1 /*
2 * Copyright (c) 2003, 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.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 import jdk.xml.internal.SecuritySupport;
37
38 /**
39 * <p>Implements pluggable Parsers.</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 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 // Define system property "jaxp.debug" to get output
65 static {
66 // Use try/catch block to support applets, which throws
67 // SecurityException out of this code.
68 try {
69 String val = SecuritySupport.getSystemProperty("jaxp.debug");
70 // Allow simply setting the prop to turn on debug
71 debug = val != null && !"false".equals(val);
72 }
73 catch (SecurityException se) {
74 debug = false;
75 }
76 }
77
78 private static void dPrint(Supplier<String> msgGen) {
79 if (debug) {
80 System.err.println("JAXP: " + msgGen.get());
81 }
82 }
83
84 /**
85 * Attempt to load a class using the class loader supplied. If that fails
86 * and fall back is enabled, the current (i.e. bootstrap) class loader is
87 * tried.
88 *
89 * If the class loader supplied is <code>null</code>, first try using the
90 * context class loader followed by the current (i.e. bootstrap) class
91 * loader.
92 *
93 * Use bootstrap classLoader if cl = null and useBSClsLoader is true
94 */
95 static private Class<?> getProviderClass(String className, ClassLoader cl,
96 boolean doFallback, boolean useBSClsLoader) throws ClassNotFoundException
97 {
98 try {
99 if (cl == null) {
100 if (useBSClsLoader) {
101 return Class.forName(className, false, FactoryFinder.class.getClassLoader());
102 } else {
103 cl = SecuritySupport.getContextClassLoader();
104 if (cl == null) {
105 throw new ClassNotFoundException();
106 }
107 else {
108 return Class.forName(className, false, cl);
109 }
110 }
111 }
112 else {
113 return Class.forName(className, false, cl);
114 }
115 }
116 catch (ClassNotFoundException e1) {
117 if (doFallback) {
118 // Use current class loader - should always be bootstrap CL
119 return Class.forName(className, false, FactoryFinder.class.getClassLoader());
120 }
121 else {
122 throw e1;
123 }
124 }
125 }
126
127 /**
128 * Create an instance of a class. Delegates to method
129 * <code>getProviderClass()</code> in order to load the class.
130 *
131 * @param type Base class / Service interface of the factory to
132 * instantiate.
133 *
134 * @param className Name of the concrete class corresponding to the
135 * service provider
136 *
137 * @param cl <code>ClassLoader</code> used to load the factory class. If <code>null</code>
138 * current <code>Thread</code>'s context classLoader is used to load the factory class.
139 *
140 * @param doFallback True if the current ClassLoader should be tried as
141 * a fallback if the class is not found using cl
142 */
143 static <T> T newInstance(Class<T> type, String className, ClassLoader cl,
144 boolean doFallback)
145 throws FactoryConfigurationError
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 <code>ClassLoader</code> used to load the factory class. If <code>null</code>
161 * current <code>Thread</code>'s context classLoader is used to load the factory class.
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 FactoryConfigurationError
172 {
173 assert type != null;
174 // make sure we have access to restricted packages
175 if (System.getSecurityManager() != null) {
176 if (className != null && className.startsWith(DEFAULT_PACKAGE)) {
177 cl = null;
178 useBSClsLoader = true;
179 }
180 }
181
182 try {
183 Class<?> providerClass = getProviderClass(className, cl, doFallback, useBSClsLoader);
184 if (!type.isAssignableFrom(providerClass)) {
185 throw new ClassCastException(className + " cannot be cast to " + type.getName());
186 }
187 Object instance = providerClass.getConstructor().newInstance();
188 final ClassLoader clD = cl;
189 dPrint(()->"created new instance of " + providerClass +
190 " using ClassLoader: " + clD);
191 return type.cast(instance);
192 }
193 catch (ClassNotFoundException x) {
194 throw new FactoryConfigurationError(x,
195 "Provider " + className + " not found");
196 }
197 catch (Exception x) {
198 throw new FactoryConfigurationError(x,
199 "Provider " + className + " could not be instantiated: " + x);
200 }
201 }
202
203 /**
204 * Finds the implementation Class object in the specified order. Main
205 * entry point.
