Copyright (c) 2004, 2018 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2004, 2018 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/

package org.eclipse.osgi.internal.loader;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.URL;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.eclipse.osgi.container.Module;
import org.eclipse.osgi.container.ModuleCapability;
import org.eclipse.osgi.container.ModuleLoader;
import org.eclipse.osgi.container.ModuleRequirement;
import org.eclipse.osgi.container.ModuleRevision;
import org.eclipse.osgi.container.ModuleRevisionBuilder;
import org.eclipse.osgi.container.ModuleWire;
import org.eclipse.osgi.container.ModuleWiring;
import org.eclipse.osgi.container.builders.OSGiManifestBuilderFactory;
import org.eclipse.osgi.container.namespaces.EquinoxModuleDataNamespace;
import org.eclipse.osgi.internal.debug.Debug;
import org.eclipse.osgi.internal.framework.EquinoxConfiguration;
import org.eclipse.osgi.internal.framework.EquinoxContainer;
import org.eclipse.osgi.internal.hookregistry.ClassLoaderHook;
import org.eclipse.osgi.internal.loader.buddy.PolicyHandler;
import org.eclipse.osgi.internal.loader.sources.MultiSourcePackage;
import org.eclipse.osgi.internal.loader.sources.NullPackageSource;
import org.eclipse.osgi.internal.loader.sources.PackageSource;
import org.eclipse.osgi.internal.loader.sources.SingleSourcePackage;
import org.eclipse.osgi.storage.BundleInfo.Generation;
import org.eclipse.osgi.util.ManifestElement;
import org.osgi.framework.Bundle;
import org.osgi.framework.BundleContext;
import org.osgi.framework.BundleException;
import org.osgi.framework.Constants;
import org.osgi.framework.FrameworkEvent;
import org.osgi.framework.namespace.BundleNamespace;
import org.osgi.framework.namespace.HostNamespace;
import org.osgi.framework.namespace.PackageNamespace;
import org.osgi.framework.wiring.BundleWiring;

This object is responsible for all classloader delegation for a bundle.
It represents the loaded state of the bundle.  BundleLoader objects
are created lazily; care should be taken not to force the creation
of a BundleLoader unless it is necessary.
See Also:
BundleLoaderSources/**
 * This object is responsible for all classloader delegation for a bundle.
 * It represents the loaded state of the bundle.  BundleLoader objects
 * are created lazily; care should be taken not to force the creation
 * of a BundleLoader unless it is necessary.
 * @see org.eclipse.osgi.internal.loader.BundleLoaderSources
 */
public class BundleLoader extends ModuleLoader {
	public final static String DEFAULT_PACKAGE = "."; //$NON-NLS-1$
	public final static String JAVA_PACKAGE = "java."; //$NON-NLS-1$

	public final static ClassContext CLASS_CONTEXT = AccessController.doPrivileged(new PrivilegedAction<ClassContext>() {
		@Override
		public ClassContext run() {
			return new ClassContext();
		}
	});
	public final static ClassLoader FW_CLASSLOADER = getClassLoader(EquinoxContainer.class);

	private static final int PRE_CLASS = 1;
	private static final int POST_CLASS = 2;
	private static final int PRE_RESOURCE = 3;
	private static final int POST_RESOURCE = 4;
	private static final int PRE_RESOURCES = 5;
	private static final int POST_RESOURCES = 6;

	private static final Pattern PACKAGENAME_FILTER = Pattern.compile("\\(osgi.wiring.package\\s*=\\s*([^)]+)\\)"); //$NON-NLS-1$

	// TODO needed instead of using Collections.emptyEnumertion until we no longer support Java 6
	@SuppressWarnings("rawtypes")
	private final static Enumeration EMPTY_ENUMERATION = Collections.enumeration(Collections.emptyList());

	private final ModuleWiring wiring;
	private final EquinoxContainer container;
	private final Debug debug;
	private final PolicyHandler policy;

	/* List of package names that are exported by this BundleLoader */
	private final Collection<String> exportedPackages;
	private final BundleLoaderSources exportSources;

	/* cache of required package sources. Key is packagename, value is PackageSource */
	private final Map<String, PackageSource> requiredSources = new HashMap<>();
	/* cache of imported packages. Key is packagename, Value is PackageSource */
	private final Map<String, PackageSource> importedSources = new HashMap<>();
	private final List<ModuleWire> requiredBundleWires;

	/* @GuardedBy("importedSources") */
	private boolean importsInitialized = false;
	/* @GuardedBy("importedSources") */
	private boolean dynamicAllPackages;
	/* If not null, list of package stems to import dynamically. */
	/* @GuardedBy("importedSources") */
	private String[] dynamicImportPackageStems;
	/* @GuardedBy("importedSources") */
	/* If not null, list of package names to import dynamically. */
	private String[] dynamicImportPackages;

	private final Object classLoaderCreatedMonitor = new Object();
	/* @GuardedBy("classLoaderCreatedMonitor") */
	private ModuleClassLoader classLoaderCreated;
	private volatile ModuleClassLoader classloader;
	private final ClassLoader parent;
	private final AtomicBoolean triggerClassLoaded = new AtomicBoolean(false);
	private final AtomicBoolean firstUseOfInvalidLoader = new AtomicBoolean(false);

	
Returns the package name from the specified class name.
The returned package is dot seperated.
Params:
name –   Name of a class.
Returns:
Dot separated package name or null if the class
        has no package name./**
	 * Returns the package name from the specified class name.
	 * The returned package is dot seperated.
	 *
	 * @param name   Name of a class.
	 * @return Dot separated package name or null if the class
	 *         has no package name.
	 */
	public final static String getPackageName(String name) {
		if (name != null) {
			int index = name.lastIndexOf('.'); /* find last period in class name */
			if (index > 0)
				return name.substring(0, index);
		}
		return DEFAULT_PACKAGE;
	}

