1 /*
2  * Copyright (c) 2013, 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.
8  *
9  * This code is distributed in the hope that it will be useful, but WITHOUT
10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12  * version 2 for more details (a copy is included in the LICENSE file that
13  * accompanied this code).
14  *
15  * You should have received a copy of the GNU General Public License version
16  * 2 along with this work; if not, write to the Free Software Foundation,
17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18  *
19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20  * or visit www.oracle.com if you need additional information or have any
21  * questions.
22  */
23 
24 import java.io.BufferedInputStream;
25 import java.io.IOException;
26 import java.io.InputStream;
27 import java.util.Map;
28 import java.util.Set;
29 import java.util.Vector;
30 import jdk.internal.org.objectweb.asm.*;
31 
32 public class BogoLoader extends ClassLoader {
33 
34     static interface VisitorMaker {
make(ClassVisitor visitor)35     ClassVisitor make(ClassVisitor visitor);
36     }
37 
38 
39     /**
40      * Use this property to verify that the desired classloading is happening.
41      */
42     private final boolean verbose = Boolean.getBoolean("bogoloader.verbose");
43     /**
44      * Use this property to disable replacement for testing purposes.
45      */
46     private final boolean noReplace = Boolean.getBoolean("bogoloader.noreplace");
47 
48     /**
49      * Set of class names that should be loaded with this loader.
50      * Others are loaded with the system class loader, except for those
51      * that are transformed.
52      */
53     private Set<String> nonSystem;
54 
55     /**
56      * Map from class names to a bytecode transformer factory.
57      */
58     private Map<String, VisitorMaker> replaced;
59 
60     /**
61      * Keep track (not terribly efficiently) of which classes have already
62      * been loaded by this class loader.
63      */
64     private final Vector<String> history = new Vector<String>();
65 
useSystemLoader(String name)66     private boolean useSystemLoader(String name) {
67         return ! nonSystem.contains(name) && ! replaced.containsKey(name);
68     }
69 
BogoLoader(Set<String> non_system, Map<String, VisitorMaker> replaced)70     public BogoLoader(Set<String> non_system, Map<String, VisitorMaker> replaced) {
71         super(Thread.currentThread().getContextClassLoader());
72         this.nonSystem = non_system;
73         this.replaced = replaced;
74     }
75 
readResource(String className)76     private byte[] readResource(String className) throws IOException {
77         return readResource(className, "class");
78     }
79 
readResource(String className, String suffix)80     private byte[] readResource(String className, String suffix) throws IOException {
81         // Note to the unwary -- "/" works on Windows, leave it alone.
82         String fileName = className.replace('.', '/') + "." + suffix;
83         InputStream origStream = getResourceAsStream(fileName);
84         if (origStream == null) {
85             throw new IOException("Resource not found : " + fileName);
86         }
87         BufferedInputStream stream = new java.io.BufferedInputStream(origStream);
88         byte[] data = new byte[stream.available()];
89         int how_many = stream.read(data);
90         // Really ought to deal with the corner cases of stream.available()
91         return data;
92     }
93 
getClass(String name)94     protected byte[] getClass(String name) throws ClassNotFoundException,
95     IOException {
96         return readResource(name, "class");
97     }
98 
99     /**
100      * Loads the named class from the system class loader unless
101      * the name appears in either replaced or nonSystem.
102      * nonSystem classes are loaded into this classloader,
103      * and replaced classes get their content from the specified array
104      * of bytes (and are also loaded into this classloader).
105      */
loadClass(String name, boolean resolve)106     protected Class<?> loadClass(String name, boolean resolve)
107             throws ClassNotFoundException {
108         Class<?> clazz;
109 
110         if (history.contains(name)) {
111             Class<?> c = this.findLoadedClass(name);
112             return c;
113         }
114         if (useSystemLoader(name)) {
115             clazz = findSystemClass(name);
116             if (verbose) System.err.println("Loading system class " + name);
117         } else {
118             history.add(name);
119             try {
120                 if (verbose) {
121                     System.err.println("Loading classloader class " + name);
122                 }
123                 byte[] classData = getClass(name);;
124                 boolean expanded = false;
125                 if (!noReplace && replaced.containsKey(name)) {
126                     if (verbose) {
127                         System.err.println("Replacing class " + name);
128                     }
129                     ClassReader cr = new ClassReader(classData);
130                     ClassWriter cw = new ClassWriter(0);
131                     VisitorMaker vm = replaced.get(name);
132                     cr.accept(vm.make(cw), 0);
133                     classData = cw.toByteArray();
134                 }
135                 clazz = defineClass(name, classData, 0, classData.length);
136             } catch (java.io.EOFException ioe) {
137                 throw new ClassNotFoundException(
138                         "IO Exception in reading class : " + name + " ", ioe);
139             } catch (ClassFormatError ioe) {
140                 throw new ClassNotFoundException(
141                         "ClassFormatError in reading class file: ", ioe);
142             } catch (IOException ioe) {
143                 throw new ClassNotFoundException(
144                         "IO Exception in reading class file: ", ioe);
145             }
146         }
147         if (clazz == null) {
148             throw new ClassNotFoundException(name);
149         }
150         if (resolve) {
151             resolveClass(clazz);
152         }
153         return clazz;
154     }
155 }
156