fb-contrib-commit

[Dave B. <dbr...@us...>]

Update of /cvsroot/fb-contrib/fb-contrib/src/com/mebigfatguy/fbcontrib/detect
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv14551/src/com/mebigfatguy/fbcontrib/detect

Added Files:
	LiteralStringComparison.java 
Log Message:
Initial checkin: LSC Detector

--- NEW FILE: LiteralStringComparison.java ---
package com.mebigfatguy.fbcontrib.detect;

import org.apache.bcel.classfile.Code;

import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.BytecodeScanningDetector;
import edu.umd.cs.findbugs.OpcodeStack;

public class LiteralStringComparison extends BytecodeScanningDetector
{
	private BugReporter bugReporter;
	private OpcodeStack stack;
	
	public LiteralStringComparison(BugReporter bugReporter) {
		this.bugReporter = bugReporter;
		stack = new OpcodeStack();
	}
	
	public Object clone() throws CloneNotSupportedException {
		return super.clone();
	}
	
	public void visitCode(Code obj) {
		stack.resetForMethodEntry(this);
		super.visitCode(obj);
	}
	
	public void sawOpcode(int seen) {
		try {
			if ((seen == INVOKEVIRTUAL) && "java/lang/String".equals(getClassConstantOperand())) {
				String calledMethodName = getNameConstantOperand();
				String calledMethodSig = getSigConstantOperand();
				
				if (("equals".equals(calledMethodName) && "(Ljava/lang/Object;)Z".equals(calledMethodSig))
				||  ("compareTo".equals(calledMethodName) && "(Ljava/lang/String;)I".equals(calledMethodSig))) {
					if (stack.getStackDepth() > 0) {
						OpcodeStack.Item itm = stack.getStackItem(0);
						Object constant = itm.getConstant();
						if ((constant != null) && constant.getClass().equals(String.class)) {
							bugReporter.reportBug( new BugInstance( this, "LSC_LITERAL_STRING_COMPARISON", LOW_PRIORITY)
								.addClass(this)
								.addMethod(this)
								.addSourceLine(this));
						}
					}
				}						
			}
		} finally {
			stack.sawOpcode(this, seen);
		}
	}

}