/*
 * Copyright (c) 1997, 2018 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package com.sun.ts.lib.util.sec.misc;

import java.util.Enumeration;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.Hashtable;
import java.util.NoSuchElementException;
import java.util.Stack;
import java.util.Set;
import java.util.HashSet;
import java.util.StringTokenizer;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.jar.JarFile;
import com.sun.ts.lib.util.sec.misc.JarIndex;
import com.sun.ts.lib.util.sec.misc.InvalidJarIndexException;
import com.sun.ts.lib.util.sec.net.www.ParseUtil;
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.net.JarURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.net.HttpURLConnection;
import java.net.URLStreamHandler;
import java.net.URLStreamHandlerFactory;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.security.AccessController;
import java.security.AccessControlException;
import java.security.CodeSigner;
import java.security.Permission;
import java.security.PrivilegedAction;
import java.security.PrivilegedExceptionAction;
import java.security.cert.Certificate;
import com.sun.ts.lib.util.sec.misc.FileURLMapper;

/**
 * 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 {
  final static String USER_AGENT_JAVA_VERSION = "UA-Java-Version";

  final static String JAVA_VERSION;

  private static final boolean DEBUG;

  static {
    JAVA_VERSION = java.security.AccessController.doPrivileged(
        new com.sun.ts.lib.util.sec.security.action.GetPropertyAction(
            "java.version"));
    DEBUG = (java.security.AccessController.doPrivileged(
        new com.sun.ts.lib.util.sec.security.action.GetPropertyAction(
            "sun.misc.URLClassPath.debug")) != null);
  }

  /* The original search path of URLs. */
  private ArrayList path = new ArrayList();

  /* The stack of unopened URLs */
  Stack urls = new Stack();

  /* The resulting search path of Loaders */
  ArrayList loaders = new ArrayList();

  /* Map of each URL opened to its corresponding Loader */
  HashMap lmap = new HashMap();

  /* The jar protocol handler to use when creating new URLs */
  private URLStreamHandler jarHandler;

  /**
   * 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);
  }

  /**
   * Appends the specified URL to the search path of directory and JAR file URLs
   * from which to load classes and resources.
   */
  public void addURL(URL url) {
    synchronized (urls) {
      if (path.contains(url))
        return;

      urls.add(0, url);
      path.add(url);
    }
  }

  /**
   * Returns the original search path of URLs.
   */
  public URL[] getURLs() {
    synchronized (urls) {
      return (URL[]) 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 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 Object 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 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 Object nextElement() {
        if (!next()) {
          throw new NoSuchElementException();
        }
        Resource r = res;
        res = null;
        return r;
      }
    };
  }

  public Enumeration 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) {
    // 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 = (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.)
      if (lmap.containsKey(url)) {
        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(url, loader);
    }
    return (Loader) loaders.get(index);
  }

  /*
   * Returns the Loader for the specified base URL.
   */
  private Loader getLoader(final URL url) throws IOException {
    try {
      return (Loader) java.security.AccessController
          .doPrivileged(new java.security.PrivilegedExceptionAction() {
            public Object 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]);
      }
    }
  }

  /**
   * Convert class path specification into an array of file URLs.
   *
   * The path of the file is encoded before conversion into URL form so that
   * reserved characters can safely appear in the path.
   */
  public static URL[] pathToURLs(String path) {
    StringTokenizer st = new StringTokenizer(path, File.pathSeparator);
    URL[] urls = new URL[st.countTokens()];
    int count = 0;
    while (st.hasMoreTokens()) {
      File f = new File(st.nextToken());
      try {
        f = new File(f.getCanonicalPath());
      } catch (IOException x) {
        // use the non-canonicalized filename
      }
      try {
        urls[count++] = ParseUtil.fileToEncodedURL(f);
      } catch (IOException x) {
      }
    }

    if (urls.length != count) {
      URL[] tmp = new URL[count];
      System.arraycopy(urls, 0, tmp, 0, count);
      urls = tmp;
    }
    return urls;
  }

  /*
   * Check whether the resource URL should be returned. Return null on security
   * check failure. Called by java.net.URLClassLoader.
   */
  public URL checkURL(URL url) {
    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.
   */
  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 {
    private final URL base;

    /*
     * 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
          InputStream is = url.openStream();
          is.close();
        }
        return url;
      } catch (Exception e) {
        return null;
      }
    }

