Bug 544477 - allow hook to prevent resource load

Change-Id: I6286f7b427d54ad0f3961bd2b21658cb573552d7
Signed-off-by: Thomas Watson <tjwatson@us.ibm.com>

4 files changed, 78 insertions, 12 deletions

diff --git a/bundles/org.eclipse.osgi.tests/bundles_src/classloader.hooks.a/org/eclipse/osgi/tests/classloader/hooks/a/TestHookConfigurator.java b/bundles/org.eclipse.osgi.tests/bundles_src/classloader.hooks.a/org/eclipse/osgi/tests/classloader/hooks/a/TestHookConfigurator.java
index 61e86e9a0..0daec7d29 100644
--- a/bundles/org.eclipse.osgi.tests/bundles_src/classloader.hooks.a/org/eclipse/osgi/tests/classloader/hooks/a/TestHookConfigurator.java
+++ b/bundles/org.eclipse.osgi.tests/bundles_src/classloader.hooks.a/org/eclipse/osgi/tests/classloader/hooks/a/TestHookConfigurator.java
@@ -13,6 +13,8 @@
  *******************************************************************************/
 package org.eclipse.osgi.tests.classloader.hooks.a;
 
+import java.net.URL;
+import java.util.NoSuchElementException;
 import org.eclipse.osgi.container.Module;
 import org.eclipse.osgi.internal.hookregistry.ClassLoaderHook;
 import org.eclipse.osgi.internal.hookregistry.HookConfigurator;
@@ -27,6 +29,8 @@ public class TestHookConfigurator implements HookConfigurator {
 	private static final String RECURSION_LOAD = "classloader.hooks.a.recursion.load";
 	private static final String RECURSION_LOAD_SUPPORTED = "classloader.hooks.a.recursion.load.supported";
 	private static final String FILTER_CLASS_PATHS = "classloader.hooks.a.filter.class.paths";
+	private static final String PREVENT_RESOURCE_LOAD_PRE = "classloader.hooks.a.fail.resource.load.pre";
+	private static final String PREVENT_RESOURCE_LOAD_POST = "classloader.hooks.a.fail.resource.load.post";
 	final ThreadLocal<Boolean> doingRecursionLoad = new ThreadLocal<Boolean>() {
 		protected Boolean initialValue() {
 			return false;
@@ -81,6 +85,20 @@ public class TestHookConfigurator implements HookConfigurator {
 				}
 				return super.getClassPathEntries(name, manager);
 			}
+
+			@Override
+			public void preFindLocalResource(String name, ClasspathManager manager) {
+				if (Boolean.getBoolean(PREVENT_RESOURCE_LOAD_PRE)) {
+					throw new NoSuchElementException();
+				}
+			}
+
+			@Override
+			public void postFindLocalResource(String name, URL resource, ClasspathManager manager) {
+				if (Boolean.getBoolean(PREVENT_RESOURCE_LOAD_POST)) {
+					throw new NoSuchElementException();
+				}
+			}
 		});
 	}
 }
diff --git a/bundles/org.eclipse.osgi.tests/src/org/eclipse/osgi/tests/hooks/framework/ClassLoaderHookTests.java b/bundles/org.eclipse.osgi.tests/src/org/eclipse/osgi/tests/hooks/framework/ClassLoaderHookTests.java
index 131d77a03..3185a16c9 100644
--- a/bundles/org.eclipse.osgi.tests/src/org/eclipse/osgi/tests/hooks/framework/ClassLoaderHookTests.java
+++ b/bundles/org.eclipse.osgi.tests/src/org/eclipse/osgi/tests/hooks/framework/ClassLoaderHookTests.java
@@ -37,6 +37,7 @@ import org.osgi.framework.wiring.FrameworkWiring;
 public class ClassLoaderHookTests extends AbstractFrameworkHookTests {
 	private static final String TEST_BUNDLE = "substitutes.a";
 	private static final String TEST_CLASSNAME = "substitutes.x.Ax";
+	private static final String TEST_CLASSNAME_RESOURCE = "substitutes/x/Ax.class";
 	private static final String HOOK_CONFIGURATOR_BUNDLE = "classloader.hooks.a";
 	private static final String HOOK_CONFIGURATOR_CLASS = "org.eclipse.osgi.tests.classloader.hooks.a.TestHookConfigurator";
 	private static final String REJECT_PROP = "classloader.hooks.a.reject";
@@ -44,6 +45,8 @@ public class ClassLoaderHookTests extends AbstractFrameworkHookTests {
 	private static final String RECURSION_LOAD = "classloader.hooks.a.recursion.load";
 	private static final String RECURSION_LOAD_SUPPORTED = "classloader.hooks.a.recursion.load.supported";
 	private static final String FILTER_CLASS_PATHS = "classloader.hooks.a.filter.class.paths";
+	private static final String PREVENT_RESOURCE_LOAD_PRE = "classloader.hooks.a.fail.resource.load.pre";
+	private static final String PREVENT_RESOURCE_LOAD_POST = "classloader.hooks.a.fail.resource.load.post";
 
