Copyright (c) 2012, 2017 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) 2012, 2017 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.framework;

import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import org.eclipse.osgi.container.Module;
import org.eclipse.osgi.container.Module.State;
import org.eclipse.osgi.container.ModuleCollisionHook;
import org.eclipse.osgi.container.ModuleContainer;
import org.eclipse.osgi.framework.util.ArrayMap;
import org.eclipse.osgi.internal.debug.Debug;
import org.eclipse.osgi.internal.messages.Msg;
import org.eclipse.osgi.internal.serviceregistry.HookContext;
import org.eclipse.osgi.internal.serviceregistry.ServiceReferenceImpl;
import org.eclipse.osgi.internal.serviceregistry.ServiceRegistry;
import org.eclipse.osgi.internal.serviceregistry.ShrinkableCollection;
import org.eclipse.osgi.report.resolution.ResolutionReport;
import org.eclipse.osgi.storage.Storage;
import org.eclipse.osgi.util.NLS;
import org.osgi.framework.Bundle;
import org.osgi.framework.BundleException;
import org.osgi.framework.InvalidSyntaxException;
import org.osgi.framework.ServiceRegistration;
import org.osgi.framework.hooks.bundle.CollisionHook;
import org.osgi.framework.hooks.resolver.ResolverHook;
import org.osgi.framework.hooks.resolver.ResolverHookFactory;
import org.osgi.framework.wiring.BundleCapability;
import org.osgi.framework.wiring.BundleRequirement;
import org.osgi.framework.wiring.BundleRevision;

class OSGiFrameworkHooks {
	static final String collisionHookName = CollisionHook.class.getName();
	private final CoreResolverHookFactory resolverHookFactory;
	private final ModuleCollisionHook collisionHook;

	OSGiFrameworkHooks(EquinoxContainer container, Storage storage) {
		resolverHookFactory = new CoreResolverHookFactory(container, storage);
		collisionHook = new BundleCollisionHook(container);
	}

	public ResolverHookFactory getResolverHookFactory() {
		return resolverHookFactory;
	}

	public ModuleCollisionHook getModuleCollisionHook() {
		return collisionHook;
	}

	static class BundleCollisionHook implements ModuleCollisionHook {
		final Debug debug;
		final EquinoxContainer container;

		public BundleCollisionHook(EquinoxContainer container) {
			this.container = container;
			this.debug = container.getConfiguration().getDebug();
		}

		@Override
		public void filterCollisions(int operationType, Module target, Collection<Module> collisionCandidates) {
			switch (container.getConfiguration().BSN_VERSION) {
				case EquinoxConfiguration.BSN_VERSION_SINGLE : {
					return;
				}
				case EquinoxConfiguration.BSN_VERSION_MULTIPLE : {
					collisionCandidates.clear();
					return;
				}
				case EquinoxConfiguration.BSN_VERSION_MANAGED : {
					Bundle targetBundle = target.getBundle();
					ArrayMap<Bundle, Module> candidateBundles = new ArrayMap<>(collisionCandidates.size());
					for (Module module : collisionCandidates) {
						candidateBundles.put(module.getBundle(), module);
					}
					notifyCollisionHooks(operationType, targetBundle, candidateBundles);
					collisionCandidates.retainAll(candidateBundles.getValues());
					return;
				}
				default :
					throw new IllegalStateException("Bad configuration: " + container.getConfiguration().BSN_VERSION); //$NON-NLS-1$
			}
		}

		private void notifyCollisionHooks(final int operationType, final Bundle target, Collection<Bundle> collisionCandidates) {
			// Note that collision hook results are honored for the system bundle.
			final Collection<Bundle> shrinkable = new ShrinkableCollection<>(collisionCandidates);
			if (System.getSecurityManager() == null) {
				notifyCollisionHooksPriviledged(operationType, target, shrinkable);
			} else {
				AccessController.doPrivileged(new PrivilegedAction<Void>() {
					@Override
					public Void run() {
						notifyCollisionHooksPriviledged(operationType, target, shrinkable);
						return null;
					}
				});
			}
		}

		void notifyCollisionHooksPriviledged(final int operationType, final Bundle target, final Collection<Bundle> collisionCandidates) {
			if (debug.DEBUG_HOOKS) {
				Debug.println("notifyCollisionHooks(" + operationType + ", " + target + ", " + collisionCandidates + ")"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$ 
			}
			ServiceRegistry registry = container.getServiceRegistry();
			if (registry != null) {
				registry.notifyHooksPrivileged(new HookContext() {
					@Override
					public void call(Object hook, ServiceRegistration<?> hookRegistration) throws Exception {
						if (hook instanceof CollisionHook) {
							((CollisionHook) hook).filterCollisions(operationType, target, collisionCandidates);
						}
					}

					@Override
					public String getHookClassName() {
						return collisionHookName;
					}

					@Override
					public String getHookMethodName() {
						return "filterCollisions"; //$NON-NLS-1$ 
					}

