GUAC-587: Use GUACAMOLE_HOME/lib as lib directory.

guacamole/src/main/java/org/glyptodon/guacamole/net/basic/extension/DirectoryClassLoader.java

@@ -0,0 +1,156 @@
+/*
+ * Copyright (C) 2015 Glyptodon LLC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package org.glyptodon.guacamole.net.basic.extension;
+
+import java.io.File;
+import java.io.FilenameFilter;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.security.AccessController;
+import java.security.PrivilegedActionException;
+import java.security.PrivilegedExceptionAction;
+import java.util.ArrayList;
+import java.util.Collection;
+import org.glyptodon.guacamole.GuacamoleException;
+
+/**
+ * A ClassLoader implementation which finds classes within .jar files within a
+ * given directory.
+ *
+ * @author Michael Jumper
+ */
+public class DirectoryClassLoader extends URLClassLoader {
+
+    /**
+     * Returns an instance of DirectoryClassLoader configured to load .jar
+     * files from the given directory. Calling this function multiple times
+     * will not affect previously-returned instances of DirectoryClassLoader.
+     *
+     * @param dir
+     *     The directory from which .jar files should be read.
+     *
+     * @return
+     *     A DirectoryClassLoader instance which loads classes from the .jar
+     *     files in the given directory.
+     *
+     * @throws GuacamoleException
+     *     If the given file is not a directory, or the contents of the given
+     *     directory cannot be read.
+     */
+    public static DirectoryClassLoader getInstance(final File dir)
+            throws GuacamoleException {
+
+        try {
+            // Attempt to create singleton classloader which loads classes from
+            // all .jar's in the lib directory defined in guacamole.properties
+            return AccessController.doPrivileged(new PrivilegedExceptionAction<DirectoryClassLoader>() {
+
+                @Override
+                public DirectoryClassLoader run() throws GuacamoleException {
+                    return new DirectoryClassLoader(dir);
+                }
+
+            });
+        }
+
+        catch (PrivilegedActionException e) {
+            throw (GuacamoleException) e.getException();
+        }
+
+    }
+
+    /**
+     * Returns all .jar files within the given directory as an array of URLs.
+     *
+     * @param dir
+     *     The directory to retrieve all .jar files from
+     *
+     * @return
+     *     An array of the URLs of all .jar files within the given directory.
+     *
+     * @throws GuacamoleException
+     *     If the given file is not a directory, or the contents of the given
+     *     directory cannot be read.
+     */
+    private static URL[] getJarURLs(File dir) throws GuacamoleException {
+
+        // Validate directory is indeed a directory
+        if (!dir.isDirectory())
+            throw new GuacamoleException(dir + " is not a directory.");
+
+        // Get list of URLs for all .jar's in the lib directory
+        Collection<URL> jarURLs = new ArrayList<URL>();
+        File[] files = dir.listFiles(new FilenameFilter() {
+
+            @Override
+            public boolean accept(File dir, String name) {
+
+                // If it ends with .jar, accept the file
+                return name.endsWith(".jar");
+
+            }
+
+        });
+
+        // Verify directory was successfully read
+        if (files == null)
+            throw new GuacamoleException("Unable to read contents of directory " + dir);
+
+        // Add the URL for each .jar to the jar URL list
+        for (File file : files) {
+
+            try {
+                jarURLs.add(file.toURI().toURL());
+            }
+            catch (MalformedURLException e) {
+                throw new GuacamoleException(e);
+            }
+
+        }
+
+        // Set delegate classloader to new URLClassLoader which loads from the
+        // .jars found above.
+
+        URL[] urls = new URL[jarURLs.size()];
+        return jarURLs.toArray(urls);
+
+    }
+
+    /**
+     * Creates a new DirectoryClassLoader configured to load .jar files from
+     * the given directory.
+     *
+     * @param dir
+     *     The directory from which .jar files should be read.
+     *
+     * @throws GuacamoleException
+     *     If the given file is not a directory, or the contents of the given
+     *     directory cannot be read.
+     */
+
+    private DirectoryClassLoader(File dir) throws GuacamoleException {
+        super(getJarURLs(dir), DirectoryClassLoader.class.getClassLoader());
+    }
+
+}

guacamole/src/main/java/org/glyptodon/guacamole/net/basic/extension/ExtensionModule.java

@@ -51,6 +51,12 @@ public class ExtensionModule extends ServletModule {
      */
     private final Logger logger = LoggerFactory.getLogger(ExtensionModule.class);
 
+    /**
+     * The name of the directory within GUACAMOLE_HOME containing any .jars
+     * which should be included in the classpath of all extensions.
+     */
+    private static final String LIB_DIRECTORY = "lib";
+
     /**
      * The name of the directory within GUACAMOLE_HOME containing all
      * extensions.
@@ -68,6 +74,34 @@ public class ExtensionModule extends ServletModule {
      */
     private final Environment environment;
 
+    /**
+     * Returns the classloader that should be used as the parent classloader
+     * for all extensions. If the GUACAMOLE_HOME/lib directory exists, this
+     * will be a classloader that loads classes from within the .jar files in
+     * that directory. Lacking the GUACAMOLE_HOME/lib directory, this will
+     * simply be the classloader associated with the ExtensionModule class.
+     *
+     * @return
+     *     The classloader that should be used as the parent classloader for
+     *     all extensions.
+     *
+     * @throws GuacamoleException
+     *     If an error occurs while retrieving the classloader.
+     */
+    private ClassLoader getParentClassLoader() throws GuacamoleException {
+
+        // Retrieve lib directory
+        File libDir = new File(environment.getGuacamoleHome(), LIB_DIRECTORY);
+
+        // If lib directory does not exist, use default class loader
+        if (!libDir.isDirectory())
+            return ExtensionModule.class.getClassLoader();
+
+        // Return classloader which loads classes from all .jars within the lib directory
+        return DirectoryClassLoader.getInstance(libDir);
+
+    }
+
     /**
      * Creates a module which loads all extensions within the
      * GUACAMOLE_HOME/extensions directory.
@@ -112,9 +146,8 @@ public class ExtensionModule extends ServletModule {
 
             try {
 
-                // FIXME: Use class loader which reads from the lib directory
                 // Load extension from file
-                Extension extension = new Extension(ExtensionModule.class.getClassLoader(), extensionFile);
+                Extension extension = new Extension(getParentClassLoader(), extensionFile);
 
                 // Add any JavaScript / CSS resources
                 javaScriptResources.addAll(extension.getJavaScriptResources());