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/* $Id: ClassForNameChecker.java,v 1.12 2005/06/11 13:13:15 eric Exp $
*
* ProGuard -- shrinking, optimization, and obfuscation of Java class files.
*
* Copyright (c) 2002-2005 Eric Lafortune (eric@graphics.cornell.edu)
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
* This program 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 for
* more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package proguard.classfile.util;
import proguard.classfile.*;
import proguard.classfile.attribute.*;
import proguard.classfile.attribute.annotation.*;
import proguard.classfile.instruction.*;
import proguard.classfile.visitor.*;
/**
* This class can check whether method references point to <code>Class.forName</code>
* or <code>.class</code>.
*
* @author Eric Lafortune
*/
class ClassForNameChecker
implements CpInfoVisitor,
MemberInfoVisitor,
AttrInfoVisitor,
InstructionVisitor
{
// These fields acts as a return variables and status variables for the visitors.
private boolean isClassForNameInvocation;
private boolean insideDotClassMethod;
private boolean firstInstructionOk;
/**
* Creates a new ClassForNameChecker.
*/
public ClassForNameChecker()
{
}
/**
* Checks whether the specified method reference points to
* <code>Class.forName</code> or <code>.class</code>.
* @param classFile the class file in which the method reference
* is located.
* @param methodrefCpInfoIndex the index of the method reference in the
* constant pool.
* @return a boolean that indicates whether the reference points to either
* method.
*/
public boolean check(ClassFile classFile, int methodrefCpInfoIndex)
{
isClassForNameInvocation = false;
classFile.constantPoolEntryAccept(methodrefCpInfoIndex, this);
return isClassForNameInvocation;
}
// Implementations for CpInfoVisitor.
public void visitIntegerCpInfo(ClassFile classFile, IntegerCpInfo integerCpInfo) {}
public void visitLongCpInfo(ClassFile classFile, LongCpInfo longCpInfo) {}
public void visitFloatCpInfo(ClassFile classFile, FloatCpInfo floatCpInfo) {}
public void visitDoubleCpInfo(ClassFile classFile, DoubleCpInfo doubleCpInfo) {}
public void visitStringCpInfo(ClassFile classFile, StringCpInfo stringCpInfo) {}
public void visitUtf8CpInfo(ClassFile classFile, Utf8CpInfo utf8CpInfo) {}
public void visitFieldrefCpInfo(ClassFile classFile, FieldrefCpInfo fieldrefCpInfo) {}
public void visitInterfaceMethodrefCpInfo(ClassFile classFile, InterfaceMethodrefCpInfo interfaceMethodrefCpInfo) {}
public void visitClassCpInfo(ClassFile classFile, ClassCpInfo classCpInfo) {}
public void visitNameAndTypeCpInfo(ClassFile classFile, NameAndTypeCpInfo nameAndTypeCpInfo) {}
/**
* Checks whether the given method reference points to
* <code>Class.forName</code> or <code>.class</code>.
*/
public void visitMethodrefCpInfo(ClassFile classFile, MethodrefCpInfo methodrefCpInfo)
{
String className = methodrefCpInfo.getClassName(classFile);
String methodName = methodrefCpInfo.getName(classFile);
String methodType = methodrefCpInfo.getType(classFile);
// Is it a reference to "Class Class.forName(String)"?
isClassForNameInvocation =
className .equals(ClassConstants.INTERNAL_CLASS_NAME_JAVA_LANG_CLASS) &&
methodName.equals(ClassConstants.INTERNAL_METHOD_NAME_CLASS_FOR_NAME) &&
methodType.equals(ClassConstants.INTERNAL_METHOD_TYPE_CLASS_FOR_NAME);
if (isClassForNameInvocation || insideDotClassMethod)
{
return;
}
// Is it a reference to .class? This construct is typically implemented
// as (static) "Class class$(String)" or "Class class$(String, boolean)".
// First check the type, which has to be right to start with.
isClassForNameInvocation =
methodType.equals(ClassConstants.INTERNAL_METHOD_TYPE_DOT_CLASS_JAVAC) ||
methodType.equals(ClassConstants.INTERNAL_METHOD_TYPE_DOT_CLASS_JIKES);
if (!isClassForNameInvocation)
{
return;
}
// Then check if the method perhaps still has its original "class$" name.
isClassForNameInvocation =
methodName.equals(ClassConstants.INTERNAL_METHOD_NAME_DOT_CLASS);
if (isClassForNameInvocation)
{
return;
}
// We're still not sure it's not a reference to .class, since the
// method name may have been changed or obfuscated.
// Perform a more detailed analysis by looking at the referenced method
// itself. Make sure we don't do this recursively.
insideDotClassMethod = true;
methodrefCpInfo.referencedMemberInfoAccept(this);
insideDotClassMethod = false;
}
// Implementations for MemberInfoVisitor.
public void visitProgramFieldInfo(ProgramClassFile programClassFile, ProgramFieldInfo programFieldInfo) {}
public void visitLibraryFieldInfo(LibraryClassFile libraryClassFile, LibraryFieldInfo libraryFieldInfo) {}
public void visitLibraryMethodInfo(LibraryClassFile libraryClassFile, LibraryMethodInfo libraryMethodInfo) {}
/**
* Checks whether the given method is a .class implementation.
