/*

 * Copyright (c) 2016, 2018, 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 jdk.jfr.internal;

import java.io.File;

import java.io.FileNotFoundException;

import java.io.IOException;

import java.io.InputStream;

import java.io.RandomAccessFile;

import java.io.Reader;

import java.lang.invoke.MethodHandles;

import java.lang.reflect.Constructor;

import java.lang.reflect.Field;

import java.lang.reflect.Method;

import java.lang.reflect.ReflectPermission;

import java.nio.channels.FileChannel;

import java.nio.channels.ReadableByteChannel;

import java.nio.file.FileVisitResult;

import java.nio.file.Files;

import java.nio.file.Path;

import java.nio.file.Paths;

import java.nio.file.SimpleFileVisitor;

import java.nio.file.StandardOpenOption;

import java.nio.file.attribute.BasicFileAttributes;

import java.security.AccessControlContext;

import java.security.AccessController;

import java.security.Permission;

import java.security.PrivilegedAction;

import java.security.PrivilegedActionException;

import java.security.PrivilegedExceptionAction;

import java.util.ArrayList;

import java.util.Iterator;

import java.util.List;

import java.util.Objects;

import java.util.PropertyPermission;

import java.util.concurrent.Callable;

import jdk.internal.misc.Unsafe;

import jdk.internal.module.Modules;

import jdk.jfr.Event;

import jdk.jfr.FlightRecorder;

import jdk.jfr.FlightRecorderListener;

import jdk.jfr.FlightRecorderPermission;

import jdk.jfr.Recording;

/**

 * Contains JFR code that does

 * {@link AccessController#doPrivileged(PrivilegedAction)}

 */

public final class SecuritySupport {

    private final static Unsafe unsafe = Unsafe.getUnsafe();

    private final static MethodHandles.Lookup LOOKUP = MethodHandles.lookup();

    private final static Module JFR_MODULE = Event.class.getModule();

    public  final static SafePath JFC_DIRECTORY = getPathInProperty("java.home", "lib/jfr");

    static final SafePath USER_HOME = getPathInProperty("user.home", null);

    static final SafePath JAVA_IO_TMPDIR = getPathInProperty("java.io.tmpdir", null);

    final static class SecureRecorderListener implements FlightRecorderListener {

        private final AccessControlContext context;

        private final FlightRecorderListener changeListener;

        SecureRecorderListener(AccessControlContext context, FlightRecorderListener changeListener) {

            this.context = Objects.requireNonNull(context);

            this.changeListener = Objects.requireNonNull(changeListener);

        }

        @Override

        public void recordingStateChanged(Recording recording) {

            AccessController.doPrivileged((PrivilegedAction<Void>) () -> {

                try {

                    changeListener.recordingStateChanged(recording);

                } catch (Throwable t) {

                    // Prevent malicious user to propagate exception callback in the wrong context

                    Logger.log(LogTag.JFR, LogLevel.WARN, "Unexpected exception in listener " + changeListener.getClass()+ " at recording state change");

                }

                return null;

            }, context);

        }

        @Override

        public void recorderInitialized(FlightRecorder recorder) {

            AccessController.doPrivileged((PrivilegedAction<Void>) () -> {

                try  {

                    changeListener.recorderInitialized(recorder);

                } catch (Throwable t) {

                    // Prevent malicious user to propagate exception callback in the wrong context

                    Logger.log(LogTag.JFR, LogLevel.WARN, "Unexpected exception in listener " + changeListener.getClass()+ " when initializing FlightRecorder");

                }

                return null;

            }, context);

        }

        public FlightRecorderListener getChangeListener() {

            return changeListener;

        }

    }

    private static final class DirectoryCleaner extends SimpleFileVisitor<Path> {

        @Override

        public FileVisitResult visitFile(Path path, BasicFileAttributes attrs) throws IOException {

            Files.delete(path);

            return FileVisitResult.CONTINUE;

        }

        @Override

        public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {

            if (exc != null) {

                throw exc;

            }

            Files.delete(dir);

            return FileVisitResult.CONTINUE;

        }

    }

    /**

     * Path created by the default file provider,and not

     * a malicious provider.

