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/*
* Copyright (c) 2009, 2019, 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 invokevirtual;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
public class Checker extends shared.Checker {
public Checker(Class staticTargetClass, Class dynamicTargetClass) {
super(staticTargetClass, dynamicTargetClass);
}
public String check (Class callerClass) {
Method m;
try {
// May cause java.lang.VerifyError
m = getOverriddenMethod();
} catch (Throwable e) {
return e.getClass().getName();
}
// Check method accessibility (it's a static property, according to JLS #6.6: Access Control)
if (m != null) {
Method staticTargetMethod = getDeclaredMethod(staticTargetClass);
if (checkAccess(staticTargetMethod, callerClass)) {
// Can't invoke abstract method
if ( Modifier.isAbstract(m.getModifiers())) {
return "java.lang.AbstractMethodError";
}
return String.format("%s.%s"
, m.getDeclaringClass().getSimpleName()
, methodName
);
} else {
// if method isn't accessible, IllegalAccessError is thrown
return "java.lang.IllegalAccessError";
}
} else {
// if method == null, NoSuchMethodError is thrown
return "java.lang.NoSuchMethodError";
}
}
public Method getOverriddenMethod() {
return getOverriddenMethod(staticTargetClass, dynamicTargetClass);
}
public Method getOverriddenMethod(Class staticTarget, Class dynamicTarget) {
// Assertion #1. C is a subclass of A
if (!staticTarget.isAssignableFrom(dynamicTarget)) {
return null;
}
Method staticTargetMethod = getDeclaredMethod(staticTarget);
Method dynamicTargetMethod = getDeclaredMethod(dynamicTarget);
if (staticTarget.equals(dynamicTarget)) {
return staticTargetMethod;
}
// TODO: ? need to find out the right behavior
if (staticTargetMethod == null) {
return null;
}
// Dynamic target doesn't have desired method, so check its superclass
if (dynamicTargetMethod == null) {
return getOverriddenMethod(staticTarget, dynamicTarget.getSuperclass());
} else {
// Private method can't override anything
if (Modifier.isPrivate(dynamicTargetMethod.getModifiers())) {
return getOverriddenMethod(staticTarget, dynamicTarget.getSuperclass());
}
}
// TODO: abstract methods
//Assertion #3.a: A.m2 is PUB || PROT || (PP && PKG(A) == PKG(C))
int staticTargetModifiers = staticTargetMethod.getModifiers();
{
boolean isPublic = Modifier.isPublic(staticTargetModifiers);
boolean isProtected = Modifier.isProtected(staticTargetModifiers);
boolean isPrivate = Modifier.isPrivate(staticTargetModifiers) ;
String staticTargetPkg = getClassPackageName(staticTarget);
String dynamicTargetPkg = getClassPackageName(dynamicTarget);
if (isPublic || isProtected
|| (!isPublic && !isProtected && !isPrivate
&& staticTargetPkg.equals(dynamicTargetPkg))) {
return dynamicTargetMethod;
}
}
// OR
//Assertion #3.b: exists m3: C.m1 != B.m3, A.m2 != B.m3, B.m3 overrides A.m2, C.m1 overrides B.m3
Class ancestor = dynamicTarget.getSuperclass();
while (ancestor != staticTarget) {
Method OverriddenM2 = getOverriddenMethod(staticTarget, ancestor);
Method m3 = getDeclaredMethod(ancestor);
Method m1 = getOverriddenMethod(ancestor, dynamicTarget);
if (m1 != null && m3 != null) {
if (m1.equals(dynamicTargetMethod) && m3.equals(OverriddenM2)) {
return dynamicTargetMethod;
}
} else {
if (m1 == null && dynamicTargetMethod == null
&& m3 == null && OverriddenM2 == null)
{
return null;
}
}
ancestor = ancestor.getSuperclass();
}
return getOverriddenMethod(staticTarget, dynamicTarget.getSuperclass());
}
}
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