/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.catalina.session;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.ArrayList;
import java.util.List;

import jakarta.servlet.ServletContext;

import org.apache.catalina.Context;
import org.apache.catalina.LifecycleException;
import org.apache.catalina.LifecycleState;
import org.apache.catalina.Loader;
import org.apache.catalina.Session;
import org.apache.catalina.security.SecurityUtil;
import org.apache.catalina.util.CustomObjectInputStream;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;
import org.apache.tomcat.util.ExceptionUtils;

Standard implementation of the Manager interface that provides
simple session persistence across restarts of this component (such as
when the entire server is shut down and restarted, or when a particular
web application is reloaded.

IMPLEMENTATION NOTE:  Correct behavior of session storing and
reloading depends upon external calls to the start() and
stop() methods of this class at the correct times.
Author:
Craig R. McClanahan/**
 * Standard implementation of the <b>Manager</b> interface that provides
 * simple session persistence across restarts of this component (such as
 * when the entire server is shut down and restarted, or when a particular
 * web application is reloaded.
 * <p>
 * <b>IMPLEMENTATION NOTE</b>:  Correct behavior of session storing and
 * reloading depends upon external calls to the <code>start()</code> and
 * <code>stop()</code> methods of this class at the correct times.
 *
 * @author Craig R. McClanahan
 */
public class StandardManager extends ManagerBase {

    private final Log log = LogFactory.getLog(StandardManager.class); // must not be static

    // ---------------------------------------------------- Security Classes

    private class PrivilegedDoLoad
        implements PrivilegedExceptionAction<Void> {

        PrivilegedDoLoad() {
            // NOOP
        }

        @Override
        public Void run() throws Exception{
           doLoad();
           return null;
        }
    }

    private class PrivilegedDoUnload
        implements PrivilegedExceptionAction<Void> {

        PrivilegedDoUnload() {
            // NOOP
        }

        @Override
        public Void run() throws Exception{
            doUnload();
            return null;
        }

    }


    // ----------------------------------------------------- Instance Variables

    
The descriptive name of this Manager implementation (for logging).
/**
     * The descriptive name of this Manager implementation (for logging).
     */
    protected static final String name = "StandardManager";


    
Path name of the disk file in which active sessions are saved
when we stop, and from which these sessions are loaded when we start.
A null value indicates that no persistence is desired.
If this pathname is relative, it will be resolved against the
temporary working directory provided by our context, available via
the jakarta.servlet.context.tempdir context attribute.
/**
     * Path name of the disk file in which active sessions are saved
     * when we stop, and from which these sessions are loaded when we start.
     * A <code>null</code> value indicates that no persistence is desired.
     * If this pathname is relative, it will be resolved against the
     * temporary working directory provided by our context, available via
     * the <code>jakarta.servlet.context.tempdir</code> context attribute.
     */
    protected String pathname = null;


    // ------------------------------------------------------------- Properties

    @Override
    public String getName() {
        return name;
    }


    
Returns:
The session persistence pathname, if any./**
     * @return The session persistence pathname, if any.
     */
    public String getPathname() {
        return pathname;
    }


    
Set the session persistence pathname to the specified value.  If no
persistence support is desired, set the pathname to null.
Params:
pathname – New session persistence pathname/**
     * Set the session persistence pathname to the specified value.  If no
     * persistence support is desired, set the pathname to <code>null</code>.
     *
     * @param pathname New session persistence pathname
     */
    public void setPathname(String pathname) {
        String oldPathname = this.pathname;
        this.pathname = pathname;
        support.firePropertyChange("pathname", oldPathname, this.pathname);
    }


    // --------------------------------------------------------- Public Methods

    @Override
    public void load() throws ClassNotFoundException, IOException {
        if (SecurityUtil.isPackageProtectionEnabled()){
            try{
                AccessController.doPrivileged( new PrivilegedDoLoad() );
            } catch (PrivilegedActionException ex){
                Exception exception = ex.getException();
                if (exception instanceof ClassNotFoundException) {
                    throw (ClassNotFoundException)exception;
                } else if (exception instanceof IOException) {
                    throw (IOException)exception;
                }
                if (log.isDebugEnabled()) {
                    log.debug("Unreported exception in load() ", exception);
                }
            }
        } else {
            doLoad();
        }
    }


