1 /*
2 * Copyright (c) 2003, 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 javax.xml.parsers;
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 Parsers.</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 * @author Huizhe.Wang@oracle.com
45 */
46 class FactoryFinder {
47 private static final String DEFAULT_PACKAGE = "com.sun.org.apache.xerces.internal";
48 /**
49 * Internal debug flag.
50 */
51 private static boolean debug = false;
52
53 /**
54 * Cache for properties in java.home/conf/jaxp.properties
55 */
56 private static final Properties cacheProps = new Properties();
57
58 /**
59 * Flag indicating if properties from java.home/conf/jaxp.properties
60 * have been cached.
61 */
62 static volatile boolean firstTime = true;
63
64 /**
65 * Security support class use to check access control before
66 * getting certain system resources.
67 */
68 private static final SecuritySupport ss = new SecuritySupport();
69
70 // Define system property "jaxp.debug" to get output
71 static {
72 // Use try/catch block to support applets, which throws
73 // SecurityException out of this code.
74 try {
75 String val = ss.getSystemProperty("jaxp.debug");
76 // Allow simply setting the prop to turn on debug
77 debug = val != null && !"false".equals(val);
78 }
79 catch (SecurityException se) {
80 debug = false;
81 }
82 }
83
84 private static void dPrint(Supplier<String> msgGen) {
85 if (debug) {
86 System.err.println("JAXP: " + msgGen.get());
87 }
88 }
89
90 /**
91 * Attempt to load a class using the class loader supplied. If that fails
92 * and fall back is enabled, the current (i.e. bootstrap) class loader is
93 * tried.
94 *
95 * If the class loader supplied is <code>null</code>, first try using the
96 * context class loader followed by the current (i.e. bootstrap) class
97 * loader.
98 *
99 * Use bootstrap classLoader if cl = null and useBSClsLoader is true
100 */
101 static private Class<?> getProviderClass(String className, ClassLoader cl,
102 boolean doFallback, boolean useBSClsLoader) throws ClassNotFoundException
103 {
104 try {
105 if (cl == null) {
106 if (useBSClsLoader) {
107 return Class.forName(className, false, FactoryFinder.class.getClassLoader());
108 } else {
109 cl = ss.getContextClassLoader();
110 if (cl == null) {
111 throw new ClassNotFoundException();
112 }
113 else {
114 return Class.forName(className, false, cl);
115 }
116 }
117 }
118 else {
119 return Class.forName(className, false, cl);
120 }
121 }
122 catch (ClassNotFoundException e1) {
123 if (doFallback) {
124 // Use current class loader - should always be bootstrap CL
125 return Class.forName(className, false, FactoryFinder.class.getClassLoader());
126 }
127 else {
128 throw e1;
129 }
130 }
131 }
132
133 /**
134 * Create an instance of a class. Delegates to method
135 * <code>getProviderClass()</code> in order to load the class.
136 *
137 * @param type Base class / Service interface of the factory to
138 * instantiate.
139 *
140 * @param className Name of the concrete class corresponding to the
141 * service provider
142 *
143 * @param cl <code>ClassLoader</code> used to load the factory class. If <code>null</code>
144 * current <code>Thread</code>'s context classLoader is used to load the factory class.
145 *
146 * @param doFallback True if the current ClassLoader should be tried as
147 * a fallback if the class is not found using cl
148 */
149 static <T> T newInstance(Class<T> type, String className, ClassLoader cl,
150 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 // make sure we have access to restricted packages
181 if (System.getSecurityManager() != null) {
182 if (className != null && className.startsWith(DEFAULT_PACKAGE)) {
183 cl = null;
184 useBSClsLoader = true;
185 }
186 }
187
188 try {
189 Class<?> providerClass = getProviderClass(className, cl, doFallback, useBSClsLoader);
190 if (!type.isAssignableFrom(providerClass)) {
191 throw new ClassCastException(className + " cannot be cast to " + type.getName());
192 }
193 Object instance = providerClass.newInstance();
194 final ClassLoader clD = cl;
195 dPrint(()->"created new instance of " + providerClass +
196 " using ClassLoader: " + clD);
197 return type.cast(instance);
198 }
199 catch (ClassNotFoundException x) {
200 throw new FactoryConfigurationError(x,
201 "Provider " + className + " not found");
202 }
203 catch (Exception x) {
204 throw new FactoryConfigurationError(x,
205 "Provider " + className + " could not be instantiated: " + x);
206 }
207 }
208
209 /**
210 * Finds the implementation Class object in the specified order. Main
211 * entry point.
