/*
 
* Copyright (c) 2013, 2015, 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 java.lang;

import java.io.InputStream;
import java.io.IOException;
import java.io.File;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.net.MalformedURLException;
import java.net.URL;
import java.security.AccessController;
import java.security.AccessControlContext;
import java.security.CodeSource;
import java.security.Policy;
import java.security.PrivilegedAction;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.security.ProtectionDomain;
import java.security.cert.Certificate;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Set;
import java.util.Stack;
import java.util.Map;
import java.util.Vector;
import java.util.Hashtable;
import java.util.WeakHashMap;
import java.util.concurrent.ConcurrentHashMap;
import sun.misc.CompoundEnumeration;
import sun.misc.Resource;
import sun.misc.URLClassPath;
import sun.misc.VM;
import sun.reflect.CallerSensitive;
import sun.reflect.Reflection;
import sun.reflect.misc.ReflectUtil;
import sun.security.util.SecurityConstants;

/**
 
* A class loader is an object that is responsible for loading classes. The
 
* class <tt>ClassLoader</tt> is an abstract class.
  
Given the <a
 
* href="#name">binary name</a> of a class, a class loader should attempt to
 
* locate or generate data that constitutes a definition for the class.
  
A
 
* typical strategy is to transform the name into a file name and then read a
 
* "class file" of that name from a file system.
 
*
 
* <p> Every {@link Class <tt>Class</tt>} object contains a {@link
 
* Class#getClassLoader() reference} to the <tt>ClassLoader</tt> that defined
 
* it.
 
*
 
* <p> <tt>Class</tt> objects for array classes are not created by class
 
* loaders, but are created automatically as required by the Java runtime.
 
* The class loader for an array class, as returned by {@link
 
* Class#getClassLoader()} is the same as the class loader for its element
 
* type; if the element type is a primitive type, then the array class has no
 
* class loader.
 
*
 
* <p> Applications implement subclasses of <tt>ClassLoader</tt> in order to
 
* extend the manner in which the Java virtual machine dynamically loads
 
* classes.
 
*
 
* <p> Class loaders may typically be used by security managers to indicate
 
* security domains.
 
*
 
* <p> The <tt>ClassLoader</tt> class uses a delegation model to search for
 
* classes and resources.
  
Each instance of <tt>ClassLoader</tt> has an
 
* associated parent class loader.
  
When requested to find a class or
 
* resource, a <tt>ClassLoader</tt> instance will delegate the search for the
 
* class or resource to its parent class loader before attempting to find the
 
* class or resource itself.
  
The virtual machine's built-in class loader,
 
* called the "bootstrap class loader", does not itself have a parent but may
 
* serve as the parent of a <tt>ClassLoader</tt> instance.
 
*
 
* <p> Class loaders that support concurrent loading of classes are known as
 
* <em>parallel capable</em> class loaders and are required to register
 
* themselves at their class initialization time by invoking the
 
* {@link
 
* #registerAsParallelCapable <tt>ClassLoader.registerAsParallelCapable</tt>}
 
* method. Note that the <tt>ClassLoader</tt> class is registered as parallel
 
* capable by default. However, its subclasses still need to register themselves
 
* if they are parallel capable. <br>
 
* In environments in which the delegation model is not strictly
 
* hierarchical, class loaders need to be parallel capable, otherwise class
 
* loading can lead to deadlocks because the loader lock is held for the
 
* duration of the class loading process (see {@link #loadClass
 
* <tt>loadClass</tt>} methods).
 
*
 
* <p> Normally, the Java virtual machine loads classes from the local file
 
* system in a platform-dependent manner.
  
For example, on UNIX systems, the
 
* virtual machine loads classes from the directory defined by the
 
* <tt>CLASSPATH</tt> environment variable.
 
*
 
* <p> However, some classes may not originate from a file; they may originate
 
* from other sources, such as the network, or they could be constructed by an
 
* application.
  
The method {@link #defineClass(String, byte[], int, int)
 
* <tt>defineClass</tt>} converts an array of bytes into an instance of class
 
* <tt>Class</tt>. Instances of this newly defined class can be created using
 
* {@link Class#newInstance <tt>Class.newInstance</tt>}.
 
*
 
* <p> The methods and constructors of objects created by a class loader may
 
* reference other classes.
  
To determine the class(es) referred to, the Java
 
* virtual machine invokes the {@link #loadClass <tt>loadClass</tt>} method of
 
* the class loader that originally created the class.
 
