/*

 * Copyright (c) 1997, 2013, 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.internal.loader;

import java.io.Closeable;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.IOException;

import java.io.InputStream;

import java.net.HttpURLConnection;

import java.net.JarURLConnection;

import java.net.MalformedURLException;

import java.net.URL;

import java.net.URLConnection;

import java.net.URLStreamHandler;

import java.net.URLStreamHandlerFactory;

import java.security.AccessControlException;

import java.security.AccessController;

import java.security.CodeSigner;

import java.security.Permission;

import java.security.PrivilegedExceptionAction;

import java.security.cert.Certificate;

import java.util.ArrayList;

import java.util.Collections;

import java.util.Enumeration;

import java.util.HashMap;

import java.util.HashSet;

import java.util.LinkedList;

import java.util.List;

import java.util.NoSuchElementException;

import java.util.Set;

import java.util.Stack;

import java.util.StringTokenizer;

import java.util.jar.JarFile;

import java.util.zip.ZipEntry;

import java.util.jar.JarEntry;

import java.util.jar.Manifest;

import java.util.jar.Attributes;

import java.util.jar.Attributes.Name;

import java.util.zip.ZipFile;

import jdk.internal.misc.JavaUtilZipFileAccess;

import jdk.internal.misc.SharedSecrets;

import jdk.internal.util.jar.InvalidJarIndexError;

import jdk.internal.util.jar.JarIndex;

import sun.net.util.URLUtil;

import sun.net.www.ParseUtil;

/**

 * This class is used to maintain a search path of URLs for loading classes

 * and resources from both JAR files and directories.

 *

 * @author  David Connelly

 */

public class URLClassPath {

    private static final String USER_AGENT_JAVA_VERSION = "UA-Java-Version";

    private static final String JAVA_VERSION;

    private static final boolean DEBUG;

    private static final boolean DISABLE_JAR_CHECKING;

    static {

        DISABLE_JAR_CHECKING = p != null ? p.equals("true") || p.equals("") : false;

    }

    /* The original search path of URLs. */

    private ArrayList<URL> path = new ArrayList<>();

    /* The stack of unopened URLs */

    Stack<URL> urls = new Stack<>();

    /* The resulting search path of Loaders */

    ArrayList<Loader> loaders = new ArrayList<>();

    /* Map of each URL opened to its corresponding Loader */

    HashMap<String, Loader> lmap = new HashMap<>();

    /* The jar protocol handler to use when creating new URLs */

    private URLStreamHandler jarHandler;

    /* Whether this URLClassLoader has been closed yet */

    private boolean closed = false;

    /**

     * Creates a new URLClassPath for the given URLs. The URLs will be

     * searched in the order specified for classes and resources. A URL

     * ending with a '/' is assumed to refer to a directory. Otherwise,

     * the URL is assumed to refer to a JAR file.

     *

     * @param urls the directory and JAR file URLs to search for classes

     *        and resources

     * @param factory the URLStreamHandlerFactory to use when creating new URLs

     */

    public URLClassPath(URL[] urls, URLStreamHandlerFactory factory) {

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

            path.add(urls[i]);

        }

        push(urls);

        if (factory != null) {

            jarHandler = factory.createURLStreamHandler("jar");

        }

    }

    public URLClassPath(URL[] urls) {

        this(urls, null);

    }

    public synchronized List<IOException> closeLoaders() {

        if (closed) {

            return Collections.emptyList();

        }

        List<IOException> result = new LinkedList<>();

        for (Loader loader : loaders) {

            try {

                loader.close();

            } catch (IOException e) {

                result.add (e);

            }

        }

        closed = true;

        return result;

    }

    /**

     * Appends the specified URL to the search path of directory and JAR

     * file URLs from which to load classes and resources.

     * <p>

     * If the URL specified is null or is already in the list of

     * URLs, then invoking this method has no effect.

     */

    public synchronized void addURL(URL url) {

        if (closed)

            return;

        synchronized (urls) {

            if (url == null || path.contains(url))

                return;

            urls.add(0, url);

            path.add(url);

        }

    }

    /**

     * Returns the original search path of URLs.