    Resource getResource(final String name, boolean check) {
      final URL url;
      try {
        url = new URL(base, ParseUtil.encodePath(name, false));
      } catch (MalformedURLException e) {
        throw new IllegalArgumentException("name");
      }
      final URLConnection uc;
      try {
        if (check) {
          URLClassPath.check(url);
        }
        uc = url.openConnection();
        InputStream in = uc.getInputStream();
      } catch (Exception e) {
        return null;
      }
      return new Resource() {
        public String getName() {
          return name;
        }

        public URL getURL() {
          return url;
        }

        public URL getCodeSourceURL() {
          return base;
        }

        public InputStream getInputStream() throws IOException {
          return uc.getInputStream();
        }

        public int getContentLength() throws IOException {
          return uc.getContentLength();
        }
      };
    }

    /*
     * Returns the Resource for the specified name, or null if not found or the
     * caller does not have the permission to get the resource.
     */
    Resource getResource(final String name) {
      return getResource(name, true);
    }

    /*
     * Returns the local class path for this loader, or null if none.
     */
    URL[] getClassPath() throws IOException {
      return null;
    }
  }

  /*
   * Inner class used to represent a Loader of resources from a JAR URL.
   */
  static class JarLoader extends Loader {
    private JarFile jar;

    private URL csu;

    private JarIndex index;

    private MetaIndex metaIndex;

    private URLStreamHandler handler;

    private HashMap lmap;

    /*
     * Creates a new JarLoader for the specified URL referring to a JAR file.
     */
    JarLoader(URL url, URLStreamHandler jarHandler, HashMap loaderMap)
        throws IOException {
      super(new URL("jar", "", -1, url + "!/", jarHandler));
      csu = url;
      handler = jarHandler;
      lmap = loaderMap;

      if (!isOptimizable(url)) {
        ensureOpen();
      } else {
        String fileName = url.getFile();
        if (fileName != null) {
          fileName = ParseUtil.decode(fileName);
          File f = new File(fileName);
          metaIndex = MetaIndex.forJar(f);
          // If the meta index is found but the file is not
          // installed, set metaIndex to null. A typical
          // senario is charsets.jar which won't be installed
          // when the user is running in certain locale environment.
          // The side effect of null metaIndex will cause
          // ensureOpen get called so that IOException is thrown.
          if (metaIndex != null && !f.exists()) {
            metaIndex = null;
          }
        }

        // metaIndex is null when either there is no such jar file
        // entry recorded in meta-index file or such jar file is
        // missing in JRE. See bug 6340399.
        if (metaIndex == null) {
          ensureOpen();
        }
      }
    }

    JarFile getJarFile() {
      return jar;
    }

    private boolean isOptimizable(URL url) {
      return "file".equals(url.getProtocol());
    }

    private void ensureOpen() throws IOException {
      if (jar == null) {
        try {
          java.security.AccessController
              .doPrivileged(new java.security.PrivilegedExceptionAction() {
                public Object run() throws IOException {
                  if (DEBUG) {
                    System.err.println("Opening " + csu);
                    Thread.dumpStack();
                  }

                  jar = getJarFile(csu);
                  index = JarIndex.getJarIndex(jar, metaIndex);
                  if (index != null) {
                    String[] jarfiles = index.getJarFiles();
                    // Add all the dependent URLs to the lmap so that loaders
                    // will not be created for them by
                    // URLClassPath.getLoader(int)
                    // if the same URL occurs later on the main class path. We
                    // set
                    // Loader to null here to avoid creating a Loader for each
                    // URL until we actually need to try to load something from
                    // them.
                    for (int i = 0; i < jarfiles.length; i++) {
                      try {
                        URL jarURL = new URL(csu, jarfiles[i]);
                        // If a non-null loader already exists, leave it alone.
                        if (!lmap.containsKey(jarURL)) {
                          lmap.put(jarURL, null);
                        }
                      } catch (MalformedURLException e) {
                        continue;
                      }
                    }
                  }
                  return null;
                }
              });
        } catch (java.security.PrivilegedActionException pae) {
          throw (IOException) pae.getException();
        }
      }
    }

    private JarFile getJarFile(URL url) throws IOException {
      // Optimize case where url refers to a local jar file
      if (isOptimizable(url)) {
        FileURLMapper p = new FileURLMapper(url);
        if (!p.exists()) {
          throw new FileNotFoundException(p.getPath());
        }
        return new JarFile(p.getPath());
      }
      URLConnection uc = getBaseURL().openConnection();
      uc.setRequestProperty(USER_AGENT_JAVA_VERSION, JAVA_VERSION);
      return ((JarURLConnection) uc).getJarFile();
    }