     *

     */

    public static final class SafePath {

        private final Path path;

        private final String text;

        public SafePath(Path p) {

            // sanitize

            text = p.toString();

            path = Paths.get(text);

        }

        public SafePath(String path) {

            this(Paths.get(path));

        }

        public Path toPath() {

            return path;

        }

        public String toString() {

            return text;

        }

    }

    private interface RunnableWithCheckedException {

        public void run() throws Exception;

    }

    private interface CallableWithoutCheckException<T> {

        public T call();

    }

    private static <U> U doPrivilegedIOWithReturn(Callable<U> function) throws IOException {

        try {

            return AccessController.doPrivileged(new PrivilegedExceptionAction<U>() {

                @Override

                public U run() throws Exception {

                    return function.call();

                }

            }, null);

        } catch (PrivilegedActionException e) {

            Throwable t = e.getCause();

            if (t instanceof IOException) {

                throw (IOException) t;

            }

            throw new IOException("Unexpected error during I/O operation. " + t.getMessage(), t);

        }

    }

    private static void doPriviligedIO(RunnableWithCheckedException function) throws IOException {

        doPrivilegedIOWithReturn(() -> {

            function.run();

            return null;

        });

    }

    private static void doPrivileged(Runnable function, Permission... perms) {

        AccessController.doPrivileged(new PrivilegedAction<Void>() {

            @Override

            public Void run() {

                function.run();

                return null;

            }

        }, null, perms);

    }

    private static void doPrivileged(Runnable function) {

        AccessController.doPrivileged(new PrivilegedAction<Void>() {

            @Override

            public Void run() {

                function.run();

                return null;

            }

        });

    }

    private static <T> T doPrivilegedWithReturn(CallableWithoutCheckException<T> function, Permission... perms) {

        return AccessController.doPrivileged(new PrivilegedAction<T>() {

            @Override

            public T run() {

                return function.call();

            }

        }, null, perms);

    }

    public static List<SafePath> getPredefinedJFCFiles() {

        List<SafePath> list = new ArrayList<>();

        try {

            Iterator<Path> pathIterator = doPrivilegedIOWithReturn(() -> {

                return Files.newDirectoryStream(JFC_DIRECTORY.toPath(), "*").iterator();

            });

            while (pathIterator.hasNext()) {

                Path path = pathIterator.next();

                if (path.toString().endsWith(".jfc")) {

                    list.add(new SafePath(path));

                }

            }

        } catch (IOException ioe) {

            Logger.log(LogTag.JFR, LogLevel.WARN, "Could not access .jfc-files in " + JFC_DIRECTORY + ", " + ioe.getMessage());

        }

        return list;

    }

    static void makeVisibleToJFR(Class<?> clazz) {

        Module classModule = clazz.getModule();

        Modules.addReads(JFR_MODULE, classModule);

        if (clazz.getPackage() != null) {

            String packageName = clazz.getPackage().getName();

            Modules.addExports(classModule, packageName, JFR_MODULE);

            Modules.addOpens(classModule, packageName, JFR_MODULE);

        }

    }

    /**

     * Adds a qualified export of the internal.jdk.jfr.internal.handlers package

     * (for EventHandler)

     */

    static void addHandlerExport(Class<?> clazz) {

        Modules.addExports(JFR_MODULE, Utils.HANDLERS_PACKAGE_NAME, clazz.getModule());

    }

    }

    static boolean getBooleanProperty(String propertyName) {

        return doPrivilegedWithReturn(() -> Boolean.getBoolean(propertyName), new PropertyPermission(propertyName, "read"));

    }

    private static SafePath getPathInProperty(String prop, String subPath) {

        return doPrivilegedWithReturn(() -> {

            String path = System.getProperty(prop);

            if (path == null) {

                return null;

            }

            File file = subPath == null ? new File(path) : new File(path, subPath);

            return new SafePath(file.getAbsolutePath());

        }, new PropertyPermission("*", "read"));

    }

    // Called by JVM during initialization of JFR

    static Thread createRecorderThread(ThreadGroup systemThreadGroup, ClassLoader contextClassLoader) {

        // The thread should have permission = new Permission[0], and not "modifyThreadGroup" and "modifyThread" on the stack,

        // but it's hard circumvent if we are going to pass in system thread group in the constructor

        Thread thread = doPrivilegedWithReturn(() -> new Thread(systemThreadGroup, "JFR Recorder Thread"), new RuntimePermission("modifyThreadGroup"), new RuntimePermission("modifyThread"));

        doPrivileged(() -> thread.setContextClassLoader(contextClassLoader), new RuntimePermission("setContextClassLoader"), new RuntimePermission("modifyThread"));

        return thread;

    }

    static void registerShutdownHook(Thread shutdownHook) {

        doPrivileged(() -> Runtime.getRuntime().addShutdownHook(shutdownHook), new RuntimePermission("shutdownHooks"));

    }

    static void setUncaughtExceptionHandler(Thread thread, Thread.UncaughtExceptionHandler eh) {

        doPrivileged(() -> thread.setUncaughtExceptionHandler(eh), new RuntimePermission("modifyThread"));

