/*

 * Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package java.util.prefs;

import java.util.StringTokenizer;

import java.io.ByteArrayOutputStream;

import java.security.AccessController;

import java.security.PrivilegedAction;

import sun.util.logging.PlatformLogger;

/**

 * Windows registry based implementation of  <tt>Preferences</tt>.

 * <tt>Preferences</tt>' <tt>systemRoot</tt> and <tt>userRoot</tt> are stored in

 * <tt>HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Prefs</tt> and

 * <tt>HKEY_CURRENT_USER\Software\JavaSoft\Prefs</tt> correspondingly.

 *

 * @author  Konstantin Kladko

 * @see Preferences

 * @see PreferencesFactory

 * @since 1.4

 */

class WindowsPreferences extends AbstractPreferences {

    static {

        PrivilegedAction<Void> load = () -> {

            System.loadLibrary("prefs");

            return null;

        };

        AccessController.doPrivileged(load);

    }

    /**

     * Logger for error messages

     */

    private static PlatformLogger logger;

    /**

     * Windows registry path to <tt>Preferences</tt>'s root nodes.

     */

    private static final byte[] WINDOWS_ROOT_PATH =

        stringToByteArray("Software\\JavaSoft\\Prefs");

    /**

     * Windows handles to <tt>HKEY_CURRENT_USER</tt> and

     * <tt>HKEY_LOCAL_MACHINE</tt> hives.

     */

    private static final int HKEY_CURRENT_USER = 0x80000001;

    private static final int HKEY_LOCAL_MACHINE = 0x80000002;

    /**

     * Mount point for <tt>Preferences</tt>'  user root.

     */

    private static final int USER_ROOT_NATIVE_HANDLE = HKEY_CURRENT_USER;

    /**

     * Mount point for <tt>Preferences</tt>'  system root.

     */

    private static final int SYSTEM_ROOT_NATIVE_HANDLE = HKEY_LOCAL_MACHINE;

    /**

     * Maximum byte-encoded path length for Windows native functions,

     * ending <tt>null</tt> character not included.

     */

    private static final int MAX_WINDOWS_PATH_LENGTH = 256;

    /**

     * User root node.

     */

    static final Preferences userRoot =

         new WindowsPreferences(USER_ROOT_NATIVE_HANDLE, WINDOWS_ROOT_PATH);

    /**

     * System root node.

     */

    static final Preferences systemRoot =

        new WindowsPreferences(SYSTEM_ROOT_NATIVE_HANDLE, WINDOWS_ROOT_PATH);

    /*  Windows error codes. */

    private static final int ERROR_SUCCESS = 0;

    private static final int ERROR_FILE_NOT_FOUND = 2;

    private static final int ERROR_ACCESS_DENIED = 5;

    /* Constants used to interpret returns of native functions    */

    private static final int NATIVE_HANDLE = 0;

    private static final int ERROR_CODE = 1;

    private static final int SUBKEYS_NUMBER = 0;

    private static final int VALUES_NUMBER = 2;

    private static final int MAX_KEY_LENGTH = 3;

    private static final int MAX_VALUE_NAME_LENGTH = 4;

    private static final int DISPOSITION = 2;

    private static final int REG_CREATED_NEW_KEY = 1;

    private static final int REG_OPENED_EXISTING_KEY = 2;

    private static final int NULL_NATIVE_HANDLE = 0;

    /* Windows security masks */

    private static final int DELETE = 0x10000;

    private static final int KEY_QUERY_VALUE = 1;

    private static final int KEY_SET_VALUE = 2;

    private static final int KEY_CREATE_SUB_KEY = 4;

    private static final int KEY_ENUMERATE_SUB_KEYS = 8;

    private static final int KEY_READ = 0x20019;

    private static final int KEY_WRITE = 0x20006;

    private static final int KEY_ALL_ACCESS = 0xf003f;

    /**

     * Initial time between registry access attempts, in ms. The time is doubled

     * after each failing attempt (except the first).

     */

    private static int INIT_SLEEP_TIME = 50;

    /**

     * Maximum number of registry access attempts.

     */

    private static int MAX_ATTEMPTS = 5;

    /**

     * BackingStore availability flag.

     */

    private boolean isBackingStoreAvailable = true;

    /**

     * Java wrapper for Windows registry API RegOpenKey()

     */

    private static native int[] WindowsRegOpenKey(int hKey, byte[] subKey,

                                                  int securityMask);

    /**

     * Retries RegOpenKey() MAX_ATTEMPTS times before giving up.

