1 /*
   2  * Copyright (c) 1997, 2017, 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 com.sun.xml.internal.bind.v2.runtime.reflect.opt;
  27 
  28 import java.io.InputStream;
  29 import java.util.logging.Level;
  30 import java.util.logging.Logger;
  31 
  32 import com.sun.xml.internal.bind.Util;
  33 import com.sun.xml.internal.bind.v2.bytecode.ClassTailor;
  34 
  35 /**
  36  * @author Kohsuke Kawaguchi
  37  */
  38 class AccessorInjector {
  39 
  40     private static final Logger logger = Util.getClassLogger();
  41 
  42     protected static final boolean noOptimize =
  43         Util.getSystemProperty(ClassTailor.class.getName()+".noOptimize")!=null;
  44 
  45     static {
  46         if(noOptimize)
  47             logger.info("The optimized code generation is disabled");
  48     }
  49 
  50     /**
  51      * Loads the optimized class and returns it.
  52      *
  53      * @return null
  54      *      if it fails for some reason.
  55      */
  56     public static Class<?> prepare(
  57         Class beanClass, String templateClassName, String newClassName, String... replacements ) {
  58 
  59         if(noOptimize)
  60             return null;
  61 
  62         try {
  63             ClassLoader cl = SecureLoader.getClassClassLoader(beanClass);
  64             if(cl==null)    return null;    // how do I inject classes to this "null" class loader? for now, back off.
  65 
  66             Class c = Injector.find(cl,newClassName);
  67             if (c==null) {
  68                 byte[] image = tailor(templateClassName,newClassName,replacements);
  69                 if (image==null) {
  70                     return null;
  71                 }
  72                 c = Injector.inject(cl,newClassName,image);
  73                 if (c == null) {
  74                     Injector.find(cl, newClassName);
  75                 }
  76             }
  77             return c;
  78         } catch(SecurityException e) {
  79             // we don't have enough permission to do this
  80             logger.log(Level.INFO,"Unable to create an optimized TransducedAccessor ",e);
  81             return null;
  82         }
  83     }
  84 
  85 
  86     /**
  87      * Customizes a class file by replacing constant pools.
  88      *
  89      * @param templateClassName
  90      *      The resource that contains the template class file.
  91      * @param replacements
  92      *      A list of pair of strings that specify the substitution
  93      *      {@code String[]{search_0, replace_0, search_1, replace_1, ..., search_n, replace_n }
  94      *
  95      *      The search strings found in the constant pool will be replaced by the corresponding
  96      *      replacement string.
  97      */
  98     private static byte[] tailor( String templateClassName, String newClassName, String... replacements ) {
  99         InputStream resource;
 100         if(CLASS_LOADER!=null)
 101             resource = CLASS_LOADER.getResourceAsStream(templateClassName+".class");
 102         else
 103             resource = ClassLoader.getSystemResourceAsStream(templateClassName+".class");
 104         if(resource==null)
 105             return null;
 106 
 107         return ClassTailor.tailor(resource,templateClassName,newClassName,replacements);
 108     }
 109 
 110     private static final ClassLoader CLASS_LOADER = SecureLoader.getClassClassLoader(AccessorInjector.class);
 111 
 112 }