*
 
* <p> For example, an application could create a network class loader to
 
* download class files from a server.
  
Sample code might look like:
 
*
 
* <blockquote><pre>
 
*
   
ClassLoader loader&nbsp;= new NetworkClassLoader(host,&nbsp;port);
 
*
   
Object main&nbsp;= loader.loadClass("Main", true).newInstance();
 
*
       
&nbsp;.&nbsp;.&nbsp;.
 
* </pre></blockquote>
 
*
 
* <p> The network class loader subclass must define the methods {@link
 
* #findClass <tt>findClass</tt>} and <tt>loadClassData</tt> to load a class
 
* from the network.
  
Once it has downloaded the bytes that make up the class,
 
* it should use the method {@link #defineClass <tt>defineClass</tt>} to
 
* create a class instance.
  
A sample implementation is:
 
*
 
* <blockquote><pre>
 
*
     
class NetworkClassLoader extends ClassLoader {
 
*
         
String host;
 
*
         
int port;
 
*
 
*
         
public Class findClass(String name) {
 
*
             
byte[] b = loadClassData(name);
 
*
             
return defineClass(name, b, 0, b.length);
 
*
         
}
 
*
 
*
         
private byte[] loadClassData(String name) {
 
*
             
// load the class data from the connection
 
*
             
&nbsp;.&nbsp;.&nbsp;.
 
*
         
}
 
*
     
}
 
* </pre></blockquote>
 
*
 
* <h3> <a name="name">Binary names</a> </h3>
 
*
 
* <p> Any class name provided as a {@link String} parameter to methods in
 
* <tt>ClassLoader</tt> must be a binary name as defined by
 
* <cite>The Java&trade; Language Specification</cite>.
 
*
 
* <p> Examples of valid class names include:
 
* <blockquote><pre>
 
*
   
"java.lang.String"
 
*
   
"javax.swing.JSpinner$DefaultEditor"
 
*
   
"java.security.KeyStore$Builder$FileBuilder$1"
 
*
   
"java.net.URLClassLoader$3$1"
 
* </pre></blockquote>
 
*
 
* @see
      
#resolveClass(Class)
 
* @since 1.0
 
*/

public abstract class ClassLoader {

    
private static native void registerNatives();
    
static {
        
registerNatives();
    
}

    
// The parent class loader for delegation
    
// Note: VM hardcoded the offset of this field, thus all new fields
    
// must be added *after* it.
    
private final ClassLoader parent;

    
/**
     
* Encapsulates the set of parallel capable loader types.
     
*/

    
private static class ParallelLoaders {
        
private ParallelLoaders() {}

        
// the set of parallel capable loader types
        
private static final Set<Class<? extends ClassLoader>> loaderTypes =
            
Collections.newSetFromMap(
                
new WeakHashMap<Class<? extends ClassLoader>, Boolean>());
        
static {
            
synchronized (loaderTypes) { loaderTypes.add(ClassLoader.class); }
        
}

        
/**
         
* Registers the given class loader type as parallel capabale.
         
* Returns {@code true} is successfully registered; {@code false} if
         
* loader's super class is not registered.
         
*/

        
static boolean register(Class<? extends ClassLoader> c) {
            
synchronized (loaderTypes) {
                
if (loaderTypes.contains(c.getSuperclass())) {
                    
// register the class loader as parallel capable
                    
// if and only if all of its super classes are.
                    
// Note: given current classloading sequence, if
                    
// the immediate super class is parallel capable,
                    
// all the super classes higher up must be too.
                    
loaderTypes.add(c);
                    
return true;
                
} else {
                    
return false;
                
}
            
}
        
}

        
/**
         
* Returns {@code true} if the given class loader type is
         
* registered as parallel capable.
         
*/

        
static boolean isRegistered(Class<? extends ClassLoader> c) {
            
synchronized (loaderTypes) {
                
return loaderTypes.contains(c);
            
}
        
}
    
}

    
// Maps class name to the corresponding lock object when the current
    
// class loader is parallel capable.
    
