src/java/org/apache/commons/vfs/impl/VFSClassLoader.java - commons-vfs - Git at Google

 /*
  * Copyright 2002-2005 The Apache Software Foundation.
  *
  * Licensed 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.commons.vfs.impl;

 import org.apache.commons.vfs.FileObject;
 import org.apache.commons.vfs.FileSystemException;
 import org.apache.commons.vfs.FileSystemManager;
 import org.apache.commons.vfs.FileType;
 import org.apache.commons.vfs.NameScope;

 import java.io.IOException;
 import java.net.URL;
 import java.security.CodeSource;
 import java.security.Permission;
 import java.security.PermissionCollection;
 import java.security.Permissions;
 import java.security.SecureClassLoader;
 import java.security.cert.Certificate;
 import java.util.ArrayList;
 import java.util.Enumeration;
 import java.util.Iterator;
 import java.util.jar.Attributes;
 import java.util.jar.Attributes.Name;


 /**
  * A class loader that can load classes and resources from a search path
  * VFS FileObjects refering both to folders and JAR files. Any FileObject
  * of type {@link FileType#FILE} is asumed to be a JAR and is opened
  * by creating a layered file system with the "jar" scheme.
  * </p><p>
  * TODO - Test this with signed Jars and a SecurityManager.
  *
  * @author <a href="mailto:brian@mmmanager.org">Brian Olsen</a>
  * @version $Revision$ $Date$
  * @see FileSystemManager#createFileSystem
  */
 public class VFSClassLoader
     extends SecureClassLoader
 {
     private final ArrayList resources = new ArrayList();

     /**
      * Constructors a new VFSClassLoader for the given file.
      *
      * @param file    the file to load the classes and resources from.
      * @param manager the FileManager to use when trying create a layered Jar file
      *                system.
      */
     public VFSClassLoader(final FileObject file,
                           final FileSystemManager manager)
         throws FileSystemException
     {
         this(new FileObject[]{file}, manager, null);
     }

     /**
      * Constructors a new VFSClassLoader for the given file.
      *
      * @param file    the file to load the classes and resources from.
      * @param manager the FileManager to use when trying create a layered Jar file
      *                system.
      * @param parent  the parent class loader for delegation.
      */
     public VFSClassLoader(final FileObject file,
                           final FileSystemManager manager,
                           final ClassLoader parent)
         throws FileSystemException
     {
         this(new FileObject[]{file}, manager, parent);
     }

     /**
      * Constructors a new VFSClassLoader for the given files.  The files will
      * be searched in the order specified.
      *
      * @param files   the files to load the classes and resources from.
      * @param manager the FileManager to use when trying create a layered Jar file
      *                system.
      */
     public VFSClassLoader(final FileObject[] files,
                           final FileSystemManager manager)
         throws FileSystemException
     {
         this(files, manager, null);
     }

     /**
      * Constructors a new VFSClassLoader for the given FileObjects.
      * The FileObjects will be searched in the order specified.
      *
      * @param files   the FileObjects to load the classes and resources from.
      * @param manager the FileManager to use when trying create a layered Jar file
      *                system.
      * @param parent  the parent class loader for delegation.
      */
     public VFSClassLoader(final FileObject[] files,
                           final FileSystemManager manager,
                           final ClassLoader parent) throws FileSystemException
     {
         super(parent);
         addFileObjects(manager, files);
     }

     /**
      * Appends the specified FileObjects to the list of FileObjects to search
      * for classes and resources.
      *
      * @param files the FileObjects to append to the search path.
      */
     private void addFileObjects(final FileSystemManager manager,
                                 final FileObject[] files) throws FileSystemException
     {
         for (int i = 0; i < files.length; i++)
         {
             FileObject file = files[i];
             if (!file.exists())
             {
                 // Does not exist - skip
                 continue;
             }

