org.eclipse.jetty.webapp.WebAppClassLoader Maven / Gradle / Ivy
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//
// ========================================================================
// Copyright (c) 1995 Mort Bay Consulting Pty Ltd and others.
//
// This program and the accompanying materials are made available under the
// terms of the Eclipse Public License v. 2.0 which is available at
// https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
// which is available at https://www.apache.org/licenses/LICENSE-2.0.
//
// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
// ========================================================================
//
package org.eclipse.jetty.webapp;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.IllegalClassFormatException;
import java.net.URL;
import java.net.URLClassLoader;
import java.security.CodeSource;
import java.security.PermissionCollection;
import java.security.PrivilegedExceptionAction;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.List;
import java.util.Locale;
import java.util.Set;
import java.util.StringTokenizer;
import java.util.concurrent.CopyOnWriteArrayList;
import org.eclipse.jetty.util.ClassVisibilityChecker;
import org.eclipse.jetty.util.IO;
import org.eclipse.jetty.util.StringUtil;
import org.eclipse.jetty.util.TypeUtil;
import org.eclipse.jetty.util.URIUtil;
import org.eclipse.jetty.util.resource.Resource;
import org.eclipse.jetty.util.resource.ResourceCollection;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* ClassLoader for HttpContext.
*
* Specializes URLClassLoader with some utility and file mapping
* methods.
*
* This loader defaults to the 2.3 servlet spec behavior where non
* system classes are loaded from the classpath in preference to the
* parent loader. Java2 compliant loading, where the parent loader
* always has priority, can be selected with the
* {@link org.eclipse.jetty.webapp.WebAppContext#setParentLoaderPriority(boolean)}
* method and influenced with {@link WebAppContext#isServerClass(Class)} and
* {@link WebAppContext#isSystemClass(Class)}.
*
* If no parent class loader is provided, then the current thread
* context classloader will be used. If that is null then the
* classloader that loaded this class is used as the parent.
*/
public class WebAppClassLoader extends URLClassLoader implements ClassVisibilityChecker
{
static
{
registerAsParallelCapable();
}
private static final Logger LOG = LoggerFactory.getLogger(WebAppClassLoader.class);
private static final ThreadLocal __loadServerClasses = new ThreadLocal<>();
private final Context _context;
private final ClassLoader _parent;
private final Set _extensions = new HashSet();
private String _name = String.valueOf(hashCode());
private final List _transformers = new CopyOnWriteArrayList<>();
/**
* The Context in which the classloader operates.
*/
public interface Context extends ClassVisibilityChecker
{
/**
* Convert a URL or path to a Resource.
* The default implementation
* is a wrapper for {@link Resource#newResource(String)}.
*
* @param urlOrPath The URL or path to convert
* @return The Resource for the URL/path
* @throws IOException The Resource could not be created.
*/
Resource newResource(String urlOrPath) throws IOException;
/**
* @return Returns the permissions.
*/
PermissionCollection getPermissions();
/**
* @return True if the classloader should delegate first to the parent
* classloader (standard java behaviour) or false if the classloader
* should first try to load from WEB-INF/lib or WEB-INF/classes (servlet
* spec recommendation).
*/
boolean isParentLoaderPriority();
List getExtraClasspath();
boolean isServerResource(String name, URL parentUrl);
boolean isSystemResource(String name, URL webappUrl);
}
/**
* Run an action with access to ServerClasses
* Run the passed {@link PrivilegedExceptionAction} with the classloader
* configured so as to allow server classes to be visible
*
* @param The type returned by the action
* @param action The action to run
* @param the type of PrivilegedExceptionAction
* @return The return from the action
* @throws Exception if thrown by the action
*/
public static T runWithServerClassAccess(PrivilegedExceptionAction action) throws Exception
{
Boolean lsc = __loadServerClasses.get();
try
{
__loadServerClasses.set(true);
return action.run();
}
finally
{
if (lsc == null)
__loadServerClasses.remove();
else
__loadServerClasses.set(lsc);
}
}
/**
* Constructor.