     */

    public URL[] getURLs() {

        synchronized (urls) {

            return path.toArray(new URL[path.size()]);

        }

    }

    /**

     * Finds the resource with the specified name on the URL search path

     * or null if not found or security check fails.

     *

     * @param name      the name of the resource

     * @param check     whether to perform a security check

     * @return a <code>URL</code> for the resource, or <code>null</code>

     * if the resource could not be found.

     */

    public URL findResource(String name, boolean check) {

        Loader loader;

        for (int i = 0; (loader = getLoader(i)) != null; i++) {

            URL url = loader.findResource(name, check);

            if (url != null) {

                return url;

            }

        }

        return null;

    }

    /**

     * Finds the first Resource on the URL search path which has the specified

     * name. Returns null if no Resource could be found.

     *

     * @param name the name of the Resource

     * @param check     whether to perform a security check

     * @return the Resource, or null if not found

     */

    public Resource getResource(String name, boolean check) {

        if (DEBUG) {

            System.err.println("URLClassPath.getResource(\"" + name + "\")");

        }

        Loader loader;

        for (int i = 0; (loader = getLoader(i)) != null; i++) {

            Resource res = loader.getResource(name, check);

            if (res != null) {

                return res;

            }

        }

        return null;

    }

    /**

     * Finds all resources on the URL search path with the given name.

     * Returns an enumeration of the URL objects.

     *

     * @param name the resource name

     * @return an Enumeration of all the urls having the specified name

     */

    public Enumeration<URL> findResources(final String name,

                                     final boolean check) {

        return new Enumeration<>() {

            private int index = 0;

            private URL url = null;

            private boolean next() {

                if (url != null) {

                    return true;

                } else {

                    Loader loader;

                    while ((loader = getLoader(index++)) != null) {

                        url = loader.findResource(name, check);

                        if (url != null) {

                            return true;

                        }

                    }

                    return false;

                }

            }

            public boolean hasMoreElements() {

                return next();

            }

            public URL nextElement() {

                if (!next()) {

                    throw new NoSuchElementException();

                }

                URL u = url;

                url = null;

                return u;

            }

        };

    }

    public Resource getResource(String name) {

        return getResource(name, true);

    }

    /**

     * Finds all resources on the URL search path with the given name.

     * Returns an enumeration of the Resource objects.

     *

     * @param name the resource name

     * @return an Enumeration of all the resources having the specified name

     */

    public Enumeration<Resource> getResources(final String name,

                                    final boolean check) {

        return new Enumeration<>() {

            private int index = 0;

            private Resource res = null;

            private boolean next() {

                if (res != null) {

                    return true;

                } else {

                    Loader loader;

                    while ((loader = getLoader(index++)) != null) {

                        res = loader.getResource(name, check);

                        if (res != null) {

                            return true;

                        }

                    }

                    return false;

                }

            }

            public boolean hasMoreElements() {

                return next();

            }

            public Resource nextElement() {

                if (!next()) {

                    throw new NoSuchElementException();

                }

                Resource r = res;

                res = null;

                return r;

            }

        };

    }

    public Enumeration<Resource> getResources(final String name) {

        return getResources(name, true);

    }

    /*

     * Returns the Loader at the specified position in the URL search

     * path. The URLs are opened and expanded as needed. Returns null

     * if the specified index is out of range.

     */

     private synchronized Loader getLoader(int index) {

        if (closed) {

            return null;

        }

         // Expand URL search path until the request can be satisfied

         // or the URL stack is empty.

        while (loaders.size() < index + 1) {

            // Pop the next URL from the URL stack

            URL url;

            synchronized (urls) {

                if (urls.empty()) {

                    return null;

                } else {

                    url = urls.pop();

                }

            }

            // Skip this URL if it already has a Loader. (Loader

            // may be null in the case where URL has not been opened

            // but is referenced by a JAR index.)

            String urlNoFragString = URLUtil.urlNoFragString(url);

            if (lmap.containsKey(urlNoFragString)) {

                continue;

            }

            // Otherwise, create a new Loader for the URL.

            Loader loader;

            try {

                loader = getLoader(url);

                // If the loader defines a local class path then add the

                // URLs to the list of URLs to be opened.