     */

    private static int[] WindowsRegOpenKey1(int hKey, byte[] subKey,

                                            int securityMask) {

        int[] result = WindowsRegOpenKey(hKey, subKey, securityMask);

        if (result[ERROR_CODE] == ERROR_SUCCESS) {

            return result;

        } else if (result[ERROR_CODE] == ERROR_FILE_NOT_FOUND) {

            logger().warning("Trying to recreate Windows registry node " +

            byteArrayToString(subKey) + " at root 0x" +

            Integer.toHexString(hKey) + ".");

            // Try recreation

            int handle = WindowsRegCreateKeyEx(hKey, subKey)[NATIVE_HANDLE];

            WindowsRegCloseKey(handle);

            return WindowsRegOpenKey(hKey, subKey, securityMask);

        } else if (result[ERROR_CODE] != ERROR_ACCESS_DENIED) {

            long sleepTime = INIT_SLEEP_TIME;

            for (int i = 0; i < MAX_ATTEMPTS; i++) {

                try {

                    Thread.sleep(sleepTime);

                } catch(InterruptedException e) {

                    return result;

                }

                sleepTime *= 2;

                result = WindowsRegOpenKey(hKey, subKey, securityMask);

                if (result[ERROR_CODE] == ERROR_SUCCESS) {

                    return result;

                }

            }

        }

        return result;

    }

     /**

     * Java wrapper for Windows registry API RegCloseKey()

     */

    private static native int WindowsRegCloseKey(int hKey);

    /**

     * Java wrapper for Windows registry API RegCreateKeyEx()

     */

    private static native int[] WindowsRegCreateKeyEx(int hKey, byte[] subKey);

    /**

     * Retries RegCreateKeyEx() MAX_ATTEMPTS times before giving up.

     */

    private static int[] WindowsRegCreateKeyEx1(int hKey, byte[] subKey) {

        int[] result = WindowsRegCreateKeyEx(hKey, subKey);

        if (result[ERROR_CODE] == ERROR_SUCCESS) {

            return result;

        } else {

            long sleepTime = INIT_SLEEP_TIME;

            for (int i = 0; i < MAX_ATTEMPTS; i++) {

                try {

                    Thread.sleep(sleepTime);

                } catch(InterruptedException e) {

                    return result;

                }

                sleepTime *= 2;

                result = WindowsRegCreateKeyEx(hKey, subKey);

                if (result[ERROR_CODE] == ERROR_SUCCESS) {

                    return result;

                }

            }

        }

        return result;

    }

    /**

     * Java wrapper for Windows registry API RegDeleteKey()

     */

    private static native int WindowsRegDeleteKey(int hKey, byte[] subKey);

    /**

     * Java wrapper for Windows registry API RegFlushKey()

     */

    private static native int WindowsRegFlushKey(int hKey);

    /**

     * Retries RegFlushKey() MAX_ATTEMPTS times before giving up.

     */

    private static int WindowsRegFlushKey1(int hKey) {

        int result = WindowsRegFlushKey(hKey);

        if (result == ERROR_SUCCESS) {

            return result;

        } else {

            long sleepTime = INIT_SLEEP_TIME;

            for (int i = 0; i < MAX_ATTEMPTS; i++) {

                try {

                    Thread.sleep(sleepTime);

                } catch(InterruptedException e) {

                    return result;

                }

                sleepTime *= 2;

                result = WindowsRegFlushKey(hKey);

                if (result == ERROR_SUCCESS) {

                    return result;

                }

            }

        }

        return result;

    }

    /**

     * Java wrapper for Windows registry API RegQueryValueEx()

     */

    private static native byte[] WindowsRegQueryValueEx(int hKey,

                                                        byte[] valueName);

    /**

     * Java wrapper for Windows registry API RegSetValueEx()

     */

    private static native int WindowsRegSetValueEx(int hKey, byte[] valueName,

                                                   byte[] value);

    /**

     * Retries RegSetValueEx() MAX_ATTEMPTS times before giving up.

