Copyright (c) 2010, 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) 2010, 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.weaving;

import java.security.*;
import java.util.*;
import org.eclipse.osgi.container.ModuleRevision;
import org.eclipse.osgi.internal.framework.EquinoxContainer;
import org.eclipse.osgi.internal.hookregistry.ClassLoaderHook;
import org.eclipse.osgi.internal.loader.BundleLoader;
import org.eclipse.osgi.internal.loader.classpath.ClasspathEntry;
import org.eclipse.osgi.internal.permadmin.BundlePermissions;
import org.eclipse.osgi.internal.serviceregistry.HookContext;
import org.eclipse.osgi.internal.serviceregistry.ServiceRegistry;
import org.eclipse.osgi.storage.BundleInfo.Generation;
import org.eclipse.osgi.storage.StorageUtil;
import org.eclipse.osgi.storage.bundlefile.BundleEntry;
import org.eclipse.osgi.util.ManifestElement;
import org.osgi.framework.*;
import org.osgi.framework.hooks.weaving.*;
import org.osgi.framework.wiring.BundleWiring;

public final class WovenClassImpl implements WovenClass, HookContext {
	private final static byte FLAG_HOOKCALLED = 0x01;
	private final static byte FLAG_HOOKSCOMPLETE = 0x02;
	private final static byte FLAG_WEAVINGCOMPLETE = 0x04;
	private final static String weavingHookName = WeavingHook.class.getName();
	private final String className;
	private final BundleEntry entry;
	private final List<String> dynamicImports;
	private final ClasspathEntry classpathEntry;
	private final BundleLoader loader;
	final ServiceRegistry registry;
	private final Map<ServiceRegistration<?>, Boolean> blackList;
	private byte[] validBytes;
	private byte[] resultBytes;
	private byte hookFlags = 0;
	private Throwable error;
	private ServiceRegistration<?> errorHook;
	private Class<?> clazz;
	private int state;
	final EquinoxContainer container;

	public WovenClassImpl(String className, byte[] bytes, BundleEntry entry, ClasspathEntry classpathEntry, BundleLoader loader, EquinoxContainer container, Map<ServiceRegistration<?>, Boolean> blacklist) {
		super();
		this.className = className;
		this.validBytes = this.resultBytes = bytes;
		this.entry = entry;
		this.dynamicImports = new DynamicImportList(this);
		this.classpathEntry = classpathEntry;
		this.loader = loader;
		this.registry = container.getServiceRegistry();
		this.container = container;
		this.blackList = blacklist;
		setState(TRANSFORMING);
	}

	@Override
	public byte[] getBytes() {
		if ((hookFlags & FLAG_HOOKSCOMPLETE) == 0) {
			checkPermission();
			return validBytes; // return raw bytes until complete
		}
		// we have called all hooks; someone is calling outside of weave call
		// need to be safe and copy the bytes.
		byte[] current = validBytes;
		byte[] results = new byte[current.length];
		System.arraycopy(current, 0, results, 0, current.length);
		return results;
	}

	@Override
	public void setBytes(byte[] newBytes) {
		checkPermission();
		if (newBytes == null)
			throw new NullPointerException("newBytes cannot be null."); //$NON-NLS-1$
		if ((hookFlags & FLAG_HOOKSCOMPLETE) != 0)
			// someone is calling this outside of weave
			throw new IllegalStateException("Weaving has completed already."); //$NON-NLS-1$
		this.resultBytes = this.validBytes = newBytes;
	}

	void checkPermission() {
		SecurityManager sm = System.getSecurityManager();
		if (sm != null)
			sm.checkPermission(new AdminPermission(loader.getWiring().getBundle(), AdminPermission.WEAVE));
	}

	@Override
	public List<String> getDynamicImports() {
		if ((hookFlags & FLAG_HOOKSCOMPLETE) == 0)
			return dynamicImports;
		// being called outside of weave; return unmodified list
		return Collections.unmodifiableList(dynamicImports);
	}

	@Override
	public boolean isWeavingComplete() {
		return (hookFlags & FLAG_WEAVINGCOMPLETE) != 0;
	}

	private void setHooksComplete() {
		// create a copy of the bytes array that noone has a reference to
		byte[] original = validBytes;
		validBytes = new byte[original.length];
		System.arraycopy(original, 0, validBytes, 0, original.length);
		hookFlags |= FLAG_HOOKSCOMPLETE;
	}

	void setWeavingCompleted(Class<?> clazz) {
		// weaving has completed; save the class and mark complete
		this.clazz = clazz;
		hookFlags |= FLAG_WEAVINGCOMPLETE;
		// Only notify listeners if weaving hooks were called.
		if ((hookFlags & FLAG_HOOKCALLED) == 0)
			return;
		// Only notify listeners if they haven't already been notified of
		// the terminal TRANSFORMING_FAILED state.
		if (error != null)
			return;
		// If clazz is null, a class definition failure occurred.
		setState(clazz == null ? DEFINE_FAILED : DEFINED);
		notifyWovenClassListeners();
	}

	@Override
	public String getClassName() {
		return className;
	}

	@Override
	public ProtectionDomain getProtectionDomain() {
		return classpathEntry.getDomain();
	}

	@Override
	public Class<?> getDefinedClass() {
		return clazz;
	}

	@Override
	public BundleWiring getBundleWiring() {
		return loader.getWiring();
	}