// Note: VM also uses this field to decide if the current class loader
    
// is parallel capable and the appropriate lock object for class loading.
    
private final ConcurrentHashMap<String, Object> parallelLockMap;

    
// Hashtable that maps packages to certs
    
private final Map <String, Certificate[]> package2certs;

    
// Shared among all packages with unsigned classes
    
private static final Certificate[] nocerts = new Certificate[0];

    
// The classes loaded by this class loader. The only purpose of this table
    
// is to keep the classes from being GC'ed until the loader is GC'ed.
    
private final Vector<Class<?>> classes = new Vector<>();

    
// The "default" domain. Set as the default ProtectionDomain on newly
    
// created classes.
    
private final ProtectionDomain defaultDomain =
        
new ProtectionDomain(new CodeSource(null, (Certificate[]) null),
                             
null, this, null);

    
// The initiating protection domains for all classes loaded by this loader
    
private final Set<ProtectionDomain> domains;

    
// Invoked by the VM to record every loaded class with this loader.
    
void addClass(Class<?> c) {
        
classes.addElement(c);
    
}

    
// The packages defined in this class loader.
  
Each package name is mapped

    
// to its corresponding Package object.
    
// @GuardedBy("itself")
    
private final HashMap<String, Package> packages = new HashMap<>();

    
private static Void checkCreateClassLoader() {
        
SecurityManager security = System.getSecurityManager();
        
if (security != null) {
            
security.checkCreateClassLoader();
        
}
        
return null;
    
}

    
private ClassLoader(Void unused, ClassLoader parent) {
        
this.parent = parent;
        
if (ParallelLoaders.isRegistered(this.getClass())) {
            
parallelLockMap = new ConcurrentHashMap<>();
            
package2certs = new ConcurrentHashMap<>();
            
domains =
                
Collections.synchronizedSet(new HashSet<ProtectionDomain>());
            
assertionLock = new Object();
        
} else {
            
// no finer-grained lock; lock on the classloader instance
            
parallelLockMap = null;
            
package2certs = new Hashtable<>();
            
domains = new HashSet<>();
            
assertionLock = this;
        
}
    
}

    
/**
     
* Creates a new class loader using the specified parent class loader for
     
* delegation.
     
*
     
* <p> If there is a security manager, its {@link
     
* SecurityManager#checkCreateClassLoader()
     
* <tt>checkCreateClassLoader</tt>} method is invoked.
  
This may result in
     
* a security exception.
  
</p>
     
*
     
* @param
  
parent
     
*
         
The parent class loader
     
*
     
* @throws
  
SecurityException
     
*
          
If a security manager exists and its
     
*
          
<tt>checkCreateClassLoader</tt> method doesn't allow creation
     
*
          
of a new class loader.
     
*
     
* @since
  
1.2
     
*/

    
protected ClassLoader(ClassLoader parent) {
        
this(checkCreateClassLoader(), parent);
    
}

    
/**
     
* Creates a new class loader using the <tt>ClassLoader</tt> returned by
     
* the method {@link #getSystemClassLoader()
     
* <tt>getSystemClassLoader()</tt>} as the parent class loader.
     
*
     
* <p> If there is a security manager, its {@link
     
* SecurityManager#checkCreateClassLoader()
     
* <tt>checkCreateClassLoader</tt>} method is invoked.
  
This may result in
     
* a security exception.
  
</p>
     
*
     
* @throws
  
SecurityException
     
*
          
If a security manager exists and its
     
*
          
<tt>checkCreateClassLoader</tt> method doesn't allow creation
     
*
          
of a new class loader.
     
*/

    
protected ClassLoader() {
        
this(checkCreateClassLoader(), getSystemClassLoader());
    
}

    
// -- Class --

    
/**
     
* Loads the class with the specified
 
<a href="#name">binary name</a>.
     
* This method searches for classes in the same manner as the {@link
     
* #loadClass(String, boolean)} method.
  
It is invoked by the Java virtual
     
* machine to resolve class references.
  
Invoking this method is equivalent
     
* to invoking {@link #loadClass(String, boolean) <tt>loadClass(name,
     
* false)</tt>}.
     
*
     
* @param
  
name
     
*
         
The
 
<a href="#name">binary name</a>
 
of the class
     
*
     
* @return
  
The resulting <tt>Class</tt> object
     
*
     
* @throws
  
ClassNotFoundException
     
*
          
If the class was not found
     
*/

    
public Class<?> loadClass(String name) throws ClassNotFoundException {
        
return loadClass(name, false);
    
}

    
/**
     
* Loads the class with the specified
 
<a href="#name">binary name</a>.
  
The
     
* default implementation of this method searches for classes in the
     
* following order:
     
*
     
* <ol>
     
*
     
*
   
<li><p> Invoke {@link #findLoadedClass(String)} to check if the class
     
*
   
has already been loaded.
  
