jna-master/contrib/platform/src/com/sun/jna/platform/win32/NtDllUtil.java
/* Copyright (c) 2010 Daniel Doubrovkine, All Rights Reserved
 *
 * The contents of this file is dual-licensed under 2
 * alternative Open Source/Free licenses: LGPL 2.1 or later and
 * Apache License 2.0. (starting with JNA version 4.0.0).
 *
 * You can freely decide which license you want to apply to
 * the project.
 *
 * You may obtain a copy of the LGPL License at:
 *
 * http://www.gnu.org/licenses/licenses.html
 *
 * A copy is also included in the downloadable source code package
 * containing JNA, in file "LGPL2.1".
 *
 * You may obtain a copy of the Apache License at:
 *
 * http://www.apache.org/licenses/
 *
 * A copy is also included in the downloadable source code package
 * containing JNA, in file "AL2.0".
 */
package com.sun.jna.platform.win32;

import com.sun.jna.platform.win32.Wdm.KEY_BASIC_INFORMATION;
import com.sun.jna.platform.win32.Wdm.KEY_INFORMATION_CLASS;
import com.sun.jna.platform.win32.WinReg.HKEY;
import com.sun.jna.ptr.IntByReference;

/**
 * NtDll Utility API.
 * @author dblock[at]dblock.org
 */
public abstract class NtDllUtil {

    /**
     * Retrieve the name of an opened registry key.
     * @param hkey Opened registry key.
     * @return Basic key name, not including node information.
     */
    public static String getKeyName(HKEY hkey) {
        IntByReference resultLength = new IntByReference();
        int rc = NtDll.INSTANCE.ZwQueryKey(hkey, KEY_INFORMATION_CLASS.KeyBasicInformation,
                null, 0, resultLength);
        if (rc != NTStatus.STATUS_BUFFER_TOO_SMALL || resultLength.getValue() <= 0) {
            throw new Win32Exception(rc);
        }
        KEY_BASIC_INFORMATION keyInformation = new KEY_BASIC_INFORMATION(
                resultLength.getValue());
        rc = NtDll.INSTANCE.ZwQueryKey(hkey, KEY_INFORMATION_CLASS.KeyBasicInformation,
                keyInformation, resultLength.getValue(), resultLength);
        if (rc != NTStatus.STATUS_SUCCESS) {
            throw new Win32Exception(rc);
        }
        return keyInformation.getName();
    }
}
