#// Usage: jjs getclassnpe.js -- <directory>

/*

 * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 *   - Redistributions of source code must retain the above copyright

 *     notice, this list of conditions and the following disclaimer.

 *

 *   - 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.

 *

 *   - Neither the name of Oracle 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.

 */

/*

 * java.lang.Object.getClass() is sometimes used to do null check. This

 * obfuscating Object.getClass() check relies on non-related intrinsic

 * performance, which is potentially not available everywhere.

 * See also http://cr.openjdk.java.net/~shade/scratch/NullChecks.java

 * This nashorn script checks for such uses in your .java files in the

 * given directory (recursively).

 */

if (arguments.length == 0) {

    print("Usage: jjs getclassnpe.js -- <directory>");

    exit(1);

}

// Java types used

var File = Java.type("java.io.File");

var Files = Java.type("java.nio.file.Files");

var StringArray = Java.type("java.lang.String[]");

var ToolProvider = Java.type("javax.tools.ToolProvider");

var MethodInvocationTree = Java.type("com.sun.source.tree.MethodInvocationTree");

var TreeScanner = Java.type("com.sun.source.util.TreeScanner");

// parse a specific .java file to check if it uses

// Object.getClass() for null check.

function checkGetClassNPE() {

    // get the system compiler tool

    var compiler = ToolProvider.systemJavaCompiler;

    // get standard file manager

    var fileMgr = compiler.getStandardFileManager(null, null, null);

    // Using Java.to convert script array (arguments) to a Java String[]

    var compUnits = fileMgr.getJavaFileObjects(

        Java.to(arguments, StringArray));

    // create a new compilation task

    var task = compiler.getTask(null, fileMgr, null, null, null, compUnits);

    // subclass SimpleTreeVisitor - to check for obj.getClass(); statements

    var GetClassNPEChecker = Java.extend(TreeScanner);

    var visitor = new GetClassNPEChecker() {

        lineMap: null,

        sourceFile: null,

        // save compilation unit details for reporting

        visitCompilationUnit: function(node, p) {

           this.sourceFile = node.sourceFile;

           this.lineMap = node.lineMap;

           return Java.super(visitor).visitCompilationUnit(node, p);

        },

        // look for "foo.getClass();" expression statements

        visitExpressionStatement: function(node, p) {

            var expr = node.expression;

            if (expr instanceof MethodInvocationTree) {

                var name = String(expr.methodSelect.identifier);

                // will match any "getClass" call with zero arguments!

                if (name == "getClass" && expr.arguments.size() == 0) {

                    print(this.sourceFile.getName()

                     + " @ "

                     + this.lineMap.getLineNumber(node.pos)

                     + ":"

                     + this.lineMap.getColumnNumber(node.pos));

                    print("\t", node);

                }

            }

        }

    }

    for each (var cu in task.parse()) {

        cu.accept(visitor, null);

    }

}

// for each ".java" file in the directory (recursively)

function main(dir) {

    Files.walk(dir.toPath()).

      forEach(function(p) {

          var name = p.toFile().absolutePath;

          if (name.endsWith(".java")) {

              try {

                  checkGetClassNPE(p.toFile().getAbsolutePath());

              } catch (e) {

                  print(e);

              }

          }

      });

}

main(new File(arguments[0]));