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// Copyright (C) 2019 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#define UMDF_USING_NTSTATUS // Avoid ntstatus redefinitions
#include "qwinregistry_p.h"
#include <QtCore/qvarlengtharray.h>
#include <QtCore/qdebug.h>
#include <QtCore/qendian.h>
#include <QtCore/qlist.h>
#include <QtCore/qwineventnotifier.h>
#include <QtCore/private/qsystemerror_p.h>
#include <ntstatus.h>
// User mode version of ZwQueryKey, as per:
// https://learn.microsoft.com/en-us/windows-hardware/drivers/ddi/wdm/nf-wdm-zwquerykey
extern "C" NTSTATUS NTSYSCALLAPI NTAPI NtQueryKey(HANDLE KeyHandle, int KeyInformationClass,
PVOID KeyInformation, ULONG Length, PULONG ResultLength);
QT_BEGIN_NAMESPACE
using namespace Qt::StringLiterals;
QWinRegistryKey::QWinRegistryKey(QObject *parent)
: QObject(parent)
{
}
// Open a key with the specified permissions (KEY_READ/KEY_WRITE).
// "access" is to explicitly use the 32- or 64-bit branch.
QWinRegistryKey::QWinRegistryKey(HKEY parentHandle, QStringView subKey,
REGSAM permissions, REGSAM access,
QObject *parent)
: QObject(parent)
{
if (RegOpenKeyExW(parentHandle, reinterpret_cast<const wchar_t *>(subKey.utf16()),
0, permissions | access, &m_key) != ERROR_SUCCESS) {
m_key = nullptr;
}
}
QWinRegistryKey::~QWinRegistryKey()
{
close();
}
void QWinRegistryKey::close()
{
if (isValid()) {
RegCloseKey(m_key);
m_key = nullptr;
}
}
QString QWinRegistryKey::name() const
{
if (!isValid())
return {};
// https://learn.microsoft.com/en-us/windows-hardware/drivers/ddi/ntddk/ns-ntddk-_key_name_information
constexpr int kKeyNameInformation = 3;
struct KeyNameInformation { ULONG length = 0; WCHAR name[1] = {}; };
// Resolve name of key iteratively by first computing the needed size,
// and then querying the name, accounting for the possibility that the
// name length changes behind our back a few times.
DWORD keyInformationSize = 0;
for (int i = 0; i < 5; ++i) {
QByteArray buffer(keyInformationSize, 0u);
auto *keyNameInformation = reinterpret_cast<KeyNameInformation *>(buffer.data());
switch (NtQueryKey(m_key, kKeyNameInformation, keyNameInformation,
keyInformationSize, &keyInformationSize)) {
case STATUS_BUFFER_TOO_SMALL:
case STATUS_BUFFER_OVERFLOW:
continue;
case STATUS_SUCCESS: {
return QString::fromWCharArray(keyNameInformation->name,
keyNameInformation->length / sizeof(wchar_t));
}
default:
return {};
}
}
return {};
}
QVariant QWinRegistryKey::value(QStringView subKey) const
{
// NOTE: Empty value name is allowed in Windows registry, it means the default
// or unnamed value of a key, you can read/write/delete such value normally.
if (!isValid())
return {};
// Use nullptr when we need to access the default value.
const auto subKeyC = subKey.isEmpty() ? nullptr : reinterpret_cast<const wchar_t *>(subKey.utf16());
// Get the size and type of the value.
DWORD dataType = REG_NONE;
DWORD dataSize = 0;
LONG ret = RegQueryValueExW(m_key, subKeyC, nullptr, &dataType, nullptr, &dataSize);
if (ret != ERROR_SUCCESS)
return {};
// Workaround for rare cases where the trailing '\0' is missing.
if (dataType == REG_SZ || dataType == REG_EXPAND_SZ)
dataSize += 2;
else if (dataType == REG_MULTI_SZ)
dataSize += 4;
// Get the value.
QVarLengthArray<unsigned char> data(dataSize);
std::fill(data.data(), data.data() + dataSize, 0u);
ret = RegQueryValueExW(m_key, subKeyC, nullptr, nullptr, data.data(), &dataSize);
if (ret != ERROR_SUCCESS)
return {};
switch (dataType) {
case REG_SZ:
case REG_EXPAND_SZ: {
if (dataSize > 0) {
return QString::fromWCharArray(
reinterpret_cast<const wchar_t *>(data.constData()));
}
return QString();
}
case REG_MULTI_SZ: {
if (dataSize > 0) {
QStringList list = {};
int i = 0;
while (true) {
const QString str = QString::fromWCharArray(
reinterpret_cast<const wchar_t *>(data.constData()) + i);
i += str.length() + 1;
if (str.isEmpty())
break;
list.append(str);
}
return list;
}
return QStringList();
}
case REG_NONE: // No specific type, treat as binary data.
case REG_BINARY: {
if (dataSize > 0) {
return QString::fromWCharArray(
reinterpret_cast<const wchar_t *>(data.constData()), data.size() / 2);
}
return QString();
}
case REG_DWORD: // Same as REG_DWORD_LITTLE_ENDIAN
return qFromLittleEndian<quint32>(data.constData());
case REG_DWORD_BIG_ENDIAN:
return qFromBigEndian<quint32>(data.constData());
case REG_QWORD: // Same as REG_QWORD_LITTLE_ENDIAN
return qFromLittleEndian<quint64>(data.constData());
default:
break;
}
return {};
}
// Returns the value of the specified subKey as a string, obtained using
// qvariant_cast from the underlying QVariant. If that value is not a string,
// or the subKey has no value, a string whose isNull() is true is returned.
// Otherwise, the resulting string (which may be empty) is returned.
QString QWinRegistryKey::stringValue(QStringView subKey) const
{
return value<QString>(subKey).value_or(QString());
}
void QWinRegistryKey::connectNotify(const QMetaMethod &signal)
{
if (signal != QMetaMethod::fromSignal(&QWinRegistryKey::valueChanged))
return;
if (!isValid())
return;
if (m_keyChangedEvent)
return;
m_keyChangedEvent.reset(CreateEvent(nullptr, false, false, nullptr));
auto *notifier = new QWinEventNotifier(m_keyChangedEvent.get(), this);
auto registerForNotification = [this] {
constexpr auto changeFilter =
REG_NOTIFY_CHANGE_NAME
| REG_NOTIFY_CHANGE_ATTRIBUTES
| REG_NOTIFY_CHANGE_LAST_SET
| REG_NOTIFY_CHANGE_SECURITY;
if (auto status = RegNotifyChangeKeyValue(m_key, true, changeFilter,
m_keyChangedEvent.get(), true); status != ERROR_SUCCESS) {
qWarning() << "Failed to register notification for registry key"
<< this << "due to" << QSystemError::windowsString(status);
}
};
QObject::connect(notifier, &QWinEventNotifier::activated, this,
[this, registerForNotification] {
emit valueChanged();
registerForNotification();
});
registerForNotification();
return QObject::connectNotify(signal);
}
#ifndef QT_NO_DEBUG_STREAM
QDebug operator<<(QDebug debug, const QWinRegistryKey &key)
{
QDebugStateSaver saver(debug);
debug.nospace();
debug << "QWinRegistryKey(";
if (key.isValid())
debug << key.name();
debug << ')';
return debug;
}
#endif
QT_END_NAMESPACE
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