	
Returns the package name from the specified resource name.
The returned package is dot seperated.
Params:
name –   Name of a resource.
Returns:
Dot separated package name or null if the resource
        has no package name./**
	 * Returns the package name from the specified resource name.
	 * The returned package is dot seperated.
	 *
	 * @param name   Name of a resource.
	 * @return Dot separated package name or null if the resource
	 *         has no package name.
	 */
	public final static String getResourcePackageName(String name) {
		if (name != null) {
			/* check for leading slash*/
			int begin = ((name.length() > 1) && (name.charAt(0) == '/')) ? 1 : 0;
			int end = name.lastIndexOf('/'); /* index of last slash */
			if (end > begin)
				return name.substring(begin, end).replace('/', '.');
		}
		return DEFAULT_PACKAGE;
	}

	public BundleLoader(ModuleWiring wiring, EquinoxContainer container, ClassLoader parent) {
		this.wiring = wiring;
		this.container = container;
		this.debug = container.getConfiguration().getDebug();
		this.parent = parent;

		// init the provided packages set
		exportSources = new BundleLoaderSources(this);
		List<ModuleCapability> exports = wiring.getModuleCapabilities(PackageNamespace.PACKAGE_NAMESPACE);
		exports = exports == null ? new ArrayList<ModuleCapability>(0) : exports;
		exportedPackages = Collections.synchronizedCollection(exports.size() > 10 ? new HashSet<String>(exports.size()) : new ArrayList<String>(exports.size()));
		initializeExports(exports, exportSources, exportedPackages);

		// init the dynamic imports tables
		addDynamicImportPackage(wiring.getModuleRequirements(PackageNamespace.PACKAGE_NAMESPACE));

		// initialize the required bundle wires
		List<ModuleWire> currentRequireBundleWires = wiring.getRequiredModuleWires(BundleNamespace.BUNDLE_NAMESPACE);
		requiredBundleWires = currentRequireBundleWires == null || currentRequireBundleWires.isEmpty() ? Collections.<ModuleWire> emptyList() : Collections.unmodifiableList(currentRequireBundleWires);

		//Initialize the policy handler
		List<ModuleCapability> moduleDatas = wiring.getRevision().getModuleCapabilities(EquinoxModuleDataNamespace.MODULE_DATA_NAMESPACE);
		@SuppressWarnings("unchecked")
		List<String> buddyList = (List<String>) (moduleDatas.isEmpty() ? null : moduleDatas.get(0).getAttributes().get(EquinoxModuleDataNamespace.CAPABILITY_BUDDY_POLICY));
		policy = buddyList != null ? new PolicyHandler(this, buddyList, container.getPackageAdmin(), container.getBootLoader()) : null;
		if (policy != null) {
			Module systemModule = container.getStorage().getModuleContainer().getModule(0);
			Bundle systemBundle = systemModule.getBundle();
			policy.open(systemBundle.getBundleContext());
		}
	}

	public ModuleWiring getWiring() {
		return wiring;
	}

	public void addFragmentExports(List<ModuleCapability> exports) {
		initializeExports(exports, exportSources, exportedPackages);
	}

	private static void initializeExports(List<ModuleCapability> exports, BundleLoaderSources sources, Collection<String> exportNames) {
		if (exports != null) {
			for (ModuleCapability export : exports) {
				String name = (String) export.getAttributes().get(PackageNamespace.PACKAGE_NAMESPACE);
				if (sources.forceSourceCreation(export)) {
					if (!exportNames.contains(name)) {
						// must force filtered and reexport sources to be created early
						// to prevent lazy normal package source creation.
						// We only do this for the first export of a package name. 
						sources.createPackageSource(export, true);
					}
				}
				exportNames.add(name);
			}
		}
	}

	final PackageSource createExportPackageSource(ModuleWire importWire, Collection<BundleLoader> visited) {
		String name = (String) importWire.getCapability().getAttributes().get(PackageNamespace.PACKAGE_NAMESPACE);
		BundleLoader providerLoader = getProviderLoader(importWire);
		if (providerLoader == null) {
			return createMultiSource(name, new PackageSource[0]);
		}
		PackageSource requiredSource = providerLoader.findRequiredSource(name, visited);
		PackageSource exportSource = providerLoader.exportSources.createPackageSource(importWire.getCapability(), false);
		if (requiredSource == null)
			return exportSource;
		return createMultiSource(name, new PackageSource[] {requiredSource, exportSource});
	}

	private static PackageSource createMultiSource(String packageName, PackageSource[] sources) {
		if (sources.length == 1)
			return sources[0];
		List<SingleSourcePackage> sourceList = new ArrayList<>(sources.length);
		for (PackageSource source : sources) {
			SingleSourcePackage[] innerSources = source.getSuppliers();
			for (SingleSourcePackage innerSource : innerSources) {
				if (!sourceList.contains(innerSource)) {
					sourceList.add(innerSource);
				}
			}
		}
		return new MultiSourcePackage(packageName, sourceList.toArray(new SingleSourcePackage[sourceList.size()]));
	}

	public ModuleClassLoader getModuleClassLoader() {
		ModuleClassLoader result = classloader;
		if (result != null) {
			return result;
		}
		// doing optimistic class loader creating here to avoid holding any locks,
		// this may result in multiple classloaders being constructed but only one will be used.
		final List<ClassLoaderHook> hooks = container.getConfiguration().getHookRegistry().getClassLoaderHooks();
		final Generation generation = (Generation) wiring.getRevision().getRevisionInfo();
		if (System.getSecurityManager() == null) {
			result = createClassLoaderPrivledged(parent, generation.getBundleInfo().getStorage().getConfiguration(), this, generation, hooks);
		} else {
			final ClassLoader cl = parent;
			result = AccessController.doPrivileged(new PrivilegedAction<ModuleClassLoader>() {
				@Override
				public ModuleClassLoader run() {
					return createClassLoaderPrivledged(cl, generation.getBundleInfo().getStorage().getConfiguration(), BundleLoader.this, generation, hooks);
				}
			});
		}

		// Synchronize on classLoaderCreatedMonitor in order to ensure hooks are called before returning.
		// Note that we do hold a lock here while calling hooks.
		// Not ideal, but hooks really should do little work from classLoaderCreated method.
		synchronized (classLoaderCreatedMonitor) {
			if (classLoaderCreated == null) {
				// must set createdClassloader before calling hooks; otherwise we could enter
				// and endless loop if the hook causes re-entry (that would be a bad hook impl)
				classLoaderCreated = result;
				// only send to hooks if this thread wins in creating the class loader.
				final ModuleClassLoader cl = result;
				// protect with doPriv to avoid bubbling up permission checks that hooks may require
				AccessController.doPrivileged(new PrivilegedAction<Object>() {
					@Override
					public Object run() {
						for (ClassLoaderHook hook : hooks) {
							hook.classLoaderCreated(cl);
						}
						return null;
					}