					@Override
					public boolean skipRegistration(ServiceRegistration<?> hookRegistration) {
						return false;
					}
				});
			}
		}
	}

	
This class encapsulates the delegation to ResolverHooks that are registered with the service
registry.  This way the resolver implementation only has to call out to a single hook
which does all the necessary service registry lookups.
This class is not thread safe and expects external synchronization.
/**
	 * This class encapsulates the delegation to ResolverHooks that are registered with the service
	 * registry.  This way the resolver implementation only has to call out to a single hook
	 * which does all the necessary service registry lookups.
	 * 
	 * This class is not thread safe and expects external synchronization.
	 *
	 */
	static class CoreResolverHookFactory implements ResolverHookFactory {
		// need a tuple to hold the service reference and hook object
		// do not use a map for performance reasons; no need to hash based on a key.
		static class HookReference {
			public HookReference(ServiceReferenceImpl<ResolverHookFactory> reference, ResolverHook hook, BundleContextImpl context) {
				this.reference = reference;
				this.hook = hook;
				this.context = context;
			}

			final ServiceReferenceImpl<ResolverHookFactory> reference;
			final ResolverHook hook;
			final BundleContextImpl context;
		}

		final Debug debug;
		final EquinoxContainer container;
		final Storage storage;
		volatile boolean inInit = false;

		public CoreResolverHookFactory(EquinoxContainer container, Storage storage) {
			this.container = container;
			this.debug = container.getConfiguration().getDebug();
			this.storage = storage;
		}

		void handleHookException(Throwable t, Object hook, String method) {
			if (debug.DEBUG_HOOKS) {
				Debug.println(hook.getClass().getName() + "." + method + "() exception:"); //$NON-NLS-1$ //$NON-NLS-2$
				if (t != null)
					Debug.printStackTrace(t);
			}
			String message = NLS.bind(Msg.SERVICE_FACTORY_EXCEPTION, hook.getClass().getName(), method);
			throw new RuntimeException(message, new BundleException(message, BundleException.REJECTED_BY_HOOK, t));
		}

		private ServiceReferenceImpl<ResolverHookFactory>[] getHookReferences(final ServiceRegistry registry, final BundleContextImpl context) {
			return AccessController.doPrivileged(new PrivilegedAction<ServiceReferenceImpl<ResolverHookFactory>[]>() {
				@Override
				public ServiceReferenceImpl<ResolverHookFactory>[] run() {
					try {
						@SuppressWarnings("unchecked")
						ServiceReferenceImpl<ResolverHookFactory>[] result = (ServiceReferenceImpl<ResolverHookFactory>[]) registry.getServiceReferences(context, ResolverHookFactory.class.getName(), null, false);
						return result;
					} catch (InvalidSyntaxException e) {
						// cannot happen; no filter
						return null;
					}
				}
			});

		}

		@Override
		public ResolverHook begin(Collection<BundleRevision> triggers) {
			if (debug.DEBUG_HOOKS) {
				Debug.println("ResolverHook.begin"); //$NON-NLS-1$
			}
			ModuleContainer mContainer = storage.getModuleContainer();
			Module systemModule = mContainer == null ? null : mContainer.getModule(0);
			ServiceRegistry registry = container.getServiceRegistry();
			if (registry == null || systemModule == null) {
				return new CoreResolverHook(Collections.<HookReference> emptyList(), systemModule);
			}

			BundleContextImpl context = (BundleContextImpl) EquinoxContainer.secureAction.getContext(systemModule.getBundle());

			ServiceReferenceImpl<ResolverHookFactory>[] refs = getHookReferences(registry, context);
			List<HookReference> hookRefs = refs == null ? Collections.<CoreResolverHookFactory.HookReference> emptyList() : new ArrayList<CoreResolverHookFactory.HookReference>(refs.length);
			if (refs != null) {
				for (ServiceReferenceImpl<ResolverHookFactory> hookRef : refs) {
					ResolverHookFactory factory = EquinoxContainer.secureAction.getService(hookRef, context);
					if (factory != null) {
						try {
							ResolverHook hook = factory.begin(triggers);
							if (hook != null)
								hookRefs.add(new HookReference(hookRef, hook, context));
						} catch (Throwable t) {
							// need to force an end call on the ResolverHooks we got and release them
							try {
								new CoreResolverHook(hookRefs, systemModule).end();
							} catch (Throwable endError) {
								// we are already in failure mode; just continue
							}
							handleHookException(t, factory, "begin"); //$NON-NLS-1$
						}
					}
				}
			}
			return new CoreResolverHook(hookRefs, systemModule);
		}

		class CoreResolverHook implements ResolutionReport.Listener, ResolverHook {
			private final List<HookReference> hooks;
			private final Module systemModule;

			private volatile ResolutionReport resolutionReport;

			CoreResolverHook(List<HookReference> hooks, Module systemModule) {
				this.hooks = hooks;
				this.systemModule = systemModule;
			}