</p></li>
     
*
     
*
   
<li><p> Invoke the {@link #loadClass(String) <tt>loadClass</tt>} method
     
*
   
on the parent class loader.
  
If the parent is <tt>null</tt> the class
     
*
   
loader built-in to the virtual machine is used, instead.
  
</p></li>
     
*
     
*
   
<li><p> Invoke the {@link #findClass(String)} method to find the
     
*
   
class.
  
</p></li>
     
*
     
* </ol>
     
*
     
* <p> If the class was found using the above steps, and the
     
* <tt>resolve</tt> flag is true, this method will then invoke the {@link
     
* #resolveClass(Class)} method on the resulting <tt>Class</tt> object.
     
*
     
* <p> Subclasses of <tt>ClassLoader</tt> are encouraged to override {@link
     
* #findClass(String)}, rather than this method.
  
</p>
     
*
     
* <p> Unless overridden, this method synchronizes on the result of
     
* {@link #getClassLoadingLock <tt>getClassLoadingLock</tt>} method
     
* during the entire class loading process.
     
*
     
* @param
  
name
     
*
         
The
 
<a href="#name">binary name</a>
 
of the class
     
*
     
* @param
  
resolve
     
*
         
If <tt>true</tt> then resolve the class
     
*
     
* @return
  
The resulting <tt>Class</tt> object
     
*
     
* @throws
  
ClassNotFoundException
     
*
          
If the class could not be found
     
*/

    
protected Class<?> loadClass(String name, boolean resolve)
        
throws ClassNotFoundException
    
{
        
synchronized (getClassLoadingLock(name)) {
            
// First, check if the class has already been loaded
            
Class<?> c = findLoadedClass(name);
            
if (c == null) {
                
long t0 = System.nanoTime();
                
try {
                    
if (parent != null) {
                        
c = parent.loadClass(name, false);
                    
} else {
                        
c = findBootstrapClassOrNull(name);
                    
}
                
} catch (ClassNotFoundException e) {
                    
// ClassNotFoundException thrown if class not found
                    
// from the non-null parent class loader
                
}

                
if (c == null) {
                    
// If still not found, then invoke findClass in order
                    
// to find the class.
                    
long t1 = System.nanoTime();
                    
c = findClass(name);

                    
// this is the defining class loader; record the stats
                    
sun.misc.PerfCounter.getParentDelegationTime().addTime(t1 - t0);
                    
sun.misc.PerfCounter.getFindClassTime().addElapsedTimeFrom(t1);
                    
sun.misc.PerfCounter.getFindClasses().increment();
                
}
            
}
            
if (resolve) {
                
resolveClass(c);
            
}
            
return c;
        
}
    
}

    
/**
     
* Returns the lock object for class loading operations.
     
* For backward compatibility, the default implementation of this method
     
* behaves as follows. If this ClassLoader object is registered as
     
* parallel capable, the method returns a dedicated object associated
     
* with the specified class name. Otherwise, the method returns this
     
* ClassLoader object.
     
*
     
* @param
  
className
     
*
         
The name of the to-be-loaded class
     
*
     
* @return the lock for class loading operations
     
*
     
* @throws NullPointerException
     
*
         
If registered as parallel capable and <tt>className</tt> is null
     
*
     
* @see #loadClass(String, boolean)
     
*
     
* @since
  
1.7
     
*/

    
protected Object getClassLoadingLock(String className) {
        
Object lock = this;
        
if (parallelLockMap != null) {
            
Object newLock = new Object();
            
lock = parallelLockMap.putIfAbsent(className, newLock);
            
if (lock == null) {
                
lock = newLock;
            
}
        
}
        
return lock;
    
}

    
// This method is invoked by the virtual machine to load a class.
    
private Class<?> loadClassInternal(String name)
        
throws ClassNotFoundException
    
{
        
// For backward compatibility, explicitly lock on 'this' when
        
// the current class loader is not parallel capable.
        
if (parallelLockMap == null) {
            
synchronized (this) {
                 
return loadClass(name);
            
}
        
} else {
            
return loadClass(name);
        
}
    
}

    
// Invoked by the VM after loading class with this loader.
    
