/*

 * Copyright 1999-2007 Sun Microsystems, Inc.  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.  Sun designates this

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

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.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.security.AccessController;

import java.security.PrivilegedAction;

import javax.sound.sampled.AudioPermission;

import sun.misc.Service;

/** Managing security in the Java Sound implementation.

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

 * SecurityManager.doPrivileged().

 *

 * @author Matthias Pfisterer

 */

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"));

        }

    }

    static void loadLibrary(final String libName) {

        try {

            if (hasSecurityManager()) {

                if(Printer.debug) Printer.debug("using security manager to load library");

                PrivilegedAction action = new PrivilegedAction() {

                        public Object run() {

                            System.loadLibrary(libName);

                            return null;

                        }

                    };

                AccessController.doPrivileged(action);

            } else {

                if(Printer.debug) Printer.debug("not using security manager to load library");

                System.loadLibrary(libName);

            }

            if (Printer.debug) Printer.debug("loaded library " + libName);

        } catch (UnsatisfiedLinkError e2) {

            if (Printer.err)Printer.err("UnsatisfiedLinkError loading native library " + libName);

            throw(e2);

        }

    }

    static String getProperty(final String propertyName) {

        String propertyValue;

        if (hasSecurityManager()) {

            if(Printer.debug) Printer.debug("using JDK 1.2 security to get property");

            try{

                PrivilegedAction action = new PrivilegedAction() {

                        public Object run() {

                            try {

                                return System.getProperty(propertyName);

                            } catch (Throwable t) {

                                return null;

                            }

                        }

                    };

                propertyValue = (String) AccessController.doPrivileged(action);

            } catch( Exception e ) {

                if(Printer.debug) Printer.debug("not using JDK 1.2 security to get properties");

                propertyValue = System.getProperty(propertyName);

            }

        } else {

            if(Printer.debug) Printer.debug("not using JDK 1.2 security to get properties");

            propertyValue = System.getProperty(propertyName);

        }

        return propertyValue;

    }

    /** 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 action = new PrivilegedAction() {

                        public Object 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");

    }

    private static ThreadGroup getTopmostThreadGroup() {

        ThreadGroup topmostThreadGroup;

        if(hasSecurityManager()) {

            try {

                // invoke the privileged action using 1.2 security

                PrivilegedAction action = new PrivilegedAction() {

                        public Object run() {

                            try {

                                return getTopmostThreadGroupImpl();

                            } catch (Throwable t) {

                                return null;

                            }

                        }

                    };

                topmostThreadGroup = (ThreadGroup) AccessController.doPrivileged(action);

                if(Printer.debug)Printer.debug("Got topmost thread group with JDK 1.2 security");

            } catch (Exception e) {

                if(Printer.debug)Printer.debug("Exception getting topmost thread group with JDK 1.2 security");

                // try without using JDK 1.2 security

                topmostThreadGroup = getTopmostThreadGroupImpl();

            }

        } else {

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

            topmostThreadGroup = getTopmostThreadGroupImpl();

        }

        return topmostThreadGroup;

    }

    private static ThreadGroup getTopmostThreadGroupImpl() {

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

        ThreadGroup g = Thread.currentThread().getThreadGroup();

        while ((g.getParent() != null) && (g.getParent().getParent() != null)) {

            g = g.getParent();

        }

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

        return g;

    }

    /** Create a Thread in the topmost ThreadGroup.

     */

    static Thread createThread(final Runnable runnable,

                               final String threadName,

                               final boolean isDaemon, final int priority,

                               final boolean doStart) {

        Thread thread = null;

        if(hasSecurityManager()) {

            PrivilegedAction action = new PrivilegedAction() {

                    public Object run() {

                        try {

                            return createThreadImpl(runnable, threadName,

                                                    isDaemon, priority,

                                                    doStart);

                        } catch (Throwable t) {

                            return null;

                        }

                    }

                };

            thread = (Thread) AccessController.doPrivileged(action);

            if(Printer.debug) Printer.debug("created thread with JDK 1.2 security");

        } else {

            if(Printer.debug)Printer.debug("not using JDK 1.2 security");

            thread = createThreadImpl(runnable, threadName, isDaemon, priority,

                                      doStart);

        }

        return thread;

    }

    private static Thread createThreadImpl(Runnable runnable,

                                           String threadName,

                                           boolean isDaemon, int priority,

                                           boolean doStart) {

        ThreadGroup threadGroup = getTopmostThreadGroupImpl();

        Thread thread = new Thread(threadGroup, runnable);

        if (threadName != null) {

            thread.setName(threadName);

        }

        thread.setDaemon(isDaemon);

        if (priority >= 0) {

            thread.setPriority(priority);

        }

        if (doStart) {

            thread.start();

        }

        return thread;

    }

    static List getProviders(final Class providerClass) {

        PrivilegedAction action = new PrivilegedAction() {

                public Object run() {

                    List p = new ArrayList();

                    Iterator ps = Service.providers(providerClass);

                    while (ps.hasNext()) {

                        try {

                            Object 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;

                }

            };

        List providers = (List) AccessController.doPrivileged(action);

        return providers;

    }

}