1 /*
   2  * Copyright (c) 2005, 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.stream;
  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 streams.</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
  45  */
  46 class FactoryFinder {
  47     // Check we have access to package.
  48     private static final String DEFAULT_PACKAGE = "com.sun.xml.internal.";
  49 
  50     /**
  51      * Internal debug flag.
  52      */
  53     private static boolean debug = false;
  54 
  55     /**
  56      * Cache for properties in java.home/conf/jaxp.properties
  57      */
  58     final private static Properties cacheProps = new Properties();
  59 
  60     /**
  61      * Flag indicating if properties from java.home/conf/jaxp.properties
  62      * have been cached.
  63      */
  64     private static volatile boolean firstTime = true;
  65 
  66     // Define system property "jaxp.debug" to get output
  67     static {
  68         // Use try/catch block to support applets, which throws
  69         // SecurityException out of this code.
  70         try {
  71             String val = SecuritySupport.getSystemProperty("jaxp.debug");
  72             // Allow simply setting the prop to turn on debug
  73             debug = val != null && !"false".equals(val);
  74         }
  75         catch (SecurityException se) {
  76             debug = false;
  77         }
  78     }
  79 
  80     private static void dPrint(Supplier<String> msgGen) {
  81         if (debug) {
  82             System.err.println("JAXP: " + msgGen.get());
  83         }
  84     }
  85 
  86     /**
  87      * Attempt to load a class using the class loader supplied. If that fails
  88      * and fall back is enabled, the current (i.e. bootstrap) class loader is
  89      * tried.
  90      *
  91      * If the class loader supplied is <code>null</code>, first try using the
  92      * context class loader followed by the current (i.e. bootstrap) class
  93      * loader.
  94      *
  95      * Use bootstrap classLoader if cl = null and useBSClsLoader is true
  96      */
  97     static private Class<?> getProviderClass(String className, ClassLoader cl,
  98             boolean doFallback, boolean useBSClsLoader) throws ClassNotFoundException
  99     {
 100         try {
 101             if (cl == null) {
 102                 if (useBSClsLoader) {
 103                     return Class.forName(className, false, FactoryFinder.class.getClassLoader());
 104                 } else {
 105                     cl = SecuritySupport.getContextClassLoader();
 106                     if (cl == null) {
 107                         throw new ClassNotFoundException();
 108                     }
 109                     else {
 110                         return Class.forName(className, false, cl);
 111                     }
 112                 }
 113             }
 114             else {
 115                 return Class.forName(className, false, cl);
 116             }
 117         }
 118         catch (ClassNotFoundException e1) {
 119             if (doFallback) {
 120                 // Use current class loader - should always be bootstrap CL
 121                 return Class.forName(className, false, FactoryFinder.class.getClassLoader());
 122             }
 123             else {
 124                 throw e1;
 125             }
 126         }
 127     }
 128 
 129     /**
 130      * Create an instance of a class. Delegates to method
 131      * <code>getProviderClass()</code> in order to load the class.
 132      *
 133      * @param type Base class / Service interface  of the factory to
 134      *             instantiate.
 135      *
 136      * @param className Name of the concrete class corresponding to the
 137      * service provider
 138      *
 139      * @param cl <code>ClassLoader</code> used to load the factory class. If <code>null</code>
 140      * current <code>Thread</code>'s context classLoader is used to load the factory class.
 141      *
 142      * @param doFallback True if the current ClassLoader should be tried as
 143      * a fallback if the class is not found using cl
 144      */
 145     static <T> T newInstance(Class<T> type, String className, ClassLoader cl, boolean doFallback)
 146         throws FactoryConfigurationError
 147     {
 148         return newInstance(type, className, cl, doFallback, false);
 149     }
 150 
 151     /**
 152      * Create an instance of a class. Delegates to method
 153      * <code>getProviderClass()</code> in order to load the class.
 154      *
 155      * @param type Base class / Service interface  of the factory to
 156      *             instantiate.
 157      *
 158      * @param className Name of the concrete class corresponding to the
 159      * service provider
 160      *
 161      * @param cl <code>ClassLoader</code> used to load the factory class. If <code>null</code>
 162      * current <code>Thread</code>'s context classLoader is used to load the factory class.
