src/main/java/org/apache/sling/jcr/classloader/internal/ClassLoaderWriterImpl.java - sling-org-apache-sling-jcr-classloader - Git at Google

 /*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
  * regarding copyright ownership.  The ASF licenses this file
  * to you under the Apache License, Version 2.0 (the
  * "License"); you may not use this file except in compliance
  * with the License.  You may obtain a copy of the License at
  *
  *   http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing,
  * software distributed under the License is distributed on an
  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  * KIND, either express or implied.  See the License for the
  * specific language governing permissions and limitations
  * under the License.
  */
 package org.apache.sling.jcr.classloader.internal;

 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.util.Map;

 import javax.jcr.Item;
 import javax.jcr.Node;
 import javax.jcr.Property;
 import javax.jcr.RepositoryException;
 import javax.jcr.Session;
 import javax.jcr.SimpleCredentials;

 import org.apache.felix.scr.annotations.Activate;
 import org.apache.felix.scr.annotations.Component;
 import org.apache.felix.scr.annotations.Deactivate;
 import org.apache.felix.scr.annotations.Properties;
 import org.apache.felix.scr.annotations.Reference;
 import org.apache.felix.scr.annotations.ReferenceCardinality;
 import org.apache.felix.scr.annotations.ReferencePolicy;
 import org.apache.felix.scr.annotations.Service;
 import org.apache.sling.commons.classloader.ClassLoaderWriter;
 import org.apache.sling.commons.classloader.DynamicClassLoaderManager;
 import org.apache.sling.commons.mime.MimeTypeService;
 import org.apache.sling.commons.osgi.PropertiesUtil;
 import org.apache.sling.jcr.api.SlingRepository;
 import org.apache.sling.settings.SlingSettingsService;
 import org.osgi.framework.Bundle;
 import org.osgi.framework.ServiceReference;
 import org.osgi.service.component.ComponentContext;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;

 /**
  * The <code>DynamicClassLoaderProviderImpl</code> provides
  * a class loader which loads classes from configured paths
  * in the repository.
  * It implements the {@link ClassLoaderWriter} interface
  * for clients to use for writing and reading such
  * classes and resources.
  */
 @Component(metatype=true, label="%loader.name", description="%loader.description",
            name="org.apache.sling.jcr.classloader.internal.DynamicClassLoaderProviderImpl")
 @Service(value = ClassLoaderWriter.class, serviceFactory = true)
 @Properties({
     @org.apache.felix.scr.annotations.Property(name="service.vendor", value="The Apache Software Foundation"),
     @org.apache.felix.scr.annotations.Property(name="service.description", value="Repository based classloader writer")
 })
 public class ClassLoaderWriterImpl
     implements ClassLoaderWriter {

     /** Logger */
     private final Logger logger = LoggerFactory.getLogger(ClassLoaderWriterImpl.class);

     private static final String CLASS_PATH_DEFAULT = "/var/classes";

     @org.apache.felix.scr.annotations.Property(value=CLASS_PATH_DEFAULT)
     private static final String CLASS_PATH_PROP = "classpath";

     private static final boolean APPEND_ID_DEFAULT = true;

     @org.apache.felix.scr.annotations.Property(boolValue=APPEND_ID_DEFAULT)
     private static final String APPEND_ID_PROP = "appendId";

     /** Node type for packages/folders. */
     private static final String NT_FOLDER = "nt:folder";

     /** Default class loader owner. */
     private static final String OWNER_DEFAULT = "admin";

     @org.apache.felix.scr.annotations.Property(value=OWNER_DEFAULT)
     private static final String OWNER_PROP = "owner";

     @Reference
     private SlingSettingsService settings;

     /** The owner of the class loader / JCR user. */
     private String classLoaderOwner;

     /** The configured class path. */
     private String classPath;

     @Reference
     private SlingRepository repository;

     @Reference(policy=ReferencePolicy.DYNAMIC, cardinality=ReferenceCardinality.OPTIONAL_UNARY)
     private volatile MimeTypeService mimeTypeService;

     @Reference(
             referenceInterface = DynamicClassLoaderManager.class,
             bind = "bindDynamicClassLoaderManager",
             unbind = "unbindDynamicClassLoaderManager")
     private volatile ServiceReference dynamicClassLoaderManager;

     /** The bundle asking for this service instance */
     private Bundle callerBundle;

     /** Cached repository class loader. */
     private volatile RepositoryClassLoader repositoryClassLoader;

