org.ehoffman.classloader.EvictingStaticTransformer Maven / Gradle / Ivy
/*
* The MIT License
* Copyright © 2016 Rex Hoffman
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package org.ehoffman.classloader;
import java.lang.instrument.ClassFileTransformer;
import java.security.ProtectionDomain;
import java.util.List;
public class EvictingStaticTransformer implements ClassFileTransformer {
private final boolean warnOnly;
private final ClassContainsStaticInitialization asmScanner;
public EvictingStaticTransformer() {
this(false);
}
public EvictingStaticTransformer(boolean warnOnly) {
this.warnOnly = warnOnly;
this.asmScanner = new ClassContainsStaticInitialization();
}
/**
* Potentially print warnings about static state, and potentially throw ClassFormatErrors when static state is found.
*
* @param loader the parent class loader, ignored.
* @param className the name of the class to verify.
* @param classBeingRedefined ignored.
* @param protectionDomain ignored.
* @param classfileBuffer contains the bytes of a java class to be transformed.
* @return always null, or a thrown {@link ClassFormatError}
*/
public byte[] transform(ClassLoader loader, String className, Class classBeingRedefined,
ProtectionDomain protectionDomain, byte[] classfileBuffer) {
List errors = asmScanner.apply(classfileBuffer);
if (errors.size() > 0) {
StringBuffer buffer = new StringBuffer();
buffer.append("Static state found in class ")
.append(className.replace('/', '.'));
if (warnOnly) {
buffer.append(" in non-dev mode this will result in ClassFormatErrors\n");
}
int count = 0;
for (String error : errors) {
buffer.append("Error ").append(++count).append(" : ").append(error).append('\n');
}
if (warnOnly) {
System.err.println(buffer);
} else {
throw new ClassFormatError(buffer.toString());
}
}
return null;
}
}