/*

 * 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

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

 *

 * 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.

 *

 */

package com.sun.naming.internal;

import java.io.InputStream;

import java.io.IOException;

import java.net.MalformedURLException;

import java.net.URLClassLoader;

import java.net.URL;

import java.security.AccessController;

import java.security.PrivilegedAction;

import java.security.PrivilegedActionException;

import java.security.PrivilegedExceptionAction;

import java.util.Enumeration;

import java.util.Hashtable;

import java.util.NoSuchElementException;

import java.util.Properties;

import javax.naming.*;

/**

 * VersionHelper was used by JNDI to accommodate differences between

 * JDK 1.1.x and the Java 2 platform. As this is no longer necessary

 * since JNDI's inclusion in the platform, this class currently

 * serves as a set of utilities for performing system-level things,

 * such as class-loading and reading system properties.

 *

 * @author Rosanna Lee

 * @author Scott Seligman

 */

final class VersionHelper12 extends VersionHelper {

    private boolean getSystemPropsFailed = false;

    VersionHelper12() {} // Disallow external from creating one of these.

    public Class loadClass(String className) throws ClassNotFoundException {

        ClassLoader cl = getContextClassLoader();

        return Class.forName(className, true, cl);

    }

    /**

      * Package private.

      */

    Class loadClass(String className, ClassLoader cl)

        throws ClassNotFoundException {

        return Class.forName(className, true, cl);

    }

    /**

     * @param className A non-null fully qualified class name.

     * @param codebase A non-null, space-separated list of URL strings.

     */

    public Class loadClass(String className, String codebase)

        throws ClassNotFoundException, MalformedURLException {

        ClassLoader cl;

        ClassLoader parent = getContextClassLoader();

        cl = URLClassLoader.newInstance(getUrlArray(codebase), parent);

        return Class.forName(className, true, cl);

    }

    String getJndiProperty(final int i) {

        return (String) AccessController.doPrivileged(

            new PrivilegedAction() {

                public Object run() {

                    try {

                        return System.getProperty(PROPS[i]);

                    } catch (SecurityException e) {

                        return null;

                    }

                }

            }

        );

    }

    String[] getJndiProperties() {

        if (getSystemPropsFailed) {

            return null;        // after one failure, don't bother trying again

        }

        Properties sysProps = (Properties) AccessController.doPrivileged(

            new PrivilegedAction() {

                public Object run() {

                    try {

                        return System.getProperties();

                    } catch (SecurityException e) {

                        getSystemPropsFailed = true;

                        return null;

                    }

                }

            }

        );

        if (sysProps == null) {

            return null;

        }

        String[] jProps = new String[PROPS.length];

        for (int i = 0; i < PROPS.length; i++) {

            jProps[i] = sysProps.getProperty(PROPS[i]);

        }

        return jProps;

    }

    InputStream getResourceAsStream(final Class c, final String name) {

        return (InputStream) AccessController.doPrivileged(

            new PrivilegedAction() {

                public Object run() {

                    return c.getResourceAsStream(name);

                }

            }

        );

    }

    InputStream getJavaHomeLibStream(final String filename) {

        return (InputStream) AccessController.doPrivileged(

            new PrivilegedAction() {

                public Object run() {

                    try {

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

                        if (javahome == null) {

                            return null;

                        }

                        String pathname = javahome + java.io.File.separator +

                            "lib" + java.io.File.separator + filename;

                        return new java.io.FileInputStream(pathname);

                    } catch (Exception e) {

                        return null;

                    }

                }

            }

        );

    }

    NamingEnumeration getResources(final ClassLoader cl, final String name)

            throws IOException

    {

        Enumeration urls;

        try {

            urls = (Enumeration) AccessController.doPrivileged(

                new PrivilegedExceptionAction() {

                    public Object run() throws IOException {

                        return (cl == null)

                            ? ClassLoader.getSystemResources(name)

                            : cl.getResources(name);

                    }

                }

            );

        } catch (PrivilegedActionException e) {

            throw (IOException)e.getException();

        }

        return new InputStreamEnumeration(urls);

    }

    ClassLoader getContextClassLoader() {

        return (ClassLoader) AccessController.doPrivileged(

            new PrivilegedAction() {

                public Object run() {

                    return Thread.currentThread().getContextClassLoader();

                }

            }

        );

    }

    /**

     * Given an enumeration of URLs, an instance of this class represents

     * an enumeration of their InputStreams.  Each operation on the URL

     * enumeration is performed within a doPrivileged block.

     * This is used to enumerate the resources under a foreign codebase.

     * This class is not MT-safe.

     */

    class InputStreamEnumeration implements NamingEnumeration {

        private final Enumeration urls;

        private Object nextElement = null;

        InputStreamEnumeration(Enumeration urls) {

            this.urls = urls;

        }

        /*

         * Returns the next InputStream, or null if there are no more.

         * An InputStream that cannot be opened is skipped.

         */

        private Object getNextElement() {

            return AccessController.doPrivileged(

                new PrivilegedAction() {

                    public Object run() {

                        while (urls.hasMoreElements()) {

                            try {

                                return ((URL)urls.nextElement()).openStream();

                            } catch (IOException e) {

                                // skip this URL

                            }

                        }

                        return null;

                    }

                }

            );

        }

        public boolean hasMore() {

            if (nextElement != null) {

                return true;

            }

            nextElement = getNextElement();

            return (nextElement != null);

        }

        public boolean hasMoreElements() {

            return hasMore();

        }

        public Object next() {

            if (hasMore()) {

                Object res = nextElement;

                nextElement = null;

                return res;

            } else {

                throw new NoSuchElementException();

            }

        }

        public Object nextElement() {

            return next();

        }

        public void close() {

        }

    }

}