private void checkPackageAccess(Class<?> cls, ProtectionDomain pd) {
        
final SecurityManager sm = System.getSecurityManager();
        
if (sm != null) {
            
if (ReflectUtil.isNonPublicProxyClass(cls)) {
                
for (Class<?> intf: cls.getInterfaces()) {
                    
checkPackageAccess(intf, pd);
                
}
                
return;
            
}

            
final String name = cls.getName();
            
final int i = name.lastIndexOf('.');
            
if (i != -1) {
                
AccessController.doPrivileged(new PrivilegedAction<Void>() {
                    
public Void run() {
                        
sm.checkPackageAccess(name.substring(0, i));
                        
return null;
                    
}
                
}, new AccessControlContext(new ProtectionDomain[] {pd}));
            
}
        
}
        
domains.add(pd);
    
}

    
/**
     
* Finds the class with the specified
 
<a href="#name">binary name</a>.
     
* This method should be overridden by class loader implementations that
     
* follow the delegation model for loading classes, and will be invoked by
     
* the {@link #loadClass <tt>loadClass</tt>} method after checking the
     
* parent class loader for the requested class.
  
The default implementation
     
* throws a <tt>ClassNotFoundException</tt>.
     
*
     
* @param
  
name
     
*
         
The
 
<a href="#name">binary name</a>
 
of the class
     
*
     
* @return
  
The resulting <tt>Class</tt> object
     
*
     
* @throws
  
ClassNotFoundException
     
*
          
If the class could not be found
     
*
     
* @since
  
1.2
     
*/

    
protected Class<?> findClass(String name) throws ClassNotFoundException {
        
throw new ClassNotFoundException(name);
    
}

    
/**
     
* Converts an array of bytes into an instance of class <tt>Class</tt>.
     
* Before the <tt>Class</tt> can be used it must be resolved.
  
This method
     
* is deprecated in favor of the version that takes a <a
     
* href="#name">binary name</a> as its first argument, and is more secure.
     
*
     
* @param
  
b
     
*
         
The bytes that make up the class data.
  
The bytes in positions
     
*
         
<tt>off</tt> through <tt>off+len-1</tt> should have the format
     
*
         
of a valid class file as defined by
     
*
         
<cite>The Java&trade; Virtual Machine Specification</cite>.
     
*
     
* @param
  
off
     
*
         
The start offset in <tt>b</tt> of the class data
     
*
     
* @param
  
len
     
*
         
The length of the class data
     
*
     
* @return
  
The <tt>Class</tt> object that was created from the specified
     
*
          
class data
     
*
     
* @throws
  
ClassFormatError
     
*
          
If the data did not contain a valid class
     
*
     
* @throws
  
IndexOutOfBoundsException
     
*
          
If either <tt>off</tt> or <tt>len</tt> is negative, or if
     
*
          
<tt>off+len</tt> is greater than <tt>b.length</tt>.
     
*
     
* @throws
  
SecurityException
     
*
          
If an attempt is made to add this class to a package that
     
*
          
contains classes that were signed by a different set of
     
*
          
certificates than this class, or if an attempt is made
     
*
          
to define a class in a package with a fully-qualified name
     
*
          
that starts with "{@code java.}".
     
*
     
* @see
  
#loadClass(String, boolean)
     
* @see
  
#resolveClass(Class)
     
*
     
* @deprecated
  
Replaced by {@link #defineClass(String, byte[], int, int)
     
* defineClass(String, byte[], int, int)}
     
*/

    
@Deprecated
    
protected final Class<?> defineClass(byte[] b, int off, int len)
        
throws ClassFormatError
    
{
        
return defineClass(null, b, off, len, null);
    
}

    
/**
     
* Converts an array of bytes into an instance of class <tt>Class</tt>.
     
* Before the <tt>Class</tt> can be used it must be resolved.
     
*
     
* <p> This method assigns a default {@link java.security.ProtectionDomain
     
* <tt>ProtectionDomain</tt>} to the newly defined class.
  
The
     
* <tt>ProtectionDomain</tt> is effectively granted the same set of
     
* permissions returned when {@link
     
* java.security.Policy#getPermissions(java.security.CodeSource)
     
* <tt>Policy.getPolicy().getPermissions(new CodeSource(null, null))</tt>}
     
* is invoked.
  
The default domain is created on the first invocation of
     
* {@link #defineClass(String, byte[], int, int) <tt>defineClass</tt>},
     
* and re-used on subsequent invocations.
     
