1 /*
2 * Copyright (c) 2016, 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 package org.graalvm.compiler.replacements.classfile;
24
25 import java.io.DataInputStream;
26 import java.io.IOException;
27 import java.lang.reflect.Modifier;
28 import java.util.ArrayList;
29 import java.util.List;
30
31 import org.graalvm.compiler.replacements.classfile.ClassfileConstant.Utf8;
32
33 import jdk.vm.ci.meta.ResolvedJavaMethod;
34 import jdk.vm.ci.meta.ResolvedJavaType;
35
36 /**
37 * Container for objects representing the {@code Code} attributes parsed from a class file.
38 *
39 * @see <a href="https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.7.3">Code
40 * attributes</a>
41 * @see <a href="https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.4">Constant
42 * Pool</a>
43 */
44 public class Classfile {
45
46 private final ResolvedJavaType type;
47 private final List<ClassfileBytecode> codeAttributes;
48
49 private static final int MAJOR_VERSION_JAVA7 = 51;
50 private static final int MAJOR_VERSION_JAVA10 = 54;
51 private static final int MAGIC = 0xCAFEBABE;
52
53 /**
54 * Creates a {@link Classfile} by parsing the class file bytes for {@code type} loadable from
55 * {@code context}.
56 *
57 * @throws NoClassDefFoundError if there is an IO error while parsing the class file
58 */
59 public Classfile(ResolvedJavaType type, DataInputStream stream, ClassfileBytecodeProvider context) throws IOException {
60 this.type = type;
61
62 // magic
63 int magic = stream.readInt();
64 assert magic == MAGIC;
65
66 int minor = stream.readUnsignedShort();
67 int major = stream.readUnsignedShort();
68 if (major < MAJOR_VERSION_JAVA7 || major > MAJOR_VERSION_JAVA10) {
69 throw new UnsupportedClassVersionError("Unsupported class file version: " + major + "." + minor);
70 }
71
72 ClassfileConstantPool cp = new ClassfileConstantPool(stream, context);
73
74 // access_flags, this_class, super_class
75 skipFully(stream, 6);
76
77 // interfaces
78 skipFully(stream, stream.readUnsignedShort() * 2);
79
80 // fields
81 skipFields(stream);
82
83 // methods
84 codeAttributes = readMethods(stream, cp);
85
86 // attributes
87 skipAttributes(stream);
88 }
89
90 public ClassfileBytecode getCode(String name, String descriptor) {
91 for (ClassfileBytecode code : codeAttributes) {
92 ResolvedJavaMethod method = code.getMethod();
93 if (method.getName().equals(name) && method.getSignature().toMethodDescriptor().equals(descriptor)) {
94 return code;
95 }
96 }
97 throw new NoSuchMethodError(type.toJavaName() + "." + name + descriptor);
98 }
99
100 private static void skipAttributes(DataInputStream stream) throws IOException {
101 int attributesCount;
102 attributesCount = stream.readUnsignedShort();
103 for (int i = 0; i < attributesCount; i++) {
104 skipFully(stream, 2); // name_index
105 int attributeLength = stream.readInt();
106 skipFully(stream, attributeLength);
107 }
108 }
109
110 static void skipFully(DataInputStream stream, int n) throws IOException {
111 long skipped = 0;
112 do {
113 long s = stream.skip(n - skipped);
114 skipped += s;
115 if (s == 0 && skipped != n) {
116 // Check for EOF (i.e., truncated class file)
117 if (stream.read() == -1) {
118 throw new IOException("truncated stream");
119 }
120 skipped++;
121 }
122 } while (skipped != n);
123 }
124
125 private ClassfileBytecode findCodeAttribute(DataInputStream stream, ClassfileConstantPool cp, String name, String descriptor, boolean isStatic) throws IOException {
126 int attributesCount;
127 attributesCount = stream.readUnsignedShort();
128 ClassfileBytecode code = null;
129 for (int i = 0; i < attributesCount; i++) {
130 String attributeName = cp.get(Utf8.class, stream.readUnsignedShort()).value;
131 int attributeLength = stream.readInt();
132 if (code == null && attributeName.equals("Code")) {
133 ResolvedJavaMethod method = cp.context.findMethod(type, name, descriptor, isStatic);
134 // Even if we will discard the Code attribute (see below), we still
135 // need to parse it to reach the following class file content.
136 code = new ClassfileBytecode(method, stream, cp);
137 if (method == null) {
138 // This is a method hidden from reflection
139 // (see sun.reflect.Reflection.filterMethods)
140 code = null;
141 }
142 } else {
143 skipFully(stream, attributeLength);
144 }
145 }
146 return code;
147 }
148
149 private static void skipFields(DataInputStream stream) throws IOException {
150 int count = stream.readUnsignedShort();
151 for (int i = 0; i < count; i++) {
152 skipFully(stream, 6); // access_flags, name_index, descriptor_index
153 skipAttributes(stream);
154 }
155 }
156
157 private List<ClassfileBytecode> readMethods(DataInputStream stream, ClassfileConstantPool cp) throws IOException {
158 int count = stream.readUnsignedShort();
159 List<ClassfileBytecode> result = new ArrayList<>(count);
160 for (int i = 0; i < count; i++) {
161 int accessFlags = stream.readUnsignedShort();
162 boolean isStatic = Modifier.isStatic(accessFlags);
163 String name = cp.get(Utf8.class, stream.readUnsignedShort()).value;
164 String descriptor = cp.get(Utf8.class, stream.readUnsignedShort()).value;
165 ClassfileBytecode code = findCodeAttribute(stream, cp, name, descriptor, isStatic);
166 if (code != null) {
167 result.add(code);
168 }
169 }
170 return result;
171 }
172
173 @Override
174 public String toString() {
175 return getClass().getSimpleName() + "<" + type.toJavaName() + ">";
176 }
177 }