--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/sun/misc/BootClassLoaderHook.java	Mon Oct 05 18:15:32 2009 -0700
@@ -0,0 +1,153 @@
+/*
+ * Copyright 2009 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+package sun.misc;
+
+import java.io.File;
+import java.io.IOException;
+
+/**
+ * BootClassLoaderHook defines an interface for a hook to inject
+ * into the bootstrap class loader.
+ *
+ * In jkernel build, the sun.jkernel.DownloadManager is set as
+ * a BootClassLoaderHook by the jkernel VM after the VM is initialized.
+ *
+ * In other JDK builds, no hook is set.
+ */
+public abstract class BootClassLoaderHook {
+    private static BootClassLoaderHook bootLoaderHook = null;
+    public static synchronized BootClassLoaderHook getHook() {
+        return bootLoaderHook;
+    }
+
+    public static synchronized void setHook(BootClassLoaderHook hook) {
+        if (!VM.isBooted()) {
+            throw new InternalError("hook can only be set after VM is booted");
+        }
+        if (bootLoaderHook != null) {
+            throw new InternalError("hook should not be reinitialized");
+        }
+        bootLoaderHook = hook;
+    }
+
+    protected BootClassLoaderHook() {
+    }
+
+    /**
+     * A method to be invoked before a class loader loads
+     * a bootstrap class.
+     *
+     * @param classname the binary name of the class
+     */
+    public static void preLoadClass(String classname) {
+        BootClassLoaderHook hook = getHook();
+        if (hook != null) {
+            hook.loadBootstrapClass(classname);
+        }
+    }
+
+    /**
+     * A method to be invoked before a class loader loads
+     * a resource.
+     *
+     * @param resourcename the resource name
+     */
+    public static void preLoadResource(String resourcename) {
+        BootClassLoaderHook hook = getHook();
+        if (hook != null) {
+            hook.getBootstrapResource(resourcename);
+        }
+    }
+
+    /**
+     * A method to be invoked before a library is loaded.
+     *
+     * @param libname the name of the library
+     */
+    public static void preLoadLibrary(String libname) {
+        BootClassLoaderHook hook = getHook();
+        if (hook != null) {
+            hook.loadLibrary(libname);
+        }
+    }
+
+    private static final File[] EMPTY_FILE_ARRAY = new File[0];
+
+    /**
+     * Returns bootstrap class paths added by the hook.
+     */
+    public static File[] getBootstrapPaths() {
+        BootClassLoaderHook hook = getHook();
+        if (hook != null) {
+            return hook.getBootstrapPaths();
+        } else {
+            return EMPTY_FILE_ARRAY;
+        }
+    }
+
+    /**
+     * Returns a pathname of a JAR or class that the hook loads
+     * per this loadClass request; or null.
+     *
+     * @param classname the binary name of the class
+     */
+    public abstract String loadBootstrapClass(String className);
+
+    /**
+     * Returns a pathname of a resource file that the hook loads
+     * per this getResource request; or null.
+     *
+     * @param resourceName the resource name
+     */
+    public abstract String getBootstrapResource(String resourceName);
+
+    /**
+     * Returns true if the hook successfully performs an operation per
+     * this loadLibrary request; or false if it fails.
+     *
+     * @param libname the name of the library
+     */
+    public abstract boolean loadLibrary(String libname);
+
+    /**
+     * Returns additional boot class paths added by the hook that
+     * should be searched by the boot class loader.
+     */
+    public abstract File[] getAdditionalBootstrapPaths();
+
+    /**
+     * Returns true if the current thread is in the process of doing
+     * a prefetching operation.
+     */
+    public abstract boolean isCurrentThreadPrefetching();
+
+    /**
+     * Returns true if the hook successfully prefetches the specified file.
+     *
+     * @param name a platform independent pathname
+     */
+    public abstract boolean prefetchFile(String name);
+}