1 /*
2 * Copyright (c) 2012, 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 build.tools.classfile;
27
28 import java.nio.file.Files;
29 import java.nio.file.Path;
30 import java.nio.file.Paths;
31 import java.io.InputStream;
32 import java.io.OutputStream;
33 import java.io.IOException;
34 import java.util.Set;
35 import java.util.HashSet;
36
37 import com.sun.tools.classfile.AccessFlags;
38 import com.sun.tools.classfile.Attributes;
39 import com.sun.tools.classfile.ClassFile;
40 import com.sun.tools.classfile.ClassReader;
41 import com.sun.tools.classfile.ClassWriter;
42 import com.sun.tools.classfile.ConstantPool;
43 import com.sun.tools.classfile.Field;
44 import com.sun.tools.classfile.Method;
45
46 public class RemoveMethods {
47
48 public static void main(String[] args) throws Exception {
49 if (args.length < 2) {
50 System.err.println("Usage: java RemoveMethods classfile output [method...]");
51 System.exit(-1);
52 }
53
54 // class file to read
55 Path input = Paths.get(args[0]);
56
57 // class file to write, if directory then use the name of the input
58 Path output = Paths.get(args[1]);
59 if (Files.isDirectory(output))
60 output = output.resolve(input.getFileName());
61
62 // the methods to remove
63 Set<String> methodsToRemove = new HashSet<>();
64 int i = 2;
65 while (i < args.length)
66 methodsToRemove.add(args[i++]);
67
68 // read class file
69 ClassFile cf;
70 try (InputStream in = Files.newInputStream(input)) {
71 cf = ClassFile.read(in);
72 }
73
74 final int magic = cf.magic;
75 final int major_version = cf.major_version;
76 final int minor_version = cf.minor_version;
77 final ConstantPool cp = cf.constant_pool;
78 final AccessFlags access_flags = cf.access_flags;
79 final int this_class = cf.this_class;
80 final int super_class = cf.super_class;
81 final int[] interfaces = cf.interfaces;
82 final Field[] fields = cf.fields;
83 final Attributes class_attrs = cf.attributes;
84
85 // remove the requested methods, no signature check at this time
86 Method[] methods = cf.methods;
87 i = 0;
88 while (i < methods.length) {
89 Method m = methods[i];
90 String name = m.getName(cp);
91 if (methodsToRemove.contains(name)) {
92 int len = methods.length;
93 Method[] newMethods = new Method[len-1];
94 if (i > 0)
95 System.arraycopy(methods, 0, newMethods, 0, i);
96 int after = methods.length - i - 1;
97 if (after > 0)
98 System.arraycopy(methods, i+1, newMethods, i, after);
99 methods = newMethods;
100 System.out.println("Removed: " + name);
101 continue;
102 }
103 i++;
104 }
105
106 // TBD, prune constant pool of entries that are no longed referenced
107
108 // re-write class file
109 cf = new ClassFile(magic, minor_version, major_version, cp, access_flags,
110 this_class, super_class, interfaces, fields, methods, class_attrs);
111 try (OutputStream out = Files.newOutputStream(output)) {
112 new ClassWriter().write(cf, out);
113 }
114 }
115 }