     */

    private static int WindowsRegSetValueEx1(int hKey, byte[] valueName,

                                             byte[] value) {

        int result = WindowsRegSetValueEx(hKey, valueName, value);

        if (result == ERROR_SUCCESS) {

            return result;

        } else {

            long sleepTime = INIT_SLEEP_TIME;

            for (int i = 0; i < MAX_ATTEMPTS; i++) {

                try {

                    Thread.sleep(sleepTime);

                } catch(InterruptedException e) {

                    return result;

                }

                sleepTime *= 2;

                result = WindowsRegSetValueEx(hKey, valueName, value);

                if (result == ERROR_SUCCESS) {

                    return result;

                }

            }

        }

        return result;

    }

    /**

     * Java wrapper for Windows registry API RegDeleteValue()

     */

    private static native int WindowsRegDeleteValue(int hKey, byte[] valueName);

    /**

     * Java wrapper for Windows registry API RegQueryInfoKey()

     */

    private static native int[] WindowsRegQueryInfoKey(int hKey);

    /**

     * Retries RegQueryInfoKey() MAX_ATTEMPTS times before giving up.

     */

    private static int[] WindowsRegQueryInfoKey1(int hKey) {

        int[] result = WindowsRegQueryInfoKey(hKey);

        if (result[ERROR_CODE] == ERROR_SUCCESS) {

            return result;

        } else {

            long sleepTime = INIT_SLEEP_TIME;

            for (int i = 0; i < MAX_ATTEMPTS; i++) {

                try {

                    Thread.sleep(sleepTime);

                } catch(InterruptedException e) {

                    return result;

                }

                sleepTime *= 2;

                result = WindowsRegQueryInfoKey(hKey);

                if (result[ERROR_CODE] == ERROR_SUCCESS) {

                    return result;

                }

            }

        }

        return result;

    }

    /**

     * Java wrapper for Windows registry API RegEnumKeyEx()

     */

    private static native byte[] WindowsRegEnumKeyEx(int hKey, int subKeyIndex,

                                                     int maxKeyLength);

    /**

     * Retries RegEnumKeyEx() MAX_ATTEMPTS times before giving up.

     */

    private static byte[] WindowsRegEnumKeyEx1(int hKey, int subKeyIndex,

                                               int maxKeyLength) {

        byte[] result = WindowsRegEnumKeyEx(hKey, subKeyIndex, maxKeyLength);

        if (result != null) {

            return result;

        } else {

            long sleepTime = INIT_SLEEP_TIME;

            for (int i = 0; i < MAX_ATTEMPTS; i++) {

                try {

                    Thread.sleep(sleepTime);

                } catch(InterruptedException e) {

                    return result;

                }

                sleepTime *= 2;

                result = WindowsRegEnumKeyEx(hKey, subKeyIndex, maxKeyLength);

                if (result != null) {

                    return result;

                }

            }

        }

        return result;

    }

    /**

     * Java wrapper for Windows registry API RegEnumValue()

     */

    private static native byte[] WindowsRegEnumValue(int hKey, int valueIndex,

                                                     int maxValueNameLength);

    /**

     * Retries RegEnumValueEx() MAX_ATTEMPTS times before giving up.

     */

    private static byte[] WindowsRegEnumValue1(int hKey, int valueIndex,

                                               int maxValueNameLength) {

        byte[] result = WindowsRegEnumValue(hKey, valueIndex,

                                            maxValueNameLength);

        if (result != null) {

            return result;

        } else {

            long sleepTime = INIT_SLEEP_TIME;

            for (int i = 0; i < MAX_ATTEMPTS; i++) {

                try {

                    Thread.sleep(sleepTime);

                } catch(InterruptedException e) {

                    return result;

                }

                sleepTime *= 2;

                result = WindowsRegEnumValue(hKey, valueIndex,

                                             maxValueNameLength);

                if (result != null) {

                    return result;

                }

            }

        }

        return result;

    }

    /**

     * Constructs a <tt>WindowsPreferences</tt> node, creating underlying

     * Windows registry node and all its Windows parents, if they are not yet

     * created.

     * Logs a warning message, if Windows Registry is unavailable.

     */

    private WindowsPreferences(WindowsPreferences parent, String name) {

        super(parent, name);

        int parentNativeHandle = parent.openKey(KEY_CREATE_SUB_KEY, KEY_READ);

        if (parentNativeHandle == NULL_NATIVE_HANDLE) {

            // if here, openKey failed and logged

            isBackingStoreAvailable = false;

            return;

        }

        int[] result =

               WindowsRegCreateKeyEx1(parentNativeHandle, toWindowsName(name));

        if (result[ERROR_CODE] != ERROR_SUCCESS) {

            logger().warning("Could not create windows registry node " +

                    byteArrayToString(windowsAbsolutePath()) +

                    " at root 0x" + Integer.toHexString(rootNativeHandle()) +

                    ". Windows RegCreateKeyEx(...) returned error code " +

                    result[ERROR_CODE] + ".");

            isBackingStoreAvailable = false;

            return;

        }

        newNode = (result[DISPOSITION] == REG_CREATED_NEW_KEY);

        closeKey(parentNativeHandle);

        closeKey(result[NATIVE_HANDLE]);

    }

    /**

     * Constructs a root node creating the underlying

     * Windows registry node and all of its parents, if they have not yet been

     * created.