     /**
      * Activate this component.
      * @param componentContext The component context
      * @param properties The configuration properties
      */
     @Activate
     protected void activate(final ComponentContext componentContext, final Map<String, Object> properties) {
         this.classPath = PropertiesUtil.toString(properties.get(CLASS_PATH_PROP), CLASS_PATH_DEFAULT);
         if ( this.classPath.endsWith("/") ) {
             this.classPath = this.classPath.substring(0, this.classPath.length() - 1);
         }
         if ( PropertiesUtil.toBoolean(properties.get(APPEND_ID_PROP), APPEND_ID_DEFAULT) ) {
             this.classPath = this.classPath + '/' + this.settings.getSlingId();
         }

         this.classLoaderOwner = PropertiesUtil.toString(properties.get(OWNER_PROP), OWNER_DEFAULT);

         this.callerBundle = componentContext.getUsingBundle();
     }

     /**
      * Deactivate this component.
      */
     @Deactivate
     protected synchronized void deactivate() {
         this.destroyRepositoryClassLoader();
         this.callerBundle = null;
     }

     /**
      * Called to handle binding the DynamicClassLoaderManager service
      * reference
      */
     @SuppressWarnings("unused")
     private void bindDynamicClassLoaderManager(final ServiceReference ref) {
         this.dynamicClassLoaderManager = ref;
     }

     /**
      * Called to handle unbinding of the DynamicClassLoaderManager service
      * reference
      */
     @SuppressWarnings("unused")
     private void unbindDynamicClassLoaderManager(final ServiceReference ref) {
         if (this.dynamicClassLoaderManager == ref) {
             this.dynamicClassLoaderManager = null;
         }
     }

     /**
      * Destroys the repository class loader if existing and ungets the
      * DynamicClassLoaderManager service if a dynamic class loader is
      * being used.
      */
     private void destroyRepositoryClassLoader() {
         final RepositoryClassLoader rcl = this.repositoryClassLoader;
         if (rcl != null) {
             this.repositoryClassLoader = null;
             rcl.destroy();
             final ServiceReference localDynamicClassLoaderManager = this.dynamicClassLoaderManager;
             final Bundle localCallerBundle = this.callerBundle;
             if ( localDynamicClassLoaderManager != null && localCallerBundle != null ) {
                 localCallerBundle.getBundleContext().ungetService(localDynamicClassLoaderManager);
             }
         }
     }

     /**
      * Return a new session.
      */
     public Session createSession() throws RepositoryException {
         // get an administrative session for potential impersonation
         final Session admin = this.repository.loginAdministrative(null);

         // do use the admin session, if the admin's user id is the same as owner
         if (admin.getUserID().equals(this.classLoaderOwner)) {
             return admin;
         }

         // else impersonate as the owner and logout the admin session again
         try {
             return admin.impersonate(new SimpleCredentials(this.classLoaderOwner, new char[0]));
         } finally {
             admin.logout();
         }
     }

     /**
      * Is this still active?
      */
     public boolean isActivate() {
         return this.repository != null;
     }

     private synchronized RepositoryClassLoader getOrCreateClassLoader() {
         if ( this.repositoryClassLoader == null || !this.repositoryClassLoader.isLive() ) {

             // make sure to cleanup any existing class loader
             this.destroyRepositoryClassLoader();

             // get the dynamic class loader for the bundle using this
             // class loader writer
             final DynamicClassLoaderManager dclm = (DynamicClassLoaderManager) this.callerBundle.getBundleContext().getService(
                 this.dynamicClassLoaderManager);

             this.repositoryClassLoader = new RepositoryClassLoader(
                     this.classPath,
                     this,
                     dclm.getDynamicClassLoader());
         }
         return this.repositoryClassLoader;
     }

     private synchronized void handleChangeEvent(final String path) {
         final RepositoryClassLoader rcl = this.repositoryClassLoader;
         if ( rcl != null ) {
             rcl.handleEvent(path);
         }
     }

     /**
      * @see org.apache.sling.commons.classloader.ClassLoaderWriter#delete(java.lang.String)
      */
     public boolean delete(final String name) {
         final String path = cleanPath(name);
         this.handleChangeEvent(path);
         Session session = null;
         try {
             session = createSession();
             if (session.itemExists(path)) {
                 Item fileItem = session.getItem(path);
                 fileItem.remove();
                 session.save();
                 return true;
             }
         } catch (final RepositoryException re) {
             logger.error("Cannot remove " + path, re);
         } finally {
             if ( session != null ) {
                 session.logout();
             }
         }