             // TODO - use federation instead
             if (manager.canCreateFileSystem(file))
             {
                 // Use contents of the file
                 file = manager.createFileSystem(file);
             }

             resources.add(file);
         }
     }

     /**
      * Finds and loads the class with the specified name from the search
      * path.
      *
      * @throws ClassNotFoundException if the class is not found.
      */
     protected Class findClass(final String name) throws ClassNotFoundException
     {
         try
         {
             final String path = name.replace('.', '/').concat(".class");
             final Resource res = loadResource(path);
             if (res == null)
             {
                 throw new ClassNotFoundException(name);
             }
             return defineClass(name, res);
         }
         catch (final IOException ioe)
         {
             throw new ClassNotFoundException(name, ioe);
         }
     }

     /**
      * Loads and verifies the class with name and located with res.
      */
     private Class defineClass(final String name, final Resource res)
         throws IOException
     {
         final URL url = res.getCodeSourceURL();
         final String pkgName = res.getPackageName();
         if (pkgName != null)
         {
             final Package pkg = getPackage(pkgName);
             if (pkg != null)
             {
                 if (pkg.isSealed())
                 {
                     if (!pkg.isSealed(url))
                     {
                         throw new FileSystemException("vfs.impl/pkg-sealed-other-url", pkgName);
                     }
                 }
                 else
                 {
                     if (isSealed(res))
                     {
                         throw new FileSystemException("vfs.impl/pkg-sealing-unsealed", pkgName);
                     }
                 }
             }
             else
             {
                 definePackage(pkgName, res);
             }
         }

         final byte[] bytes = res.getBytes();
         final Certificate[] certs =
             res.getFileObject().getContent().getCertificates();
         final CodeSource cs = new CodeSource(url, certs);
         return defineClass(name, bytes, 0, bytes.length, cs);
     }

     /**
      * Returns true if the we should seal the package where res resides.
      */
     private boolean isSealed(final Resource res)
         throws FileSystemException
     {
         final String sealed = res.getPackageAttribute(Attributes.Name.SEALED);
         return "true".equalsIgnoreCase(sealed);
     }

     /**
      * Reads attributes for the package and defines it.
      */
     private Package definePackage(final String name,
                                   final Resource res)
         throws FileSystemException
     {
         // TODO - check for MANIFEST_ATTRIBUTES capability first
         final String specTitle = res.getPackageAttribute(Name.SPECIFICATION_TITLE);
         final String specVendor = res.getPackageAttribute(Attributes.Name.SPECIFICATION_VENDOR);
         final String specVersion = res.getPackageAttribute(Name.SPECIFICATION_VERSION);
         final String implTitle = res.getPackageAttribute(Name.IMPLEMENTATION_TITLE);
         final String implVendor = res.getPackageAttribute(Name.IMPLEMENTATION_VENDOR);
         final String implVersion = res.getPackageAttribute(Name.IMPLEMENTATION_VERSION);

         final URL sealBase;
         if (isSealed(res))
         {
             sealBase = res.getCodeSourceURL();
         }
         else
         {
             sealBase = null;
         }

         return definePackage(name, specTitle, specVersion, specVendor,
             implTitle, implVersion, implVendor, sealBase);
     }

     /**
      * Calls super.getPermissions both for the code source and also
      * adds the permissions granted to the parent layers.
      */
     protected PermissionCollection getPermissions(final CodeSource cs)
     {
         try
         {
             final String url = cs.getLocation().toString();
             FileObject file = lookupFileObject(url);
             if (file == null)
             {
                 return super.getPermissions(cs);
             }

             FileObject parentLayer = file.getFileSystem().getParentLayer();
             if (parentLayer == null)
             {
                 return super.getPermissions(cs);
             }

             Permissions combi = new Permissions();
             PermissionCollection permCollect = super.getPermissions(cs);
             copyPermissions(permCollect, combi);

             for (FileObject parent = parentLayer;
                  parent != null;
                  parent = parent.getFileSystem().getParentLayer())
             {
                 final CodeSource parentcs =
                     new CodeSource(parent.getURL(),
                         parent.getContent().getCertificates());
                 permCollect = super.getPermissions(parentcs);
                 copyPermissions(permCollect, combi);
             }

             return combi;
         }
         catch (final FileSystemException fse)
         {
             throw new SecurityException(fse.getMessage());
         }
     }