				});
				// finally set the class loader for use after calling hooks
				classloader = classLoaderCreated;
			} else {
				// return the classLoaderCreated here; not the final classloader
				// this is necessary in case re-entry by a hook.classLoaderCreated method
				result = classLoaderCreated;
				if (debug.DEBUG_LOADER) {
					Debug.println("BundleLoader[" + this + "].getModuleClassLoader() - created duplicate classloader"); //$NON-NLS-1$ //$NON-NLS-2$
				}
			}
		}
		return result;
	}

	@Override
	protected void loadFragments(Collection<ModuleRevision> fragments) {
		addFragmentExports(wiring.getModuleCapabilities(PackageNamespace.PACKAGE_NAMESPACE));
		loadClassLoaderFragments(fragments);
		clearManifestLocalizationCache();
	}

	protected void clearManifestLocalizationCache() {
		Generation hostGen = (Generation) wiring.getRevision().getRevisionInfo();
		hostGen.clearManifestCache();
		List<ModuleWire> hostWires = wiring.getProvidedModuleWires(HostNamespace.HOST_NAMESPACE);
		// doing a null check because there is no lock on the module database here
		if (hostWires != null) {
			for (ModuleWire fragmentWire : hostWires) {
				Generation fragGen = (Generation) fragmentWire.getRequirer().getRevisionInfo();
				fragGen.clearManifestCache();
			}
		}
	}

	void loadClassLoaderFragments(Collection<ModuleRevision> fragments) {
		ModuleClassLoader current = classloader;
		if (current != null) {
			current.loadFragments(fragments);
		}
	}

	static ModuleClassLoader createClassLoaderPrivledged(ClassLoader parent, EquinoxConfiguration configuration, BundleLoader delegate, Generation generation, List<ClassLoaderHook> hooks) {
		// allow hooks to extend the ModuleClassLoader implementation
		for (ClassLoaderHook hook : hooks) {
			ModuleClassLoader hookClassLoader = hook.createClassLoader(parent, configuration, delegate, generation);
			if (hookClassLoader != null) {
				// first one to return non-null wins.
				return hookClassLoader;
			}
		}
		// just use the default one
		return new EquinoxClassLoader(parent, configuration, delegate, generation);
	}

	public void close() {
		if (policy != null) {
			Module systemModule = container.getStorage().getModuleContainer().getModule(0);
			BundleContext context = systemModule.getBundle().getBundleContext();
			if (context != null) {
				policy.close(context);
			}
		}
		ModuleClassLoader current = classloader;
		if (current != null) {
			current.close();
		}
	}

	@Override
	protected ClassLoader getClassLoader() {
		return getModuleClassLoader();
	}

	public ClassLoader getParentClassLoader() {
		return this.parent;
	}

	
This method gets a resource from the bundle.  The resource is searched 
for in the same manner as it would if it was being loaded from a bundle 
(i.e. all hosts, fragments, import, required bundles and 
local resources are searched).
Params:
name – the name of the desired resource.
Returns:
the resulting resource URL or null if it does not exist./**
	 * This method gets a resource from the bundle.  The resource is searched 
	 * for in the same manner as it would if it was being loaded from a bundle 
	 * (i.e. all hosts, fragments, import, required bundles and 
	 * local resources are searched).
	 *
	 * @param name the name of the desired resource.
	 * @return the resulting resource URL or null if it does not exist.
	 */
	final URL getResource(String name) {
		return getModuleClassLoader().getResource(name);
	}

	
Finds a class local to this bundle.  Only the classloader for this bundle is searched.
Params:
name – The name of the class to find.
Throws:
ClassNotFoundException – 
Returns:
The loaded Class or null if the class is not found./**
	 * Finds a class local to this bundle.  Only the classloader for this bundle is searched.
	 * @param name The name of the class to find.
	 * @return The loaded Class or null if the class is not found.
	 * @throws ClassNotFoundException 
	 */
	public Class<?> findLocalClass(String name) throws ClassNotFoundException {
		long start = 0;
		if (debug.DEBUG_LOADER) {
			Debug.println("BundleLoader[" + this + "].findLocalClass(" + name + ")"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
			start = System.currentTimeMillis();
		}
		try {
			Class<?> clazz = getModuleClassLoader().findLocalClass(name);
			if (debug.DEBUG_LOADER && clazz != null) {
				long time = System.currentTimeMillis() - start;
				Debug.println("BundleLoader[" + this + "] found local class " + name + " " + time + "ms"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
			}
			return clazz;
		} catch (ClassNotFoundException e) {
			if (e.getCause() instanceof BundleException) {
				// Here we assume this is because of a lazy activation error
				throw e;
			}
			return null;
		}
	}

	
Finds the class for a bundle.  This method is used for delegation by the bundle's classloader.
/**
	 * Finds the class for a bundle.  This method is used for delegation by the bundle's classloader.
	 */
	public Class<?> findClass(String name) throws ClassNotFoundException {
		return findClass(name, true);
	}

	Class<?> findClass(String name, boolean checkParent) throws ClassNotFoundException {
		if (checkParent && parent != null && name.startsWith(JAVA_PACKAGE))
			// 1) if startsWith "java." delegate to parent and terminate search
			// we want to throw ClassNotFoundExceptions if a java.* class cannot be loaded from the parent.
			return parent.loadClass(name);
		return findClassInternal(name, checkParent);
	}