     * Logs a warning message, if Windows Registry is unavailable.

     * @param rootNativeHandle Native handle to one of Windows top level keys.

     * @param rootDirectory Path to root directory, as a byte-encoded string.

     */

    private  WindowsPreferences(int rootNativeHandle, byte[] rootDirectory) {

        super(null, "");

        int[] result =

                WindowsRegCreateKeyEx1(rootNativeHandle, rootDirectory);

        if (result[ERROR_CODE] != ERROR_SUCCESS) {

            logger().warning("Could not open/create prefs root node " +

                    byteArrayToString(windowsAbsolutePath()) +

                    " at root 0x" + Integer.toHexString(rootNativeHandle()) +

                    ". Windows RegCreateKeyEx(...) returned error code " +

                    result[ERROR_CODE] + ".");

            isBackingStoreAvailable = false;

            return;

        }

        // Check if a new node

        newNode = (result[DISPOSITION] == REG_CREATED_NEW_KEY);

        closeKey(result[NATIVE_HANDLE]);

    }

    /**

     * Returns Windows absolute path of the current node as a byte array.

     * Java "/" separator is transformed into Windows "\".

     * @see Preferences#absolutePath()

     */

    private byte[] windowsAbsolutePath() {

        ByteArrayOutputStream bstream = new ByteArrayOutputStream();

        bstream.write(WINDOWS_ROOT_PATH, 0, WINDOWS_ROOT_PATH.length-1);

        StringTokenizer tokenizer = new StringTokenizer(absolutePath(), "/");

        while (tokenizer.hasMoreTokens()) {

            bstream.write((byte)'\\');

            String nextName = tokenizer.nextToken();

            byte[] windowsNextName = toWindowsName(nextName);

            bstream.write(windowsNextName, 0, windowsNextName.length-1);

        }

        bstream.write(0);

        return bstream.toByteArray();

    }

    /**

     * Opens current node's underlying Windows registry key using a

     * given security mask.

     * @param securityMask Windows security mask.

     * @return Windows registry key's handle.

     * @see #openKey(byte[], int)

     * @see #openKey(int, byte[], int)

     * @see #closeKey(int)

     */

    private int openKey(int securityMask) {

        return openKey(securityMask, securityMask);

    }

    /**

     * Opens current node's underlying Windows registry key using a

     * given security mask.

     * @param mask1 Preferred Windows security mask.

     * @param mask2 Alternate Windows security mask.

     * @return Windows registry key's handle.

     * @see #openKey(byte[], int)

     * @see #openKey(int, byte[], int)

     * @see #closeKey(int)

     */

    private int openKey(int mask1, int mask2) {

        return openKey(windowsAbsolutePath(), mask1,  mask2);

    }

     /**

     * Opens Windows registry key at a given absolute path using a given

     * security mask.

     * @param windowsAbsolutePath Windows absolute path of the

     *        key as a byte-encoded string.

     * @param mask1 Preferred Windows security mask.

     * @param mask2 Alternate Windows security mask.

     * @return Windows registry key's handle.

     * @see #openKey(int)

     * @see #openKey(int, byte[],int)

     * @see #closeKey(int)

     */

    private int openKey(byte[] windowsAbsolutePath, int mask1, int mask2) {

        /*  Check if key's path is short enough be opened at once

            otherwise use a path-splitting procedure */

        if (windowsAbsolutePath.length <= MAX_WINDOWS_PATH_LENGTH + 1) {

            int[] result = WindowsRegOpenKey1(rootNativeHandle(),

                                              windowsAbsolutePath, mask1);

            if (result[ERROR_CODE] == ERROR_ACCESS_DENIED && mask2 != mask1)

                result = WindowsRegOpenKey1(rootNativeHandle(),

                                            windowsAbsolutePath, mask2);

            if (result[ERROR_CODE] != ERROR_SUCCESS) {

                logger().warning("Could not open windows registry node " +

                        byteArrayToString(windowsAbsolutePath()) +

                        " at root 0x" +