1 /*
   2  * Copyright (c) 2004, 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 javax.xml.datatype;
  27 
  28 import java.io.File;
  29 import java.security.AccessController;
  30 import java.security.PrivilegedAction;
  31 import java.util.Iterator;
  32 import java.util.Properties;
  33 import java.util.ServiceConfigurationError;
  34 import java.util.ServiceLoader;
  35 import java.util.function.Supplier;
  36 import jdk.xml.internal.SecuritySupport;
  37 
  38 /**
  39  * <p>Implements pluggable Datatypes.</p>
  40  *
  41  * <p>This class is duplicated for each JAXP subpackage so keep it in
  42  * sync.  It is package private for secure class loading.</p>
  43  *
  44  * @author Santiago.PericasGeertsen@sun.com
  45  */
  46 class FactoryFinder {
  47     private static final String DEFAULT_PACKAGE = "com.sun.org.apache.xerces.internal";
  48 
  49     /**
  50      * Internal debug flag.
  51      */
  52     private static boolean debug = false;
  53 
  54     /**
  55      * Cache for properties in java.home/conf/jaxp.properties
  56      */
  57     private final static Properties cacheProps = new Properties();
  58 
  59     /**
  60      * Flag indicating if properties from java.home/conf/jaxp.properties
  61      * have been cached.
  62      */
  63     private static volatile boolean firstTime = true;
  64 
  65     // Define system property "jaxp.debug" to get output
  66     static {
  67         // Use try/catch block to support applets, which throws
  68         // SecurityException out of this code.
  69         try {
  70             String val = SecuritySupport.getSystemProperty("jaxp.debug");
  71             // Allow simply setting the prop to turn on debug
  72             debug = val != null && !"false".equals(val);
  73         }
  74         catch (SecurityException se) {
  75             debug = false;
  76         }
  77     }
  78 
  79     private static void dPrint(Supplier<String> msgGen) {
  80         if (debug) {
  81             System.err.println("JAXP: " + msgGen.get());
  82         }
  83     }
  84 
  85     /**
  86      * Attempt to load a class using the class loader supplied. If that fails
  87      * and fall back is enabled, the current (i.e. bootstrap) class loader is
  88      * tried.
  89      *
  90      * If the class loader supplied is <code>null</code>, first try using the
  91      * context class loader followed by the current (i.e. bootstrap) class
  92      * loader.
  93      *
  94      * Use bootstrap classLoader if cl = null and useBSClsLoader is true
  95      */
  96     static private Class<?> getProviderClass(String className, ClassLoader cl,
  97             boolean doFallback, boolean useBSClsLoader) throws ClassNotFoundException
  98     {
  99         try {
 100             if (cl == null) {
 101                 if (useBSClsLoader) {
 102                     return Class.forName(className, false, FactoryFinder.class.getClassLoader());
 103                 } else {
 104                     cl = SecuritySupport.getContextClassLoader();
 105                     if (cl == null) {
 106                         throw new ClassNotFoundException();
 107                     }
 108                     else {
 109                         return Class.forName(className, false, cl);
 110                     }
 111                 }
 112             }
 113             else {
 114                 return Class.forName(className, false, cl);
 115             }
 116         }
 117         catch (ClassNotFoundException e1) {
 118             if (doFallback) {
 119                 // Use current class loader - should always be bootstrap CL
 120                 return Class.forName(className, false, FactoryFinder.class.getClassLoader());
 121             }
 122             else {
 123                 throw e1;
 124             }
 125         }
 126     }
 127 
 128     /**
 129      * Create an instance of a class. Delegates to method
 130      * <code>getProviderClass()</code> in order to load the class.
 131      *
 132      * @param type Base class / Service interface  of the factory to
 133      *             instantiate.
 134      *
 135      * @param className Name of the concrete class corresponding to the
 136      * service provider
 137      *
 138      * @param cl <code>ClassLoader</code> used to load the factory class. If <code>null</code>
 139      * current <code>Thread</code>'s context classLoader is used to load the factory class.
 140      *
 141      * @param doFallback True if the current ClassLoader should be tried as
 142      * a fallback if the class is not found using cl
 143      */
 144     static <T> T newInstance(Class<T> type, String className, ClassLoader cl, boolean doFallback)
 145         throws  DatatypeConfigurationException
 146     {
 147         return newInstance(type, className, cl, doFallback, false);
 148     }
 149 
 150     /**
 151      * Create an instance of a class. Delegates to method
 152      * <code>getProviderClass()</code> in order to load the class.
 153      *
 154      * @param type Base class / Service interface  of the factory to
 155      *             instantiate.
 156      *
 157      * @param className Name of the concrete class corresponding to the
 158      * service provider
 159      *
 160      * @param cl ClassLoader to use to load the class, null means to use
 161      * the bootstrap ClassLoader
 162      *
 163      * @param doFallback True if the current ClassLoader should be tried as
 164      * a fallback if the class is not found using cl
 165      *
 166      * @param useBSClsLoader True if cl=null actually meant bootstrap classLoader. This parameter
 167      * is needed since DocumentBuilderFactory/SAXParserFactory defined null as context classLoader.
