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
37 /**
38 * <p>Implements pluggable streams.</p>
39 *
40 * <p>This class is duplicated for each JAXP subpackage so keep it in
41 * sync. It is package private for secure class loading.</p>
42 *
43 * @author Santiago.PericasGeertsen@sun.com
44 */
45 class FactoryFinder {
46 // Check we have access to package.
47 private static final String DEFAULT_PACKAGE = "com.sun.xml.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 final private 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 /**
66 * Security support class use to check access control before
67 * getting certain system resources.
68 */
69 final private static SecuritySupport ss = new SecuritySupport();
70
71 // Define system property "jaxp.debug" to get output
72 static {
73 // Use try/catch block to support applets, which throws
74 // SecurityException out of this code.
75 try {
76 String val = ss.getSystemProperty("jaxp.debug");
77 // Allow simply setting the prop to turn on debug
78 debug = val != null && !"false".equals(val);
79 }
80 catch (SecurityException se) {
81 debug = false;
82 }
83 }
84
85 private static void dPrint(Supplier<String> msgGen) {
86 if (debug) {
87 System.err.println("JAXP: " + msgGen.get());
88 }
89 }
90
91 /**
92 * Attempt to load a class using the class loader supplied. If that fails
93 * and fall back is enabled, the current (i.e. bootstrap) class loader is
94 * tried.
95 *
96 * If the class loader supplied is <code>null</code>, first try using the
97 * context class loader followed by the current (i.e. bootstrap) class
98 * loader.
99 *
100 * Use bootstrap classLoader if cl = null and useBSClsLoader is true
101 */
102 static private Class getProviderClass(String className, ClassLoader cl,
103 boolean doFallback, boolean useBSClsLoader) throws ClassNotFoundException
104 {
105 try {
106 if (cl == null) {
107 if (useBSClsLoader) {
108 return Class.forName(className, false, FactoryFinder.class.getClassLoader());
109 } else {
110 cl = ss.getContextClassLoader();
111 if (cl == null) {
112 throw new ClassNotFoundException();
113 }
114 else {
115 return Class.forName(className, false, cl);
116 }
117 }
118 }
119 else {
120 return Class.forName(className, false, cl);
121 }
122 }
123 catch (ClassNotFoundException e1) {
124 if (doFallback) {
125 // Use current class loader - should always be bootstrap CL
126 return Class.forName(className, false, FactoryFinder.class.getClassLoader());
127 }
128 else {
129 throw e1;
130 }
131 }
132 }
133
134 /**
135 * Create an instance of a class. Delegates to method
136 * <code>getProviderClass()</code> in order to load the class.
137 *
138 * @param type Base class / Service interface of the factory to
139 * instantiate.
140 *
141 * @param className Name of the concrete class corresponding to the
142 * service provider
143 *
144 * @param cl <code>ClassLoader</code> used to load the factory class. If <code>null</code>
145 * current <code>Thread</code>'s context classLoader is used to load the factory class.
146 *
147 * @param doFallback True if the current ClassLoader should be tried as
148 * a fallback if the class is not found using cl
149 */
150 static <T> T newInstance(Class<T> type, String className, ClassLoader cl, boolean doFallback)
151 throws FactoryConfigurationError
152 {
153 return newInstance(type, className, cl, doFallback, false);
154 }
155
156 /**
157 * Create an instance of a class. Delegates to method
158 * <code>getProviderClass()</code> in order to load the class.
159 *
160 * @param type Base class / Service interface of the factory to
161 * instantiate.
162 *
163 * @param className Name of the concrete class corresponding to the
164 * service provider
165 *
166 * @param cl <code>ClassLoader</code> used to load the factory class. If <code>null</code>
167 * current <code>Thread</code>'s context classLoader is used to load the factory class.
168 *
169 * @param doFallback True if the current ClassLoader should be tried as
170 * a fallback if the class is not found using cl
171 *
172 * @param useBSClsLoader True if cl=null actually meant bootstrap classLoader. This parameter
173 * is needed since DocumentBuilderFactory/SAXParserFactory defined null as context classLoader.
174 */
175 static <T> T newInstance(Class<T> type, String className, ClassLoader cl,
176 boolean doFallback, boolean useBSClsLoader)
177 throws FactoryConfigurationError
178 {
179 assert type != null;
180
181 // make sure we have access to restricted packages
182 if (System.getSecurityManager() != null) {
183 if (className != null && className.startsWith(DEFAULT_PACKAGE)) {
184 cl = null;
185 useBSClsLoader = true;
186 }
187 }
188
189 try {
190 Class<?> providerClass = getProviderClass(className, cl, doFallback, useBSClsLoader);
191 if (!type.isAssignableFrom(providerClass)) {
192 throw new ClassCastException(className + " cannot be cast to " + type.getName());
193 }
194 Object instance = providerClass.newInstance();
195 final ClassLoader clD = cl;
196 dPrint(()->"created new instance of " + providerClass +
197 " using ClassLoader: " + clD);
198 return type.cast(instance);
199 }
200 catch (ClassNotFoundException x) {
201 throw new FactoryConfigurationError(
202 "Provider " + className + " not found", x);
203 }
204 catch (Exception x) {
205 throw new FactoryConfigurationError(
206 "Provider " + className + " could not be instantiated: " + x,
207 x);
208 }
209 }
210
211 /**
212 * Finds the implementation Class object in the specified order.