 	private Map<String, String> configuration;
 	private Framework framework;
@@ -56,6 +59,8 @@ public class ClassLoaderHookTests extends AbstractFrameworkHookTests {
 		setRecursionLoad(false);
 		setRecursionLoadSupported(false);
 		setFilterClassPaths(false);
+		setPreventResourceLoadPre(false);
+		setPreventResourceLoadPost(false);
 		String loc = bundleInstaller.getBundleLocation(HOOK_CONFIGURATOR_BUNDLE);
 		loc = loc.substring(loc.indexOf("file:"));
 		classLoader.addURL(new URL(loc));
@@ -100,6 +105,14 @@ public class ClassLoaderHookTests extends AbstractFrameworkHookTests {
 		System.setProperty(FILTER_CLASS_PATHS, Boolean.toString(value));
 	}
 
+	private void setPreventResourceLoadPre(boolean value) {
+		System.setProperty(PREVENT_RESOURCE_LOAD_PRE, Boolean.toString(value));
+	}
+
+	private void setPreventResourceLoadPost(boolean value) {
+		System.setProperty(PREVENT_RESOURCE_LOAD_POST, Boolean.toString(value));
+	}
+
 	public void testRejectTransformationFromWeavingHook() throws Exception {
 		setRejectTransformation(true);
 		initAndStartFramework();
@@ -193,4 +206,22 @@ public class ClassLoaderHookTests extends AbstractFrameworkHookTests {
 			// expected
 		}
 	}
+
+	public void testPreventResourceLoadFromClassLoadingHook() throws Exception {
+		setPreventResourceLoadPre(false);
+		setPreventResourceLoadPost(false);
+		initAndStartFramework();
+		Bundle b = installBundle();
+		URL resource = b.getResource(TEST_CLASSNAME_RESOURCE);
+		assertNotNull("Could not find resource.", resource);
+
+		setPreventResourceLoadPre(true);
+		resource = b.getResource(TEST_CLASSNAME_RESOURCE);
+		assertNull("Could find resource.", resource);
+
+		setPreventResourceLoadPre(false);
+		setPreventResourceLoadPost(true);
+		resource = b.getResource(TEST_CLASSNAME_RESOURCE);
+		assertNull("Could find resource.", resource);
+	}
 }
diff --git a/bundles/org.eclipse.osgi/container/src/org/eclipse/osgi/internal/hookregistry/ClassLoaderHook.java b/bundles/org.eclipse.osgi/container/src/org/eclipse/osgi/internal/hookregistry/ClassLoaderHook.java
index 557544b60..8e0a52949 100644
--- a/bundles/org.eclipse.osgi/container/src/org/eclipse/osgi/internal/hookregistry/ClassLoaderHook.java
+++ b/bundles/org.eclipse.osgi/container/src/org/eclipse/osgi/internal/hookregistry/ClassLoaderHook.java
@@ -18,6 +18,7 @@ import java.io.FileNotFoundException;
 import java.net.URL;
 import java.util.ArrayList;
 import java.util.Enumeration;
+import java.util.NoSuchElementException;
 import org.eclipse.osgi.internal.framework.EquinoxConfiguration;
 import org.eclipse.osgi.internal.loader.BundleLoader;
 import org.eclipse.osgi.internal.loader.ModuleClassLoader;
@@ -61,7 +62,7 @@ public abstract class ClassLoaderHook {
 
