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
24import java.io.BufferedInputStream;
25import java.io.IOException;
26import java.io.InputStream;
27import java.util.Map;
28import java.util.Set;
29import java.util.Vector;
30import jdk.internal.org.objectweb.asm.*;
31// Compile with -XDignore.symbol.file=true
32
33public class BogoLoader extends ClassLoader {
34
35    static interface VisitorMaker {
36    ClassVisitor make(ClassVisitor visitor);
37    }
38
39
40    /**
41     * Use this property to verify that the desired classloading is happening.
42     */
43    private final boolean verbose = Boolean.getBoolean("bogoloader.verbose");
44    /**
45     * Use this property to disable replacement for testing purposes.
46     */
47    private final boolean noReplace = Boolean.getBoolean("bogoloader.noreplace");
48
49    /**
50     * Set of class names that should be loaded with this loader.
51     * Others are loaded with the system class loader, except for those
52     * that are transformed.
53     */
54    private Set<String> nonSystem;
55
56    /**
57     * Map from class names to a bytecode transformer factory.
58     */
59    private Map<String, VisitorMaker> replaced;
60
61    /**
62     * Keep track (not terribly efficiently) of which classes have already
63     * been loaded by this class loader.
64     */
65    private final Vector<String> history = new Vector<String>();
66
67    private boolean useSystemLoader(String name) {
68        return ! nonSystem.contains(name) && ! replaced.containsKey(name);
69    }
70
71    public BogoLoader(Set<String> non_system, Map<String, VisitorMaker> replaced) {
72        super(Thread.currentThread().getContextClassLoader());
73        this.nonSystem = non_system;
74        this.replaced = replaced;
75    }
76
77    private byte[] readResource(String className) throws IOException {
78        return readResource(className, "class");
79    }
80
81    private byte[] readResource(String className, String suffix) throws IOException {
82        // Note to the unwary -- "/" works on Windows, leave it alone.
83        String fileName = className.replace('.', '/') + "." + suffix;
84        InputStream origStream = getResourceAsStream(fileName);
85        if (origStream == null) {
86            throw new IOException("Resource not found : " + fileName);
87        }
88        BufferedInputStream stream = new java.io.BufferedInputStream(origStream);
89        byte[] data = new byte[stream.available()];
90        int how_many = stream.read(data);
91        // Really ought to deal with the corner cases of stream.available()
92        return data;
93    }
94
95    protected byte[] getClass(String name) throws ClassNotFoundException,
96    IOException {
97        return readResource(name, "class");
98    }
99
100    /**
101     * Loads the named class from the system class loader unless
102     * the name appears in either replaced or nonSystem.
103     * nonSystem classes are loaded into this classloader,
104     * and replaced classes get their content from the specified array
105     * of bytes (and are also loaded into this classloader).
106     */
107    protected Class<?> loadClass(String name, boolean resolve)
108            throws ClassNotFoundException {
109        Class<?> clazz;
110
111        if (history.contains(name)) {
112            Class<?> c = this.findLoadedClass(name);
113            return c;
114        }
115        if (useSystemLoader(name)) {
116            clazz = findSystemClass(name);
117            if (verbose) System.err.println("Loading system class " + name);
118        } else {
119            history.add(name);
120            try {
121                if (verbose) {
122                    System.err.println("Loading classloader class " + name);
123                }
124                byte[] classData = getClass(name);;
125                boolean expanded = false;
126                if (!noReplace && replaced.containsKey(name)) {
127                    if (verbose) {
128                        System.err.println("Replacing class " + name);
129                    }
130                    ClassReader cr = new ClassReader(classData);
131                    ClassWriter cw = new ClassWriter(0);
132                    VisitorMaker vm = replaced.get(name);
133                    cr.accept(vm.make(cw), 0);
134                    classData = cw.toByteArray();
135                }
136                clazz = defineClass(name, classData, 0, classData.length);
137            } catch (java.io.EOFException ioe) {
138                throw new ClassNotFoundException(
139                        "IO Exception in reading class : " + name + " ", ioe);
140            } catch (ClassFormatError ioe) {
141                throw new ClassNotFoundException(
142                        "ClassFormatError in reading class file: ", ioe);
143            } catch (IOException ioe) {
144                throw new ClassNotFoundException(
145                        "IO Exception in reading class file: ", ioe);
146            }
147        }
148        if (clazz == null) {
149            throw new ClassNotFoundException(name);
150        }
151        if (resolve) {
152            resolveClass(clazz);
153        }
154        return clazz;
155    }
156}
157