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/*
* Copyright (c) 2003, 2021, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package javax.xml.parsers;
import java.io.File;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Iterator;
import java.util.Properties;
import java.util.ServiceConfigurationError;
import java.util.ServiceLoader;
import java.util.function.Supplier;
import jdk.xml.internal.SecuritySupport;
/**
* Implements pluggable Parsers.
*
* This class is duplicated for each JAXP subpackage so keep it in
* sync. It is package private for secure class loading.
*
* @author Santiago PericasGeertsen
*/
class FactoryFinder {
private static final String DEFAULT_PACKAGE = "com.sun.org.apache.xerces.internal";
/**
* Internal debug flag.
*/
private static boolean debug = false;
/**
* Cache for properties in java.home/conf/jaxp.properties
*/
private static final Properties cacheProps = new Properties();
/**
* Flag indicating if properties from java.home/conf/jaxp.properties
* have been cached.
*/
static volatile boolean firstTime = true;
// Define system property "jaxp.debug" to get output
static {
// Use try/catch block to support applets, which throws
// SecurityException out of this code.
try {
String val = SecuritySupport.getSystemProperty("jaxp.debug");
// Allow simply setting the prop to turn on debug
debug = val != null && !"false".equals(val);
}
catch (SecurityException se) {
debug = false;
}
}
private static void dPrint(Supplier msgGen) {
if (debug) {
System.err.println("JAXP: " + msgGen.get());
}
}
/**
* Attempt to load a class using the class loader supplied. If that fails
* and fall back is enabled, the current (i.e. bootstrap) class loader is
* tried.
*
* If the class loader supplied is null, first try using the
* context class loader followed by the current (i.e. bootstrap) class
* loader.
*
* Use bootstrap classLoader if cl = null and useBSClsLoader is true
*/
static private Class getProviderClass(String className, ClassLoader cl,
boolean doFallback, boolean useBSClsLoader) throws ClassNotFoundException
{
try {
if (cl == null) {
if (useBSClsLoader) {
return Class.forName(className, false, FactoryFinder.class.getClassLoader());
} else {
cl = SecuritySupport.getContextClassLoader();
if (cl == null) {
throw new ClassNotFoundException();
}
else {
return Class.forName(className, false, cl);
}
}
}
else {
return Class.forName(className, false, cl);
}
}
catch (ClassNotFoundException e1) {
if (doFallback) {
// Use current class loader - should always be bootstrap CL
return Class.forName(className, false, FactoryFinder.class.getClassLoader());
}
else {
throw e1;
}
}
}
/**
* Create an instance of a class. Delegates to method
* getProviderClass() in order to load the class.
*
* @param type Base class / Service interface of the factory to
* instantiate.
*
* @param className Name of the concrete class corresponding to the
* service provider
*
* @param cl ClassLoader used to load the factory class. If null
* current Thread's context classLoader is used to load the factory class.
*
* @param doFallback True if the current ClassLoader should be tried as
* a fallback if the class is not found using cl
*/
static T newInstance(Class type, String className, ClassLoader cl,
boolean doFallback)
throws FactoryConfigurationError
{
return newInstance(type, className, cl, doFallback, false);
}
/**
* Create an instance of a class. Delegates to method
* getProviderClass() in order to load the class.
*
* @param type Base class / Service interface of the factory to
* instantiate.
*
* @param className Name of the concrete class corresponding to the
* service provider
*
* @param cl ClassLoader used to load the factory class. If null
* current Thread's context classLoader is used to load the factory class.
*
* @param doFallback True if the current ClassLoader should be tried as
* a fallback if the class is not found using cl
*
* @param useBSClsLoader True if cl=null actually meant bootstrap classLoader. This parameter
* is needed since DocumentBuilderFactory/SAXParserFactory defined null as context classLoader.