         // fall back to false if item does not exist or in case of error
         return false;
     }

     /**
      * @see org.apache.sling.commons.classloader.ClassLoaderWriter#getOutputStream(java.lang.String)
      */
     public OutputStream getOutputStream(final String name) {
         final String path = cleanPath(name);
         return new RepositoryOutputStream(this, path);
     }

     /**
      * @see org.apache.sling.commons.classloader.ClassLoaderWriter#rename(java.lang.String, java.lang.String)
      */
     public boolean rename(final String oldName, final String newName) {
         final String oldPath = cleanPath(oldName);
         final String newPath = cleanPath(newName);

         Session session = null;
         try {
             session = this.createSession();
             session.move(oldPath, newPath);
             session.save();

             this.handleChangeEvent(oldName);
             this.handleChangeEvent(newName);

             return true;
         } catch (final RepositoryException re) {
             logger.error("Cannot rename " + oldName + " to " + newName, re);
         } finally {
             if ( session != null ) {
                 session.logout();
             }
         }

         // fall back to false in case of error or non-existence of oldFileName
         return false;
     }

     /**
      * Creates a folder hierarchy in the repository.
      * We synchronize this method to reduce potential conflicts.
      * Although each write uses its own session it might occur
      * that more than one session tries to create the same path
      * (or parent path) at the same time. By synchronizing this
      * we avoid this situation - however this method is written
      * in a fail safe manner anyway.
      */
     private synchronized boolean mkdirs(final Session session, final String path) {
         try {
             // quick test
             if (session.itemExists(path) && session.getItem(path).isNode()) {
                 return true;
             }

             // check path walking it down
             Node current = session.getRootNode();
             final String[] names = path.split("/");
             for (int i = 0; i < names.length; i++) {
                 if (names[i] == null || names[i].length() == 0) {
                     continue;
                 } else if (current.hasNode(names[i])) {
                     current = current.getNode(names[i]);
                 } else {
                     final Node parentNode = current;
                     try {
                         // adding the node could cause an exception
                         // for example if another thread tries to
                         // create the node "at the same time"
                         current = parentNode.addNode(names[i], NT_FOLDER);
                         session.save();
                     } catch (final RepositoryException re) {
                         // let's first refresh the session
                         // we don't catch an exception here, because if
                         // session refresh fails, we might have a serious problem!
                         session.refresh(false);
                         // let's check if the node is available now
                         if ( parentNode.hasNode(names[i]) ) {
                             current = parentNode.getNode(names[i]);
                         } else {
                             // we try it one more time to create the node - and fail otherwise
                             current = parentNode.addNode(names[i], NT_FOLDER);
                             session.save();
                         }
                     }
                 }
             }

             return true;

         } catch (final RepositoryException re) {
             logger.error("Cannot create folder path:" + path, re);
             // discard changes
             try {
                 session.refresh(false);
             } catch (final RepositoryException e) {
                 // we simply ignore this
             }
         }

         // false in case of error or no need to create
         return false;
     }

     /**
      * Helper method to clean the path.
      * It replaces backslashes with slashes and cuts off trailing spaces.
      * It uses the first configured class path to access the path.
      */
     private String cleanPath(String path) {
         // replace backslash by slash
         path = path.replace('\\', '/');

         // cut off trailing slash
         while (path.endsWith("/")) {
             path = path.substring(0, path.length() - 1);
         }

         return this.classPath + path;
     }

     private static class RepositoryOutputStream extends ByteArrayOutputStream {

         private final ClassLoaderWriterImpl repositoryOutputProvider;

         private final String fileName;

         RepositoryOutputStream(ClassLoaderWriterImpl repositoryOutputProvider,
                 String fileName) {
             this.repositoryOutputProvider = repositoryOutputProvider;
             this.fileName = fileName;
         }

         /**
          * @see java.io.ByteArrayOutputStream#close()
          */
         @Override
         public void close() throws IOException {
             super.close();

