Method FindJavaFromRegistryKey

launcher/java/JavaUtils.cpp:178–243

#if defined(Q_OS_WIN32)
QList<JavaInstallPtr> JavaUtils::FindJavaFromRegistryKey(DWORD keyType, QString keyName, QString keyJavaDir, QString subkeySuffix)
{
    QList<JavaInstallPtr> javas;

    QString archType = "unknown";
    if (keyType == KEY_WOW64_64KEY)
        archType = "64";
    else if (keyType == KEY_WOW64_32KEY)
        archType = "32";

    for (HKEY baseRegistry : { HKEY_CURRENT_USER, HKEY_LOCAL_MACHINE }) {
        HKEY jreKey;
        if (RegOpenKeyExW(baseRegistry, keyName.toStdWString().c_str(), 0, KEY_READ | keyType | KEY_ENUMERATE_SUB_KEYS, &jreKey) ==
            ERROR_SUCCESS) {
            // Read the current type version from the registry.
            // This will be used to find any key that contains the JavaHome value.

            WCHAR subKeyName[255];
            DWORD subKeyNameSize, numSubKeys, retCode;

            // Get the number of subkeys
            RegQueryInfoKeyW(jreKey, NULL, NULL, NULL, &numSubKeys, NULL, NULL, NULL, NULL, NULL, NULL, NULL);

            // Iterate until RegEnumKeyEx fails
            if (numSubKeys > 0) {
                for (DWORD i = 0; i < numSubKeys; i++) {
                    subKeyNameSize = 255;
                    retCode = RegEnumKeyExW(jreKey, i, subKeyName, &subKeyNameSize, NULL, NULL, NULL, NULL);
                    QString newSubkeyName = QString::fromWCharArray(subKeyName);
                    if (retCode == ERROR_SUCCESS) {
                        // Now open the registry key for the version that we just got.
                        QString newKeyName = keyName + "\\" + newSubkeyName + subkeySuffix;

                        HKEY newKey;
                        if (RegOpenKeyExW(baseRegistry, newKeyName.toStdWString().c_str(), 0, KEY_READ | keyType, &newKey) ==
                            ERROR_SUCCESS) {
                            // Read the JavaHome value to find where Java is installed.
                            DWORD valueSz = 0;
                            if (RegQueryValueExW(newKey, keyJavaDir.toStdWString().c_str(), NULL, NULL, NULL, &valueSz) == ERROR_SUCCESS) {
                                WCHAR* value = new WCHAR[valueSz];
                                RegQueryValueExW(newKey, keyJavaDir.toStdWString().c_str(), NULL, NULL, (BYTE*)value, &valueSz);

                                QString newValue = QString::fromWCharArray(value);
                                delete[] value;

                                // Now, we construct the version object and add it to the list.
                                JavaInstallPtr javaVersion(new JavaInstall());

                                javaVersion->id = newSubkeyName;
                                javaVersion->arch = archType;
                                javaVersion->path = QDir(FS::PathCombine(newValue, "bin")).absoluteFilePath("javaw.exe");
                                javas.append(javaVersion);
                            }

                            RegCloseKey(newKey);
                        }
                    }
                }