254 lines
9.0 KiB
Java
254 lines
9.0 KiB
Java
/*
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* Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package sun.instrument;
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import java.lang.instrument.Instrumentation;
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import java.lang.instrument.ClassFileTransformer;
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import java.security.ProtectionDomain;
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/*
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* Copyright 2003 Wily Technology, Inc.
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*/
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/**
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* Support class for the InstrumentationImpl. Manages the list of registered transformers.
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* Keeps everything in the right order, deals with sync of the list,
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* and actually does the calling of the transformers.
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*/
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public class TransformerManager
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{
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private class TransformerInfo {
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final ClassFileTransformer mTransformer;
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String mPrefix;
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TransformerInfo(ClassFileTransformer transformer) {
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mTransformer = transformer;
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mPrefix = null;
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}
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ClassFileTransformer transformer() {
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return mTransformer;
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}
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String getPrefix() {
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return mPrefix;
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}
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void setPrefix(String prefix) {
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mPrefix = prefix;
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}
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}
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/**
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* a given instance of this list is treated as immutable to simplify sync;
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* we pay copying overhead whenever the list is changed rather than every time
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* the list is referenced.
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* The array is kept in the order the transformers are added via addTransformer
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* (first added is 0, last added is length-1)
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* Use an array, not a List or other Collection. This keeps the set of classes
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* used by this code to a minimum. We want as few dependencies as possible in this
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* code, since it is used inside the class definition system. Any class referenced here
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* cannot be transformed by Java code.
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*/
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private TransformerInfo[] mTransformerList;
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/***
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* Is this TransformerManager for transformers capable of retransformation?
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*/
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private boolean mIsRetransformable;
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TransformerManager(boolean isRetransformable) {
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mTransformerList = new TransformerInfo[0];
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mIsRetransformable = isRetransformable;
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}
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boolean isRetransformable() {
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return mIsRetransformable;
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}
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public synchronized void
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addTransformer( ClassFileTransformer transformer) {
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TransformerInfo[] oldList = mTransformerList;
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TransformerInfo[] newList = new TransformerInfo[oldList.length + 1];
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System.arraycopy( oldList,
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0,
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newList,
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0,
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oldList.length);
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newList[oldList.length] = new TransformerInfo(transformer);
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mTransformerList = newList;
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}
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public synchronized boolean
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removeTransformer(ClassFileTransformer transformer) {
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boolean found = false;
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TransformerInfo[] oldList = mTransformerList;
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int oldLength = oldList.length;
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int newLength = oldLength - 1;
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// look for it in the list, starting at the last added, and remember
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// where it was if we found it
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int matchingIndex = 0;
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for ( int x = oldLength - 1; x >= 0; x-- ) {
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if ( oldList[x].transformer() == transformer ) {
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found = true;
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matchingIndex = x;
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break;
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}
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}
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// make a copy of the array without the matching element
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if ( found ) {
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TransformerInfo[] newList = new TransformerInfo[newLength];
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// copy up to but not including the match
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if ( matchingIndex > 0 ) {
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System.arraycopy( oldList,
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0,
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newList,
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0,
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matchingIndex);
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}
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// if there is anything after the match, copy it as well
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if ( matchingIndex < (newLength) ) {
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System.arraycopy( oldList,
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matchingIndex + 1,
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newList,
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matchingIndex,
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(newLength) - matchingIndex);
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}
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mTransformerList = newList;
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}
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return found;
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}
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synchronized boolean
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includesTransformer(ClassFileTransformer transformer) {
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for (TransformerInfo info : mTransformerList) {
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if ( info.transformer() == transformer ) {
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return true;
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}
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}
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return false;
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}
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// This function doesn't actually snapshot anything, but should be
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// used to set a local variable, which will snapshot the transformer
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// list because of the copying semantics of mTransformerList (see
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// the comment for mTransformerList).
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private TransformerInfo[]
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getSnapshotTransformerList() {
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return mTransformerList;
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}
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public byte[]
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transform( ClassLoader loader,
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String classname,
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Class<?> classBeingRedefined,
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ProtectionDomain protectionDomain,
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byte[] classfileBuffer) {
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boolean someoneTouchedTheBytecode = false;
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TransformerInfo[] transformerList = getSnapshotTransformerList();
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byte[] bufferToUse = classfileBuffer;
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// order matters, gotta run 'em in the order they were added
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for ( int x = 0; x < transformerList.length; x++ ) {
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TransformerInfo transformerInfo = transformerList[x];
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ClassFileTransformer transformer = transformerInfo.transformer();
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byte[] transformedBytes = null;
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try {
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transformedBytes = transformer.transform( loader,
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classname,
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classBeingRedefined,
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protectionDomain,
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bufferToUse);
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}
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catch (Throwable t) {
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// don't let any one transformer mess it up for the others.
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// This is where we need to put some logging. What should go here? FIXME
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}
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if ( transformedBytes != null ) {
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someoneTouchedTheBytecode = true;
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bufferToUse = transformedBytes;
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}
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}
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// if someone modified it, return the modified buffer.
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// otherwise return null to mean "no transforms occurred"
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byte [] result;
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if ( someoneTouchedTheBytecode ) {
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result = bufferToUse;
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}
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else {
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result = null;
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}
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return result;
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}
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int
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getTransformerCount() {
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TransformerInfo[] transformerList = getSnapshotTransformerList();
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return transformerList.length;
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}
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boolean
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setNativeMethodPrefix(ClassFileTransformer transformer, String prefix) {
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TransformerInfo[] transformerList = getSnapshotTransformerList();
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for ( int x = 0; x < transformerList.length; x++ ) {
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TransformerInfo transformerInfo = transformerList[x];
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ClassFileTransformer aTransformer = transformerInfo.transformer();
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if ( aTransformer == transformer ) {
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transformerInfo.setPrefix(prefix);
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return true;
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}
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}
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return false;
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}
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String[]
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getNativeMethodPrefixes() {
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TransformerInfo[] transformerList = getSnapshotTransformerList();
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String[] prefixes = new String[transformerList.length];
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for ( int x = 0; x < transformerList.length; x++ ) {
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TransformerInfo transformerInfo = transformerList[x];
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prefixes[x] = transformerInfo.getPrefix();
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}
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return prefixes;
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}
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}
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