/*

 * Copyright (c) 1999, 2014, 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 com.sun.media.sound;

import java.io.BufferedInputStream;

import java.io.InputStream;

import java.io.File;

import java.io.FileInputStream;

import java.util.ArrayList;

import java.util.Iterator;

import java.util.List;

import java.util.Properties;

import java.util.ServiceLoader;

import java.security.AccessController;

import java.security.PrivilegedAction;

import javax.sound.sampled.AudioPermission;

/** Managing security in the Java Sound implementation.

 * This class contains all code that uses and is used by

 * SecurityManager.doPrivileged().

 *

 * @author Matthias Pfisterer

 */

final class JSSecurityManager {

    /** Prevent instantiation.

     */

    private JSSecurityManager() {

    }

    /** Checks if the VM currently has a SecurityManager installed.

     * Note that this may change over time. So the result of this method

     * should not be cached.

     *

     * @return true if a SecurityManger is installed, false otherwise.

     */

    private static boolean hasSecurityManager() {

        return (System.getSecurityManager() != null);

    }

    static void checkRecordPermission() throws SecurityException {

        if(Printer.trace) Printer.trace("JSSecurityManager.checkRecordPermission()");

        SecurityManager sm = System.getSecurityManager();

        if (sm != null) {

            sm.checkPermission(new AudioPermission("record"));

        }

    }

    /** Load properties from a file.

        This method tries to load properties from the filename give into

        the passed properties object.

        If the file cannot be found or something else goes wrong,

        the method silently fails.

        @param properties The properties bundle to store the values of the

        properties file.

        @param filename The filename of the properties file to load. This

        filename is interpreted as relative to the subdirectory "lib" in

        the JRE directory.

     */

    static void loadProperties(final Properties properties,

                               final String filename) {

        if(hasSecurityManager()) {

            try {

                // invoke the privileged action using 1.2 security

                PrivilegedAction<Void> action = new PrivilegedAction<Void>() {

                        public Void run() {

                            loadPropertiesImpl(properties, filename);

                            return null;

                        }

                    };

                AccessController.doPrivileged(action);

                if(Printer.debug)Printer.debug("Loaded properties with JDK 1.2 security");

            } catch (Exception e) {

                if(Printer.debug)Printer.debug("Exception loading properties with JDK 1.2 security");

                // try without using JDK 1.2 security

                loadPropertiesImpl(properties, filename);

            }

        } else {

            // not JDK 1.2 security, assume we already have permission

            loadPropertiesImpl(properties, filename);

        }

    }

    private static void loadPropertiesImpl(Properties properties,

                                           String filename) {

        if(Printer.trace)Printer.trace(">> JSSecurityManager: loadPropertiesImpl()");

        String fname = System.getProperty("java.home");

        try {

            if (fname == null) {

                throw new Error("Can't find java.home ??");

            }

            File f = new File(fname, "lib");

            f = new File(f, filename);

            fname = f.getCanonicalPath();

            InputStream in = new FileInputStream(fname);

            BufferedInputStream bin = new BufferedInputStream(in);

            try {

                properties.load(bin);

            } finally {

                if (in != null) {

                    in.close();

                }

            }

        } catch (Throwable t) {

            if (Printer.trace) {

                System.err.println("Could not load properties file \"" + fname + "\"");

                t.printStackTrace();

            }

        }

        if(Printer.trace)Printer.trace("<< JSSecurityManager: loadPropertiesImpl() completed");

    }

    /** Create a Thread in the current ThreadGroup.

     */

    static Thread createThread(final Runnable runnable,

                               final String threadName,

                               final boolean isDaemon, final int priority,

                               final boolean doStart) {

        Thread thread = new Thread(runnable);

        if (threadName != null) {

            thread.setName(threadName);

        }

        thread.setDaemon(isDaemon);

        if (priority >= 0) {

            thread.setPriority(priority);

        }

        if (doStart) {

            thread.start();

        }

        return thread;

    }

    static synchronized <T> List<T> getProviders(final Class<T> providerClass) {

        List<T> p = new ArrayList<>(7);

        // ServiceLoader creates "lazy" iterator instance, but it ensures that

        // next/hasNext run with permissions that are restricted by whatever

        // creates the ServiceLoader instance, so it requires to be called from

        // privileged section

        final PrivilegedAction<Iterator<T>> psAction =

                new PrivilegedAction<Iterator<T>>() {

                    @Override

                    public Iterator<T> run() {

                        return ServiceLoader.load(providerClass).iterator();

                    }

                };

        final Iterator<T> ps = AccessController.doPrivileged(psAction);

        // the iterator's hasNext() method looks through classpath for

        // the provider class names, so it requires read permissions

        PrivilegedAction<Boolean> hasNextAction = new PrivilegedAction<Boolean>() {

            public Boolean run() {

                return ps.hasNext();

            }

        };

        while (AccessController.doPrivileged(hasNextAction)) {

            try {

                // the iterator's next() method creates instances of the

                // providers and it should be called in the current security

                // context

                T provider = ps.next();

                if (providerClass.isInstance(provider)) {

                    // $$mp 2003-08-22

                    // Always adding at the beginning reverses the

                    // order of the providers. So we no longer have

                    // to do this in AudioSystem and MidiSystem.

                    p.add(0, provider);

                }

            } catch (Throwable t) {

                //$$fb 2002-11-07: do not fail on SPI not found

                if (Printer.err) t.printStackTrace();

            }

        }

        return p;

    }

}