*
* @param context the context for this classloader
* @throws IOException if unable to initialize from context
*/
public WebAppClassLoader(Context context)
throws IOException
{
this(null, context);
}
/**
* Constructor.
*
* @param parent the parent classloader
* @param context the context for this classloader
* @throws IOException if unable to initialize classloader
*/
public WebAppClassLoader(ClassLoader parent, Context context)
throws IOException
{
super(new URL[]{}, parent != null ? parent
: (Thread.currentThread().getContextClassLoader() != null ? Thread.currentThread().getContextClassLoader()
: (WebAppClassLoader.class.getClassLoader() != null ? WebAppClassLoader.class.getClassLoader()
: ClassLoader.getSystemClassLoader())));
_parent = getParent();
_context = context;
if (_parent == null)
throw new IllegalArgumentException("no parent classloader!");
_extensions.add(".jar");
_extensions.add(".zip");
// TODO remove this system property
String extensions = System.getProperty(WebAppClassLoader.class.getName() + ".extensions");
if (extensions != null)
{
StringTokenizer tokenizer = new StringTokenizer(extensions, StringUtil.DEFAULT_DELIMS);
while (tokenizer.hasMoreTokens())
{
_extensions.add(tokenizer.nextToken().trim());
}
}
if (context.getExtraClasspath() != null)
{
for (Resource resource : context.getExtraClasspath())
{
addClassPath(resource);
}
}
}
/**
* @return the name of the classloader
*/
public String getName()
{
return _name;
}
/**
* @param name the name of the classloader
*/
public void setName(String name)
{
_name = name;
}
public Context getContext()
{
return _context;
}
/**
* @param resource Comma or semicolon separated path of filenames or URLs
* pointing to directories or jar files. Directories should end
* with '/'.
* @throws IOException if unable to add classpath from resource
*/
public void addClassPath(Resource resource)
throws IOException
{
if (resource instanceof ResourceCollection)
{
for (Resource r : ((ResourceCollection)resource).getResources())
{
addClassPath(r);
}
}
else
{
// Resolve file path if possible
File file = resource.getFile();
if (file != null)
{
URL url = resource.getURI().toURL();
addURL(url);
}
else if (resource.isDirectory())
{
addURL(resource.getURI().toURL());
}
else
{
if (LOG.isDebugEnabled())
LOG.debug("Check file exists and is not nested jar: {}", resource);
throw new IllegalArgumentException("File not resolvable or incompatible with URLClassloader: " + resource);
}
}
}
/**
* @param classPath Comma or semicolon separated path of filenames or URLs
* pointing to directories or jar files. Directories should end
* with '/'.
* @throws IOException if unable to add classpath
*/
public void addClassPath(String classPath)
throws IOException
{
if (classPath == null)
return;
for (Resource resource : Resource.fromList(classPath, false, _context::newResource))
{
addClassPath(resource);
}
}
/**
* @param file Checks if this file type can be added to the classpath.
*/
private boolean isFileSupported(String file)
{
int dot = file.lastIndexOf('.');
return dot != -1 && _extensions.contains(file.substring(dot));
}
/**
* Add elements to the class path for the context from the jar and zip files found
* in the specified resource.
*
* @param lib the resource that contains the jar and/or zip files.