	private Class<?> findClassInternal(String name, boolean checkParent) throws ClassNotFoundException {
		if (debug.DEBUG_LOADER)
			Debug.println("BundleLoader[" + this + "].findClassInternal(" + name + ")"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
		String pkgName = getPackageName(name);
		boolean bootDelegation = false;
		// follow the OSGi delegation model
		if (checkParent && parent != null && container.isBootDelegationPackage(pkgName)) {
			// 2) if part of the bootdelegation list then delegate to parent and continue of failure
			try {
				return parent.loadClass(name);
			} catch (ClassNotFoundException cnfe) {
				// we want to continue
				bootDelegation = true;
			}
		}
		Class<?> result = null;
		try {
			result = (Class<?>) searchHooks(name, PRE_CLASS);
		} catch (ClassNotFoundException e) {
			throw e;
		} catch (FileNotFoundException e) {
			// will not happen
		}
		if (result != null)
			return result;
		// 3) search the imported packages
		PackageSource source = findImportedSource(pkgName, null);
		if (source != null) {
			if (debug.DEBUG_LOADER) {
				Debug.println("BundleLoader[" + this + "] loading from import package: " + source); //$NON-NLS-1$ //$NON-NLS-2$
			}
			// 3) found import source terminate search at the source
			result = source.loadClass(name);
			if (result != null)
				return result;
			throw new ClassNotFoundException(name + " cannot be found by " + this); //$NON-NLS-1$
		}
		// 4) search the required bundles
		source = findRequiredSource(pkgName, null);
		if (source != null) {
			if (debug.DEBUG_LOADER) {
				Debug.println("BundleLoader[" + this + "] loading from required bundle package: " + source); //$NON-NLS-1$ //$NON-NLS-2$
			}
			// 4) attempt to load from source but continue on failure
			result = source.loadClass(name);
		}
		// 5) search the local bundle
		if (result == null)
			result = findLocalClass(name);
		if (result != null)
			return result;
		// 6) attempt to find a dynamic import source; only do this if a required source was not found
		if (source == null) {
			source = findDynamicSource(pkgName);
			if (source != null) {
				result = source.loadClass(name);
				if (result != null)
					return result;
				// must throw CNFE if dynamic import source does not have the class
				throw new ClassNotFoundException(name + " cannot be found by " + this); //$NON-NLS-1$
			}
		}

		if (result == null)
			try {
				result = (Class<?>) searchHooks(name, POST_CLASS);
			} catch (ClassNotFoundException e) {
				throw e;
			} catch (FileNotFoundException e) {
				// will not happen
			}
		// do buddy policy loading
		if (result == null && policy != null)
			result = policy.doBuddyClassLoading(name);
		if (result != null)
			return result;
		// hack to support backwards compatibility for bootdelegation
		// or last resort; do class context trick to work around VM bugs
		if (parent != null && !bootDelegation && ((checkParent && container.getConfiguration().compatibilityBootDelegation) || isRequestFromVM())) {
			// we don't need to continue if a CNFE is thrown here.
			try {
				return parent.loadClass(name);
			} catch (ClassNotFoundException e) {
				// we want to generate our own exception below
			}
		}
		throw new ClassNotFoundException(name + " cannot be found by " + this); //$NON-NLS-1$
	}

	@SuppressWarnings("unchecked")
	private <E> E searchHooks(String name, int type) throws ClassNotFoundException, FileNotFoundException {

		List<ClassLoaderHook> loaderHooks = container.getConfiguration().getHookRegistry().getClassLoaderHooks();
		if (loaderHooks == null)
			return null;
		E result = null;
		for (ClassLoaderHook hook : loaderHooks) {
			switch (type) {
				case PRE_CLASS :
					result = (E) hook.preFindClass(name, getModuleClassLoader());
					break;
				case POST_CLASS :
					result = (E) hook.postFindClass(name, getModuleClassLoader());
					break;
				case PRE_RESOURCE :
					result = (E) hook.preFindResource(name, getModuleClassLoader());
					break;
				case POST_RESOURCE :
					result = (E) hook.postFindResource(name, getModuleClassLoader());
					break;
				case PRE_RESOURCES :
					result = (E) hook.preFindResources(name, getModuleClassLoader());
					break;
				case POST_RESOURCES :
					result = (E) hook.postFindResources(name, getModuleClassLoader());
					break;
			}
			if (result != null) {
				return result;
			}
		}
		return result;
	}

	private boolean isRequestFromVM() {
		if (!container.getConfiguration().contextBootDelegation)
			return false;
		// works around VM bugs that require all classloaders to have access to parent packages
		Class<?>[] context = CLASS_CONTEXT.getClassContext();
		if (context == null || context.length < 2)
			return false;
		// skip the first class; it is the ClassContext class
		for (int i = 1; i < context.length; i++) {
			Class<?> clazz = context[i];
			// Find the first class in the context which is not BundleLoader or the ModuleClassLoader;
			// We ignore ClassLoader because ModuleClassLoader extends it.
			// We ignore Class because of Class.forName (bug 471551)
			if (clazz != BundleLoader.class && !ModuleClassLoader.class.isAssignableFrom(clazz) && clazz != ClassLoader.class && clazz != Class.class && !clazz.getName().equals("java.lang.J9VMInternals")) { //$NON-NLS-1$
				if (Bundle.class.isAssignableFrom(clazz)) {
					// We ignore any requests from Bundle (e.g. Bundle.loadClass case)
					return false;
				}
				// only find in parent if the class is not loaded with a ModuleClassLoader
				ClassLoader cl = getClassLoader(clazz);
				// extra check incase an adaptor adds another class into the stack besides an instance of ClassLoader
				if (cl != FW_CLASSLOADER) {
					// if the class is loaded from a class loader implemented by a bundle then we do not boot delegate
					ClassLoader last = null;
					while (cl != null && cl != last) {
						last = cl;
						if (cl instanceof ModuleClassLoader) {
							return false;
						}
						cl = getClassLoader(cl.getClass());
					}

					// request is not from a bundle
					return true;
				}
			}
		}
		return false;
	}

	private static ClassLoader getClassLoader(final Class<?> clazz) {
		if (System.getSecurityManager() == null)
			return clazz.getClassLoader();
		return AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() {
			@Override
			public ClassLoader run() {
				return clazz.getClassLoader();
			}
		});
	}

	
Finds the resource for a bundle.  This method is used for delegation by the bundle's classloader.
/**
	 * Finds the resource for a bundle.  This method is used for delegation by the bundle's classloader.
	 */
	public URL findResource(String name) {
		if (debug.DEBUG_LOADER)
			Debug.println("BundleLoader[" + this + "].findResource(" + name + ")"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
		if ((name.length() > 1) && (name.charAt(0) == '/')) /* if name has a leading slash */
			name = name.substring(1); /* remove leading slash before search */
		String pkgName = getResourcePackageName(name);
		boolean bootDelegation = false;
		// follow the OSGi delegation model
		// First check the parent classloader for system resources, if it is a java resource.
		if (parent != null) {
			if (pkgName.startsWith(JAVA_PACKAGE))
				// 1) if startsWith "java." delegate to parent and terminate search
				// we never delegate java resource requests past the parent
				return parent.getResource(name);
			else if (container.isBootDelegationPackage(pkgName)) {
				// 2) if part of the bootdelegation list then delegate to parent and continue of failure
				URL result = parent.getResource(name);
				if (result != null)
					return result;
				bootDelegation = true;
			}
		}