	@Override
	public void call(final Object hook, ServiceRegistration<?> hookRegistration) throws Exception {
		if (error != null)
			return; // do not call any other hooks once an error has occurred.
		if (hook instanceof WeavingHook) {
			if (skipRegistration(hookRegistration)) {
				// Note we double check blacklist here just
				// in case another thread blacklisted since the first check
				return;
			}
			if ((hookFlags & FLAG_HOOKCALLED) == 0) {
				hookFlags |= FLAG_HOOKCALLED;
				// only do this check on the first weaving hook call
				if (!validBytes(validBytes)) {
					validBytes = StorageUtil.getBytes(entry.getInputStream(), (int) entry.getSize(), 8 * 1024);
				}
			}
			try {
				((WeavingHook) hook).weave(this);
			} catch (WeavingException e) {
				error = e;
				errorHook = hookRegistration;
				// do not blacklist on weaving exceptions
			} catch (Throwable t) {
				error = t; // save the error to fail later
				errorHook = hookRegistration;
				// put the registration on the black list
				blackList.put(hookRegistration, Boolean.TRUE);
			}
		}
	}

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

	private boolean validBytes(byte[] checkBytes) {
		if (checkBytes == null || checkBytes.length < 4)
			return false;
		if ((checkBytes[0] & 0xCA) != 0xCA)
			return false;
		if ((checkBytes[1] & 0xFE) != 0xFE)
			return false;
		if ((checkBytes[2] & 0xBA) != 0xBA)
			return false;
		if ((checkBytes[3] & 0xBE) != 0xBE)
			return false;
		return true;
	}

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

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

	private void notifyWovenClassListeners() {
		final HookContext context = new HookContext() {
			@Override
			public void call(Object hook, ServiceRegistration<?> hookRegistration) throws Exception {
				if (!(hook instanceof WovenClassListener))
					return;
				try {
					((WovenClassListener) hook).modified(WovenClassImpl.this);
				} catch (Exception e) {
					WovenClassImpl.this.container.getEventPublisher().publishFrameworkEvent(FrameworkEvent.ERROR, hookRegistration.getReference().getBundle(), e);
				}
			}

			@Override
			public String getHookClassName() {
				return WovenClassListener.class.getName();
			}

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

			@Override
			public boolean skipRegistration(ServiceRegistration<?> hookRegistration) {
				return false;
			}
		};
		if (System.getSecurityManager() == null)
			registry.notifyHooksPrivileged(context);
		else {
			try {
				AccessController.doPrivileged(new PrivilegedExceptionAction<Void>() {
					@Override
					public Void run() {
						registry.notifyHooksPrivileged(context);
						return null;
					}
				});
			} catch (PrivilegedActionException e) {
				throw (RuntimeException) e.getException();
			}
		}
	}

	byte[] callHooks() throws Throwable {
		SecurityManager sm = System.getSecurityManager();
		byte[] wovenBytes = null;
		List<String> newImports = null;
		boolean rejected = false;
		try {
			if (sm == null) {
				registry.notifyHooksPrivileged(this);
			} else {
				try {
					AccessController.doPrivileged(new PrivilegedExceptionAction<Void>() {
						@Override
						public Void run() {
							registry.notifyHooksPrivileged(WovenClassImpl.this);
							return null;
						}
					});
				} catch (PrivilegedActionException e) {
					throw (RuntimeException) e.getException();
				}
			}
		} finally {
			if ((hookFlags & FLAG_HOOKCALLED) != 0) {
				for (ClassLoaderHook classLoaderHook : container.getConfiguration().getHookRegistry().getClassLoaderHooks()) {
					rejected |= classLoaderHook.rejectTransformation(className, resultBytes, classpathEntry, entry, loader.getModuleClassLoader().getClasspathManager());
				}
				if (!rejected) {
					wovenBytes = resultBytes;
					newImports = dynamicImports;
				}
				setHooksComplete();
				// Make sure setHooksComplete() has been called. The woven class
				// must be immutable in TRANSFORMED or TRANSFORMING_FAILED.
				// If error is not null, a weaving hook threw an exception.
				setState(error == null ? TRANSFORMED : TRANSFORMING_FAILED);
				// only notify listeners if the transformation was not rejected
				if (!rejected) {
					notifyWovenClassListeners();
				}
			}
		}

		if (error != null)
			throw error;

		if (newImports != null) {
			// add any new dynamic imports
			for (String newImport : newImports) {
				try {
					ManifestElement[] importElements = ManifestElement.parseHeader(Constants.IMPORT_PACKAGE, newImport);
					// Grant implied import package permissions for all dynamic
					// import packages to the woven bundle.
					addImpliedImportPackagePermissions(importElements);
					loader.addDynamicImportPackage(importElements);
				} catch (BundleException e) {
					// should not have happened; checked at add.
				}
			}
		}

		return wovenBytes;
	}

	private void addImpliedImportPackagePermissions(ManifestElement[] importElements) {
		ProtectionDomain wovenDomain = ((Generation) ((ModuleRevision) getBundleWiring().getRevision()).getRevisionInfo()).getDomain();
		if (wovenDomain != null) {
			// security is enabled; add the permissions
			for (ManifestElement clause : importElements)
				for (String pkg : clause.getValueComponents())
					((BundlePermissions) wovenDomain.getPermissions()).addWovenPermission(new PackagePermission(pkg, PackagePermission.IMPORT));
		}
	}

	@Override
	public String toString() {
		return className;
	}

	public ServiceRegistration<?> getErrorHook() {
		return errorHook;
	}

	@Override
	public int getState() {
		return state;
	}

	private void setState(int value) {
		state = value;
	}
}