 	/**
 	 * Gets called by a classpath manager when looking for ClasspathEntry objects.  This method allows 
-	 * a classloading hook to add additional ClasspathEntry objects
+	 * a class loading hook to add additional ClasspathEntry objects
 	 * @param cpEntries the list of ClasspathEntry objects currently available for the requested classpath
 	 * @param cp the name of the requested classpath
 	 * @param hostmanager the classpath manager the requested ClasspathEntry is for
@@ -223,7 +224,7 @@ public abstract class ClassLoaderHook {
 	/**
 	 * Gets called by a classpath manager during {@link ClasspathManager#findLocalClass(String)} before 
 	 * searching the local classloader for a class.  A classpath manager will call this method for 
-	 * each configured class loading stat hook.
+	 * each configured class loading hook.
 	 * @param name the name of the requested class
 	 * @param manager the classpath manager used to find and load the requested class
 	 * @throws ClassNotFoundException to prevent the requested class from loading
@@ -235,11 +236,12 @@ public abstract class ClassLoaderHook {
 	/**
 	 * Gets called by a classpath manager during {@link ClasspathManager#findLocalClass(String)} after
 	 * searching the local classloader for a class. A classpath manager will call this method for 
-	 * each configured class loading stat hook.
+	 * each configured class loading hook.
 	 * @param name the name of the requested class
 	 * @param clazz the loaded class or null if not found
 	 * @param manager the classpath manager used to find and load the requested class
-	 * @throws ClassNotFoundException 
+	 * @throws ClassNotFoundException to prevent the requested class from loading.  This is highly discouraged
+	 * because if the class is non-null it is already too late to throw an exception.
 	 */
 	public void postFindLocalClass(String name, Class<?> clazz, ClasspathManager manager) throws ClassNotFoundException {
 		// do nothing
@@ -248,9 +250,10 @@ public abstract class ClassLoaderHook {
 	/**
 	 * Gets called by a classpath manager during {@link ClasspathManager#findLocalResource(String)} before
 	 * searching the local classloader for a resource. A classpath manager will call this method for 
-	 * each configured class loading stat hook.
+	 * each configured class loading hook.
 	 * @param name the name of the requested resource
 	 * @param manager the classpath manager used to find the requested resource
+	 * @throws NoSuchElementException will prevent the local resource from loading
 	 */
 	public void preFindLocalResource(String name, ClasspathManager manager) {
 		// do nothing
@@ -259,10 +262,11 @@ public abstract class ClassLoaderHook {
 	/**
 	 * Gets called by a classpath manager during {@link ClasspathManager#findLocalResource(String)} after
 	 * searching the local classloader for a resource. A classpath manager will call this method for 
-	 * each configured class loading stat hook.
+	 * each configured class loading hook.
 	 * @param name the name of the requested resource
 	 * @param resource the URL to the requested resource or null if not found
 	 * @param manager the classpath manager used to find the requested resource
+	 * @throws NoSuchElementException will prevent the local resource from loading
 	 */
 	public void postFindLocalResource(String name, URL resource, ClasspathManager manager) {
 		// do nothing
@@ -270,7 +274,7 @@ public abstract class ClassLoaderHook {
 
 	/**
 	 * Gets called by a classpath manager after an attempt is made to define a class.  This method allows 
-	 * a class loading stat hook to record data about a class definition. 
+	 * a class loading hook to record data about a class definition. 
 	 * @param name the name of the class that got defined
 	 * @param clazz the class object that got defined or null if an error occurred while defining a class
 	 * @param classbytes the class bytes used to define the class
diff --git a/bundles/org.eclipse.osgi/container/src/org/eclipse/osgi/internal/loader/classpath/ClasspathManager.java b/bundles/org.eclipse.osgi/container/src/org/eclipse/osgi/internal/loader/classpath/ClasspathManager.java
index af0115e47..dc6ea5bb1 100644
--- a/bundles/org.eclipse.osgi/container/src/org/eclipse/osgi/internal/loader/classpath/ClasspathManager.java
+++ b/bundles/org.eclipse.osgi/container/src/org/eclipse/osgi/internal/loader/classpath/ClasspathManager.java
@@ -25,6 +25,7 @@ import java.util.Collections;
 import java.util.Enumeration;
 import java.util.List;
 import java.util.ListIterator;
+import java.util.NoSuchElementException;
 import org.eclipse.osgi.container.Module;
 import org.eclipse.osgi.container.ModuleCapability;
 import org.eclipse.osgi.container.ModuleContainerAdaptor.ContainerEvent;
@@ -357,18 +358,30 @@ public class ClasspathManager {
 	 */
 	public URL findLocalResource(String resource) {
 		List<ClassLoaderHook> hooks = hookRegistry.getClassLoaderHooks();
+		boolean hookFailed = false;
 		for (ClassLoaderHook hook : hooks) {
-			hook.preFindLocalResource(resource, this);
+			try {
+				hook.preFindLocalResource(resource, this);
+			} catch (NoSuchElementException e) {
+				// mark the resource load as failed, but continue to all the hooks
+				hookFailed = true;
+			}
 		}
 		URL result = null;
 		try {
-			result = findLocalResourceImpl(resource, -1);
-			return result;
+			if (!hookFailed) {
+				result = findLocalResourceImpl(resource, -1);
+			}
 		} finally {
 			for (ClassLoaderHook hook : hooks) {
-				hook.postFindLocalResource(resource, result, this);
+				try {
+					hook.postFindLocalResource(resource, result, this);
+				} catch (NoSuchElementException e) {
+					result = null;
+				}
 			}
 		}
+		return result;
 	}
 
 	private URL findLocalResourceImpl(String resource, int classPathIndex) {
@@ -431,7 +444,7 @@ public class ClasspathManager {
 			ClasspathEntry[] hookEntries = hook.getClassPathEntries(resource, this);
 			if (hookEntries != null) {
 				findLocalResources(resource, hookEntries, m, classPathIndex, resources);
-				return resources.size() > 0 ? Collections.enumeration(resources): EMPTY_ENUMERATION;
+				return resources.size() > 0 ? Collections.enumeration(resources) : EMPTY_ENUMERATION;
 			}
 		}