     /**
      * Copies the permissions from src to dest.
      */
     protected void copyPermissions(final PermissionCollection src,
                                    final PermissionCollection dest)
     {
         for (Enumeration elem = src.elements(); elem.hasMoreElements();)
         {
             final Permission permission = (Permission) elem.nextElement();
             dest.add(permission);
         }
     }

     /**
      * Does a reverse lookup to find the FileObject when we only have the
      * URL.
      */
     private FileObject lookupFileObject(final String name)
     {
         final Iterator it = resources.iterator();
         while (it.hasNext())
         {
             final FileObject object = (FileObject) it.next();
             if (name.equals(object.getName().getURI()))
             {
                 return object;
             }
         }
         return null;
     }

     /**
      * Finds the resource with the specified name from the search path.
      * This returns null if the resource is not found.
      */
     protected URL findResource(final String name)
     {
         try
         {
             final Resource res = loadResource(name);
             if (res != null)
             {
                 return res.getURL();
             }
         }
         catch (final Exception mue)
         {
             // Ignore
             // TODO - report?
         }

         return null;
     }

     /**
      * Returns an Enumeration of all the resources in the search path
      * with the specified name.
      * TODO - Implement this.
      */
     protected Enumeration findResources(final String name)
     {
         return new Enumeration()
         {
             public boolean hasMoreElements()
             {
                 return false;
             }

             public Object nextElement()
             {
                 return null;
             }
         };
     }

     /**
      * Searches through the search path of for the first class or resource
      * with specified name.
      */
     private Resource loadResource(final String name) throws FileSystemException
     {
         final Iterator it = resources.iterator();
         while (it.hasNext())
         {
             final FileObject baseFile = (FileObject) it.next();
             final FileObject file =
                 baseFile.resolveFile(name, NameScope.DESCENDENT_OR_SELF);
             if (file.exists())
             {
                 return new Resource(name, baseFile, file);
             }
         }

         return null;
     }
 }
	/*
	* Copyright 2002-2005 The Apache Software Foundation.
	*
	* Licensed 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.commons.vfs.impl;

	import org.apache.commons.vfs.FileObject;
	import org.apache.commons.vfs.FileSystemException;
	import org.apache.commons.vfs.FileSystemManager;
	import org.apache.commons.vfs.FileType;
	import org.apache.commons.vfs.NameScope;

	import java.io.IOException;
	import java.net.URL;
	import java.security.CodeSource;
	import java.security.Permission;
	import java.security.PermissionCollection;
	import java.security.Permissions;
	import java.security.SecureClassLoader;
	import java.security.cert.Certificate;
	import java.util.ArrayList;
	import java.util.Enumeration;
	import java.util.Iterator;
	import java.util.jar.Attributes;
	import java.util.jar.Attributes.Name;


	/**
	* A class loader that can load classes and resources from a search path
	* VFS FileObjects refering both to folders and JAR files. Any FileObject
	* of type {@link FileType#FILE} is asumed to be a JAR and is opened
	* by creating a layered file system with the "jar" scheme.
	* </p><p>
	* TODO - Test this with signed Jars and a SecurityManager.
	*
	* @author <a href="mailto:brian@mmmanager.org">Brian Olsen</a>
	* @version $Revision$ $Date$
	* @see FileSystemManager#createFileSystem
	*/
	public class VFSClassLoader
	extends SecureClassLoader
	{
	private final ArrayList resources = new ArrayList();

	/**
	* Constructors a new VFSClassLoader for the given file.
	*
	* @param file the file to load the classes and resources from.
	* @param manager the FileManager to use when trying create a layered Jar file
	* system.
	*/
	public VFSClassLoader(final FileObject file,
	final FileSystemManager manager)
	throws FileSystemException
	{
	this(new FileObject[]{file}, manager, null);
	}