*/
public void addJars(Resource lib)
{
if (lib.exists() && lib.isDirectory())
{
String[] entries = lib.list();
if (entries != null)
{
Arrays.sort(entries);
for (String entry : entries)
{
try
{
Resource resource = lib.addPath(entry);
if (LOG.isDebugEnabled())
LOG.debug("addJar - {}", resource);
String fnlc = resource.getName().toLowerCase(Locale.ENGLISH);
// don't check if this is a directory (prevents use of symlinks), see Bug 353165
if (isFileSupported(fnlc))
{
String jar = URIUtil.encodeSpecific(resource.toString(), ",;");
addClassPath(jar);
}
}
catch (Exception ex)
{
LOG.warn("Unable to load WEB-INF/lib JAR {}", entry, ex);
}
}
}
}
}
@Override
public PermissionCollection getPermissions(CodeSource cs)
{
PermissionCollection permissions = _context.getPermissions();
PermissionCollection pc = (permissions == null) ? super.getPermissions(cs) : permissions;
return pc;
}
@Override
public Enumeration getResources(String name) throws IOException
{
List fromParent = new ArrayList<>();
List fromWebapp = new ArrayList<>();
Enumeration urls = _parent.getResources(name);
while (urls != null && urls.hasMoreElements())
{
URL url = urls.nextElement();
if (Boolean.TRUE.equals(__loadServerClasses.get()) || !_context.isServerResource(name, url))
fromParent.add(url);
}
urls = this.findResources(name);
while (urls != null && urls.hasMoreElements())
{
URL url = urls.nextElement();
if (!_context.isSystemResource(name, url) || fromParent.isEmpty())
fromWebapp.add(url);
}
List resources;
if (_context.isParentLoaderPriority())
{
fromParent.addAll(fromWebapp);
resources = fromParent;
}
else
{
fromWebapp.addAll(fromParent);
resources = fromWebapp;
}
if (LOG.isDebugEnabled())
LOG.debug("getResources {} {}", name, resources);
return Collections.enumeration(resources);
}
/**
* Get a resource from the classloader
*
* NOTE: this method provides a convenience of hacking off a leading /
* should one be present. This is non-standard and it is recommended
* to not rely on this behavior
*/
@Override
public URL getResource(String name)
{
URL resource = null;
if (_context.isParentLoaderPriority())
{
URL parentUrl = _parent.getResource(name);
// return if we have a url the webapp is allowed to see
if (parentUrl != null &&
(Boolean.TRUE.equals(__loadServerClasses.get()) ||
!_context.isServerResource(name, parentUrl)))
resource = parentUrl;
else
{
URL webappUrl = this.findResource(name);
// If found here then OK to use regardless of system or server classes
// If it is a system resource, we've already tried to load from parent, so
// would have returned it.
// If it is a server resource, doesn't matter as we have loaded it from the
// webapp
if (webappUrl != null)
resource = webappUrl;
}
}
else
{
URL webappUrl = this.findResource(name);
if (webappUrl != null && !_context.isSystemResource(name, webappUrl))
resource = webappUrl;
else
{
// Couldn't find or see a webapp resource, so try a parent
URL parentUrl = _parent.getResource(name);
if (parentUrl != null &&
(Boolean.TRUE.equals(__loadServerClasses.get()) ||
!_context.isServerResource(name, parentUrl)))
resource = parentUrl;
// We couldn't find a parent resource, so OK to return a webapp one if it exists
// and we just couldn't see it before
else if (webappUrl != null)
resource = webappUrl;
}
}
// Perhaps this failed due to leading /
if (resource == null && name.startsWith("/"))
resource = getResource(name.substring(1));
if (LOG.isDebugEnabled())
LOG.debug("getResource {} {}", name, resource);
return resource;
}
@Override
protected Class loadClass(String name, boolean resolve) throws ClassNotFoundException
{
synchronized (getClassLoadingLock(name))
{
ClassNotFoundException ex = null;
Class parentClass = null;
Class webappClass = null;
// Has this loader loaded the class already?
webappClass = findLoadedClass(name);
if (webappClass != null)
{
return webappClass;
}
// Should we try the parent loader first?
if (_context.isParentLoaderPriority())
{
// Try the parent loader
try
{
parentClass = _parent.loadClass(name);
if (parentClass == null)
throw new ClassNotFoundException("Bad ClassLoader: returned null for loadClass(" + name + ")");
// If the webapp is allowed to see this class
if (Boolean.TRUE.equals(__loadServerClasses.get()) || !_context.isServerClass(parentClass))
{
return parentClass;
}
}
catch (ClassNotFoundException e)
{
// Save it for later
ex = e;
}
// Try the webapp loader
try
{
// If found here then OK to use regardless of system or server classes
// If it is a system class, we've already tried to load from parent, so
// would have returned it.