 163      *
 164      * @param doFallback True if the current ClassLoader should be tried as
 165      * a fallback if the class is not found using cl
 166      *
 167      * @param useBSClsLoader True if cl=null actually meant bootstrap classLoader. This parameter
 168      * is needed since DocumentBuilderFactory/SAXParserFactory defined null as context classLoader.
 169      */
 170     static <T> T newInstance(Class<T> type, String className, ClassLoader cl,
 171                               boolean doFallback, boolean useBSClsLoader)
 172         throws FactoryConfigurationError
 173     {
 174         assert type != null;
 175 
 176         // make sure we have access to restricted packages
 177         if (System.getSecurityManager() != null) {
 178             if (className != null && className.startsWith(DEFAULT_PACKAGE)) {
 179                 cl = null;
 180                 useBSClsLoader = true;
 181             }
 182         }
 183 
 184         try {
 185             Class<?> providerClass = getProviderClass(className, cl, doFallback, useBSClsLoader);
 186             if (!type.isAssignableFrom(providerClass)) {
 187                 throw new ClassCastException(className + " cannot be cast to " + type.getName());
 188             }
 189             Object instance = providerClass.getConstructor().newInstance();
 190             final ClassLoader clD = cl;
 191             dPrint(()->"created new instance of " + providerClass +
 192                        " using ClassLoader: " + clD);
 193             return type.cast(instance);
 194         }
 195         catch (ClassNotFoundException x) {
 196             throw new FactoryConfigurationError(
 197                 "Provider " + className + " not found", x);
 198         }
 199         catch (Exception x) {
 200             throw new FactoryConfigurationError(
 201                 "Provider " + className + " could not be instantiated: " + x,
 202                 x);
 203         }
 204     }
 205 
 206     /**
 207      * Finds the implementation Class object in the specified order.
 208      *
 209      * @return Class object of factory, never null
 210      *
 211      * @param type                  Base class / Service interface  of the
 212      *                              factory to find.
 213      *
 214      * @param fallbackClassName     Implementation class name, if nothing else
 215      *                              is found.  Use null to mean no fallback.
 216      *
 217      * Package private so this code can be shared.
 218      */
 219     static <T> T find(Class<T> type, String fallbackClassName)
 220         throws FactoryConfigurationError
 221     {
 222         return find(type, type.getName(), null, fallbackClassName);
 223     }
 224 
 225     /**
 226      * Finds the implementation Class object in the specified order.  Main
 227      * entry point.
 228      * @return Class object of factory, never null
 229      *
 230      * @param type                  Base class / Service interface  of the
 231      *                              factory to find.
 232      *
 233      * @param factoryId             Name of the factory to find, same as
 234      *                              a property name
 235      *
 236      * @param cl                    ClassLoader to be used to load the class, null means to use
 237      * the bootstrap ClassLoader
 238      *
 239      * @param fallbackClassName     Implementation class name, if nothing else
 240      *                              is found.  Use null to mean no fallback.
 241      *
 242      * Package private so this code can be shared.
