BogoLoader.java revision 15491:6f390eafc676 
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
32public class BogoLoader extends ClassLoader {
33
34    static interface VisitorMaker {
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
66    private boolean useSystemLoader(String name) {
67        return ! nonSystem.contains(name) && ! replaced.containsKey(name);
68    }
69
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
76    private byte[] readResource(String className) throws IOException {
77        return readResource(className, "class");
78    }
79
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
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     */
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