    }

    static void moveReplace(SafePath from, SafePath to) throws IOException {

        doPrivilegedIOWithReturn(() -> Files.move(from.toPath(), to.toPath()));

    }

    static void clearDirectory(SafePath safePath) throws IOException {

        doPriviligedIO(() -> Files.walkFileTree(safePath.toPath(), new DirectoryCleaner()));

    }

    static SafePath toRealPath(SafePath safePath) throws Exception {

        return new SafePath(doPrivilegedIOWithReturn(() -> safePath.toPath().toRealPath()));

    }

    static boolean existDirectory(SafePath directory) throws IOException {

        return doPrivilegedIOWithReturn(() -> Files.exists(directory.toPath()));

    }

    static RandomAccessFile createRandomAccessFile(SafePath path) throws Exception {

        return doPrivilegedIOWithReturn(() -> new RandomAccessFile(path.toPath().toFile(), "rw"));

    }

    public static InputStream newFileInputStream(SafePath safePath) throws IOException {

        return doPrivilegedIOWithReturn(() -> Files.newInputStream(safePath.toPath()));

    }

    public static long getFileSize(SafePath safePath) throws IOException {

        return doPrivilegedIOWithReturn(() -> Files.size(safePath.toPath()));

    }

    static SafePath createDirectories(SafePath safePath) throws IOException {

        Path p = doPrivilegedIOWithReturn(() -> Files.createDirectories(safePath.toPath()));

        return new SafePath(p);

    }

    public static boolean exists(SafePath safePath) throws IOException {

        return doPrivilegedIOWithReturn(() -> Files.exists(safePath.toPath()));

    }

    public static boolean isDirectory(SafePath safePath) throws IOException {

        return doPrivilegedIOWithReturn(() -> Files.isDirectory(safePath.toPath()));

    }

    static void delete(SafePath localPath) throws IOException {

        doPriviligedIO(() -> Files.delete(localPath.toPath()));

    }

    static boolean isWritable(SafePath safePath) throws IOException {

        return doPrivilegedIOWithReturn(() -> Files.isWritable(safePath.toPath()));

    }

    static void deleteOnExit(SafePath safePath) {

        doPrivileged(() -> safePath.toPath().toFile().deleteOnExit());

    }

    static ReadableByteChannel newFileChannelToRead(SafePath safePath) throws IOException {

        return doPrivilegedIOWithReturn(() -> FileChannel.open(safePath.toPath(), StandardOpenOption.READ));

    }

    public static InputStream getResourceAsStream(String name) throws IOException {

        return doPrivilegedIOWithReturn(() -> SecuritySupport.class.getResourceAsStream(name));

    }

    public static Reader newFileReader(SafePath safePath) throws FileNotFoundException, IOException {

        return doPrivilegedIOWithReturn(() -> Files.newBufferedReader(safePath.toPath()));

    }

    static void touch(SafePath path) throws IOException {

        doPriviligedIO(() -> new RandomAccessFile(path.toPath().toFile(), "rw").close());

    }

    static void setAccessible(Method method) {

        doPrivileged(() -> method.setAccessible(true), new ReflectPermission("suppressAccessChecks"));

    }

    static void setAccessible(Field field) {

        doPrivileged(() -> field.setAccessible(true), new ReflectPermission("suppressAccessChecks"));

    }

    static void setAccessible(Constructor<?> constructor) {

        doPrivileged(() -> constructor.setAccessible(true), new ReflectPermission("suppressAccessChecks"));

    }

    static void ensureClassIsInitialized(Class<?> clazz) {

        unsafe.ensureClassInitialized(clazz);

    }

    static Class<?> defineClass(Class<?> lookupClass, byte[] bytes) {

        return AccessController.doPrivileged(new PrivilegedAction<>() {

            @Override

            public Class<?> run() {

                try {

                    return MethodHandles.privateLookupIn(lookupClass, LOOKUP).defineClass(bytes);

                } catch (IllegalAccessException e) {

                    throw new InternalError(e);

                }

            }

        });

    }

    static Thread createThreadWitNoPermissions(String threadName, Runnable runnable) {

        return doPrivilegedWithReturn(() -> new Thread(runnable, threadName), new Permission[0]);

    }

    static void setDaemonThread(Thread t, boolean daeomn) {

      doPrivileged(()-> t.setDaemon(daeomn), new RuntimePermission("modifyThread"));

    }

    public static SafePath getAbsolutePath(SafePath path) throws IOException {

        return new SafePath(doPrivilegedIOWithReturn((()-> path.toPath().toAbsolutePath())));

    }

}