// If it is a server class, doesn't matter as we have loaded it from the
// webapp
webappClass = this.findClass(name);
if (resolve)
resolveClass(webappClass);
return webappClass;
}
catch (ClassNotFoundException e)
{
if (ex == null)
ex = e;
else if (e != ex)
ex.addSuppressed(e);
}
throw ex;
}
else
{
// Not parent loader priority, so...
webappClass = loadAsResource(name, true);
if (webappClass != null)
{
return webappClass;
}
// Try the parent loader
try
{
parentClass = _parent.loadClass(name);
// If the webapp is allowed to see this class
if (Boolean.TRUE.equals(__loadServerClasses.get()) || !_context.isServerClass(parentClass))
{
return parentClass;
}
}
catch (ClassNotFoundException e)
{
ex = e;
}
// We couldn't find a parent class, so OK to return a webapp one if it exists
// and we just couldn't see it before
webappClass = loadAsResource(name, false);
if (webappClass != null)
{
return webappClass;
}
throw ex == null ? new ClassNotFoundException(name) : ex;
}
}
}
public void addTransformer(ClassFileTransformer transformer)
{
_transformers.add(transformer);
}
public boolean removeTransformer(ClassFileTransformer transformer)
{
return _transformers.remove(transformer);
}
/**
* Look for the classname as a resource to avoid loading a class that is
* potentially a system resource.
*
* @param name the name of the class to load
* @param checkSystemResource if true and the class isn't a system class we return it
* @return the loaded class
* @throws ClassNotFoundException if the class cannot be found
*/
protected Class loadAsResource(final String name, boolean checkSystemResource) throws ClassNotFoundException
{
// Try the webapp classloader first
// Look in the webapp classloader as a resource, to avoid
// loading a system class.
Class webappClass = null;
String path = TypeUtil.toClassReference(name);
URL webappUrl = findResource(path);
if (webappUrl != null && (!checkSystemResource || !_context.isSystemResource(name, webappUrl)))
{
webappClass = this.foundClass(name, webappUrl);
resolveClass(webappClass);
if (LOG.isDebugEnabled())
LOG.debug("WAP webapp loaded {}", webappClass);
}
return webappClass;
}
@Override
protected Class findClass(final String name) throws ClassNotFoundException
{
if (_transformers.isEmpty())
{
return super.findClass(name);
}
String path = TypeUtil.toClassReference(name);
URL url = findResource(path);
if (url == null)
throw new ClassNotFoundException(name);
return foundClass(name, url);
}
protected Class foundClass(final String name, URL url) throws ClassNotFoundException
{
if (_transformers.isEmpty())
return super.findClass(name);
InputStream content = null;
try
{
content = url.openStream();
byte[] bytes = IO.readBytes(content);
for (ClassFileTransformer transformer : _transformers)
{
byte[] tmp = transformer.transform(this, name, null, null, bytes);
if (tmp != null)
bytes = tmp;
}
return defineClass(name, bytes, 0, bytes.length);
}
catch (IOException e)
{
throw new ClassNotFoundException(name, e);
}
catch (IllegalClassFormatException e)
{
throw new ClassNotFoundException(name, e);
}
finally
{
if (content != null)
{
try
{
content.close();
}
catch (IOException e)
{
throw new ClassNotFoundException(name, e);
}
}
}
}
@Override
public void close() throws IOException
{
super.close();
}
@Override
public String toString()
{
return String.format("%s{%s}@%x", this.getClass().getSimpleName(), _name, hashCode());
}
@Override
public boolean isSystemClass(Class clazz)
{
return _context.isSystemClass(clazz);
}
@Override
public boolean isServerClass(Class clazz)
{
return _context.isServerClass(clazz);
}
}