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#include <QtCore/qstringlist.h>

#include "registry.h"

/*!

  Returns the path part of a registry key.

  e.g.

      For a key

          "Software\\Microsoft\\VisualStudio\\8.0\\Setup\\VC\\ProductDir"

      it returns

          "Software\\Microsoft\\VisualStudio\\8.0\\Setup\\VC\\"

*/

static QString keyPath(const QString &rKey)

{

    int idx = rKey.lastIndexOf(QLatin1Char('\\'));

    if (idx == -1)

        return QString();

    return rKey.left(idx + 1);

}

/*!

  Returns the name part of a registry key.

  e.g.

      For a key

          "Software\\Microsoft\\VisualStudio\\8.0\\Setup\\VC\\ProductDir"

      it returns

          "ProductDir"

*/

static QString keyName(const QString &rKey)

{

    int idx = rKey.lastIndexOf(QLatin1Char('\\'));

    if (idx == -1)

        return rKey;

    QString res(rKey.mid(idx + 1));

    if (res == "Default" || res == ".")

        res = "";

    return res;

}

QString readRegistryKey(HKEY parentHandle, const QString &rSubkey)

{

    QString result;

#ifdef Q_OS_WIN32

    QString rSubkeyName = keyName(rSubkey);

    QString rSubkeyPath = keyPath(rSubkey);

    HKEY handle = 0;

    LONG res = RegOpenKeyEx(parentHandle, (wchar_t*)rSubkeyPath.utf16(), 0, KEY_READ, &handle);

    if (res != ERROR_SUCCESS)

        return QString();

    // get the size and type of the value

    DWORD dataType;

    DWORD dataSize;

    res = RegQueryValueEx(handle, (wchar_t*)rSubkeyName.utf16(), 0, &dataType, 0, &dataSize);

    if (res != ERROR_SUCCESS) {

        RegCloseKey(handle);

        return QString();

    }

    // get the value

    QByteArray data(dataSize, 0);

    res = RegQueryValueEx(handle, (wchar_t*)rSubkeyName.utf16(), 0, 0,

                          reinterpret_cast<unsigned char*>(data.data()), &dataSize);

    if (res != ERROR_SUCCESS) {

        RegCloseKey(handle);

        return QString();

    }

    switch (dataType) {

        case REG_EXPAND_SZ:

        case REG_SZ: {

            result = QString::fromWCharArray(((const wchar_t *)data.constData()));

            break;

        }

        case REG_MULTI_SZ: {

            QStringList l;

            int i = 0;

            for (;;) {

                QString s = QString::fromWCharArray((const wchar_t *)data.constData() + i);

                i += s.length() + 1;

                if (s.isEmpty())

                    break;

                l.append(s);

            }

            result = l.join(", ");

            break;

        }

        case REG_NONE:

        case REG_BINARY: {

            result = QString::fromWCharArray((const wchar_t *)data.constData(), data.size() / 2);

            break;

        }

        case REG_DWORD_BIG_ENDIAN:

        case REG_DWORD: {

            Q_ASSERT(data.size() == sizeof(int));

            int i;

            memcpy((char*)&i, data.constData(), sizeof(int));

            result = QString::number(i);

            break;

        }

        default:

            qWarning("QSettings: unknown data %d type in windows registry", dataType);

            break;

    }

    RegCloseKey(handle);

#endif

    return result;

}