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Dynamic scripting for the JVM
/***
* ASM: a very small and fast Java bytecode manipulation framework
* Copyright (c) 2000-2011 INRIA, France Telecom
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.snapscript.asm.tree.analysis;
import java.util.List;
import org.snapscript.asm.Type;
/**
* An extended {@link BasicVerifier} that performs more precise verifications.
* This verifier computes exact class types, instead of using a single "object
* reference" type (as done in the {@link BasicVerifier}).
*
* @author Eric Bruneton
* @author Bing Ran
*/
public class SimpleVerifier extends BasicVerifier {
/**
* The class that is verified.
*/
private final Type currentClass;
/**
* The super class of the class that is verified.
*/
private final Type currentSuperClass;
/**
* The interfaces implemented by the class that is verified.
*/
private final List currentClassInterfaces;
/**
* If the class that is verified is an interface.
*/
private final boolean isInterface;
/**
* The loader to use for referenced classes.
*/
private ClassLoader loader = getClass().getClassLoader();
/**
* Constructs a new {@link SimpleVerifier}.
*/
public SimpleVerifier() {
this(null, null, false);
}
/**
* Constructs a new {@link SimpleVerifier} to verify a specific class. This
* class will not be loaded into the JVM since it may be incorrect.
*
* @param currentClass
* the class that is verified.
* @param currentSuperClass
* the super class of the class that is verified.
* @param isInterface
* if the class that is verified is an interface.
*/
public SimpleVerifier(final Type currentClass,
final Type currentSuperClass, final boolean isInterface) {
this(currentClass, currentSuperClass, null, isInterface);
}
/**
* Constructs a new {@link SimpleVerifier} to verify a specific class. This
* class will not be loaded into the JVM since it may be incorrect.
*
* @param currentClass
* the class that is verified.
* @param currentSuperClass
* the super class of the class that is verified.
* @param currentClassInterfaces
* the interfaces implemented by the class that is verified.
* @param isInterface
* if the class that is verified is an interface.
*/
public SimpleVerifier(final Type currentClass,
final Type currentSuperClass,
final List currentClassInterfaces, final boolean isInterface) {
this(ASM5, currentClass, currentSuperClass, currentClassInterfaces,
isInterface);
}
protected SimpleVerifier(final int api, final Type currentClass,
final Type currentSuperClass,
final List currentClassInterfaces, final boolean isInterface) {
super(api);
this.currentClass = currentClass;
this.currentSuperClass = currentSuperClass;
this.currentClassInterfaces = currentClassInterfaces;
this.isInterface = isInterface;
}
/**
* Set the ClassLoader which will be used to load referenced
* classes. This is useful if you are verifying multiple interdependent
* classes.
*
* @param loader
* a ClassLoader to use
*/
public void setClassLoader(final ClassLoader loader) {
this.loader = loader;
}
@Override
public BasicValue newValue(final Type type) {
if (type == null) {
return BasicValue.UNINITIALIZED_VALUE;
}
boolean isArray = type.getSort() == Type.ARRAY;
if (isArray) {
switch (type.getElementType().getSort()) {
case Type.BOOLEAN:
case Type.CHAR:
case Type.BYTE:
case Type.SHORT:
return new BasicValue(type);
}
}
BasicValue v = super.newValue(type);
if (BasicValue.REFERENCE_VALUE.equals(v)) {
if (isArray) {
v = newValue(type.getElementType());
String desc = v.getType().getDescriptor();
for (int i = 0; i < type.getDimensions(); ++i) {
desc = '[' + desc;
}
v = new BasicValue(Type.getType(desc));
} else {
v = new BasicValue(type);
}
}
return v;
}
@Override
protected boolean isArrayValue(final BasicValue value) {
Type t = value.getType();
return t != null
&& ("Lnull;".equals(t.getDescriptor()) || t.getSort() == Type.ARRAY);
}
@Override
protected BasicValue getElementValue(final BasicValue objectArrayValue)
throws AnalyzerException {
Type arrayType = objectArrayValue.getType();
if (arrayType != null) {
if (arrayType.getSort() == Type.ARRAY) {
return newValue(Type.getType(arrayType.getDescriptor()
.substring(1)));
} else if ("Lnull;".equals(arrayType.getDescriptor())) {
return objectArrayValue;
}
}
throw new Error("Internal error");
}
@Override
protected boolean isSubTypeOf(final BasicValue value,
final BasicValue expected) {
Type expectedType = expected.getType();
Type type = value.getType();
switch (expectedType.getSort()) {
case Type.INT:
case Type.FLOAT:
case Type.LONG:
case Type.DOUBLE:
return type.equals(expectedType);
case Type.ARRAY:
case Type.OBJECT:
if ("Lnull;".equals(type.getDescriptor())) {
return true;
} else if (type.getSort() == Type.OBJECT
|| type.getSort() == Type.ARRAY) {
return isAssignableFrom(expectedType, type);
} else {
return false;
}
default:
throw new Error("Internal error");
}
}
@Override
public BasicValue merge(final BasicValue v, final BasicValue w) {
if (!v.equals(w)) {
Type t = v.getType();
Type u = w.getType();
if (t != null
&& (t.getSort() == Type.OBJECT || t.getSort() == Type.ARRAY)) {
if (u != null
&& (u.getSort() == Type.OBJECT || u.getSort() == Type.ARRAY)) {
if ("Lnull;".equals(t.getDescriptor())) {
return w;
}
if ("Lnull;".equals(u.getDescriptor())) {
return v;
}
if (isAssignableFrom(t, u)) {
return v;
}
if (isAssignableFrom(u, t)) {
return w;
}
// TODO case of array classes of the same dimension
// TODO should we look also for a common super interface?
// problem: there may be several possible common super
// interfaces
do {
if (t == null || isInterface(t)) {
return BasicValue.REFERENCE_VALUE;
}
t = getSuperClass(t);
if (isAssignableFrom(t, u)) {
return newValue(t);
}
} while (true);
}
}
return BasicValue.UNINITIALIZED_VALUE;
}
return v;
}
protected boolean isInterface(final Type t) {
if (currentClass != null && t.equals(currentClass)) {
return isInterface;
}
return getClass(t).isInterface();
}
protected Type getSuperClass(final Type t) {
if (currentClass != null && t.equals(currentClass)) {
return currentSuperClass;
}
Class c = getClass(t).getSuperclass();
return c == null ? null : Type.getType(c);
}
protected boolean isAssignableFrom(final Type t, final Type u) {
if (t.equals(u)) {
return true;
}
if (currentClass != null && t.equals(currentClass)) {
if (getSuperClass(u) == null) {
return false;
} else {
if (isInterface) {
return u.getSort() == Type.OBJECT
|| u.getSort() == Type.ARRAY;
}
return isAssignableFrom(t, getSuperClass(u));
}
}
if (currentClass != null && u.equals(currentClass)) {
if (isAssignableFrom(t, currentSuperClass)) {
return true;
}
if (currentClassInterfaces != null) {
for (int i = 0; i < currentClassInterfaces.size(); ++i) {
Type v = currentClassInterfaces.get(i);
if (isAssignableFrom(t, v)) {
return true;
}
}
}
return false;
}
Class tc = getClass(t);
if (tc.isInterface()) {
tc = Object.class;
}
return tc.isAssignableFrom(getClass(u));
}
protected Class getClass(final Type t) {
try {
if (t.getSort() == Type.ARRAY) {
return Class.forName(t.getDescriptor().replace('/', '.'),
false, loader);
}
return Class.forName(t.getClassName(), false, loader);
} catch (ClassNotFoundException e) {
throw new RuntimeException(e.toString());
}
}
}