		URL result = null;
		try {
			result = (URL) searchHooks(name, PRE_RESOURCE);
		} catch (FileNotFoundException e) {
			return null;
		} catch (ClassNotFoundException e) {
			// will not happen
		}
		if (result != null)
			return result;
		// 3) search the imported packages
		PackageSource source = findImportedSource(pkgName, null);
		if (source != null) {
			if (debug.DEBUG_LOADER) {
				Debug.println("BundleLoader[" + this + "] loading from import package: " + source); //$NON-NLS-1$ //$NON-NLS-2$
			}
			// 3) found import source terminate search at the source
			return source.getResource(name);
		}
		// 4) search the required bundles
		source = findRequiredSource(pkgName, null);
		if (source != null) {
			if (debug.DEBUG_LOADER) {
				Debug.println("BundleLoader[" + this + "] loading from required bundle package: " + source); //$NON-NLS-1$ //$NON-NLS-2$
			}
			// 4) attempt to load from source but continue on failure
			result = source.getResource(name);
		}
		// 5) search the local bundle
		if (result == null)
			result = findLocalResource(name);
		if (result != null)
			return result;
		// 6) attempt to find a dynamic import source; only do this if a required source was not found
		if (source == null) {
			source = findDynamicSource(pkgName);
			if (source != null)
				// must return the result of the dynamic import and do not continue
				return source.getResource(name);
		}

		if (result == null)
			try {
				result = (URL) searchHooks(name, POST_RESOURCE);
			} catch (FileNotFoundException e) {
				return null;
			} catch (ClassNotFoundException e) {
				// will not happen
			}
		// do buddy policy loading
		if (result == null && policy != null)
			result = policy.doBuddyResourceLoading(name);
		if (result != null)
			return result;
		// hack to support backwards compatibility for bootdelegation
		// or last resort; do class context trick to work around VM bugs
		if (parent != null && !bootDelegation && (container.getConfiguration().compatibilityBootDelegation || isRequestFromVM()))
			// we don't need to continue if the resource is not found here
			return parent.getResource(name);
		return result;
	}

	
Finds the resources for a bundle.  This  method is used for delegation by the bundle's classloader.
/**
	 * Finds the resources for a bundle.  This  method is used for delegation by the bundle's classloader.
	 */
	public Enumeration<URL> findResources(String name) throws IOException {
		if (debug.DEBUG_LOADER)
			Debug.println("BundleLoader[" + this + "].findResources(" + name + ")"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
		// do not delegate to parent because ClassLoader#getResources already did and it is final!!
		if ((name.length() > 1) && (name.charAt(0) == '/')) /* if name has a leading slash */
			name = name.substring(1); /* remove leading slash before search */
		String pkgName = getResourcePackageName(name);
		Enumeration<URL> result = emptyEnumeration();
		boolean bootDelegation = false;
		// follow the OSGi delegation model
		// First check the parent classloader for system resources, if it is a java resource.
		if (parent != null) {
			if (pkgName.startsWith(JAVA_PACKAGE))
				// 1) if startsWith "java." delegate to parent and terminate search
				// we never delegate java resource requests past the parent
				return parent.getResources(name);
			else if (container.isBootDelegationPackage(pkgName)) {
				// 2) if part of the bootdelegation list then delegate to parent and continue
				result = compoundEnumerations(result, parent.getResources(name));
				bootDelegation = true;
			}
		}
		try {
			Enumeration<URL> hookResources = searchHooks(name, PRE_RESOURCES);
			if (hookResources != null) {
				return compoundEnumerations(result, hookResources);
			}
		} catch (ClassNotFoundException e) {
			// will not happen
		} catch (FileNotFoundException e) {
			return result;
		}

		// 3) search the imported packages
		PackageSource source = findImportedSource(pkgName, null);
		if (source != null) {
			if (debug.DEBUG_LOADER) {
				Debug.println("BundleLoader[" + this + "] loading from import package: " + source); //$NON-NLS-1$ //$NON-NLS-2$
			}
			// 3) found import source terminate search at the source
			return compoundEnumerations(result, source.getResources(name));
		}
		// 4) search the required bundles
		source = findRequiredSource(pkgName, null);
		if (source != null) {
			if (debug.DEBUG_LOADER) {
				Debug.println("BundleLoader[" + this + "] loading from required bundle package: " + source); //$NON-NLS-1$ //$NON-NLS-2$
			}
			// 4) attempt to load from source but continue on failure
			result = compoundEnumerations(result, source.getResources(name));
		}
		// 5) search the local bundle
		// compound the required source results with the local ones
		Enumeration<URL> localResults = findLocalResources(name);
		result = compoundEnumerations(result, localResults);
		// 6) attempt to find a dynamic import source; only do this if a required source was not found
		if (source == null && !result.hasMoreElements()) {
			source = findDynamicSource(pkgName);
			if (source != null)
				return compoundEnumerations(result, source.getResources(name));
		}
		if (!result.hasMoreElements())
			try {
				Enumeration<URL> hookResources = searchHooks(name, POST_RESOURCES);
				result = compoundEnumerations(result, hookResources);
			} catch (ClassNotFoundException e) {
				// will not happen
			} catch (FileNotFoundException e) {
				return null;
			}
		if (policy != null) {
			Enumeration<URL> buddyResult = policy.doBuddyResourcesLoading(name);
			result = compoundEnumerations(result, buddyResult);
		}
		// hack to support backwards compatibility for bootdelegation
		// or last resort; do class context trick to work around VM bugs
		if (!result.hasMoreElements()) {
			if (parent != null && !bootDelegation && (container.getConfiguration().compatibilityBootDelegation || isRequestFromVM()))
				// we don't need to continue if the resource is not found here
				return parent.getResources(name);
		}
		return result;
	}

	private boolean isSubPackage(String parentPackage, String subPackage) {
		String prefix = (parentPackage.length() == 0 || parentPackage.equals(DEFAULT_PACKAGE)) ? "" : parentPackage + '.'; //$NON-NLS-1$
		return subPackage.startsWith(prefix);
	}