206 * @return Class object of factory, never null
207 *
208 * @param type Base class / Service interface of the
209 * factory to find.
210 * @param fallbackClassName Implementation class name, if nothing else
211 * is found. Use null to mean no fallback.
212 *
213 * Package private so this code can be shared.
214 */
215 static <T> T find(Class<T> type, String fallbackClassName)
216 throws FactoryConfigurationError
217 {
218 final String factoryId = type.getName();
219 dPrint(()->"find factoryId =" + factoryId);
220
221 // Use the system property first
222 try {
223 String systemProp = SecuritySupport.getSystemProperty(factoryId);
224 if (systemProp != null) {
225 dPrint(()->"found system property, value=" + systemProp);
226 return newInstance(type, systemProp, null, true);
227 }
228 }
229 catch (SecurityException se) {
230 if (debug) se.printStackTrace();
231 }
232
233 // try to read from $java.home/conf/jaxp.properties
234 try {
235 if (firstTime) {
236 synchronized (cacheProps) {
237 if (firstTime) {
238 String configFile = SecuritySupport.getSystemProperty("java.home") + File.separator +
239 "conf" + File.separator + "jaxp.properties";
240 File f = new File(configFile);
241 firstTime = false;
242 if (SecuritySupport.doesFileExist(f)) {
243 dPrint(()->"Read properties file "+f);
244 cacheProps.load(SecuritySupport.getFileInputStream(f));
245 }
246 }
247 }
248 }
249 final String factoryClassName = cacheProps.getProperty(factoryId);
250
251 if (factoryClassName != null) {
252 dPrint(()->"found in ${java.home}/conf/jaxp.properties, value=" + factoryClassName);
253 return newInstance(type, factoryClassName, null, true);
254 }
255 }
256 catch (Exception ex) {
257 if (debug) ex.printStackTrace();
258 }
259
260 // Try Jar Service Provider Mechanism
261 T provider = findServiceProvider(type);
262 if (provider != null) {
263 return provider;
264 }
265 if (fallbackClassName == null) {
266 throw new FactoryConfigurationError(
267 "Provider for " + factoryId + " cannot be found");
268 }
269
270 dPrint(()->"loaded from fallback value: " + fallbackClassName);
271 return newInstance(type, fallbackClassName, null, true);
272 }
273
274 /*
275 * Try to find provider using the ServiceLoader API
276 *
277 * @param type Base class / Service interface of the factory to find.
278 *
279 * @return instance of provider class if found or null
280 */
281 private static <T> T findServiceProvider(final Class<T> type) {
282 try {
283 return AccessController.doPrivileged(new PrivilegedAction<T>() {
284 public T run() {
285 final ServiceLoader<T> serviceLoader = ServiceLoader.load(type);
286 final Iterator<T> iterator = serviceLoader.iterator();
287 if (iterator.hasNext()) {
288 return iterator.next();
289 } else {
290 return null;
291 }
292 }
293 });
294 } catch(ServiceConfigurationError e) {
295 // It is not possible to wrap an error directly in
296 // FactoryConfigurationError - so we need to wrap the
297 // ServiceConfigurationError in a RuntimeException.
298 // The alternative would be to modify the logic in
299 // FactoryConfigurationError to allow setting a
300 // Throwable as the cause, but that could cause
301 // compatibility issues down the road.
302 final RuntimeException x = new RuntimeException(
303 "Provider for " + type + " cannot be created", e);
304 final FactoryConfigurationError error =
305 new FactoryConfigurationError(x, x.getMessage());
306 throw error;
307 }
308 }
309
310 }