*
     
* <p> To assign a specific <tt>ProtectionDomain</tt> to the class, use
     
* the {@link #defineClass(String, byte[], int, int,
     
* java.security.ProtectionDomain) <tt>defineClass</tt>} method that takes a
     
* <tt>ProtectionDomain</tt> as one of its arguments.
  
</p>
     
*
     
* @param
  
name
     
*
         
The expected
 
<a href="#name">binary name</a>
 
of the class, or
     
*
         
<tt>null</tt> if not known
     
*
     
* @param
  
b
     
*
         
The bytes that make up the class data.
  
The bytes in positions
     
*
         
<tt>off</tt> through <tt>off+len-1</tt> should have the format
     
*
         
of a valid class file as defined by
     
*
         
<cite>The Java&trade; Virtual Machine Specification</cite>.
     
*
     
* @param
  
off
     
*
         
The start offset in <tt>b</tt> of the class data
     
*
     
* @param
  
len
     
*
         
The length of the class data
     
*
     
* @return
  
The <tt>Class</tt> object that was created from the specified
     
*
          
class data.
     
*
     
* @throws
  
ClassFormatError
     
*
          
If the data did not contain a valid class
     
*
     
* @throws
  
IndexOutOfBoundsException
     
*
          
If either <tt>off</tt> or <tt>len</tt> is negative, or if
     
*
          
<tt>off+len</tt> is greater than <tt>b.length</tt>.
     
*
     
* @throws
  
SecurityException
     
*
          
If an attempt is made to add this class to a package that
     
*
          
contains classes that were signed by a different set of
     
*
          
certificates than this class (which is unsigned), or if
     
*
          
<tt>name</tt> begins with "<tt>java.</tt>".
     
*
     
* @see
  
#loadClass(String, boolean)
     
* @see
  
#resolveClass(Class)
     
* @see
  
java.security.CodeSource
     
* @see
  
java.security.SecureClassLoader
     
*
     
* @since
  
1.1
     
*/

    
protected final Class<?> defineClass(String name, byte[] b, int off, int len)
        
throws ClassFormatError
    
{
        
return defineClass(name, b, off, len, null);
    
}

    
/* Determine protection domain, and check that:
        
- not define java.* class,
        
- signer of this class matches signers for the rest of the classes in
          
package.
    
*/

    
private ProtectionDomain preDefineClass(String name,
                                            
ProtectionDomain pd)
    
{
        
if (!checkName(name))
            
throw new NoClassDefFoundError("IllegalName: " + name);

        
// Note:
  
Checking logic in java.lang.invoke.MemberName.checkForTypeAlias
        
// relies on the fact that spoofing is impossible if a class has a name
        
// of the form "java.*"
        
if ((name != null) && name.startsWith("java.")) {
            
throw new SecurityException
                
("Prohibited package name: " +
                 
name.substring(0, name.lastIndexOf('.')));
        
}
        
if (pd == null) {
            
pd = defaultDomain;
        
}

        
if (name != null) checkCerts(name, pd.getCodeSource());

        
return pd;
    
}

    
private String defineClassSourceLocation(ProtectionDomain pd)
    
{
        
CodeSource cs = pd.getCodeSource();
        
String source = null;
        
if (cs != null && cs.getLocation() != null) {
            
source = cs.getLocation().toString();
        
}
        
return source;
    
}

    
private void postDefineClass(Class<?> c, ProtectionDomain pd)
    
{
        
if (pd.getCodeSource() != null) {
            
Certificate certs[] = pd.getCodeSource().getCertificates();
            
if (certs != null)
                
setSigners(c, certs);
        
}
    
}

    
/**
     
* Converts an array of bytes into an instance of class <tt>Class</tt>,
     
* with an optional <tt>ProtectionDomain</tt>.
  
If the domain is
     
* <tt>null</tt>, then a default domain will be assigned to the class as
     
* specified in the documentation for {@link #defineClass(String, byte[],
     
* int, int)}.
  
Before the class can be used it must be resolved.
     
*
     
* <p> The first class defined in a package determines the exact set of
     
* certificates that all subsequent classes defined in that package must
     
* contain.
  
The set of certificates for a class is obtained from the
     
* {@link java.security.CodeSource <tt>CodeSource</tt>} within the
     
* <tt>ProtectionDomain</tt> of the class.
  
Any classes added to that
     
* package must contain the same set of certificates or a
     
* <tt>SecurityException</tt> will be thrown.
  
Note that if
     
* <tt>name</tt> is <tt>null</tt>, this check is not performed.
     