    
Load any currently active sessions that were previously unloaded
to the appropriate persistence mechanism, if any.  If persistence is not
supported, this method returns without doing anything.
Throws:
ClassNotFoundException – if a serialized class cannot be
 found during the reload
IOException – if an input/output error occurs/**
     * Load any currently active sessions that were previously unloaded
     * to the appropriate persistence mechanism, if any.  If persistence is not
     * supported, this method returns without doing anything.
     *
     * @exception ClassNotFoundException if a serialized class cannot be
     *  found during the reload
     * @exception IOException if an input/output error occurs
     */
    protected void doLoad() throws ClassNotFoundException, IOException {
        if (log.isDebugEnabled()) {
            log.debug("Start: Loading persisted sessions");
        }

        // Initialize our internal data structures
        sessions.clear();

        // Open an input stream to the specified pathname, if any
        File file = file();
        if (file == null) {
            return;
        }
        if (log.isDebugEnabled()) {
            log.debug(sm.getString("standardManager.loading", pathname));
        }
        Loader loader = null;
        ClassLoader classLoader = null;
        Log logger = null;
        try (FileInputStream fis = new FileInputStream(file.getAbsolutePath());
                BufferedInputStream bis = new BufferedInputStream(fis)) {
            Context c = getContext();
            loader = c.getLoader();
            logger = c.getLogger();
            if (loader != null) {
                classLoader = loader.getClassLoader();
            }
            if (classLoader == null) {
                classLoader = getClass().getClassLoader();
            }

            // Load the previously unloaded active sessions
            synchronized (sessions) {
                try (ObjectInputStream ois = new CustomObjectInputStream(bis, classLoader, logger,
                        getSessionAttributeValueClassNamePattern(),
                        getWarnOnSessionAttributeFilterFailure())) {
                    Integer count = (Integer) ois.readObject();
                    int n = count.intValue();
                    if (log.isDebugEnabled())
                        log.debug("Loading " + n + " persisted sessions");
                    for (int i = 0; i < n; i++) {
                        StandardSession session = getNewSession();
                        session.readObjectData(ois);
                        session.setManager(this);
                        sessions.put(session.getIdInternal(), session);
                        session.activate();
                        if (!session.isValidInternal()) {
                            // If session is already invalid,
                            // expire session to prevent memory leak.
                            session.setValid(true);
                            session.expire();
                        }
                        sessionCounter++;
                    }
                } finally {
                    // Delete the persistent storage file
                    if (file.exists()) {
                        if (!file.delete()) {
                            log.warn(sm.getString("standardManager.deletePersistedFileFail", file));
                        }
                    }
                }
            }
        } catch (FileNotFoundException e) {
            if (log.isDebugEnabled()) {
                log.debug("No persisted data file found");
            }
            return;
        }

        if (log.isDebugEnabled()) {
            log.debug("Finish: Loading persisted sessions");
        }
    }


    @Override
    public void unload() throws IOException {
        if (SecurityUtil.isPackageProtectionEnabled()) {
            try {
                AccessController.doPrivileged(new PrivilegedDoUnload());
            } catch (PrivilegedActionException ex){
                Exception exception = ex.getException();
                if (exception instanceof IOException) {
                    throw (IOException)exception;
                }
                if (log.isDebugEnabled()) {
                    log.debug("Unreported exception in unLoad()", exception);
                }
            }
        } else {
            doUnload();
        }
    }


    
Save any currently active sessions in the appropriate persistence
mechanism, if any.  If persistence is not supported, this method
returns without doing anything.
Throws:
IOException – if an input/output error occurs/**
     * Save any currently active sessions in the appropriate persistence
     * mechanism, if any.  If persistence is not supported, this method
     * returns without doing anything.
     *
     * @exception IOException if an input/output error occurs
     */
    protected void doUnload() throws IOException {

        if (log.isDebugEnabled())
            log.debug(sm.getString("standardManager.unloading.debug"));

        if (sessions.isEmpty()) {
            log.debug(sm.getString("standardManager.unloading.nosessions"));
            return; // nothing to do
        }