			@Override
			public void filterResolvable(Collection<BundleRevision> candidates) {
				if (debug.DEBUG_HOOKS) {
					Debug.println("ResolverHook.filterResolvable(" + candidates + ")"); //$NON-NLS-1$ //$NON-NLS-2$
				}
				if (isBootInit()) {
					// only allow the system bundle and its fragments resolve during boot up and init
					for (Iterator<BundleRevision> iCandidates = candidates.iterator(); iCandidates.hasNext();) {
						BundleRevision revision = iCandidates.next();
						if ((revision.getTypes() & BundleRevision.TYPE_FRAGMENT) == 0) {
							// host bundle; check if it is the system bundle
							if (revision.getBundle().getBundleId() != 0) {
								iCandidates.remove();
							}
						}
						// just leave all fragments.  Only the ones that are system bundle fragments will resolve
						// since we removed all the other possible hosts.
					}
				}
				if (hooks.isEmpty())
					return;
				candidates = new ShrinkableCollection<>(candidates);
				for (HookReference hookRef : hooks) {
					if (hookRef.reference.getBundle() == null) {
						handleHookException(null, hookRef.hook, "filterResolvable"); //$NON-NLS-1$
					} else {
						try {
							hookRef.hook.filterResolvable(candidates);
						} catch (Throwable t) {
							handleHookException(t, hookRef.hook, "filterResolvable"); //$NON-NLS-1$
						}
					}
				}
			}

			private boolean isBootInit() {
				return systemModule == null || !Module.RESOLVED_SET.contains(systemModule.getState()) || (systemModule.getState().equals(State.STARTING) && inInit);
			}

			@Override
			public void filterSingletonCollisions(BundleCapability singleton, Collection<BundleCapability> collisionCandidates) {
				if (debug.DEBUG_HOOKS) {
					Debug.println("ResolverHook.filterSingletonCollisions(" + singleton + ", " + collisionCandidates + ")"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
				}
				if (hooks.isEmpty())
					return;
				collisionCandidates = new ShrinkableCollection<>(collisionCandidates);
				for (HookReference hookRef : hooks) {
					if (hookRef.reference.getBundle() == null) {
						handleHookException(null, hookRef.hook, "filterSingletonCollisions"); //$NON-NLS-1$
					} else {
						try {
							hookRef.hook.filterSingletonCollisions(singleton, collisionCandidates);
						} catch (Throwable t) {
							handleHookException(t, hookRef.hook, "filterSingletonCollisions"); //$NON-NLS-1$
						}
					}
				}
			}

			@Override
			public void filterMatches(BundleRequirement requirement, Collection<BundleCapability> candidates) {
				if (debug.DEBUG_HOOKS) {
					Debug.println("ResolverHook.filterMatches(" + requirement + ", " + candidates + ")"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
				}
				if (hooks.isEmpty())
					return;
				candidates = new ShrinkableCollection<>(candidates);
				for (HookReference hookRef : hooks) {
					if (hookRef.reference.getBundle() == null) {
						handleHookException(null, hookRef.hook, "filterMatches"); //$NON-NLS-1$
					} else {
						try {
							hookRef.hook.filterMatches(requirement, candidates);
						} catch (Throwable t) {
							handleHookException(t, hookRef.hook, "filterMatches"); //$NON-NLS-1$
						}
					}
				}
			}

			@Override
			public void end() {
				if (debug.DEBUG_HOOKS) {
					Debug.println("ResolverHook.end"); //$NON-NLS-1$
				}
				if (hooks.isEmpty())
					return;
				try {
					HookReference missingHook = null;
					Throwable endError = null;
					HookReference endBadHook = null;
					for (HookReference hookRef : hooks) {
						// We do not remove unregistered services here because we are going to remove all of them at the end
						if (hookRef.reference.getBundle() == null) {
							if (missingHook == null)
								missingHook = hookRef;
						} else {
							try {
								if (hookRef.hook instanceof ResolutionReport.Listener)
									((ResolutionReport.Listener) hookRef.hook).handleResolutionReport(resolutionReport);
								hookRef.hook.end();
							} catch (Throwable t) {
								// Must continue on to the next hook.end method
								// save the error for throwing at the end
								if (endError == null) {
									endError = t;
									endBadHook = hookRef;
								}
							}
						}
					}
					if (missingHook != null)
						handleHookException(null, missingHook.hook, "end"); //$NON-NLS-1$
					if (endError != null)
						handleHookException(endError, endBadHook.hook, "end"); //$NON-NLS-1$
				} finally {
					for (HookReference hookRef : hooks) {
						hookRef.context.ungetService(hookRef.reference);
					}
					hooks.clear();
				}
			}

			@Override
			public void handleResolutionReport(ResolutionReport report) {
				resolutionReport = report;
			}
		}
	}

	public void initBegin() {
		resolverHookFactory.inInit = true;
	}

	public void initEnd() {
		resolverHookFactory.inInit = false;
	}
}