* You should always pass in the
 
<a href="#name">binary name</a>
 
of the
     
* class you are defining as well as the bytes.
  
This ensures that the
     
* class you are defining is indeed the class you think it is.
     
*
     
* <p> The specified <tt>name</tt> cannot begin with "<tt>java.</tt>", since
     
* all classes in the "<tt>java.*</tt> packages can only be defined by the
     
* bootstrap class loader.
  
If <tt>name</tt> is not <tt>null</tt>, it
     
* must be equal to the
 
<a href="#name">binary name</a>
 
of the class
     
* specified by the byte array "<tt>b</tt>", otherwise a {@link
     
* NoClassDefFoundError <tt>NoClassDefFoundError</tt>} will be thrown. </p>
     
*
     
* @param
  
name
     
*
         
The expected
 
<a href="#name">binary name</a>
 
of the class, or
     
*
         
<tt>null</tt> if not known
     
*
     
* @param
  
b
     
*
         
The bytes that make up the class data. The bytes in positions
     
*
         
<tt>off</tt> through <tt>off+len-1</tt> should have the format
     
*
         
of a valid class file as defined by
     
*
         
<cite>The Java&trade; Virtual Machine Specification</cite>.
     
*
     
* @param
  
off
     
*
         
The start offset in <tt>b</tt> of the class data
     
*
     
* @param
  
len
     
*
         
The length of the class data
     
*
     
* @param
  
protectionDomain
     
*
         
The ProtectionDomain of the class
     
*
     
* @return
  
The <tt>Class</tt> object created from the data,
     
*
          
and optional <tt>ProtectionDomain</tt>.
     
*
     
* @throws
  
ClassFormatError
     
*
          
If the data did not contain a valid class
     
*
     
* @throws
  
NoClassDefFoundError
     
*
          
If <tt>name</tt> is not equal to the <a href="#name">binary
     
*
          
name</a> of the class specified by <tt>b</tt>
     
*
     
* @throws
  
IndexOutOfBoundsException
     
*
          
If either <tt>off</tt> or <tt>len</tt> is negative, or if
     
*
          
<tt>off+len</tt> is greater than <tt>b.length</tt>.
     
*
     
* @throws
  
SecurityException
     
*
          
If an attempt is made to add this class to a package that
     
*
          
contains classes that were signed by a different set of
     
*
          
certificates than this class, or if <tt>name</tt> begins with
     
*
          
"<tt>java.</tt>".
     
*/

    
protected final Class<?> defineClass(String name, byte[] b, int off, int len,
                                         
ProtectionDomain protectionDomain)
        
throws ClassFormatError
    
{
        
protectionDomain = preDefineClass(name, protectionDomain);
        
String source = defineClassSourceLocation(protectionDomain);
        
Class<?> c = defineClass1(name, b, off, len, protectionDomain, source);
        
postDefineClass(c, protectionDomain);
        
return c;
    
}

    
/**
     
* Converts a {@link java.nio.ByteBuffer <tt>ByteBuffer</tt>}
     
* into an instance of class <tt>Class</tt>,
     
* with an optional <tt>ProtectionDomain</tt>.
  
If the domain is
     
* <tt>null</tt>, then a default domain will be assigned to the class as
     
* specified in the documentation for {@link #defineClass(String, byte[],
     
* int, int)}.
  
Before the class can be used it must be resolved.
     
*
     
* <p>The rules about the first class defined in a package determining the
     
* set of certificates for the package, and the restrictions on class names
     
* are identical to those specified in the documentation for {@link
     
* #defineClass(String, byte[], int, int, ProtectionDomain)}.
     
*
     
* <p> An invocation of this method of the form
     
* <i>cl</i><tt>.defineClass(</tt><i>name</i><tt>,</tt>
     
* <i>bBuffer</i><tt>,</tt> <i>pd</i><tt>)</tt> yields exactly the same
     
* result as the statements
     
*
     
*<p> <tt>
     
* ...<br>
     
* byte[] temp = new byte[bBuffer.{@link
     
* java.nio.ByteBuffer#remaining remaining}()];<br>
     
*bBuffer.{@link java.nio.ByteBuffer#get(byte[])
     
* get}(temp);<br>
     
*return {@link #defineClass(String, byte[], int, int, ProtectionDomain)
     
* cl.defineClass}(name, temp, 0,
     
* temp.length, pd);<br>
     
* </tt></p>
     
*
     
* @param
  
name
     
*
         
The expected
 
<a href="#name">binary name</a>. of the class, or
     
*
         
<tt>null</tt> if not known
     
*
     
* @param
  
b
     
*
         
The bytes that make up the class data. The bytes from positions
     
*
         
<tt>b.position()</tt> through <tt>b.position() + b.limit() -1
     
*
         
</tt> should have the format of a valid class file as defined by
     
*
         
<cite>The Java&trade; Virtual Machine Specification</cite>.
     