 168      */
 169     static <T> T newInstance(Class<T> type, String className, ClassLoader cl,
 170             boolean doFallback, boolean useBSClsLoader)
 171         throws DatatypeConfigurationException
 172     {
 173         assert type != null;
 174 
 175         // make sure we have access to restricted packages
 176         if (System.getSecurityManager() != null) {
 177             if (className != null && className.startsWith(DEFAULT_PACKAGE)) {
 178                 cl = null;
 179                 useBSClsLoader = true;
 180             }
 181         }
 182 
 183         try {
 184             Class<?> providerClass = getProviderClass(className, cl, doFallback, useBSClsLoader);
 185             if (!type.isAssignableFrom(providerClass)) {
 186                 throw new ClassCastException(className + " cannot be cast to " + type.getName());
 187             }
 188             Object instance = providerClass.getConstructor().newInstance();
 189             final ClassLoader clD = cl;
 190             dPrint(()->"created new instance of " + providerClass +
 191                        " using ClassLoader: " + clD);
 192             return type.cast(instance);
 193         }
 194         catch (ClassNotFoundException x) {
 195             throw new DatatypeConfigurationException(
 196                 "Provider " + className + " not found", x);
 197         }
 198         catch (Exception x) {
 199             throw new DatatypeConfigurationException(
 200                 "Provider " + className + " could not be instantiated: " + x,
 201                 x);
 202         }
 203     }
 204 
 205     /**
 206      * Finds the implementation Class object in the specified order.  Main
 207      * entry point.
 208      * @return Class object of factory, never null
 209      *
 210      * @param type                  Base class / Service interface  of the
 211      *                              factory to find.
 212      * @param fallbackClassName     Implementation class name, if nothing else
 213      *                              is found.  Use null to mean no fallback.
 214      *
 215      * Package private so this code can be shared.
 216      */
 217     static <T> T find(Class<T> type, String fallbackClassName)
 218         throws DatatypeConfigurationException
 219     {
 220         final String factoryId = type.getName();
 221         dPrint(()->"find factoryId =" + factoryId);
 222 
 223         // Use the system property first
 224         try {
 225             String systemProp = SecuritySupport.getSystemProperty(factoryId);
 226             if (systemProp != null) {
 227                 dPrint(()->"found system property, value=" + systemProp);
 228                 return newInstance(type, systemProp, null, true);
 229             }
 230         }
 231         catch (SecurityException se) {
 232             if (debug) se.printStackTrace();
 233         }
 234 
 235         // try to read from $java.home/conf/jaxp.properties
 236         try {
 237             if (firstTime) {
 238                 synchronized (cacheProps) {
 239                     if (firstTime) {
 240                         String configFile = SecuritySupport.getSystemProperty("java.home") + File.separator +
 241                             "conf" + File.separator + "jaxp.properties";
 242                         File f = new File(configFile);
 243                         firstTime = false;
 244                         if (SecuritySupport.doesFileExist(f)) {
 245                             dPrint(()->"Read properties file "+f);
 246                             cacheProps.load(SecuritySupport.getFileInputStream(f));
 247                         }
 248                     }
 249                 }
 250             }
 251             final String factoryClassName = cacheProps.getProperty(factoryId);
 252 
 253             if (factoryClassName != null) {
 254                 dPrint(()->"found in ${java.home}/conf/jaxp.properties, value=" + factoryClassName);
 255                 return newInstance(type, factoryClassName, null, true);
 256             }
 257         }
 258         catch (Exception ex) {
 259             if (debug) ex.printStackTrace();
 260         }
 261 
 262         // Try Jar Service Provider Mechanism
 263         final T provider = findServiceProvider(type);
 264         if (provider != null) {
 265             return provider;
 266         }
 267         if (fallbackClassName == null) {
 268             throw new DatatypeConfigurationException(
 269                 "Provider for " + factoryId + " cannot be found");
 270         }
 271 
 272         dPrint(()->"loaded from fallback value: " + fallbackClassName);
 273         return newInstance(type, fallbackClassName, null, true);
 274     }
 275 
 276     /*
 277      * Try to find provider using the ServiceLoader API
 278      *
 279      * @param type Base class / Service interface  of the factory to find.
 280      *
 281      * @return instance of provider class if found or null
 282      */
 283     private static <T> T findServiceProvider(final Class<T> type)
 284             throws DatatypeConfigurationException
 285     {
 286         try {
 287             return AccessController.doPrivileged(new PrivilegedAction<T>() {
 288                 public T run() {
 289                     final ServiceLoader<T> serviceLoader = ServiceLoader.load(type);
 290                     final Iterator<T> iterator = serviceLoader.iterator();
 291                     if (iterator.hasNext()) {
 292                         return iterator.next();
 293                     } else {
 294                         return null;
 295                     }
 296                 }
 297             });
 298         } catch(ServiceConfigurationError e) {
 299             final DatatypeConfigurationException error =
 300                     new DatatypeConfigurationException(
 301                         "Provider for " + type + " cannot be found", e);
 302             throw error;
 303         }
 304     }
 305 
 306 }
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