| /* |
| * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| package org.graalvm.compiler.replacements.classfile; |
| |
| import java.io.DataInputStream; |
| import java.io.IOException; |
| import java.lang.reflect.Modifier; |
| import java.util.ArrayList; |
| import java.util.List; |
| |
| import org.graalvm.compiler.replacements.classfile.ClassfileConstant.Utf8; |
| |
| import jdk.vm.ci.meta.ResolvedJavaMethod; |
| import jdk.vm.ci.meta.ResolvedJavaType; |
| |
| /** |
| * Container for objects representing the {@code Code} attributes parsed from a class file. |
| * |
| * @see <a href="https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.7.3">Code |
| * attributes</a> |
| * @see <a href="https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.4">Constant |
| * Pool</a> |
| */ |
| public class Classfile { |
| |
| private final ResolvedJavaType type; |
| private final List<ClassfileBytecode> codeAttributes; |
| |
| private static final int MAJOR_VERSION_JAVA7 = 51; |
| private static final int MAJOR_VERSION_JAVA9 = 53; |
| |
| /** |
| * Creates a {@link Classfile} by parsing the class file bytes for {@code type} loadable from |
| * {@code context}. |
| * |
| * @throws NoClassDefFoundError if there is an IO error while parsing the class file |
| */ |
| public Classfile(ResolvedJavaType type, DataInputStream stream, ClassfileBytecodeProvider context) throws IOException { |
| this.type = type; |
| |
| // magic |
| int magic = stream.readInt(); |
| assert magic == 0xCAFEBABE; |
| |
| int minor = stream.readUnsignedShort(); |
| int major = stream.readUnsignedShort(); |
| if (major < MAJOR_VERSION_JAVA7 || major > MAJOR_VERSION_JAVA9) { |
| throw new UnsupportedClassVersionError("Unsupported class file version: " + major + "." + minor); |
| } |
| |
| ClassfileConstantPool cp = new ClassfileConstantPool(stream, context); |
| |
| // access_flags, this_class, super_class |
| skipFully(stream, 6); |
| |
| // interfaces |
| skipFully(stream, stream.readUnsignedShort() * 2); |
| |
| // fields |
| skipFields(stream); |
| |
| // methods |
| codeAttributes = readMethods(stream, cp); |
| |
| // attributes |
| skipAttributes(stream); |
| } |
| |
| public ClassfileBytecode getCode(String name, String descriptor) { |
| for (ClassfileBytecode code : codeAttributes) { |
| ResolvedJavaMethod method = code.getMethod(); |
| if (method.getName().equals(name) && method.getSignature().toMethodDescriptor().equals(descriptor)) { |
| return code; |
| } |
| } |
| throw new NoSuchMethodError(type.toJavaName() + "." + name + descriptor); |
| } |
| |
| private static void skipAttributes(DataInputStream stream) throws IOException { |
| int attributesCount; |
| attributesCount = stream.readUnsignedShort(); |
| for (int i = 0; i < attributesCount; i++) { |
| skipFully(stream, 2); // name_index |
| int attributeLength = stream.readInt(); |
| skipFully(stream, attributeLength); |
| } |
| } |
| |
| static void skipFully(DataInputStream stream, int n) throws IOException { |
| long skipped = 0; |
| do { |
| long s = stream.skip(n - skipped); |
| skipped += s; |
| if (s == 0 && skipped != n) { |
| // Check for EOF (i.e., truncated class file) |
| if (stream.read() == -1) { |
| throw new IOException("truncated stream"); |
| } |
| skipped++; |
| } |
| } while (skipped != n); |
| } |
| |
| private ClassfileBytecode findCodeAttribute(DataInputStream stream, ClassfileConstantPool cp, String name, String descriptor, boolean isStatic) throws IOException { |
| int attributesCount; |
| attributesCount = stream.readUnsignedShort(); |
| ClassfileBytecode code = null; |
| for (int i = 0; i < attributesCount; i++) { |
| String attributeName = cp.get(Utf8.class, stream.readUnsignedShort()).value; |
| int attributeLength = stream.readInt(); |
| if (code == null && attributeName.equals("Code")) { |
| ResolvedJavaMethod method = ClassfileBytecodeProvider.findMethod(type, name, descriptor, isStatic); |
| // Even if we will discard the Code attribute (see below), we still |
| // need to parse it to reach the following class file content. |
| code = new ClassfileBytecode(method, stream, cp); |
| if (method == null) { |
| // This is a method hidden from reflection |
| // (see sun.reflect.Reflection.filterMethods) |
| code = null; |
| } |
| } else { |
| skipFully(stream, attributeLength); |
| } |
| } |
| return code; |
| } |
| |
| private static void skipFields(DataInputStream stream) throws IOException { |
| int count = stream.readUnsignedShort(); |
| for (int i = 0; i < count; i++) { |
| skipFully(stream, 6); // access_flags, name_index, descriptor_index |
| skipAttributes(stream); |
| } |
| } |
| |
| private List<ClassfileBytecode> readMethods(DataInputStream stream, ClassfileConstantPool cp) throws IOException { |
| int count = stream.readUnsignedShort(); |
| List<ClassfileBytecode> result = new ArrayList<>(count); |
| for (int i = 0; i < count; i++) { |
| int accessFlags = stream.readUnsignedShort(); |
| boolean isStatic = Modifier.isStatic(accessFlags); |
| String name = cp.get(Utf8.class, stream.readUnsignedShort()).value; |
| String descriptor = cp.get(Utf8.class, stream.readUnsignedShort()).value; |
| ClassfileBytecode code = findCodeAttribute(stream, cp, name, descriptor, isStatic); |
| if (code != null) { |
| result.add(code); |
| } |
| } |
| return result; |
| } |
| |
| @Override |
| public String toString() { |
| return getClass().getSimpleName() + "<" + type.toJavaName() + ">"; |
| } |
| } |