    /*
     * Returns the index of this JarLoader if it exists.
     */
    JarIndex getIndex() {
      try {
        ensureOpen();
      } catch (IOException e) {
        throw (InternalError) new InternalError().initCause(e);
      }
      return index;
    }

    /*
     * Creates the resource and if the check flag is set to true, checks if is
     * its okay to return the resource.
     */
    Resource checkResource(final String name, boolean check,
        final JarEntry entry) {

      final URL url;
      try {
        url = new URL(getBaseURL(), ParseUtil.encodePath(name, false));
        if (check) {
          URLClassPath.check(url);
        }
      } catch (MalformedURLException e) {
        return null;
        // throw new IllegalArgumentException("name");
      } catch (IOException e) {
        return null;
      } catch (AccessControlException e) {
        return null;
      }

      return new Resource() {
        public String getName() {
          return name;
        }

        public URL getURL() {
          return url;
        }

        public URL getCodeSourceURL() {
          return csu;
        }

        public InputStream getInputStream() throws IOException {
          return jar.getInputStream(entry);
        }

        public int getContentLength() {
          return (int) entry.getSize();
        }

        public Manifest getManifest() throws IOException {
          return jar.getManifest();
        };

        public Certificate[] getCertificates() {
          return entry.getCertificates();
        };

        public CodeSigner[] getCodeSigners() {
          return entry.getCodeSigners();
        };
      };
    }

    /*
     * Returns true iff atleast one resource in the jar file has the same
     * package name as that of the specified resource name.
     */
    boolean validIndex(final String name) {
      String packageName = name;
      int pos;
      if ((pos = name.lastIndexOf("/")) != -1) {
        packageName = name.substring(0, pos);
      }

      String entryName;
      ZipEntry entry;
      Enumeration enum_ = jar.entries();
      while (enum_.hasMoreElements()) {
        entry = (ZipEntry) enum_.nextElement();
        entryName = entry.getName();
        if ((pos = entryName.lastIndexOf("/")) != -1)
          entryName = entryName.substring(0, pos);
        if (entryName.equals(packageName)) {
          return true;
        }
      }
      return false;
    }

    /*
     * Returns the URL for a resource with the specified name
     */
    URL findResource(final String name, boolean check) {
      Resource rsc = getResource(name, check);
      if (rsc != null) {
        return rsc.getURL();
      }
      return null;
    }

    /*
     * Returns the JAR Resource for the specified name.
     */
    Resource getResource(final String name, boolean check) {
      if (metaIndex != null) {
        if (!metaIndex.mayContain(name)) {
          return null;
        }
      }

      try {
        ensureOpen();
      } catch (IOException e) {
        throw (InternalError) new InternalError().initCause(e);
      }
      final JarEntry entry = jar.getJarEntry(name);
      if (entry != null)
        return checkResource(name, check, entry);

      if (index == null)
        return null;

      HashSet visited = new HashSet();
      return getResource(name, check, visited);
    }

    /*
     * Version of getResource() that tracks the jar files that have been visited
     * by linking through the index files. This helper method uses a HashSet to
     * store the URLs of jar files that have been searched and uses it to avoid
     * going into an infinite loop, looking for a non-existent resource
     */
    Resource getResource(final String name, boolean check, Set visited) {

      Resource res;
      Object[] jarFiles;
      boolean done = false;
      int count = 0;
      LinkedList jarFilesList = null;

      /*
       * If there no jar files in the index that can potential contain this
       * resource then return immediately.
       */
      if ((jarFilesList = index.get(name)) == null)
        return null;

      do {
        jarFiles = jarFilesList.toArray();
        int size = jarFilesList.size();
        /* loop through the mapped jar file list */
        while (count < size) {
          String jarName = (String) jarFiles[count++];
          JarLoader newLoader;
          final URL url;

          try {
            url = new URL(csu, jarName);
            if ((newLoader = (JarLoader) lmap.get(url)) == null) {
              /*
               * no loader has been set up for this jar file before
               */
              newLoader = (JarLoader) AccessController
                  .doPrivileged(new PrivilegedExceptionAction() {
                    public Object run() throws IOException {
                      return new JarLoader(url, handler, lmap);
                    }
                  });

              /*
               * this newly opened jar file has its own index, merge it into the
               * parent's index, taking into account the relative path.
               */
              JarIndex newIndex = newLoader.getIndex();
              if (newIndex != null) {
                int pos = jarName.lastIndexOf("/");
                newIndex.merge(this.index,
                    (pos == -1 ? null : jarName.substring(0, pos + 1)));
              }

              /* put it in the global hashtable */
              lmap.put(url, newLoader);
            }
          } catch (java.security.PrivilegedActionException pae) {
            continue;
          } catch (MalformedURLException e) {
            continue;
          }