             Session session = null;
             try {
                 // get an own session for writing
                 session = repositoryOutputProvider.createSession();
                 final int lastPos = fileName.lastIndexOf('/');
                 final String path = (lastPos == -1 ? null : fileName.substring(0, lastPos));
                 final String name = (lastPos == -1 ? fileName : fileName.substring(lastPos + 1));
                 if ( lastPos != -1 ) {
                     if ( !repositoryOutputProvider.mkdirs(session, path) ) {
                         throw new IOException("Unable to create path for " + path);
                     }
                 }
                 Node fileNode = null;
                 Node contentNode = null;
                 Node parentNode = null;
                 if (session.itemExists(fileName)) {
                     final Item item = session.getItem(fileName);
                     if (item.isNode()) {
                         final Node node = item.isNode() ? (Node) item : item.getParent();
                         if ("jcr:content".equals(node.getName())) {
                             // replace the content properties of the jcr:content
                             // node
                             parentNode = node;
                             contentNode = node;
                         } else if (node.isNodeType("nt:file")) {
                             // try to set the content properties of jcr:content
                             // node
                             parentNode = node;
                             contentNode = node.getNode("jcr:content");
                         } else { // fileName is a node
                             // try to set the content properties of the node
                             parentNode = node;
                             contentNode = node;
                         }
                     } else {
                         // replace property with an nt:file node (if possible)
                         parentNode = item.getParent();
                         item.remove();
                         session.save();
                         fileNode = parentNode.addNode(name, "nt:file");
                     }
                 } else {
                     if (lastPos <= 0) {
                         parentNode = session.getRootNode();
                     } else {
                         Item parent = session.getItem(path);
                         if (!parent.isNode()) {
                             throw new IOException("Parent at " + path + " is not a node.");
                         }
                         parentNode = (Node) parent;
                     }
                     fileNode = parentNode.addNode(name, "nt:file");
                 }

                 // if we have a file node, create the contentNode
                 if (fileNode != null) {
                     contentNode = fileNode.addNode("jcr:content", "nt:resource");
                 }

                 final MimeTypeService mtService = this.repositoryOutputProvider.mimeTypeService;

                 String mimeType = (mtService == null ? null : mtService.getMimeType(fileName));
                 if (mimeType == null) {
                     mimeType = "application/octet-stream";
                 }

                 contentNode.setProperty("jcr:lastModified", System.currentTimeMillis());
                 contentNode.setProperty("jcr:data", new ByteArrayInputStream(buf, 0, size()));
                 contentNode.setProperty("jcr:mimeType", mimeType);

                 session.save();
                 this.repositoryOutputProvider.handleChangeEvent(fileName);
             } catch (final RepositoryException re) {
                 throw (IOException)new IOException("Cannot write file " + fileName + ", reason: " + re.toString()).initCause(re);
             } finally {
                 if ( session != null ) {
                     session.logout();
                 }
             }
         }
     }

     /**
      * @see org.apache.sling.commons.classloader.ClassLoaderWriter#getInputStream(java.lang.String)
      */
     public InputStream getInputStream(final String name)
     throws IOException {
         final String path = cleanPath(name) + "/jcr:content/jcr:data";
         Session session = null;
         try {
             session = this.createSession();
             if ( session.itemExists(path) ) {
                 final Property prop = (Property)session.getItem(path);
                 final InputStream is = prop.getStream();
                 final ByteArrayOutputStream baos = new ByteArrayOutputStream();
                 int l = 0;
                 final byte[] buf = new byte[2048];
                 while ( (l = is.read(buf)) > -1 ) {
                     if ( l > 0 ) {
                         baos.write(buf, 0, l);
                     }
                 }
                 return new ByteArrayInputStream(baos.toByteArray());
             }
             throw new FileNotFoundException("Unable to find " + name);
         } catch (final RepositoryException re) {
             throw (IOException) new IOException(
                         "Failed to get InputStream for " + name).initCause(re);
         } finally {
             if ( session != null ) {
                 session.logout();
             }
         }
     }

     /**
      * @see org.apache.sling.commons.classloader.ClassLoaderWriter#getLastModified(java.lang.String)
      */
     public long getLastModified(final String name) {
         final String path = cleanPath(name) + "/jcr:content/jcr:lastModified";
         Session session = null;
         try {
             session = this.createSession();
             if ( session.itemExists(path) ) {
                 final Property prop = (Property)session.getItem(path);
                 return prop.getLong();
             }
         } catch (final RepositoryException se) {
             logger.error("Cannot get last modification time for " + name, se);
         } finally {
             if ( session != null ) {
                 session.logout();
             }
         }