	/**
	* Constructors a new VFSClassLoader for the given file.
	*
	* @param file the file to load the classes and resources from.
	* @param manager the FileManager to use when trying create a layered Jar file
	* system.
	* @param parent the parent class loader for delegation.
	*/
	public VFSClassLoader(final FileObject file,
	final FileSystemManager manager,
	final ClassLoader parent)
	throws FileSystemException
	{
	this(new FileObject[]{file}, manager, parent);
	}

	/**
	* Constructors a new VFSClassLoader for the given files. The files will
	* be searched in the order specified.
	*
	* @param files the files to load the classes and resources from.
	* @param manager the FileManager to use when trying create a layered Jar file
	* system.
	*/
	public VFSClassLoader(final FileObject[] files,
	final FileSystemManager manager)
	throws FileSystemException
	{
	this(files, manager, null);
	}

	/**
	* Constructors a new VFSClassLoader for the given FileObjects.
	* The FileObjects will be searched in the order specified.
	*
	* @param files the FileObjects to load the classes and resources from.
	* @param manager the FileManager to use when trying create a layered Jar file
	* system.
	* @param parent the parent class loader for delegation.
	*/
	public VFSClassLoader(final FileObject[] files,
	final FileSystemManager manager,
	final ClassLoader parent) throws FileSystemException
	{
	super(parent);
	addFileObjects(manager, files);
	}

	/**
	* Appends the specified FileObjects to the list of FileObjects to search
	* for classes and resources.
	*
	* @param files the FileObjects to append to the search path.
	*/
	private void addFileObjects(final FileSystemManager manager,
	final FileObject[] files) throws FileSystemException
	{
	for (int i = 0; i < files.length; i++)
	{
	FileObject file = files[i];
	if (!file.exists())
	{
	// Does not exist - skip
	continue;
	}

	// TODO - use federation instead
	if (manager.canCreateFileSystem(file))
	{
	// Use contents of the file
	file = manager.createFileSystem(file);
	}

	resources.add(file);
	}
	}

	/**
	* Finds and loads the class with the specified name from the search
	* path.
	*
	* @throws ClassNotFoundException if the class is not found.
	*/
	protected Class findClass(final String name) throws ClassNotFoundException
	{
	try
	{
	final String path = name.replace('.', '/').concat(".class");
	final Resource res = loadResource(path);
	if (res == null)
	{
	throw new ClassNotFoundException(name);
	}
	return defineClass(name, res);
	}
	catch (final IOException ioe)
	{
	throw new ClassNotFoundException(name, ioe);
	}
	}

	/**
	* Loads and verifies the class with name and located with res.
	*/
	private Class defineClass(final String name, final Resource res)
	throws IOException
	{
	final URL url = res.getCodeSourceURL();
	final String pkgName = res.getPackageName();
	if (pkgName != null)
	{
	final Package pkg = getPackage(pkgName);
	if (pkg != null)
	{
	if (pkg.isSealed())
	{
	if (!pkg.isSealed(url))
	{
	throw new FileSystemException("vfs.impl/pkg-sealed-other-url", pkgName);
	}
	}
	else
	{
	if (isSealed(res))
	{
	throw new FileSystemException("vfs.impl/pkg-sealing-unsealed", pkgName);
	}
	}
	}
	else
	{
	definePackage(pkgName, res);
	}
	}

	final byte[] bytes = res.getBytes();
	final Certificate[] certs =
	res.getFileObject().getContent().getCertificates();
	final CodeSource cs = new CodeSource(url, certs);
	return defineClass(name, bytes, 0, bytes.length, cs);
	}

	/**
	* Returns true if the we should seal the package where res resides.
	*/
	private boolean isSealed(final Resource res)
	throws FileSystemException
	{
	final String sealed = res.getPackageAttribute(Attributes.Name.SEALED);
	return "true".equalsIgnoreCase(sealed);
	}