213 *
214 * @return Class object of factory, never null
215 *
216 * @param type Base class / Service interface of the
217 * factory to find.
218 *
219 * @param fallbackClassName Implementation class name, if nothing else
220 * is found. Use null to mean no fallback.
221 *
222 * Package private so this code can be shared.
223 */
224 static <T> T find(Class<T> type, String fallbackClassName)
225 throws FactoryConfigurationError
226 {
227 return find(type, type.getName(), null, fallbackClassName);
228 }
229
230 /**
231 * Finds the implementation Class object in the specified order. Main
232 * entry point.
233 * @return Class object of factory, never null
234 *
235 * @param type Base class / Service interface of the
236 * factory to find.
237 *
238 * @param factoryId Name of the factory to find, same as
239 * a property name
240 *
241 * @param cl ClassLoader to be used to load the class, null means to use
242 * the bootstrap ClassLoader
243 *
244 * @param fallbackClassName Implementation class name, if nothing else
245 * is found. Use null to mean no fallback.
246 *
247 * Package private so this code can be shared.
248 */
249 static <T> T find(Class<T> type, String factoryId, ClassLoader cl, String fallbackClassName)
250 throws FactoryConfigurationError
251 {
252 dPrint(()->"find factoryId =" + factoryId);
253
254 // Use the system property first
255 try {
256
257 final String systemProp;
258 if (type.getName().equals(factoryId)) {
259 systemProp = ss.getSystemProperty(factoryId);
260 } else {
261 systemProp = System.getProperty(factoryId);
262 }
263 if (systemProp != null) {
264 dPrint(()->"found system property, value=" + systemProp);
265 return newInstance(type, systemProp, cl, true);
266 }
267 }
268 catch (SecurityException se) {
269 throw new FactoryConfigurationError(
270 "Failed to read factoryId '" + factoryId + "'", se);
271 }
272
273 // Try read $java.home/conf/stax.properties followed by
274 // $java.home/conf/jaxp.properties if former not present
275 String configFile = null;
276 try {
277 if (firstTime) {
278 synchronized (cacheProps) {
279 if (firstTime) {
280 configFile = ss.getSystemProperty("java.home") + File.separator +
281 "conf" + File.separator + "stax.properties";
282 final File fStax = new File(configFile);
283 firstTime = false;
284 if (ss.doesFileExist(fStax)) {
285 dPrint(()->"Read properties file "+fStax);
286 cacheProps.load(ss.getFileInputStream(fStax));
287 }
288 else {
289 configFile = ss.getSystemProperty("java.home") + File.separator +
290 "conf" + File.separator + "jaxp.properties";
291 final File fJaxp = new File(configFile);
292 if (ss.doesFileExist(fJaxp)) {
293 dPrint(()->"Read properties file "+fJaxp);
294 cacheProps.load(ss.getFileInputStream(fJaxp));
295 }
296 }
297 }
298 }
299 }
300 final String factoryClassName = cacheProps.getProperty(factoryId);
301
302 if (factoryClassName != null) {
303 final String foundIn = configFile;
304 dPrint(()->"found in " + foundIn + " value=" + factoryClassName);
305 return newInstance(type, factoryClassName, cl, true);
306 }
307 }
308 catch (Exception ex) {
309 if (debug) ex.printStackTrace();
310 }
311
312 if (type.getName().equals(factoryId)) {
313 // Try Jar Service Provider Mechanism
314 final T provider = findServiceProvider(type, cl);
315 if (provider != null) {
316 return provider;
317 }
318 } else {
319 // We're in the case where a 'custom' factoryId was provided,
320 // and in every case where that happens, we expect that
321 // fallbackClassName will be null.
322 assert fallbackClassName == null;
323 }
324 if (fallbackClassName == null) {
325 throw new FactoryConfigurationError(
326 "Provider for " + factoryId + " cannot be found", null);
327 }
328
329 dPrint(()->"loaded from fallback value: " + fallbackClassName);
330 return newInstance(type, fallbackClassName, cl, true);
331 }
332
333 /*
334 * Try to find provider using the ServiceLoader API
335 *
336 * @param type Base class / Service interface of the factory to find.
337 *
338 * @return instance of provider class if found or null
339 */
340 private static <T> T findServiceProvider(final Class<T> type, final ClassLoader cl) {
341 try {
342 return AccessController.doPrivileged(new PrivilegedAction<T>() {
343 @Override
344 public T run() {
345 final ServiceLoader<T> serviceLoader;
346 if (cl == null) {
347 //the current thread's context class loader
348 serviceLoader = ServiceLoader.load(type);
349 } else {
350 serviceLoader = ServiceLoader.load(type, cl);
351 }
352 final Iterator<T> iterator = serviceLoader.iterator();
353 if (iterator.hasNext()) {
354 return iterator.next();
355 } else {
356 return null;
357 }
358 }
359 });
360 } catch(ServiceConfigurationError e) {
361 // It is not possible to wrap an error directly in
362 // FactoryConfigurationError - so we need to wrap the
363 // ServiceConfigurationError in a RuntimeException.
364 // The alternative would be to modify the logic in
365 // FactoryConfigurationError to allow setting a
366 // Throwable as the cause, but that could cause
367 // compatibility issues down the road.
368 final RuntimeException x = new RuntimeException(
369 "Provider for " + type + " cannot be created", e);
370 final FactoryConfigurationError error =
371 new FactoryConfigurationError(x, x.getMessage());
372 throw error;
373 }
374 }
375
376 }