         // fall back to "non-existent" in case of problems
         return -1;
     }

     /**
      * @see org.apache.sling.commons.classloader.ClassLoaderWriter#getClassLoader()
      */
     public ClassLoader getClassLoader() {
         return this.getOrCreateClassLoader();
     }
 }
	/*
	* Licensed to the Apache Software Foundation (ASF) under one
	* or more contributor license agreements. See the NOTICE file
	* distributed with this work for additional information
	* regarding copyright ownership. The ASF licenses this file
	* to you under the Apache License, Version 2.0 (the
	* "License"); you may not use this file except in compliance
	* with the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing,
	* software distributed under the License is distributed on an
	* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
	* KIND, either express or implied. See the License for the
	* specific language governing permissions and limitations
	* under the License.
	*/
	package org.apache.sling.jcr.classloader.internal;

	import java.io.ByteArrayInputStream;
	import java.io.ByteArrayOutputStream;
	import java.io.FileNotFoundException;
	import java.io.IOException;
	import java.io.InputStream;
	import java.io.OutputStream;
	import java.util.Map;

	import javax.jcr.Item;
	import javax.jcr.Node;
	import javax.jcr.Property;
	import javax.jcr.RepositoryException;
	import javax.jcr.Session;
	import javax.jcr.SimpleCredentials;

	import org.apache.felix.scr.annotations.Activate;
	import org.apache.felix.scr.annotations.Component;
	import org.apache.felix.scr.annotations.Deactivate;
	import org.apache.felix.scr.annotations.Properties;
	import org.apache.felix.scr.annotations.Reference;
	import org.apache.felix.scr.annotations.ReferenceCardinality;
	import org.apache.felix.scr.annotations.ReferencePolicy;
	import org.apache.felix.scr.annotations.Service;
	import org.apache.sling.commons.classloader.ClassLoaderWriter;
	import org.apache.sling.commons.classloader.DynamicClassLoaderManager;
	import org.apache.sling.commons.mime.MimeTypeService;
	import org.apache.sling.commons.osgi.PropertiesUtil;
	import org.apache.sling.jcr.api.SlingRepository;
	import org.apache.sling.settings.SlingSettingsService;
	import org.osgi.framework.Bundle;
	import org.osgi.framework.ServiceReference;
	import org.osgi.service.component.ComponentContext;
	import org.slf4j.Logger;
	import org.slf4j.LoggerFactory;

	/**
	* The <code>DynamicClassLoaderProviderImpl</code> provides
	* a class loader which loads classes from configured paths
	* in the repository.
	* It implements the {@link ClassLoaderWriter} interface
	* for clients to use for writing and reading such
	* classes and resources.
	*/
	@Component(metatype=true, label="%loader.name", description="%loader.description",
	name="org.apache.sling.jcr.classloader.internal.DynamicClassLoaderProviderImpl")
	@Service(value = ClassLoaderWriter.class, serviceFactory = true)
	@Properties({
	@org.apache.felix.scr.annotations.Property(name="service.vendor", value="The Apache Software Foundation"),
	@org.apache.felix.scr.annotations.Property(name="service.description", value="Repository based classloader writer")
	})
	public class ClassLoaderWriterImpl
	implements ClassLoaderWriter {

	/** Logger */
	private final Logger logger = LoggerFactory.getLogger(ClassLoaderWriterImpl.class);

	private static final String CLASS_PATH_DEFAULT = "/var/classes";

	@org.apache.felix.scr.annotations.Property(value=CLASS_PATH_DEFAULT)
	private static final String CLASS_PATH_PROP = "classpath";

	private static final boolean APPEND_ID_DEFAULT = true;

	@org.apache.felix.scr.annotations.Property(boolValue=APPEND_ID_DEFAULT)
	private static final String APPEND_ID_PROP = "appendId";

	/** Node type for packages/folders. */
	private static final String NT_FOLDER = "nt:folder";

	/** Default class loader owner. */
	private static final String OWNER_DEFAULT = "admin";

	@org.apache.felix.scr.annotations.Property(value=OWNER_DEFAULT)
	private static final String OWNER_PROP = "owner";

	@Reference
	private SlingSettingsService settings;

	/** The owner of the class loader / JCR user. */
	private String classLoaderOwner;

	/** The configured class path. */
	private String classPath;

	@Reference
	private SlingRepository repository;

	@Reference(policy=ReferencePolicy.DYNAMIC, cardinality=ReferenceCardinality.OPTIONAL_UNARY)
	private volatile MimeTypeService mimeTypeService;

	@Reference(
	referenceInterface = DynamicClassLoaderManager.class,
	bind = "bindDynamicClassLoaderManager",
	unbind = "unbindDynamicClassLoaderManager")
	private volatile ServiceReference dynamicClassLoaderManager;

