1 /*
   2  * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package jdk.nashorn.tools.jjs;
  27 
  28 import java.io.IOException;
  29 import java.io.File;
  30 import java.util.ArrayList;
  31 import java.util.Collections;
  32 import java.util.EnumSet;
  33 import java.util.HashSet;
  34 import java.util.LinkedHashMap;
  35 import java.util.List;
  36 import java.util.Map;
  37 import java.util.Set;
  38 import java.util.stream.Collectors;
  39 import java.util.stream.Stream;
  40 import javax.tools.JavaCompiler;
  41 import javax.tools.JavaFileManager.Location;
  42 import javax.tools.JavaFileObject;
  43 import javax.tools.StandardJavaFileManager;
  44 import javax.tools.StandardLocation;
  45 import javax.tools.ToolProvider;
  46 
  47 /**
  48  * A helper class to compute properties of a Java package object. Properties of
  49  * package object are (simple) top level class names in that java package and
  50  * immediate subpackages of that package.
  51  */
  52 final class PackagesHelper {
  53     // JavaCompiler may be null on certain platforms (eg. JRE)
  54     private static final JavaCompiler compiler;
  55     static {
  56         // Use javac only if security manager is not around!
  57         compiler = System.getSecurityManager() == null? ToolProvider.getSystemJavaCompiler() : null;
  58     }
  59 
  60     /**
  61      * Is Java package properties helper available?
  62      *
  63      * @return true if package properties support is available
  64      */
  65     static boolean isAvailable() {
  66         return compiler != null;
  67     }
  68 
  69     private final StandardJavaFileManager fm;
  70     private final Set<JavaFileObject.Kind> fileKinds;
  71 
  72     /**
  73      * Construct a new PackagesHelper.
  74      *
  75      * @param classPath Class path to compute properties of java package objects
  76      */
  77     PackagesHelper(final String classPath) throws IOException {
  78         assert isAvailable() : "no java compiler found!";
  79 
  80         fm = compiler.getStandardFileManager(null, null, null);
  81         fileKinds = EnumSet.of(JavaFileObject.Kind.CLASS);
  82 
  83         if (classPath != null && !classPath.isEmpty()) {
  84             fm.setLocation(StandardLocation.CLASS_PATH, getFiles(classPath));
  85         } else {
  86             // no classpath set. Make sure that it is empty and not any default like "."
  87             fm.setLocation(StandardLocation.CLASS_PATH, Collections.<File>emptyList());
  88         }
  89     }
  90 
  91     // LRU cache for java package properties lists
  92     private final LinkedHashMap<String, List<String>> propsCache =
  93         new LinkedHashMap<String, List<String>>(32, 0.75f, true) {
  94             private static final int CACHE_SIZE = 100;
  95             private static final long serialVersionUID = 1;
  96 
  97             @Override
  98             protected boolean removeEldestEntry(final Map.Entry<String, List<String>> eldest) {
  99                 return size() > CACHE_SIZE;
 100             }
 101         };
 102 
 103     /**
 104      * Return the list of properties of the given Java package or package prefix
 105      *
 106      * @param pkg Java package name or package prefix name
 107      * @return the list of properties of the given Java package or package prefix
 108      */
 109     List<String> getPackageProperties(final String pkg) {
 110         // check the cache first
 111         if (propsCache.containsKey(pkg)) {
 112             return propsCache.get(pkg);
 113         }
 114 
 115         try {
 116             // make sorted list of properties
 117             final List<String> props = new ArrayList<>(listPackage(pkg));
 118             Collections.sort(props);
 119             propsCache.put(pkg, props);
 120             return props;
 121         } catch (final IOException exp) {
 122             if (Main.DEBUG) {
 123                 exp.printStackTrace();
 124             }
 125             return Collections.<String>emptyList();
 126         }
 127     }
 128 
 129     public void close() throws IOException {
 130         fm.close();
 131     }
 132 
 133     private Set<String> listPackage(final String pkg) throws IOException {
 134         final Set<String> props = new HashSet<>();
 135         listPackage(StandardLocation.PLATFORM_CLASS_PATH, pkg, props);
 136         listPackage(StandardLocation.CLASS_PATH, pkg, props);
 137         return props;
 138     }
 139 
 140     private void listPackage(final Location loc, final String pkg, final Set<String> props)
 141             throws IOException {
 142         for (JavaFileObject file : fm.list(loc, pkg, fileKinds, true)) {
 143             final String binaryName = fm.inferBinaryName(loc, file);
 144             // does not start with the given package prefix
 145             if (!binaryName.startsWith(pkg + ".")) {
 146                 continue;
 147             }
 148 
 149             final int nextDot = binaryName.indexOf('.', pkg.length() + 1);
 150             final int start = pkg.length() + 1;
 151 
 152             if (nextDot != -1) {
 153                 // subpackage - eg. "regex" for "java.util"
 154                 props.add(binaryName.substring(start, nextDot));
 155             } else {
 156                 // class - filter out nested, inner, anonymous, local classes.
 157                 // Dynalink supported public nested classes as properties of
 158                 // StaticClass object anyway. We don't want to expose those
 159                 // "$" internal names as properties of package object.
 160 
 161                 final String clsName = binaryName.substring(start);
 162                 if (clsName.indexOf('$') == -1) {
 163                     props.add(clsName);
 164                 }
 165             }
 166         }
 167     }
 168 
 169     // return list of File objects for the given class path
 170     private static List<File> getFiles(final String classPath) {
 171         return Stream.of(classPath.split(File.pathSeparator))
 172                     .map(File::new)
 173                     .collect(Collectors.toList());
 174     }
 175 }