| /******************************************************************************* |
| * Copyright (c) 2011, 2019 Igor Fedorenko |
| * |
| * This program and the accompanying materials |
| * are made available under the terms of the Eclipse Public License 2.0 |
| * which accompanies this distribution, and is available at |
| * https://www.eclipse.org/legal/epl-2.0/ |
| * |
| * SPDX-License-Identifier: EPL-2.0 |
| * |
| * Contributors: |
| * Igor Fedorenko - initial API and implementation |
| * IBM Corporation - bug fixes |
| *******************************************************************************/ |
| package org.eclipse.jdt.launching.internal.javaagent; |
| |
| import java.io.IOException; |
| import java.io.InputStream; |
| import java.lang.instrument.ClassFileTransformer; |
| import java.lang.instrument.IllegalClassFormatException; |
| import java.lang.instrument.Instrumentation; |
| import java.net.URL; |
| import java.security.CodeSource; |
| import java.security.ProtectionDomain; |
| |
| import org.eclipse.jdt.launching.internal.weaving.ClassfileTransformer; |
| |
| public class Premain { |
| private static final ClassfileTransformer transformer = new ClassfileTransformer(); |
| |
| public static void premain(final String agentArgs, final Instrumentation inst) { |
| final boolean debuglog = "debuglog".equals(agentArgs); //$NON-NLS-1$ |
| |
| // disable instrumentation if Object.class class format is not supported |
| short major = readJavaLangObjectMajor(debuglog); |
| if (major < 0 || major > ClassfileTransformer.MAX_CLASS_MAJOR) { |
| String vendor = System.getProperty("java.vendor"); //$NON-NLS-1$ |
| String version = System.getProperty("java.version"); //$NON-NLS-1$ |
| System.err.printf("JRE %s/%s is not supported, advanced source lookup disabled.\n Eclipse debugger will use less precise source lookup implementation for this debug session, but everything else will continue to work otherwise.\n" //$NON-NLS-1$ |
| + "Upgrading Eclipse to the latest version will likely make this warning go away.", vendor, version); //$NON-NLS-1$ |
| return; |
| } |
| |
| inst.addTransformer(new ClassFileTransformer() { |
| @Override |
| public byte[] transform(ClassLoader loader, final String className, Class<?> classBeingRedefined, ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException { |
| try { |
| if (protectionDomain == null) { |
| return null; |
| } |
| |
| if (className == null) { |
| return null; |
| } |
| |
| final CodeSource codeSource = protectionDomain.getCodeSource(); |
| if (codeSource == null) { |
| return null; |
| } |
| |
| final URL locationUrl = codeSource.getLocation(); |
| if (locationUrl == null) { |
| return null; |
| } |
| |
| final String location = locationUrl.toExternalForm(); |
| |
| return transformer.transform(classfileBuffer, location); |
| } |
| catch (Exception e) { |
| System.err.printf("Could not instrument class %s: %s.\n", className, e.getMessage()); //$NON-NLS-1$ |
| if (debuglog) { |
| e.printStackTrace(System.err); |
| } |
| } |
| return null; |
| } |
| }); |
| |
| if (debuglog) { |
| System.err.println("Advanced source lookup enabled."); //$NON-NLS-1$ |
| } |
| } |
| |
| private static short readJavaLangObjectMajor(boolean debuglog) { |
| // https://docs.oracle.com/javase/specs/jvms/se10/html/jvms-4.html |
| // We need class major_version, i.e. the u2 field starting at offset 6 |
| |
| final int offset = 6; |
| |
| final InputStream is = ClassLoader.getSystemResourceAsStream("java/lang/Object.class"); //$NON-NLS-1$ |
| if (is == null) { |
| if (debuglog) { |
| System.err.println("Could not open java/lang/Object.class system resource stream."); //$NON-NLS-1$ |
| } |
| return -1; |
| } |
| |
| byte[] bytes = new byte[offset + 2]; |
| try { |
| try { |
| if (is.read(bytes) < bytes.length) { |
| if (debuglog) { |
| System.err.println("Could not read java/lang/Object.class system resource stream."); //$NON-NLS-1$ |
| } |
| return -1; |
| } |
| } |
| finally { |
| is.close(); |
| } |
| } |
| catch (IOException e) { |
| if (debuglog) { |
| System.err.println("Could not read java/lang/Object.class system resource stream."); //$NON-NLS-1$ |
| e.printStackTrace(System.err); |
| } |
| return -1; |
| } |
| |
| int magic = ((bytes[0] & 0xFF) << 24) | ((bytes[1] & 0xFF) << 16) | ((bytes[2] & 0xFF) << 8) | (bytes[3] & 0xFF); |
| if (magic != 0xCAFEBABE) { |
| if (debuglog) { |
| System.err.println("Invalid java/lang/Object.class magic."); //$NON-NLS-1$ |
| } |
| return -1; |
| } |
| |
| return (short) (((bytes[offset] & 0xFF) << 8) | (bytes[offset + 1] & 0xFF)); |
| } |
| |
| } |