*/
public void visitProgramMethodInfo(ProgramClassFile programClassFile, ProgramMethodInfo programMethodInfo)
{
programMethodInfo.attributesAccept(programClassFile, this);
}
// Implementations for AttrInfoVisitor.
public void visitUnknownAttrInfo(ClassFile classFile, UnknownAttrInfo unknownAttrInfo) {}
public void visitInnerClassesAttrInfo(ClassFile classFile, InnerClassesAttrInfo innerClassesAttrInfo) {}
public void visitEnclosingMethodAttrInfo(ClassFile classFile, EnclosingMethodAttrInfo enclosingMethodAttrInfo) {}
public void visitConstantValueAttrInfo(ClassFile classFile, FieldInfo fieldInfo, ConstantValueAttrInfo constantValueAttrInfo) {}
public void visitExceptionsAttrInfo(ClassFile classFile, MethodInfo methodInfo, ExceptionsAttrInfo exceptionsAttrInfo) {}
public void visitLineNumberTableAttrInfo(ClassFile classFile, MethodInfo methodInfo, CodeAttrInfo codeAttrInfo, LineNumberTableAttrInfo lineNumberTableAttrInfo) {}
public void visitLocalVariableTableAttrInfo(ClassFile classFile, MethodInfo methodInfo, CodeAttrInfo codeAttrInfo, LocalVariableTableAttrInfo localVariableTableAttrInfo) {}
public void visitLocalVariableTypeTableAttrInfo(ClassFile classFile, MethodInfo methodInfo, CodeAttrInfo codeAttrInfo, LocalVariableTypeTableAttrInfo localVariableTypeTableAttrInfo) {}
public void visitSourceFileAttrInfo(ClassFile classFile, SourceFileAttrInfo sourceFileAttrInfo) {}
public void visitSourceDirAttrInfo(ClassFile classFile, SourceDirAttrInfo sourceDirAttrInfo) {}
public void visitDeprecatedAttrInfo(ClassFile classFile, DeprecatedAttrInfo deprecatedAttrInfo) {}
public void visitSyntheticAttrInfo(ClassFile classFile, SyntheticAttrInfo syntheticAttrInfo) {}
public void visitSignatureAttrInfo(ClassFile classFile, SignatureAttrInfo signatureAttrInfo) {}
public void visitRuntimeVisibleAnnotationAttrInfo(ClassFile classFile, RuntimeVisibleAnnotationsAttrInfo runtimeVisibleAnnotationsAttrInfo) {}
public void visitRuntimeInvisibleAnnotationAttrInfo(ClassFile classFile, RuntimeInvisibleAnnotationsAttrInfo runtimeInvisibleAnnotationsAttrInfo) {}
public void visitRuntimeVisibleParameterAnnotationAttrInfo(ClassFile classFile, RuntimeVisibleParameterAnnotationsAttrInfo runtimeVisibleParameterAnnotationsAttrInfo) {}
public void visitRuntimeInvisibleParameterAnnotationAttrInfo(ClassFile classFile, RuntimeInvisibleParameterAnnotationsAttrInfo runtimeInvisibleParameterAnnotationsAttrInfo) {}
public void visitAnnotationDefaultAttrInfo(ClassFile classFile, AnnotationDefaultAttrInfo annotationDefaultAttrInfo) {}
/**
* Checks whether the given code is an implementation of class$(String) or
* class$(String, boolean).
*/
public void visitCodeAttrInfo(ClassFile classFile, MethodInfo methodInfo, CodeAttrInfo codeAttrInfo)
{
// Check whether the first instruction recalls the first argument of
// this method.
firstInstructionOk = false;
codeAttrInfo.instructionAccept(classFile, methodInfo, this, 0);
// Continue checking whether the second instruction invokes
// Class.forName.
if (firstInstructionOk)
{
codeAttrInfo.instructionAccept(classFile, methodInfo, this, 1);
}
}
// Implementations for InstructionVisitor.
public void visitSimpleInstruction(ClassFile classFile, MethodInfo methodInfo, CodeAttrInfo codeAttrInfo, int offset, SimpleInstruction simpleInstruction) {}
public void visitBranchInstruction(ClassFile classFile, MethodInfo methodInfo, CodeAttrInfo codeAttrInfo, int offset, BranchInstruction branchInstruction) {}
public void visitTableSwitchInstruction(ClassFile classFile, MethodInfo methodInfo, CodeAttrInfo codeAttrInfo, int offset, TableSwitchInstruction tableSwitchInstruction) {}
public void visitLookUpSwitchInstruction(ClassFile classFile, MethodInfo methodInfo, CodeAttrInfo codeAttrInfo, int offset, LookUpSwitchInstruction lookUpSwitchInstruction) {}
/**
* Checks whether this is a valid first instruction for a .class implementation.
*/
public void visitVariableInstruction(ClassFile classFile, MethodInfo methodInfo, CodeAttrInfo codeAttrInfo, int offset, VariableInstruction variableInstruction)
{
firstInstructionOk = variableInstruction.opcode == InstructionConstants.OP_ALOAD_0;
}
/**
* Checks whether this is a valid second instruction for a .class implementation.
*/
public void visitCpInstruction(ClassFile classFile, MethodInfo methodInfo, CodeAttrInfo codeAttrInfo, int offset, CpInstruction cpInstruction)
{
if (firstInstructionOk &&
cpInstruction.opcode == InstructionConstants.OP_INVOKESTATIC)
{
classFile.constantPoolEntryAccept(cpInstruction.cpIndex, this);
}
}
}
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