*/
@SuppressWarnings("removal")
static T newInstance(Class type, String className, ClassLoader cl,
boolean doFallback, boolean useBSClsLoader)
throws FactoryConfigurationError
{
assert type != null;
// make sure we have access to restricted packages
if (System.getSecurityManager() != null) {
if (className != null && className.startsWith(DEFAULT_PACKAGE)) {
cl = null;
useBSClsLoader = true;
}
}
try {
Class providerClass = getProviderClass(className, cl, doFallback, useBSClsLoader);
if (!type.isAssignableFrom(providerClass)) {
throw new ClassCastException(className + " cannot be cast to " + type.getName());
}
Object instance = providerClass.getConstructor().newInstance();
final ClassLoader clD = cl;
dPrint(()->"created new instance of " + providerClass +
" using ClassLoader: " + clD);
return type.cast(instance);
}
catch (ClassNotFoundException x) {
throw new FactoryConfigurationError(x,
"Provider " + className + " not found");
}
catch (Exception x) {
throw new FactoryConfigurationError(x,
"Provider " + className + " could not be instantiated: " + x);
}
}
/**
* Finds the implementation Class object in the specified order. Main
* entry point.
* @return Class object of factory, never null
*
* @param type Base class / Service interface of the
* factory to find.
* @param fallbackClassName Implementation class name, if nothing else
* is found. Use null to mean no fallback.
*
* Package private so this code can be shared.
*/
static T find(Class type, String fallbackClassName)
throws FactoryConfigurationError
{
final String factoryId = type.getName();
dPrint(()->"find factoryId =" + factoryId);
// Use the system property first
try {
String systemProp = SecuritySupport.getSystemProperty(factoryId);
if (systemProp != null) {
dPrint(()->"found system property, value=" + systemProp);
return newInstance(type, systemProp, null, true);
}
}
catch (SecurityException se) {
if (debug) se.printStackTrace();
}
// try to read from $java.home/conf/jaxp.properties
try {
if (firstTime) {
synchronized (cacheProps) {
if (firstTime) {
String configFile = SecuritySupport.getSystemProperty("java.home") + File.separator +
"conf" + File.separator + "jaxp.properties";
File f = new File(configFile);
firstTime = false;
if (SecuritySupport.doesFileExist(f)) {
dPrint(()->"Read properties file "+f);
cacheProps.load(SecuritySupport.getFileInputStream(f));
}
}
}
}
final String factoryClassName = cacheProps.getProperty(factoryId);
if (factoryClassName != null) {
dPrint(()->"found in ${java.home}/conf/jaxp.properties, value=" + factoryClassName);
return newInstance(type, factoryClassName, null, true);
}
}
catch (Exception ex) {
if (debug) ex.printStackTrace();
}
// Try Jar Service Provider Mechanism
T provider = findServiceProvider(type);
if (provider != null) {
return provider;
}
if (fallbackClassName == null) {
throw new FactoryConfigurationError(
"Provider for " + factoryId + " cannot be found");
}
dPrint(()->"loaded from fallback value: " + fallbackClassName);
return newInstance(type, fallbackClassName, null, true);
}
/*
* Try to find provider using the ServiceLoader API
*
* @param type Base class / Service interface of the factory to find.
*
* @return instance of provider class if found or null
*/
@SuppressWarnings("removal")
private static T findServiceProvider(final Class type) {
try {
return AccessController.doPrivileged(new PrivilegedAction() {
public T run() {
final ServiceLoader serviceLoader = ServiceLoader.load(type);
final Iterator iterator = serviceLoader.iterator();
if (iterator.hasNext()) {
return iterator.next();
} else {
return null;
}
}
});
} catch(ServiceConfigurationError e) {
// It is not possible to wrap an error directly in
// FactoryConfigurationError - so we need to wrap the
// ServiceConfigurationError in a RuntimeException.
// The alternative would be to modify the logic in
// FactoryConfigurationError to allow setting a
// Throwable as the cause, but that could cause
// compatibility issues down the road.
final RuntimeException x = new RuntimeException(
"Provider for " + type + " cannot be created", e);
final FactoryConfigurationError error =
new FactoryConfigurationError(x, x.getMessage());
throw error;
}
}
}