readreturnshouldbechecked.java

一个查找java程序里bug的程序的源代码,该程序本身也是java写的,对提高java编程水平很有用

/*
 * FindBugs - Find bugs in Java programs
 * Copyright (C) 2003,2004 University of Maryland
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library 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
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package edu.umd.cs.findbugs.detect;

import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.BytecodeScanningDetector;
import edu.umd.cs.findbugs.visitclass.Constants2;
import org.apache.bcel.Repository;
import org.apache.bcel.classfile.Method;

public class ReadReturnShouldBeChecked extends BytecodeScanningDetector implements Constants2 {

	boolean sawRead = false;
	boolean sawSkip = false;
	int sawAvailable = 0;
	boolean wasBufferedInputStream = false;
	private BugReporter bugReporter;
	private int readPC, skipPC;
	private String lastCallClass = null, lastCallMethod = null, lastCallSig = null;

	public ReadReturnShouldBeChecked(BugReporter bugReporter) {
		this.bugReporter = bugReporter;
	}

	public void visit(Method obj) {
		sawAvailable = 0;
		sawRead = false;
		sawSkip = false;
		//check =  (obj.getAccessFlags() & (ACC_PUBLIC | ACC_PROTECTED)) != 0;
	}


	public void sawOpcode(int seen) {

		boolean isInputStream = false;
		boolean isBufferedInputStream = false;
		if (seen == INVOKEVIRTUAL || seen == INVOKEINTERFACE) {
			lastCallClass = getDottedClassConstantOperand();
			lastCallMethod = getNameConstantOperand();
			lastCallSig = getDottedSigConstantOperand();
	        if (!lastCallClass.startsWith("[")) 
		try {
		   isInputStream 
			= (Repository.instanceOf(lastCallClass,
				"java.io.InputStream")
			 || Repository.implementationOf(lastCallClass,
				"java.io.DataInput")
			 || Repository.instanceOf(lastCallClass,
				"java.io.Reader"))
			&& !Repository.instanceOf(lastCallClass, 
				"java.io.ByteArrayInputStream");
		    isBufferedInputStream = Repository.instanceOf(getDottedClassConstantOperand(), "java.io.BufferedInputStream");
		} catch (ClassNotFoundException e) {
		}
		}

		if (seen == INVOKEVIRTUAL || seen == INVOKEINTERFACE) 
		  if (getNameConstantOperand().equals("available")
		        && getSigConstantOperand().equals("()I")
		      || getNameConstantOperand().startsWith("get")
		        && getNameConstantOperand().endsWith("Length")
		        && getSigConstantOperand().equals("()I")
		      ||  getClassConstantOperand().equals("java/io/File")
		        && getNameConstantOperand().equals("length")
		        && getSigConstantOperand().equals("()J")) {
			sawAvailable = 70;
			return;
		}
		sawAvailable--;
		if ((seen == INVOKEVIRTUAL || seen == INVOKEINTERFACE)
		        && isInputStream
		        && getNameConstantOperand().equals("read")
		        && (
				getSigConstantOperand().equals("([B)I")
				|| getSigConstantOperand().equals("([BII)I")
		            || getSigConstantOperand().equals("([C)I")
		            || getSigConstantOperand().equals("([CII)I")
				)
		        && sawAvailable <= 0) {
			sawRead = true;
			readPC = getPC();
			return;
			}
		if ((seen == INVOKEVIRTUAL || seen == INVOKEINTERFACE)
		        && isInputStream
		        && getNameConstantOperand().equals("skip")
		        && getSigConstantOperand().equals("(J)J")) {
			// if not ByteArrayInput Stream
			//  and either no recent calls to length
			//        or it is a BufferedInputStream
			if (sawAvailable <= 0 || isBufferedInputStream) {
				wasBufferedInputStream = isBufferedInputStream;
				sawSkip = true;
				skipPC = getPC();
				return;
			}
		}

		if ((seen == POP) || (seen == POP2)) {
			if (sawRead) {
				bugReporter.reportBug(new BugInstance(this, "RR_NOT_CHECKED", NORMAL_PRIORITY)
				        .addClassAndMethod(this)
				        .addCalledMethod(lastCallClass, lastCallMethod, lastCallSig)
				        .addSourceLine(this, readPC));
			} else if (sawSkip) {

				bugReporter.reportBug(new BugInstance(this, "SR_NOT_CHECKED",
				        (wasBufferedInputStream ? HIGH_PRIORITY : NORMAL_PRIORITY))
				        .addClassAndMethod(this)
				        .addCalledMethod(lastCallClass, lastCallMethod, lastCallSig)
				        .addSourceLine(this, skipPC));
			}
		}
		sawRead = false;
		sawSkip = false;
	}
}