1 /*
   2  * Copyright (c) 2015, 2016, 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.lang.reflect.Modifier;
  29 import java.io.IOException;
  30 import java.util.ArrayList;
  31 import java.util.Collections;
  32 import java.util.LinkedHashMap;
  33 import java.util.List;
  34 import java.util.Map;
  35 import java.util.Set;
  36 import jdk.nashorn.internal.runtime.Context;
  37 
  38 /**
  39  * Abstract helper class to compute properties of a Java package object. Properties of
  40  * package object are (simple) top level class names in that java package and
  41  * immediate subpackages of that package.
  42  */
  43 abstract class PackagesHelper {
  44     private final Context context;
  45 
  46     /**
  47      * Construct a new PackagesHelper.
  48      *
  49      * @param context the current Nashorn Context
  50      */
  51     PackagesHelper(final Context context) throws IOException {
  52         this.context = context;
  53     }
  54 
  55     static PackagesHelper create(final Context context) throws IOException {
  56         return isJavacHelperAvailable()? new JavacPackagesHelper(context) : new JrtPackagesHelper(context);
  57     }
  58 
  59     // LRU cache for java package properties lists
  60     private final LinkedHashMap<String, List<String>> propsCache =
  61         new LinkedHashMap<String, List<String>>(32, 0.75f, true) {
  62             private static final int CACHE_SIZE = 100;
  63             private static final long serialVersionUID = 1;
  64 
  65             @Override
  66             protected boolean removeEldestEntry(final Map.Entry<String, List<String>> eldest) {
  67                 return size() > CACHE_SIZE;
  68             }
  69         };
  70 
  71     /**
  72      * Return the list of properties of the given Java package or package prefix
  73      *
  74      * @param pkg Java package name or package prefix name
  75      * @return the list of properties of the given Java package or package prefix
  76      */
  77     final List<String> getPackageProperties(final String pkg) {
  78         // check the cache first
  79         if (propsCache.containsKey(pkg)) {
  80             return propsCache.get(pkg);
  81         }
  82 
  83         try {
  84             // make sorted list of properties
  85             final List<String> props = new ArrayList<>(listPackage(pkg));
  86             Collections.sort(props);
  87             propsCache.put(pkg, props);
  88             return props;
  89         } catch (final IOException exp) {
  90             if (Main.DEBUG) {
  91                 exp.printStackTrace();
  92             }
  93             return Collections.<String>emptyList();
  94         }
  95     }
  96 
  97     /**
  98      * Close resources (like file system) used, if any.
  99      */
 100     abstract void close() throws IOException;
 101 
 102     /**
 103      * Return the set of properties of a given package object.
 104      *
 105      * @param pkg package start string
 106      * @return set of properties of the given Java package
 107      */
 108     abstract Set<String> listPackage(final String pkg) throws IOException;
 109 
 110     final boolean isClassAccessible(final String className) {
 111         try {
 112             final Class<?> clz = context.findClass(className);
 113             return Modifier.isPublic(clz.getModifiers());
 114         } catch (final ClassNotFoundException cnfe) {
 115         }
 116         return false;
 117     }
 118 
 119     final boolean isPackageAccessible(final String pkgName) {
 120         try {
 121             Context.checkPackageAccess(pkgName);
 122             return true;
 123         } catch (final SecurityException se) {
 124             return false;
 125         }
 126     }
 127 
 128     private static boolean isJavacHelperAvailable() {
 129         try {
 130             boolean result = JavacPackagesHelper.isAvailable();
 131             if (Main.DEBUG && !result) {
 132                 System.err.println("javac packages helper is not available");
 133             }
 134             return result;
 135         } catch (final LinkageError err) {
 136             if (Main.DEBUG) {
 137                 System.err.println("javac packages helper is not available");
 138                 err.printStackTrace();
 139             }
 140             return false;
 141         }
 142     }
 143 }