	@Override
	protected Collection<String> listResources(String path, String filePattern, int options) {
		String pkgName = getResourcePackageName(path.endsWith("/") ? path : path + '/'); //$NON-NLS-1$
		if ((path.length() > 1) && (path.charAt(0) == '/')) /* if name has a leading slash */
			path = path.substring(1); /* remove leading slash before search */
		boolean subPackages = (options & BundleWiring.LISTRESOURCES_RECURSE) != 0;
		List<String> packages = new ArrayList<>();
		// search imported package names
		Map<String, PackageSource> importSources = getImportedSources(null);
		Collection<PackageSource> imports;
		synchronized (importSources) {
			imports = new ArrayList<>(importSources.values());
		}
		for (PackageSource source : imports) {
			String id = source.getId();
			if (id.equals(pkgName) || (subPackages && isSubPackage(pkgName, id)))
				packages.add(id);
		}

		// now add package names from required bundles
		Collection<BundleLoader> visited = new ArrayList<>();
		visited.add(this); // always add ourselves so we do not recurse back to ourselves
		for (ModuleWire bundleWire : requiredBundleWires) {
			BundleLoader loader = getProviderLoader(bundleWire);
			if (loader != null) {
				loader.addProvidedPackageNames(pkgName, packages, subPackages, visited);
			}
		}

		boolean localSearch = (options & BundleWiring.LISTRESOURCES_LOCAL) != 0;
		// Use LinkedHashSet for optimized performance of contains() plus
		// ordering guarantees.
		LinkedHashSet<String> result = new LinkedHashSet<>();
		Set<String> importedPackages = new HashSet<>(0);
		for (String name : packages) {
			// look for import source
			PackageSource externalSource = findImportedSource(name, null);
			if (externalSource != null) {
				// record this package is imported
				importedPackages.add(name);
			} else {
				// look for require bundle source
				externalSource = findRequiredSource(name, null);
			}
			// only add the content of the external source if this is not a localSearch
			if (externalSource != null && !localSearch) {
				String packagePath = name.replace('.', '/');
				Collection<String> externalResources = externalSource.listResources(packagePath, filePattern);
				for (String resource : externalResources) {
					if (!result.contains(resource)) // prevent duplicates; could happen if the package is split or exporter has fragments/multiple jars
						result.add(resource);
				}
			}
		}

		// now search locally
		Collection<String> localResources = getModuleClassLoader().listLocalResources(path, filePattern, options);
		for (String resource : localResources) {
			String resourcePkg = getResourcePackageName(resource);
			if (!importedPackages.contains(resourcePkg) && !result.contains(resource))
				result.add(resource);
		}
		return result;
	}

	@Override
	protected List<URL> findEntries(String path, String filePattern, int options) {
		return getModuleClassLoader().findEntries(path, filePattern, options);
	}

	public static <E> Enumeration<E> compoundEnumerations(Enumeration<E> list1, Enumeration<E> list2) {
		if (list2 == null || !list2.hasMoreElements())
			return list1 == null ? BundleLoader.<E> emptyEnumeration() : list1;
		if (list1 == null || !list1.hasMoreElements())
			return list2 == null ? BundleLoader.<E> emptyEnumeration() : list2;
		List<E> compoundResults = new ArrayList<>();
		while (list1.hasMoreElements())
			compoundResults.add(list1.nextElement());
		while (list2.hasMoreElements()) {
			E item = list2.nextElement();
			if (!compoundResults.contains(item)) //don't add duplicates
				compoundResults.add(item);
		}
		return Collections.enumeration(compoundResults);
	}

	@SuppressWarnings("unchecked")
	private static <E> Enumeration<E> emptyEnumeration() {
		return EMPTY_ENUMERATION;
	}

	
Finds a resource local to this bundle.  Only the classloader for this bundle is searched.
Params:
name – The name of the resource to find.
Returns:
The URL to the resource or null if the resource is not found./**
	 * Finds a resource local to this bundle.  Only the classloader for this bundle is searched.
	 * @param name The name of the resource to find.
	 * @return The URL to the resource or null if the resource is not found.
	 */
	public URL findLocalResource(final String name) {
		return getModuleClassLoader().findLocalResource(name);
	}

	
Returns an Enumeration of URLs representing all the resources with
the given name. Only the classloader for this bundle is searched.
Params:
name – the resource name
Returns:
an Enumeration of URLs for the resources/**
	 * Returns an Enumeration of URLs representing all the resources with
	 * the given name. Only the classloader for this bundle is searched.
	 *
	 * @param  name the resource name
	 * @return an Enumeration of URLs for the resources
	 */
	public Enumeration<URL> findLocalResources(String name) {
		return getModuleClassLoader().findLocalResources(name);
	}

	
Return a string representation of this loader.
Returns:
String/**
	 * Return a string representation of this loader.
	 * @return String
	 */
	@Override
	public final String toString() {
		ModuleRevision revision = wiring.getRevision();
		String name = revision.getSymbolicName();
		if (name == null)
			name = "unknown"; //$NON-NLS-1$
		return name + '_' + revision.getVersion();
	}

	
Return true if the target package name matches
a name in the DynamicImport-Package manifest header.
Params:
pkgname – The name of the requested class' package.
Returns:
true if the package should be imported./**
	 * Return true if the target package name matches
	 * a name in the DynamicImport-Package manifest header.
	 *
	 * @param pkgname The name of the requested class' package.
	 * @return true if the package should be imported.
	 */
	private final boolean isDynamicallyImported(String pkgname) {
		if (this instanceof SystemBundleLoader)
			return false; // system bundle cannot dynamically import
		// must check for startsWith("java.") to satisfy R3 section 4.7.2
		if (pkgname.startsWith("java.")) //$NON-NLS-1$
			return true;

		synchronized (importedSources) {
			/* "*" shortcut */
			if (dynamicAllPackages)
				return true;

			/* match against specific names */
			if (dynamicImportPackages != null)
				for (String dynamicImportPackage : dynamicImportPackages) {
					if (pkgname.equals(dynamicImportPackage)) {
						return true;
					}
				}

