1 /*
   2  * Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package sun.misc;
  27 
  28 import java.io.File;
  29 import java.io.IOException;
  30 import java.net.URLStreamHandlerFactory;
  31 import sun.misc.URLClassPath;
  32 
  33 /**
  34  * BootClassLoaderHook defines an interface for a hook to inject
  35  * into the bootstrap class loader.
  36  *
  37  * With jkernel now removed, no hook is set
  38  */
  39 public abstract class BootClassLoaderHook {
  40     private static BootClassLoaderHook bootLoaderHook = null;
  41     public static synchronized BootClassLoaderHook getHook() {
  42         return bootLoaderHook;
  43     }
  44 
  45     public static synchronized void setHook(BootClassLoaderHook hook) {
  46         if (!VM.isBooted()) {
  47             throw new InternalError("hook can only be set after VM is booted");
  48         }
  49         if (bootLoaderHook != null) {
  50             throw new InternalError("hook should not be reinitialized");
  51         }
  52         bootLoaderHook = hook;
  53     }
  54 
  55     protected BootClassLoaderHook() {
  56     }
  57 
  58     /**
  59      * A method to be invoked before a class loader loads
  60      * a bootstrap class.
  61      *
  62      * @param classname the binary name of the class
  63      */
  64     public static void preLoadClass(String classname) {
  65         BootClassLoaderHook hook = getHook();
  66         if (hook != null) {
  67             hook.loadBootstrapClass(classname);
  68         }
  69     }
  70 
  71     /**
  72      * A method to be invoked before a class loader loads
  73      * a resource.
  74      *
  75      * @param resourcename the resource name
  76      */
  77     public static void preLoadResource(String resourcename) {
  78         BootClassLoaderHook hook = getHook();
  79         if (hook != null) {
  80             hook.getBootstrapResource(resourcename);
  81         }
  82     }
  83 
  84     /**
  85      * A method to be invoked before a library is loaded.
  86      *
  87      * @param libname the name of the library
  88      */
  89     public static void preLoadLibrary(String libname) {
  90         BootClassLoaderHook hook = getHook();
  91         if (hook != null) {
  92             hook.loadLibrary(libname);
  93         }
  94     }
  95 
  96     /**
  97      * Returns a pathname of a JAR or class that the hook loads
  98      * per this loadClass request; or null.
  99      *
 100      * @param classname the binary name of the class
 101      */
 102     public abstract String loadBootstrapClass(String className);
 103 
 104     /**
 105      * Returns a pathname of a resource file that the hook loads
 106      * per this getResource request; or null.
 107      *
 108      * @param resourceName the resource name
 109      */
 110     public abstract String getBootstrapResource(String resourceName);
 111 
 112     /**
 113      * Returns true if the hook successfully performs an operation per
 114      * this loadLibrary request; or false if it fails.
 115      *
 116      * @param libname the name of the library
 117      */
 118     public abstract boolean loadLibrary(String libname);
 119 
 120     /**
 121      * Returns a bootstrap class path constructed by the hook.
 122      *
 123      * @param bcp VM's bootstrap class path
 124      * @param factory Launcher's URL stream handler
 125      */
 126     public abstract URLClassPath getBootstrapClassPath(URLClassPath bcp,
 127             URLStreamHandlerFactory factory);
 128 
 129     /**
 130      * Returns true if the current thread is in the process of doing
 131      * a prefetching operation.
 132      */
 133     public abstract boolean isCurrentThreadPrefetching();
 134 
 135     /**
 136      * Returns true if the hook successfully prefetches the specified file.
 137      *
 138      * @param name a platform independent pathname
 139      */
 140     public abstract boolean prefetchFile(String name);
 141 }