 243      */
 244     static <T> T find(Class<T> type, String factoryId, ClassLoader cl, String fallbackClassName)
 245         throws FactoryConfigurationError
 246     {
 247         dPrint(()->"find factoryId =" + factoryId);
 248 
 249         // Use the system property first
 250         try {
 251 
 252             final String systemProp;
 253             if (type.getName().equals(factoryId)) {
 254                 systemProp = SecuritySupport.getSystemProperty(factoryId);
 255             } else {
 256                 systemProp = System.getProperty(factoryId);
 257             }
 258             if (systemProp != null) {
 259                 dPrint(()->"found system property, value=" + systemProp);
 260                 return newInstance(type, systemProp, cl, true);
 261             }
 262         }
 263         catch (SecurityException se) {
 264             throw new FactoryConfigurationError(
 265                     "Failed to read factoryId '" + factoryId + "'", se);
 266         }
 267 
 268         // Try read $java.home/conf/stax.properties followed by
 269         // $java.home/conf/jaxp.properties if former not present
 270         String configFile = null;
 271         try {
 272             if (firstTime) {
 273                 synchronized (cacheProps) {
 274                     if (firstTime) {
 275                         configFile = SecuritySupport.getSystemProperty("java.home") + File.separator +
 276                             "conf" + File.separator + "stax.properties";
 277                         final File fStax = new File(configFile);
 278                         firstTime = false;
 279                         if (SecuritySupport.doesFileExist(fStax)) {
 280                             dPrint(()->"Read properties file "+fStax);
 281                             cacheProps.load(SecuritySupport.getFileInputStream(fStax));
 282                         }
 283                         else {
 284                             configFile = SecuritySupport.getSystemProperty("java.home") + File.separator +
 285                                 "conf" + File.separator + "jaxp.properties";
 286                             final File fJaxp = new File(configFile);
 287                             if (SecuritySupport.doesFileExist(fJaxp)) {
 288                                 dPrint(()->"Read properties file "+fJaxp);
 289                                 cacheProps.load(SecuritySupport.getFileInputStream(fJaxp));
 290                             }
 291                         }
 292                     }
 293                 }
 294             }
 295             final String factoryClassName = cacheProps.getProperty(factoryId);
 296 
 297             if (factoryClassName != null) {
 298                 final String foundIn = configFile;
 299                 dPrint(()->"found in " + foundIn + " value=" + factoryClassName);
 300                 return newInstance(type, factoryClassName, cl, true);
 301             }
 302         }
 303         catch (Exception ex) {
 304             if (debug) ex.printStackTrace();
 305         }
 306 
 307         if (type.getName().equals(factoryId)) {
 308             // Try Jar Service Provider Mechanism
 309             final T provider = findServiceProvider(type, cl);
 310             if (provider != null) {
 311                 return provider;
 312             }
 313         } else {
 314             // We're in the case where a 'custom' factoryId was provided,
 315             // and in every case where that happens, we expect that
 316             // fallbackClassName will be null.
 317             assert fallbackClassName == null;
 318         }
 319         if (fallbackClassName == null) {
 320             throw new FactoryConfigurationError(
 321                 "Provider for " + factoryId + " cannot be found", null);
 322         }
 323 
 324         dPrint(()->"loaded from fallback value: " + fallbackClassName);
 325         return newInstance(type, fallbackClassName, cl, true);
 326     }
 327 
 328     /*
 329      * Try to find provider using the ServiceLoader API
 330      *
 331      * @param type Base class / Service interface  of the factory to find.
 332      *
 333      * @return instance of provider class if found or null
 334      */
 335     private static <T> T findServiceProvider(final Class<T> type, final ClassLoader cl) {
 336         try {
 337             return AccessController.doPrivileged(new PrivilegedAction<T>() {
 338                 @Override
 339                 public T run() {
 340                     final ServiceLoader<T> serviceLoader;
 341                     if (cl == null) {
 342                         //the current thread's context class loader
 343                         serviceLoader = ServiceLoader.load(type);
 344                     } else {
 345                         serviceLoader = ServiceLoader.load(type, cl);
 346                     }
 347                     final Iterator<T> iterator = serviceLoader.iterator();
 348                     if (iterator.hasNext()) {
 349                         return iterator.next();
 350                     } else {
 351                         return null;
 352                     }
 353                 }
 354             });
 355         } catch(ServiceConfigurationError e) {
 356             // It is not possible to wrap an error directly in
 357             // FactoryConfigurationError - so we need to wrap the
 358             // ServiceConfigurationError in a RuntimeException.
 359             // The alternative would be to modify the logic in
 360             // FactoryConfigurationError to allow setting a
 361             // Throwable as the cause, but that could cause
 362             // compatibility issues down the road.
 363             final RuntimeException x = new RuntimeException(
 364                     "Provider for " + type + " cannot be created", e);
 365             final FactoryConfigurationError error =
 366                     new FactoryConfigurationError(x, x.getMessage());
 367             throw error;
 368           }
 369       }
 370 
 371 }
--- EOF ---