	/** The bundle asking for this service instance */
	private Bundle callerBundle;

	/** Cached repository class loader. */
	private volatile RepositoryClassLoader repositoryClassLoader;

	/**
	* Activate this component.
	* @param componentContext The component context
	* @param properties The configuration properties
	*/
	@Activate
	protected void activate(final ComponentContext componentContext, final Map<String, Object> properties) {
	this.classPath = PropertiesUtil.toString(properties.get(CLASS_PATH_PROP), CLASS_PATH_DEFAULT);
	if ( this.classPath.endsWith("/") ) {
	this.classPath = this.classPath.substring(0, this.classPath.length() - 1);
	}
	if ( PropertiesUtil.toBoolean(properties.get(APPEND_ID_PROP), APPEND_ID_DEFAULT) ) {
	this.classPath = this.classPath + '/' + this.settings.getSlingId();
	}

	this.classLoaderOwner = PropertiesUtil.toString(properties.get(OWNER_PROP), OWNER_DEFAULT);

	this.callerBundle = componentContext.getUsingBundle();
	}

	/**
	* Deactivate this component.
	*/
	@Deactivate
	protected synchronized void deactivate() {
	this.destroyRepositoryClassLoader();
	this.callerBundle = null;
	}

	/**
	* Called to handle binding the DynamicClassLoaderManager service
	* reference
	*/
	@SuppressWarnings("unused")
	private void bindDynamicClassLoaderManager(final ServiceReference ref) {
	this.dynamicClassLoaderManager = ref;
	}

	/**
	* Called to handle unbinding of the DynamicClassLoaderManager service
	* reference
	*/
	@SuppressWarnings("unused")
	private void unbindDynamicClassLoaderManager(final ServiceReference ref) {
	if (this.dynamicClassLoaderManager == ref) {
	this.dynamicClassLoaderManager = null;
	}
	}

	/**
	* Destroys the repository class loader if existing and ungets the
	* DynamicClassLoaderManager service if a dynamic class loader is
	* being used.
	*/
	private void destroyRepositoryClassLoader() {
	final RepositoryClassLoader rcl = this.repositoryClassLoader;
	if (rcl != null) {
	this.repositoryClassLoader = null;
	rcl.destroy();
	final ServiceReference localDynamicClassLoaderManager = this.dynamicClassLoaderManager;
	final Bundle localCallerBundle = this.callerBundle;
	if ( localDynamicClassLoaderManager != null && localCallerBundle != null ) {
	localCallerBundle.getBundleContext().ungetService(localDynamicClassLoaderManager);
	}
	}
	}

	/**
	* Return a new session.
	*/
	public Session createSession() throws RepositoryException {
	// get an administrative session for potential impersonation
	final Session admin = this.repository.loginAdministrative(null);

	// do use the admin session, if the admin's user id is the same as owner
	if (admin.getUserID().equals(this.classLoaderOwner)) {
	return admin;
	}

	// else impersonate as the owner and logout the admin session again
	try {
	return admin.impersonate(new SimpleCredentials(this.classLoaderOwner, new char[0]));
	} finally {
	admin.logout();
	}
	}

	/**
	* Is this still active?
	*/
	public boolean isActivate() {
	return this.repository != null;
	}

	private synchronized RepositoryClassLoader getOrCreateClassLoader() {
	if ( this.repositoryClassLoader == null \|\| !this.repositoryClassLoader.isLive() ) {

	// make sure to cleanup any existing class loader
	this.destroyRepositoryClassLoader();

	// get the dynamic class loader for the bundle using this
	// class loader writer
	final DynamicClassLoaderManager dclm = (DynamicClassLoaderManager) this.callerBundle.getBundleContext().getService(
	this.dynamicClassLoaderManager);

	this.repositoryClassLoader = new RepositoryClassLoader(
	this.classPath,
	this,
	dclm.getDynamicClassLoader());
	}
	return this.repositoryClassLoader;
	}

	private synchronized void handleChangeEvent(final String path) {
	final RepositoryClassLoader rcl = this.repositoryClassLoader;
	if ( rcl != null ) {
	rcl.handleEvent(path);
	}
	}

