.c_str(), securityAttributes);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "RegSaveKeyW failed." };
}
}
inline RegResult RegKey::TrySaveKey(
const std::wstring& filename,
SECURITY_ATTRIBUTES* const securityAttributes
) const noexcept
{
_ASSERTE(IsValid());
return RegResult{ ::RegSaveKeyW(m_hKey, filename.c_str(), securityAttributes) };
}
inline void RegKey::EnableReflectionKey()
{
LSTATUS retCode = ::RegEnableReflectionKey(m_hKey);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "RegEnableReflectionKey failed." };
}
}
inline RegResult RegKey::TryEnableReflectionKey() noexcept
{
return RegResult{ ::RegEnableReflectionKey(m_hKey) };
}
inline void RegKey::DisableReflectionKey()
{
LSTATUS retCode = ::RegDisableReflectionKey(m_hKey);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "RegDisableReflectionKey failed." };
}
}
inline RegResult RegKey::TryDisableReflectionKey() noexcept
{
return RegResult{ ::RegDisableReflectionKey(m_hKey) };
}
inline void RegKey::ConnectRegistry(const std::wstring& machineName, const HKEY hKeyPredefined)
{
// Safely close any previously opened key
Close();
HKEY hKeyResult = nullptr;
LSTATUS retCode = ::RegConnectRegistryW(machineName.c_str(), hKeyPredefined, &hKeyResult);
if (retCode != ERROR_SUCCESS)
{
throw RegException{ retCode, "RegConnectRegistryW failed." };
}
// Take ownership of the result key
m_hKey = hKeyResult;
}
inline RegResult RegKey::TryConnectRegistry(const std::wstring& machineName,
const HKEY hKeyPredefined) noexcept
{
// Safely close any previously opened key
Close();
HKEY hKeyResult = nullptr;
RegResult retCode{ ::RegConnectRegistryW(machineName.c_str(), hKeyPredefined, &hKeyResult) };
if (retCode.Failed())
{
return retCode;
}
// Take ownership of the result key
m_hKey = hKeyResult;
_ASSERTE(retCode.IsOk());
return retCode;
}
inline std::wstring RegKey::RegTypeToString(const DWORD regType)
{
switch (regType)
{
case REG_SZ: return L"REG_SZ";
case REG_EXPAND_SZ: return L"REG_EXPAND_SZ";
case REG_MULTI_SZ: return L"REG_MULTI_SZ";
case REG_DWORD: return L"REG_DWORD";
case REG_QWORD: return L"REG_QWORD";
case REG_BINARY: return L"REG_BINARY";
default: return L"Unknown/unsupported registry type";
}
}
//------------------------------------------------------------------------------
// RegException Inline Methods
//------------------------------------------------------------------------------
inline RegException::RegException(const LSTATUS errorCode, const char* const message)
: std::system_error{ errorCode, std::system_category(), message }
{}
inline RegException::RegException(const LSTATUS errorCode, const std::string& message)
: std::system_error{ errorCode, std::system_category(), message }
{}
//------------------------------------------------------------------------------
// RegResult Inline Methods
//------------------------------------------------------------------------------
inline RegResult::RegResult(const LSTATUS result) noexcept
: m_result{ result }
{}
inline bool RegResult::IsOk() const noexcept
{
return m_result == ERROR_SUCCESS;
}
inline bool RegResult::Failed() const noexcept
{
return m_result != ERROR_SUCCESS;
}
inline RegResult::operator bool() const noexcept
{
return IsOk();
}
inline LSTATUS RegResult::Code() const noexcept
{
return m_result;
}
inline std::wstring RegResult::ErrorMessage() const
{
return ErrorMessage(MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT));
}
inline std::wstring RegResult::ErrorMessage(const DWORD languageId) const
{
// Invoke FormatMessage() to retrieve the error message from Windows
detail::ScopedLocalFree<wchar_t> messagePtr;
DWORD retCode = ::FormatMessageW(
FORMAT_MESSAGE_ALLOCATE_BUFFER |
FORMAT_MESSAGE_FROM_SYSTEM |
FORMAT_MESSAGE_IGNORE_INSERTS,
nullptr,
m_result,
languageId,
reinterpret_cast<LPWSTR>(messagePtr.AddressOf()),
0,
nullptr
);
if (retCode == 0)
{
// FormatMessage failed: return an empty string
return std::wstring{};
}
// Safely copy the C-string returned by FormatMessage() into a std::wstring object,
// and return it back to the caller.
return std::wstring{ messagePtr.Get() };
}
//------------------------------------------------------------------------------
// RegExpected Inline Methods
//------------------------------------------------------------------------------
template <typename T>
inline RegExpected<T>::RegExpected(const RegResult& errorCode) noexcept
: m_var{ errorCode }
{}
template <typename T>
inline RegExpected<T>::RegExpected(const T& value)
: m_var{ value }
{}
template <typename T>
inline RegExpected<T>::RegExpected(T&& value)
: m_var{ std::move(value) }
{}
template <typename T>
inline RegExpected<T>::operator bool() const noexcept
{
return IsValid();
}
template <typename T>
inline bool RegExpected<T>::IsValid() const noexcept
{
return std::holds_alternative<T>(m_var);
}
template <typename T>
inline const T& RegExpected<T>::GetValue() const
{
// Check that the object stores a valid value
_ASSERTE(IsValid());
// If the object is in a valid state, the variant stores an instance of T
return std::get<T>(m_var);
}
template <typename T>
inline RegResult RegExpected<T>::GetError() const
{
// Check that the object is in an invalid state
_ASSERTE(!IsValid());
// If the object is in an invalid state, the variant stores a RegResult
// that represents an error code from the Windows Registry API
return std::get<RegResult>(m_var);
}
} // namespace winreg
#endif // GIOVANNI_DICANIO_WINREG_HPP_INCLUDED