			/* match against names with trailing wildcards */
			if (dynamicImportPackageStems != null)
				for (String dynamicImportPackageStem : dynamicImportPackageStems) {
					if (pkgname.startsWith(dynamicImportPackageStem)) {
						return true;
					}
				}
		}
		return false;
	}

	final void addExportedProvidersFor(String packageName, List<PackageSource> result, Collection<BundleLoader> visited) {
		if (visited.contains(this))
			return;
		visited.add(this);
		// See if we locally provide the package.
		PackageSource local = null;
		if (isExportedPackage(packageName))
			local = exportSources.getPackageSource(packageName);
		else if (isSubstitutedExport(packageName)) {
			result.add(findImportedSource(packageName, visited));
			return; // should not continue to required bundles in this case
		}
		// Must search required bundles that are exported first.
		for (ModuleWire bundleWire : requiredBundleWires) {
			if (local != null || BundleNamespace.VISIBILITY_REEXPORT.equals(bundleWire.getRequirement().getDirectives().get(BundleNamespace.REQUIREMENT_VISIBILITY_DIRECTIVE))) {
				// always add required bundles first if we locally provide the package
				// This allows a bundle to provide a package from a required bundle without 
				// re-exporting the whole required bundle.
				BundleLoader loader = getProviderLoader(bundleWire);
				if (loader != null) {
					loader.addExportedProvidersFor(packageName, result, visited);
				}
			}
		}
		// now add the locally provided package.
		if (local != null)
			result.add(local);
	}

	private BundleLoader getProviderLoader(ModuleWire wire) {
		ModuleWiring provider = wire.getProviderWiring();
		if (provider == null) {
			if (firstUseOfInvalidLoader.getAndSet(true)) {
				// publish a framework event once per loader, include an exception to show the stack
				String message = "Invalid class loader from a refreshed bundle is being used: " + toString(); //$NON-NLS-1$
				container.getEventPublisher().publishFrameworkEvent(FrameworkEvent.ERROR, wiring.getBundle(), new IllegalStateException(message));
			}
			return null;
		}
		return (BundleLoader) provider.getModuleLoader();
	}

	final void addProvidedPackageNames(String packageName, List<String> result, boolean subPackages, Collection<BundleLoader> visited) {
		if (visited.contains(this))
			return;
		visited.add(this);
		synchronized (exportedPackages) {
			for (String exported : exportedPackages) {
				if (exported.equals(packageName) || (subPackages && isSubPackage(packageName, exported))) {
					if (!result.contains(exported))
						result.add(exported);
				}
			}
		}
		for (String substituted : wiring.getSubstitutedNames()) {
			if (substituted.equals(packageName) || (subPackages && isSubPackage(packageName, substituted))) {
				if (!result.contains(substituted))
					result.add(substituted);
			}
		}
		for (ModuleWire bundleWire : requiredBundleWires) {
			if (BundleNamespace.VISIBILITY_REEXPORT.equals(bundleWire.getRequirement().getDirectives().get(BundleNamespace.REQUIREMENT_VISIBILITY_DIRECTIVE))) {
				BundleLoader loader = getProviderLoader(bundleWire);
				if (loader != null) {
					loader.addProvidedPackageNames(packageName, result, subPackages, visited);
				}
			}
		}
	}

	public final boolean isExportedPackage(String name) {
		return exportedPackages.contains(name);
	}

	final boolean isSubstitutedExport(String name) {
		return wiring.isSubstitutedPackage(name);
	}

	private void addDynamicImportPackage(List<ModuleRequirement> packageImports) {
		if (packageImports == null || packageImports.isEmpty()) {
			return;
		}
		List<String> dynamicImports = new ArrayList<>(packageImports.size());
		for (ModuleRequirement packageImport : packageImports) {
			if (PackageNamespace.RESOLUTION_DYNAMIC.equals(packageImport.getDirectives().get(PackageNamespace.REQUIREMENT_RESOLUTION_DIRECTIVE))) {
				Matcher matcher = PACKAGENAME_FILTER.matcher(packageImport.getDirectives().get(PackageNamespace.REQUIREMENT_FILTER_DIRECTIVE));
				if (matcher.find()) {
					String dynamicName = matcher.group(1);
					if (dynamicName != null) {
						dynamicImports.add(dynamicName);
					}
				}
			}
		}
		if (dynamicImports.size() > 0)
			addDynamicImportPackage(dynamicImports.toArray(new String[dynamicImports.size()]));
	}

	
Adds a list of DynamicImport-Package manifest elements to the dynamic
import tables of this BundleLoader.  Duplicate packages are checked and
not added again.  This method is not thread safe.  Callers should ensure
synchronization when calling this method.
Params:
packages – the DynamicImport-Package elements to add./**
	 * Adds a list of DynamicImport-Package manifest elements to the dynamic
	 * import tables of this BundleLoader.  Duplicate packages are checked and
	 * not added again.  This method is not thread safe.  Callers should ensure
	 * synchronization when calling this method.
	 * @param packages the DynamicImport-Package elements to add.
	 */
	private void addDynamicImportPackage(String[] packages) {
		if (packages == null)
			return;

		synchronized (importedSources) {
			int size = packages.length;
			List<String> stems;
			if (dynamicImportPackageStems == null) {
				stems = new ArrayList<>(size);
			} else {
				stems = new ArrayList<>(size + dynamicImportPackageStems.length);
				for (String dynamicImportPackageStem : dynamicImportPackageStems) {
					stems.add(dynamicImportPackageStem);
				}
			}

			List<String> names;
			if (dynamicImportPackages == null) {
				names = new ArrayList<>(size);
			} else {
				names = new ArrayList<>(size + dynamicImportPackages.length);
				for (String dynamicImportPackage : dynamicImportPackages) {
					names.add(dynamicImportPackage);
				}
			}

			for (int i = 0; i < size; i++) {
				String name = packages[i];
				if (isDynamicallyImported(name))
					continue;
				if (name.equals("*")) { //$NON-NLS-1$
					// shortcut
					dynamicAllPackages = true;
					return;
				}

				if (name.endsWith(".*")) //$NON-NLS-1$
					stems.add(name.substring(0, name.length() - 1));
				else
					names.add(name);
			}

			size = stems.size();
			if (size > 0)
				dynamicImportPackageStems = stems.toArray(new String[size]);

			size = names.size();
			if (size > 0)
				dynamicImportPackages = names.toArray(new String[size]);
		}
	}