	/**
	* @see org.apache.sling.commons.classloader.ClassLoaderWriter#delete(java.lang.String)
	*/
	public boolean delete(final String name) {
	final String path = cleanPath(name);
	this.handleChangeEvent(path);
	Session session = null;
	try {
	session = createSession();
	if (session.itemExists(path)) {
	Item fileItem = session.getItem(path);
	fileItem.remove();
	session.save();
	return true;
	}
	} catch (final RepositoryException re) {
	logger.error("Cannot remove " + path, re);
	} finally {
	if ( session != null ) {
	session.logout();
	}
	}

	// fall back to false if item does not exist or in case of error
	return false;
	}

	/**
	* @see org.apache.sling.commons.classloader.ClassLoaderWriter#getOutputStream(java.lang.String)
	*/
	public OutputStream getOutputStream(final String name) {
	final String path = cleanPath(name);
	return new RepositoryOutputStream(this, path);
	}

	/**
	* @see org.apache.sling.commons.classloader.ClassLoaderWriter#rename(java.lang.String, java.lang.String)
	*/
	public boolean rename(final String oldName, final String newName) {
	final String oldPath = cleanPath(oldName);
	final String newPath = cleanPath(newName);

	Session session = null;
	try {
	session = this.createSession();
	session.move(oldPath, newPath);
	session.save();

	this.handleChangeEvent(oldName);
	this.handleChangeEvent(newName);

	return true;
	} catch (final RepositoryException re) {
	logger.error("Cannot rename " + oldName + " to " + newName, re);
	} finally {
	if ( session != null ) {
	session.logout();
	}
	}

	// fall back to false in case of error or non-existence of oldFileName
	return false;
	}

	/**
	* Creates a folder hierarchy in the repository.
	* We synchronize this method to reduce potential conflicts.
	* Although each write uses its own session it might occur
	* that more than one session tries to create the same path
	* (or parent path) at the same time. By synchronizing this
	* we avoid this situation - however this method is written
	* in a fail safe manner anyway.
	*/
	private synchronized boolean mkdirs(final Session session, final String path) {
	try {
	// quick test
	if (session.itemExists(path) && session.getItem(path).isNode()) {
	return true;
	}

	// check path walking it down
	Node current = session.getRootNode();
	final String[] names = path.split("/");
	for (int i = 0; i < names.length; i++) {
	if (names[i] == null \|\| names[i].length() == 0) {
	continue;
	} else if (current.hasNode(names[i])) {
	current = current.getNode(names[i]);
	} else {
	final Node parentNode = current;
	try {
	// adding the node could cause an exception
	// for example if another thread tries to
	// create the node "at the same time"
	current = parentNode.addNode(names[i], NT_FOLDER);
	session.save();
	} catch (final RepositoryException re) {
	// let's first refresh the session
	// we don't catch an exception here, because if
	// session refresh fails, we might have a serious problem!
	session.refresh(false);
	// let's check if the node is available now
	if ( parentNode.hasNode(names[i]) ) {
	current = parentNode.getNode(names[i]);
	} else {
	// we try it one more time to create the node - and fail otherwise
	current = parentNode.addNode(names[i], NT_FOLDER);
	session.save();
	}
	}
	}
	}

	return true;

	} catch (final RepositoryException re) {
	logger.error("Cannot create folder path:" + path, re);
	// discard changes
	try {
	session.refresh(false);
	} catch (final RepositoryException e) {
	// we simply ignore this
	}
	}

	// false in case of error or no need to create
	return false;
	}

	/**
	* Helper method to clean the path.
	* It replaces backslashes with slashes and cuts off trailing spaces.
	* It uses the first configured class path to access the path.
	*/
	private String cleanPath(String path) {
	// replace backslash by slash
	path = path.replace('\\', '/');

	// cut off trailing slash
	while (path.endsWith("/")) {
	path = path.substring(0, path.length() - 1);
	}

	return this.classPath + path;
	}

	private static class RepositoryOutputStream extends ByteArrayOutputStream {

	private final ClassLoaderWriterImpl repositoryOutputProvider;

	private final String fileName;

	RepositoryOutputStream(ClassLoaderWriterImpl repositoryOutputProvider,
	String fileName) {
	this.repositoryOutputProvider = repositoryOutputProvider;
	this.fileName = fileName;
	}

	/**
	* @see java.io.ByteArrayOutputStream#close()
	*/
	@Override
	public void close() throws IOException {
	super.close();