          /*
           * Note that the addition of the url to the list of visited jars
           * incorporates a check for presence in the hashmap
           */
          boolean visitedURL = !visited.add(url);
          if (!visitedURL) {
            try {
              newLoader.ensureOpen();
            } catch (IOException e) {
              throw (InternalError) new InternalError().initCause(e);
            }
            final JarEntry entry = newLoader.jar.getJarEntry(name);
            if (entry != null) {
              return newLoader.checkResource(name, check, entry);
            }

            /*
             * Verify that at least one other resource with the same package
             * name as the lookedup resource is present in the new jar
             */
            if (!newLoader.validIndex(name)) {
              /* the mapping is wrong */
              throw new InvalidJarIndexException("Invalid index");
            }
          }

          /*
           * If newLoader is the current loader or if it is a loader that has
           * already been searched or if the new loader does not have an index
           * then skip it and move on to the next loader.
           */
          if (visitedURL || newLoader == this || newLoader.getIndex() == null) {
            continue;
          }

          /*
           * Process the index of the new loader
           */
          if ((res = newLoader.getResource(name, check, visited)) != null) {
            return res;
          }
        }
        // Get the list of jar files again as the list could have grown
        // due to merging of index files.
        jarFilesList = index.get(name);

        // If the count is unchanged, we are done.
      } while (count < jarFilesList.size());
      return null;
    }

    /*
     * Returns the JAR file local class path, or null if none.
     */
    URL[] getClassPath() throws IOException {
      if (index != null) {
        return null;
      }

      if (metaIndex != null) {
        return null;
      }

      ensureOpen();
      parseExtensionsDependencies();
      if (SharedSecrets.javaUtilJarAccess().jarFileHasClassPathAttribute(jar)) { // Only
                                                                                 // get
                                                                                 // manifest
                                                                                 // when
                                                                                 // necessary
        Manifest man = jar.getManifest();
        if (man != null) {
          Attributes attr = man.getMainAttributes();
          if (attr != null) {
            String value = attr.getValue(Name.CLASS_PATH);
            if (value != null) {
              return parseClassPath(csu, value);
            }
          }
        }
      }
      return null;
    }

    /*
     * parse the standard extension dependencies
     */
    private void parseExtensionsDependencies() throws IOException {
      ExtensionDependency.checkExtensionsDependencies(jar);
    }

    /*
     * Parses value of the Class-Path manifest attribute and returns an array of
     * URLs relative to the specified base URL.
     */
    private URL[] parseClassPath(URL base, String value)
        throws MalformedURLException {
      StringTokenizer st = new StringTokenizer(value);
      URL[] urls = new URL[st.countTokens()];
      int i = 0;
      while (st.hasMoreTokens()) {
        String path = st.nextToken();
        urls[i] = new URL(base, path);
        i++;
      }
      return urls;
    }
  }

  /*
   * Inner class used to represent a loader of classes and resources from a file
   * URL that refers to a directory.
   */
  private static class FileLoader extends Loader {
    private File dir;

    FileLoader(URL url) throws IOException {
      super(url);
      if (!"file".equals(url.getProtocol())) {
        throw new IllegalArgumentException("url");
      }
      String path = url.getFile().replace('/', File.separatorChar);
      path = ParseUtil.decode(path);
      dir = new File(path);
    }

    /*
     * Returns the URL for a resource with the specified name
     */
    URL findResource(final String name, boolean check) {
      Resource rsc = getResource(name, check);
      if (rsc != null) {
        return rsc.getURL();
      }
      return null;
    }

    Resource getResource(final String name, boolean check) {
      final URL url;
      try {
        URL normalizedBase = new URL(getBaseURL(), ".");
        url = new URL(getBaseURL(), ParseUtil.encodePath(name, false));

        if (url.getFile().startsWith(normalizedBase.getFile()) == false) {
          // requested resource had ../..'s in path
          return null;
        }

        if (check)
          URLClassPath.check(url);
        final File file = new File(dir, name.replace('/', File.separatorChar));
        if (file.exists()) {
          return new Resource() {
            public String getName() {
              return name;
            };

            public URL getURL() {
              return url;
            };

            public URL getCodeSourceURL() {
              return getBaseURL();
            };

            public InputStream getInputStream() throws IOException {
              return new FileInputStream(file);
            };

            public int getContentLength() throws IOException {
              return (int) file.length();
            };
          };
        }
      } catch (Exception e) {
        return null;
      }
      return null;
    }
  }
}