	
Adds a list of DynamicImport-Package manifest elements to the dynamic
import tables of this BundleLoader.  Duplicate packages are checked and
not added again.
Params:
packages – the DynamicImport-Package elements to add./**
	 * Adds a list of DynamicImport-Package manifest elements to the dynamic
	 * import tables of this BundleLoader.  Duplicate packages are checked and
	 * not added again.
	 * @param packages the DynamicImport-Package elements to add.
	 */
	public final void addDynamicImportPackage(ManifestElement[] packages) {
		if (packages == null)
			return;
		List<String> dynamicImports = new ArrayList<>(packages.length);
		StringBuilder importSpec = new StringBuilder();
		for (ManifestElement dynamicImportElement : packages) {
			String[] names = dynamicImportElement.getValueComponents();
			Collections.addAll(dynamicImports, names);
			if (importSpec.length() > 0) {
				importSpec.append(',');
			}
			importSpec.append(dynamicImportElement.toString());
		}

		if (dynamicImports.size() > 0) {
			addDynamicImportPackage(dynamicImports.toArray(new String[dynamicImports.size()]));

			Map<String, String> dynamicImportMap = new HashMap<>();
			dynamicImportMap.put(Constants.DYNAMICIMPORT_PACKAGE, importSpec.toString());

			try {
				ModuleRevisionBuilder builder = OSGiManifestBuilderFactory.createBuilder(dynamicImportMap);
				wiring.addDynamicImports(builder);
			} catch (BundleException e) {
				throw new RuntimeException(e);
			}

		}
	}

	/*
	 * Finds a packagesource that is either imported or required from another bundle.
	 * This will not include an local package source
	 */
	private PackageSource findSource(String pkgName) {
		if (pkgName == null)
			return null;
		PackageSource result = findImportedSource(pkgName, null);
		if (result != null)
			return result;
		// Note that dynamic imports are not checked to avoid aggressive wiring (bug 105779)  
		return findRequiredSource(pkgName, null);
	}

	private PackageSource findImportedSource(String pkgName, Collection<BundleLoader> visited) {
		Map<String, PackageSource> imports = getImportedSources(visited);
		synchronized (imports) {
			return imports.get(pkgName);
		}
	}

	private Map<String, PackageSource> getImportedSources(Collection<BundleLoader> visited) {
		synchronized (importedSources) {
			if (importsInitialized) {
				return importedSources;
			}
			List<ModuleWire> importWires = wiring.getRequiredModuleWires(PackageNamespace.PACKAGE_NAMESPACE);
			if (importWires != null) {
				for (ModuleWire importWire : importWires) {
					PackageSource source = createExportPackageSource(importWire, visited);
					if (source != null) {
						importedSources.put(source.getId(), source);
					}
				}
			}
			importsInitialized = true;
			return importedSources;
		}
	}

	private PackageSource findDynamicSource(String pkgName) {
		if (!isExportedPackage(pkgName) && isDynamicallyImported(pkgName)) {
			if (debug.DEBUG_LOADER) {
				Debug.println("BundleLoader[" + this + "] attempting to resolve dynamic package: " + pkgName); //$NON-NLS-1$ //$NON-NLS-2$
			}
			ModuleRevision revision = wiring.getRevision();
			ModuleWire dynamicWire = revision.getRevisions().getModule().getContainer().resolveDynamic(pkgName, revision);
			if (dynamicWire != null) {
				PackageSource source = createExportPackageSource(dynamicWire, null);
				if (debug.DEBUG_LOADER) {
					Debug.println("BundleLoader[" + this + "] using dynamic import source: " + source); //$NON-NLS-1$ //$NON-NLS-2$
				}
				synchronized (importedSources) {
					importedSources.put(source.getId(), source);
				}
				return source;
			}
		}
		return null;
	}

	private PackageSource findRequiredSource(String pkgName, Collection<BundleLoader> visited) {
		if (requiredBundleWires.isEmpty()) {
			return null;
		}
		synchronized (requiredSources) {
			PackageSource result = requiredSources.get(pkgName);
			if (result != null)
				return result.isNullSource() ? null : result;
		}
		if (visited == null)
			visited = new ArrayList<>();
		if (!visited.contains(this))
			visited.add(this); // always add ourselves so we do not recurse back to ourselves
		List<PackageSource> result = new ArrayList<>(3);
		for (ModuleWire bundleWire : requiredBundleWires) {
			BundleLoader loader = getProviderLoader(bundleWire);
			if (loader != null) {
				loader.addExportedProvidersFor(pkgName, result, visited);
			}
		}
		// found some so cache the result for next time and return
		PackageSource source;
		if (result.size() == 0) {
			// did not find it in our required bundles lets record the failure
			// so we do not have to do the search again for this package.
			source = NullPackageSource.getNullPackageSource(pkgName);
		} else if (result.size() == 1) {
			// if there is just one source, remember just the single source 
			source = result.get(0);
		} else {
			// if there was more than one source, build a multisource and cache that.
			PackageSource[] srcs = result.toArray(new PackageSource[result.size()]);
			source = createMultiSource(pkgName, srcs);
		}
		synchronized (requiredSources) {
			requiredSources.put(source.getId(), source);
		}
		return source.isNullSource() ? null : source;
	}

	/*
	 * Gets the package source for the pkgName.  This will include the local package source
	 * if the bundle exports the package.  This is used to compare the PackageSource of a 
	 * package from two different bundles.
	 */
	public final PackageSource getPackageSource(String pkgName) {
		PackageSource result = findSource(pkgName);
		if (!isExportedPackage(pkgName))
			return result;
		// if the package is exported then we need to get the local source
		PackageSource localSource = exportSources.getPackageSource(pkgName);
		if (result == null)
			return localSource;
		if (localSource == null)
			return result;
		return createMultiSource(pkgName, new PackageSource[] {result, localSource});
	}

	static final class ClassContext extends SecurityManager {
		// need to make this method public
		@Override
		public Class<?>[] getClassContext() {
			return super.getClassContext();
		}
	}

	@Override
	protected boolean getAndSetTrigger() {
		return triggerClassLoaded.getAndSet(true);
	}

	@Override
	public boolean isTriggerSet() {
		return triggerClassLoaded.get();
	}
}