        // Open an output stream to the specified pathname, if any
        File file = file();
        if (file == null) {
            return;
        }
        if (log.isDebugEnabled()) {
            log.debug(sm.getString("standardManager.unloading", pathname));
        }

        // Keep a note of sessions that are expired
        List<StandardSession> list = new ArrayList<>();

        try (FileOutputStream fos = new FileOutputStream(file.getAbsolutePath());
                BufferedOutputStream bos = new BufferedOutputStream(fos);
                ObjectOutputStream oos = new ObjectOutputStream(bos)) {

            synchronized (sessions) {
                if (log.isDebugEnabled()) {
                    log.debug("Unloading " + sessions.size() + " sessions");
                }
                // Write the number of active sessions, followed by the details
                oos.writeObject(Integer.valueOf(sessions.size()));
                for (Session s : sessions.values()) {
                    StandardSession session = (StandardSession) s;
                    list.add(session);
                    session.passivate();
                    session.writeObjectData(oos);
                }
            }
        }

        // Expire all the sessions we just wrote
        if (log.isDebugEnabled()) {
            log.debug("Expiring " + list.size() + " persisted sessions");
        }
        for (StandardSession session : list) {
            try {
                session.expire(false);
            } catch (Throwable t) {
                ExceptionUtils.handleThrowable(t);
            } finally {
                session.recycle();
            }
        }

        if (log.isDebugEnabled()) {
            log.debug("Unloading complete");
        }
    }


    
Start this component and implement the requirements of LifecycleBase.startInternal(). 
Throws:
LifecycleException – if this component detects a fatal error
 that prevents this component from being used/**
     * Start this component and implement the requirements
     * of {@link org.apache.catalina.util.LifecycleBase#startInternal()}.
     *
     * @exception LifecycleException if this component detects a fatal error
     *  that prevents this component from being used
     */
    @Override
    protected synchronized void startInternal() throws LifecycleException {

        super.startInternal();

        // Load unloaded sessions, if any
        try {
            load();
        } catch (Throwable t) {
            ExceptionUtils.handleThrowable(t);
            log.error(sm.getString("standardManager.managerLoad"), t);
        }

        setState(LifecycleState.STARTING);
    }


    
Stop this component and implement the requirements of LifecycleBase.stopInternal(). 
Throws:
LifecycleException – if this component detects a fatal error
 that prevents this component from being used/**
     * Stop this component and implement the requirements
     * of {@link org.apache.catalina.util.LifecycleBase#stopInternal()}.
     *
     * @exception LifecycleException if this component detects a fatal error
     *  that prevents this component from being used
     */
    @Override
    protected synchronized void stopInternal() throws LifecycleException {

        if (log.isDebugEnabled()) {
            log.debug("Stopping");
        }

        setState(LifecycleState.STOPPING);

        // Write out sessions
        try {
            unload();
        } catch (Throwable t) {
            ExceptionUtils.handleThrowable(t);
            log.error(sm.getString("standardManager.managerUnload"), t);
        }

        // Expire all active sessions
        Session sessions[] = findSessions();
        for (Session session : sessions) {
            try {
                if (session.isValid()) {
                    session.expire();
                }
            } catch (Throwable t) {
                ExceptionUtils.handleThrowable(t);
            } finally {
                // Measure against memory leaking if references to the session
                // object are kept in a shared field somewhere
                session.recycle();
            }
        }

        // Require a new random number generator if we are restarted
        super.stopInternal();
    }


    // ------------------------------------------------------ Protected Methods

    
Return a File object representing the pathname to our
persistence file, if any.
Returns:
the file/**
     * Return a File object representing the pathname to our
     * persistence file, if any.
     * @return the file
     */
    protected File file() {
        if (pathname == null || pathname.length() == 0) {
            return null;
        }
        File file = new File(pathname);
        if (!file.isAbsolute()) {
            Context context = getContext();
            ServletContext servletContext = context.getServletContext();
            File tempdir = (File) servletContext.getAttribute(ServletContext.TEMPDIR);
            if (tempdir != null) {
                file = new File(tempdir, pathname);
            }
        }
        return file;
    }
}