1 /*
2 * Copyright (c) 2016, 2017, 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
25 package org.graalvm.compiler.replacements.classfile;
26
27 import java.io.DataInputStream;
28 import java.io.IOException;
29 import java.lang.reflect.Modifier;
30 import java.util.ArrayList;
31 import java.util.List;
32
33 import org.graalvm.compiler.replacements.classfile.ClassfileConstant.Utf8;
34
35 import jdk.vm.ci.meta.ResolvedJavaMethod;
36 import jdk.vm.ci.meta.ResolvedJavaType;
37
38 /**
39 * Container for objects representing the {@code Code} attributes parsed from a class file.
40 *
41 * @see <a href="https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.7.3">Code
42 * attributes</a>
43 * @see <a href="https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.4">Constant
44 * Pool</a>
45 */
46 public class Classfile {
47
48 private final ResolvedJavaType type;
49 private final List<ClassfileBytecode> codeAttributes;
50
51 private static final int MAJOR_VERSION_JAVA_MIN = 51; // JDK7
52 private static final int MAJOR_VERSION_JAVA_MAX = 57; // JDK13
53 private static final int MAGIC = 0xCAFEBABE;
54
55 /**
56 * Creates a {@link Classfile} by parsing the class file bytes for {@code type} loadable from
57 * {@code context}.
58 *
59 * @throws NoClassDefFoundError if there is an IO error while parsing the class file
60 */
61 public Classfile(ResolvedJavaType type, DataInputStream stream, ClassfileBytecodeProvider context) throws IOException {
62 this.type = type;
63
64 // magic
65 int magic = stream.readInt();
66 assert magic == MAGIC;
67
68 int minor = stream.readUnsignedShort();
69 int major = stream.readUnsignedShort();
70 if (major < MAJOR_VERSION_JAVA_MIN || major > MAJOR_VERSION_JAVA_MAX) {
71 throw new UnsupportedClassVersionError("Unsupported class file version: " + major + "." + minor);
72 }
73
74 ClassfileConstantPool cp = new ClassfileConstantPool(stream, context);
75
76 // access_flags, this_class, super_class
77 skipFully(stream, 6);
78
79 // interfaces
80 skipFully(stream, stream.readUnsignedShort() * 2);
81
82 // fields
83 skipFields(stream);
84
85 // methods
86 codeAttributes = readMethods(stream, cp);
87
88 // attributes
89 skipAttributes(stream);
90 }
91
92 public ClassfileBytecode getCode(String name, String descriptor) {
93 for (ClassfileBytecode code : codeAttributes) {
94 ResolvedJavaMethod method = code.getMethod();
95 if (method.getName().equals(name) && method.getSignature().toMethodDescriptor().equals(descriptor)) {
96 return code;
97 }
98 }
99 throw new NoSuchMethodError(type.toJavaName() + "." + name + descriptor);
100 }
101
102 private static void skipAttributes(DataInputStream stream) throws IOException {
103 int attributesCount;
104 attributesCount = stream.readUnsignedShort();
105 for (int i = 0; i < attributesCount; i++) {
106 skipFully(stream, 2); // name_index
107 int attributeLength = stream.readInt();
108 skipFully(stream, attributeLength);
109 }
110 }
111
112 static void skipFully(DataInputStream stream, int n) throws IOException {
113 long skipped = 0;
114 do {
115 long s = stream.skip(n - skipped);
116 skipped += s;
117 if (s == 0 && skipped != n) {
118 // Check for EOF (i.e., truncated class file)
119 if (stream.read() == -1) {
120 throw new IOException("truncated stream");
121 }
122 skipped++;
123 }
124 } while (skipped != n);
125 }
126
127 private ClassfileBytecode findCodeAttribute(DataInputStream stream, ClassfileConstantPool cp, String name, String descriptor, boolean isStatic) throws IOException {
128 int attributesCount;
129 attributesCount = stream.readUnsignedShort();
130 ClassfileBytecode code = null;
131 for (int i = 0; i < attributesCount; i++) {
132 String attributeName = cp.get(Utf8.class, stream.readUnsignedShort()).value;
133 int attributeLength = stream.readInt();
134 if (code == null && attributeName.equals("Code")) {
135 ResolvedJavaMethod method = cp.context.findMethod(type, name, descriptor, isStatic);
136 // Even if we will discard the Code attribute (see below), we still
137 // need to parse it to reach the following class file content.
138 code = new ClassfileBytecode(method, stream, cp);
139 if (method == null) {
140 // This is a method hidden from reflection
141 // (see sun.reflect.Reflection.filterMethods)
142 code = null;
143 }
144 } else {
145 skipFully(stream, attributeLength);
146 }
147 }
148 return code;
149 }
150
151 private static void skipFields(DataInputStream stream) throws IOException {
152 int count = stream.readUnsignedShort();
153 for (int i = 0; i < count; i++) {
154 skipFully(stream, 6); // access_flags, name_index, descriptor_index
155 skipAttributes(stream);
156 }
157 }
158
159 private List<ClassfileBytecode> readMethods(DataInputStream stream, ClassfileConstantPool cp) throws IOException {
160 int count = stream.readUnsignedShort();
161 List<ClassfileBytecode> result = new ArrayList<>(count);
162 for (int i = 0; i < count; i++) {
163 int accessFlags = stream.readUnsignedShort();
164 boolean isStatic = Modifier.isStatic(accessFlags);
165 String name = cp.get(Utf8.class, stream.readUnsignedShort()).value;
166 String descriptor = cp.get(Utf8.class, stream.readUnsignedShort()).value;
167 ClassfileBytecode code = findCodeAttribute(stream, cp, name, descriptor, isStatic);
168 if (code != null) {
169 result.add(code);
170 }
171 }
172 return result;
173 }
174
175 @Override
176 public String toString() {
177 return getClass().getSimpleName() + "<" + type.toJavaName() + ">";
178 }
179 }