                URL[] urls = loader.getClassPath();

                if (urls != null) {

                    push(urls);

                }

            } catch (IOException e) {

                // Silently ignore for now...

                continue;

            }

            // Finally, add the Loader to the search path.

            loaders.add(loader);

            lmap.put(urlNoFragString, loader);

        }

        return loaders.get(index);

    }

    /*

     * Returns the Loader for the specified base URL.

     */

    private Loader getLoader(final URL url) throws IOException {

        try {

            return java.security.AccessController.doPrivileged(

                new java.security.PrivilegedExceptionAction<>() {

                public Loader run() throws IOException {

                    String file = url.getFile();

                    if (file != null && file.endsWith("/")) {

                        if ("file".equals(url.getProtocol())) {

                            return new FileLoader(url);

                        } else {

                            return new Loader(url);

                        }

                    } else {

                        return new JarLoader(url, jarHandler, lmap);

                    }

                }

            });

        } catch (java.security.PrivilegedActionException pae) {

            throw (IOException)pae.getException();

        }

    }

    /*

     * Pushes the specified URLs onto the list of unopened URLs.

     */

    private void push(URL[] us) {

        synchronized (urls) {

            for (int i = us.length - 1; i >= 0; --i) {

                urls.push(us[i]);

            }

        }

    }

    /*

     * Check whether the resource URL should be returned.

     * Return null on security check failure.

     * Called by java.net.URLClassLoader.

     */

    public static URL checkURL(URL url) {

        if (url != null) {

            try {

                check(url);

            } catch (Exception e) {

                return null;

            }

        }

        return url;

    }

    /*

     * Check whether the resource URL should be returned.

     * Throw exception on failure.

     * Called internally within this file.

     */

    public static void check(URL url) throws IOException {

        SecurityManager security = System.getSecurityManager();

        if (security != null) {

            URLConnection urlConnection = url.openConnection();

            Permission perm = urlConnection.getPermission();

            if (perm != null) {

                try {

                    security.checkPermission(perm);

                } catch (SecurityException se) {

                    // fallback to checkRead/checkConnect for pre 1.2

                    // security managers

                    if ((perm instanceof java.io.FilePermission) &&

                        perm.getActions().indexOf("read") != -1) {

                        security.checkRead(perm.getName());

                    } else if ((perm instanceof

                        java.net.SocketPermission) &&

                        perm.getActions().indexOf("connect") != -1) {

                        URL locUrl = url;

                        if (urlConnection instanceof JarURLConnection) {

                            locUrl = ((JarURLConnection)urlConnection).getJarFileURL();

                        }

                        security.checkConnect(locUrl.getHost(),

                                              locUrl.getPort());

                    } else {

                        throw se;

                    }

                }

            }

        }

    }

    /**

     * Inner class used to represent a loader of resources and classes

     * from a base URL.

     */

    private static class Loader implements Closeable {

        private final URL base;

        private JarFile jarfile; // if this points to a jar file

        /*

         * Creates a new Loader for the specified URL.

         */

        Loader(URL url) {

            base = url;

        }

        /*

         * Returns the base URL for this Loader.

         */

        URL getBaseURL() {

            return base;

        }

        URL findResource(final String name, boolean check) {

            URL url;

            try {

                url = new URL(base, ParseUtil.encodePath(name, false));

            } catch (MalformedURLException e) {

                throw new IllegalArgumentException("name");

            }

            try {

                if (check) {

                    URLClassPath.check(url);

                }

                /*

                 * For a HTTP connection we use the HEAD method to

                 * check if the resource exists.

                 */

                URLConnection uc = url.openConnection();

                if (uc instanceof HttpURLConnection) {

                    HttpURLConnection hconn = (HttpURLConnection)uc;

                    hconn.setRequestMethod("HEAD");

                    if (hconn.getResponseCode() >= HttpURLConnection.HTTP_BAD_REQUEST) {

                        return null;

                    }

                } else {

                    // our best guess for the other cases

                    uc.setUseCaches(false);

                    InputStream is = uc.getInputStream();

                    is.close();

                }

                return url;

            } catch (Exception e) {

                return null;

            }

        }

        Resource getResource(final String name, boolean check) {

            final URL url;

            try {