1 #// Usage: jjs exceptionswallow.js -- <directory>
   2 
   3 /*
   4  * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  *   - Redistributions of source code must retain the above copyright
  11  *     notice, this list of conditions and the following disclaimer.
  12  *
  13  *   - Redistributions in binary form must reproduce the above copyright
  14  *     notice, this list of conditions and the following disclaimer in the
  15  *     documentation and/or other materials provided with the distribution.
  16  *
  17  *   - Neither the name of Oracle nor the names of its
  18  *     contributors may be used to endorse or promote products derived
  19  *     from this software without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
  22  * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  23  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  24  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  25  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  26  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  27  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  28  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  29  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  30  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  31  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  32  */
  33 
  34 // This example demonstrates Java subclassing by Java.extend
  35 // and javac Compiler and Tree API. This example looks for
  36 // empty catch blocks ("exception swallow") and reports those.
  37 
  38 if (arguments.length == 0) {
  39     print("Usage: jjs exceptionswallow.js -- <directory>");
  40     exit(1);
  41 }
  42  
  43 // Java types used
  44 var File = Java.type("java.io.File");
  45 var Files = Java.type("java.nio.file.Files");
  46 var StringArray = Java.type("java.lang.String[]");
  47 var ToolProvider = Java.type("javax.tools.ToolProvider");
  48 var Tree = Java.type("com.sun.source.tree.Tree");
  49 var EmptyStatementTree = Java.type("com.sun.source.tree.EmptyStatementTree");
  50 var Trees = Java.type("com.sun.source.util.Trees");
  51 var TreeScanner = Java.type("com.sun.source.util.TreeScanner");
  52 
  53 // printEmptyCatch
  54 
  55 function printEmptyCatch() {
  56     // get the system compiler tool
  57     var compiler = ToolProvider.systemJavaCompiler;
  58     // get standard file manager
  59     var fileMgr = compiler.getStandardFileManager(null, null, null);
  60     // Using Java.to convert script array (arguments) to a Java String[]
  61     var compUnits = fileMgr.getJavaFileObjects(
  62         Java.to(arguments, StringArray));
  63     // create a new compilation task
  64     var task = compiler.getTask(null, fileMgr, null, null, null, compUnits);
  65 
  66     // SourcePositions object to get positions of AST nodes
  67     var sourcePositions = Trees.instance(task).sourcePositions;
  68 
  69     // subclass SimpleTreeVisitor - to print empty catch
  70     var EmptyCatchFinder = Java.extend(TreeScanner);
  71    
  72     function hasOnlyEmptyStats(stats) {
  73         var itr = stats.iterator();
  74         while (itr.hasNext()) {
  75             if (! (itr.next() instanceof EmptyStatementTree)) {
  76                 return false;
  77             }
  78         }
  79 
  80         return true;
  81     }
  82  
  83     var visitor = new EmptyCatchFinder() {
  84         // current CompilationUnitTree
  85         compUnit: null,
  86         // current LineMap (pos -> line, column)
  87         lineMap: null,
  88         // current compilation unit's file name
  89         fileName: null,
  90 
  91         // overrides of TreeScanner methods
  92 
  93         visitCompilationUnit: function(node, p) {
  94             // capture info about current Compilation unit
  95             this.compUnit = node;
  96             this.lineMap = node.lineMap;
  97             this.fileName = node.sourceFile.name;
  98 
  99             // Using Java.super API to call super class method here
 100             return Java.super(visitor).visitCompilationUnit(node, p);
 101         },
 102 
 103         visitCatch: function (node, p) {
 104             var stats = node.block.statements;
 105             if (stats.empty || hasOnlyEmptyStats(stats)) {
 106                 // print information on this empty catch
 107                 var pos = sourcePositions.getStartPosition(this.compUnit, node);
 108                 var line = this.lineMap.getLineNumber(pos);
 109                 var col = this.lineMap.getColumnNumber(pos);
 110                 print("Exception swallow" + " @ " + this.fileName + ":" + line + ":" + col);
 111                 // print(node);
 112             }
 113         }
 114     }
 115  
 116     for each (var cu in task.parse()) {
 117         cu.accept(visitor, null);
 118     }
 119 }
 120  
 121 // for each ".java" file in directory (recursively) and check it!
 122 function main(dir) {
 123     Files.walk(dir.toPath()).
 124       forEach(function(p) {
 125         var name = p.toFile().absolutePath;
 126         if (name.endsWith(".java")) {
 127             try {
 128                 printEmptyCatch(p.toFile().getAbsolutePath());
 129             } catch (e) {
 130                 print(e);
 131             }
 132         }
 133       });
 134 }
 135  
 136 main(new File(arguments[0]));