212 * @return Class object of factory, never null
213 *
214 * @param type Base class / Service interface of the
215 * factory to find.
216 * @param fallbackClassName Implementation class name, if nothing else
217 * is found. Use null to mean no fallback.
218 *
219 * Package private so this code can be shared.
220 */
221 static <T> T find(Class<T> type, String fallbackClassName)
222 throws FactoryConfigurationError
223 {
224 final String factoryId = type.getName();
225 dPrint(()->"find factoryId =" + factoryId);
226
227 // Use the system property first
228 try {
229 String systemProp = ss.getSystemProperty(factoryId);
230 if (systemProp != null) {
231 dPrint(()->"found system property, value=" + systemProp);
232 return newInstance(type, systemProp, null, true);
233 }
234 }
235 catch (SecurityException se) {
236 if (debug) se.printStackTrace();
237 }
238
239 // try to read from $java.home/conf/jaxp.properties
240 try {
241 if (firstTime) {
242 synchronized (cacheProps) {
243 if (firstTime) {
244 String configFile = ss.getSystemProperty("java.home") + File.separator +
245 "conf" + File.separator + "jaxp.properties";
246 File f = new File(configFile);
247 firstTime = false;
248 if (ss.doesFileExist(f)) {
249 dPrint(()->"Read properties file "+f);
250 cacheProps.load(ss.getFileInputStream(f));
251 }
252 }
253 }
254 }
255 final String factoryClassName = cacheProps.getProperty(factoryId);
256
257 if (factoryClassName != null) {
258 dPrint(()->"found in ${java.home}/conf/jaxp.properties, value=" + factoryClassName);
259 return newInstance(type, factoryClassName, null, true);
260 }
261 }
262 catch (Exception ex) {
263 if (debug) ex.printStackTrace();
264 }
265
266 // Try Jar Service Provider Mechanism
267 T provider = findServiceProvider(type);
268 if (provider != null) {
269 return provider;
270 }
271 if (fallbackClassName == null) {
272 throw new FactoryConfigurationError(
273 "Provider for " + factoryId + " cannot be found");
274 }
275
276 dPrint(()->"loaded from fallback value: " + fallbackClassName);
277 return newInstance(type, fallbackClassName, null, true);
278 }
279
280 /*
281 * Try to find provider using the ServiceLoader API
282 *
283 * @param type Base class / Service interface of the factory to find.
284 *
285 * @return instance of provider class if found or null
286 */
287 private static <T> T findServiceProvider(final Class<T> type) {
288 try {
289 return AccessController.doPrivileged(new PrivilegedAction<T>() {
290 public T run() {
291 final ServiceLoader<T> serviceLoader = ServiceLoader.load(type);
292 final Iterator<T> iterator = serviceLoader.iterator();
293 if (iterator.hasNext()) {
294 return iterator.next();
295 } else {
296 return null;
297 }
298 }
299 });
300 } catch(ServiceConfigurationError e) {
301 // It is not possible to wrap an error directly in
302 // FactoryConfigurationError - so we need to wrap the
303 // ServiceConfigurationError in a RuntimeException.
304 // The alternative would be to modify the logic in
305 // FactoryConfigurationError to allow setting a
306 // Throwable as the cause, but that could cause
307 // compatibility issues down the road.
308 final RuntimeException x = new RuntimeException(
309 "Provider for " + type + " cannot be created", e);
310 final FactoryConfigurationError error =
311 new FactoryConfigurationError(x, x.getMessage());
312 throw error;
313 }
314 }
315
316 }