	Session session = null;
	try {
	// get an own session for writing
	session = repositoryOutputProvider.createSession();
	final int lastPos = fileName.lastIndexOf('/');
	final String path = (lastPos == -1 ? null : fileName.substring(0, lastPos));
	final String name = (lastPos == -1 ? fileName : fileName.substring(lastPos + 1));
	if ( lastPos != -1 ) {
	if ( !repositoryOutputProvider.mkdirs(session, path) ) {
	throw new IOException("Unable to create path for " + path);
	}
	}
	Node fileNode = null;
	Node contentNode = null;
	Node parentNode = null;
	if (session.itemExists(fileName)) {
	final Item item = session.getItem(fileName);
	if (item.isNode()) {
	final Node node = item.isNode() ? (Node) item : item.getParent();
	if ("jcr:content".equals(node.getName())) {
	// replace the content properties of the jcr:content
	// node
	parentNode = node;
	contentNode = node;
	} else if (node.isNodeType("nt:file")) {
	// try to set the content properties of jcr:content
	// node
	parentNode = node;
	contentNode = node.getNode("jcr:content");
	} else { // fileName is a node
	// try to set the content properties of the node
	parentNode = node;
	contentNode = node;
	}
	} else {
	// replace property with an nt:file node (if possible)
	parentNode = item.getParent();
	item.remove();
	session.save();
	fileNode = parentNode.addNode(name, "nt:file");
	}
	} else {
	if (lastPos <= 0) {
	parentNode = session.getRootNode();
	} else {
	Item parent = session.getItem(path);
	if (!parent.isNode()) {
	throw new IOException("Parent at " + path + " is not a node.");
	}
	parentNode = (Node) parent;
	}
	fileNode = parentNode.addNode(name, "nt:file");
	}

	// if we have a file node, create the contentNode
	if (fileNode != null) {
	contentNode = fileNode.addNode("jcr:content", "nt:resource");
	}

	final MimeTypeService mtService = this.repositoryOutputProvider.mimeTypeService;

	String mimeType = (mtService == null ? null : mtService.getMimeType(fileName));
	if (mimeType == null) {
	mimeType = "application/octet-stream";
	}

	contentNode.setProperty("jcr:lastModified", System.currentTimeMillis());
	contentNode.setProperty("jcr:data", new ByteArrayInputStream(buf, 0, size()));
	contentNode.setProperty("jcr:mimeType", mimeType);

	session.save();
	this.repositoryOutputProvider.handleChangeEvent(fileName);
	} catch (final RepositoryException re) {
	throw (IOException)new IOException("Cannot write file " + fileName + ", reason: " + re.toString()).initCause(re);
	} finally {
	if ( session != null ) {
	session.logout();
	}
	}
	}
	}

	/**
	* @see org.apache.sling.commons.classloader.ClassLoaderWriter#getInputStream(java.lang.String)
	*/
	public InputStream getInputStream(final String name)
	throws IOException {
	final String path = cleanPath(name) + "/jcr:content/jcr:data";
	Session session = null;
	try {
	session = this.createSession();
	if ( session.itemExists(path) ) {
	final Property prop = (Property)session.getItem(path);
	final InputStream is = prop.getStream();
	final ByteArrayOutputStream baos = new ByteArrayOutputStream();
	int l = 0;
	final byte[] buf = new byte[2048];
	while ( (l = is.read(buf)) > -1 ) {
	if ( l > 0 ) {
	baos.write(buf, 0, l);
	}
	}
	return new ByteArrayInputStream(baos.toByteArray());
	}
	throw new FileNotFoundException("Unable to find " + name);
	} catch (final RepositoryException re) {
	throw (IOException) new IOException(
	"Failed to get InputStream for " + name).initCause(re);
	} finally {
	if ( session != null ) {
	session.logout();
	}
	}
	}

	/**
	* @see org.apache.sling.commons.classloader.ClassLoaderWriter#getLastModified(java.lang.String)
	*/
	public long getLastModified(final String name) {
	final String path = cleanPath(name) + "/jcr:content/jcr:lastModified";
	Session session = null;
	try {
	session = this.createSession();
	if ( session.itemExists(path) ) {
	final Property prop = (Property)session.getItem(path);
	return prop.getLong();
	}
	} catch (final RepositoryException se) {
	logger.error("Cannot get last modification time for " + name, se);
	} finally {
	if ( session != null ) {
	session.logout();
	}
	}

	// fall back to "non-existent" in case of problems
	return -1;
	}

	/**
	* @see org.apache.sling.commons.classloader.ClassLoaderWriter#getClassLoader()
	*/
	public ClassLoader getClassLoader() {
	return this.getOrCreateClassLoader();
	}
	}