	/**
	* Reads attributes for the package and defines it.
	*/
	private Package definePackage(final String name,
	final Resource res)
	throws FileSystemException
	{
	// TODO - check for MANIFEST_ATTRIBUTES capability first
	final String specTitle = res.getPackageAttribute(Name.SPECIFICATION_TITLE);
	final String specVendor = res.getPackageAttribute(Attributes.Name.SPECIFICATION_VENDOR);
	final String specVersion = res.getPackageAttribute(Name.SPECIFICATION_VERSION);
	final String implTitle = res.getPackageAttribute(Name.IMPLEMENTATION_TITLE);
	final String implVendor = res.getPackageAttribute(Name.IMPLEMENTATION_VENDOR);
	final String implVersion = res.getPackageAttribute(Name.IMPLEMENTATION_VERSION);

	final URL sealBase;
	if (isSealed(res))
	{
	sealBase = res.getCodeSourceURL();
	}
	else
	{
	sealBase = null;
	}

	return definePackage(name, specTitle, specVersion, specVendor,
	implTitle, implVersion, implVendor, sealBase);
	}

	/**
	* Calls super.getPermissions both for the code source and also
	* adds the permissions granted to the parent layers.
	*/
	protected PermissionCollection getPermissions(final CodeSource cs)
	{
	try
	{
	final String url = cs.getLocation().toString();
	FileObject file = lookupFileObject(url);
	if (file == null)
	{
	return super.getPermissions(cs);
	}

	FileObject parentLayer = file.getFileSystem().getParentLayer();
	if (parentLayer == null)
	{
	return super.getPermissions(cs);
	}

	Permissions combi = new Permissions();
	PermissionCollection permCollect = super.getPermissions(cs);
	copyPermissions(permCollect, combi);

	for (FileObject parent = parentLayer;
	parent != null;
	parent = parent.getFileSystem().getParentLayer())
	{
	final CodeSource parentcs =
	new CodeSource(parent.getURL(),
	parent.getContent().getCertificates());
	permCollect = super.getPermissions(parentcs);
	copyPermissions(permCollect, combi);
	}

	return combi;
	}
	catch (final FileSystemException fse)
	{
	throw new SecurityException(fse.getMessage());
	}
	}

	/**
	* Copies the permissions from src to dest.
	*/
	protected void copyPermissions(final PermissionCollection src,
	final PermissionCollection dest)
	{
	for (Enumeration elem = src.elements(); elem.hasMoreElements();)
	{
	final Permission permission = (Permission) elem.nextElement();
	dest.add(permission);
	}
	}

	/**
	* Does a reverse lookup to find the FileObject when we only have the
	* URL.
	*/
	private FileObject lookupFileObject(final String name)
	{
	final Iterator it = resources.iterator();
	while (it.hasNext())
	{
	final FileObject object = (FileObject) it.next();
	if (name.equals(object.getName().getURI()))
	{
	return object;
	}
	}
	return null;
	}

	/**
	* Finds the resource with the specified name from the search path.
	* This returns null if the resource is not found.
	*/
	protected URL findResource(final String name)
	{
	try
	{
	final Resource res = loadResource(name);
	if (res != null)
	{
	return res.getURL();
	}
	}
	catch (final Exception mue)
	{
	// Ignore
	// TODO - report?
	}

	return null;
	}

	/**
	* Returns an Enumeration of all the resources in the search path
	* with the specified name.
	* TODO - Implement this.
	*/
	protected Enumeration findResources(final String name)
	{
	return new Enumeration()
	{
	public boolean hasMoreElements()
	{
	return false;
	}

	public Object nextElement()
	{
	return null;
	}
	};
	}

	/**
	* Searches through the search path of for the first class or resource
	* with specified name.
	*/
	private Resource loadResource(final String name) throws FileSystemException
	{
	final Iterator it = resources.iterator();
	while (it.hasNext())
	{
	final FileObject baseFile = (FileObject) it.next();
	final FileObject file =
	baseFile.resolveFile(name, NameScope.DESCENDENT_OR_SELF);
	if (file.exists())
	{
	return new Resource(name, baseFile, file);
	}
	}

	return null;
	}
	}