*
     
* @param
  
protectionDomain
     
*
         
The ProtectionDomain of the class, or <tt>null</tt>.
     
*
     
* @return
  
The <tt>Class</tt> object created from the data,
     
*
          
and optional <tt>ProtectionDomain</tt>.
     
*
     
* @throws
  
ClassFormatError
     
*
          
If the data did not contain a valid class.
     
*
     
* @throws
  
NoClassDefFoundError
     
*
          
If <tt>name</tt> is not equal to the <a href="#name">binary
     
*
          
name</a> of the class specified by <tt>b</tt>
     
*
     
* @throws
  
SecurityException
     
*
          
If an attempt is made to add this class to a package that
     
*
          
contains classes that were signed by a different set of
     
*
          
certificates than this class, or if <tt>name</tt> begins with
     
*
          
"<tt>java.</tt>".
     
*
     
* @see
      
#defineClass(String, byte[], int, int, ProtectionDomain)
     
*
     
* @since
  
1.5
     
*/

    
protected final Class<?> defineClass(String name, java.nio.ByteBuffer b,
                                         
ProtectionDomain protectionDomain)
        
throws ClassFormatError
    
{
        
int len = b.remaining();

        
// Use byte[] if not a direct ByteBufer:
        
if (!b.isDirect()) {
            
if (b.hasArray()) {
                
return defineClass(name, b.array(),
                                   
b.position() + b.arrayOffset(), len,
                                   
protectionDomain);
            
} else {
                
// no array, or read-only array
                
byte[] tb = new byte[len];
                
b.get(tb);
  
// get bytes out of byte buffer.
                
return defineClass(name, tb, 0, len, protectionDomain);
            
}
        
}

        
protectionDomain = preDefineClass(name, protectionDomain);
        
String source = defineClassSourceLocation(protectionDomain);
        
Class<?> c = defineClass2(name, b, b.position(), len, protectionDomain, source);
        
postDefineClass(c, protectionDomain);
        
return c;
    
}

    
private native Class<?> defineClass0(String name, byte[] b, int off, int len,
                                         
ProtectionDomain pd);

    
private native Class<?> defineClass1(String name, byte[] b, int off, int len,
                                         
ProtectionDomain pd, String source);

    
private native Class<?> defineClass2(String name, java.nio.ByteBuffer b,
                                         
int off, int len, ProtectionDomain pd,
                                         
String source);

    
// true if the name is null or has the potential to be a valid binary name
    
private boolean checkName(String name) {
        
if ((name == null) || (name.length() == 0))
            
return true;
        
if ((name.indexOf('/') != -1)
            
|| (!VM.allowArraySyntax() && (name.charAt(0) == '[')))
            
return false;
        
return true;
    
}

    
private void checkCerts(String name, CodeSource cs) {
        
int i = name.lastIndexOf('.');
        
String pname = (i == -1) ? "" : name.substring(0, i);

        
Certificate[] certs = null;
        
if (cs != null) {
            
certs = cs.getCertificates();
        
}
        
Certificate[] pcerts = null;
        
if (parallelLockMap == null) {
            
synchronized (this) {
                
pcerts = package2certs.get(pname);
                
if (pcerts == null) {
                    
package2certs.put(pname, (certs == null? nocerts:certs));
                
}
            
}
        
} else {
            
pcerts = ((ConcurrentHashMap<String, Certificate[]>)package2certs).
                
putIfAbsent(pname, (certs == null? nocerts:certs));
        
}
        
if (pcerts != null && !compareCerts(pcerts, certs)) {
            
throw new SecurityException("class \""+ name +
                 
"\"'s signer information does not match signer information of other classes in the same package");
        
}
    
}

    
/**
     
* check to make sure the certs for the new class (certs) are the same as
     
* the certs for the first class inserted in the package (pcerts)
     
*/

    
private boolean compareCerts(Certificate[] pcerts,
                                 
Certificate[] certs)
    
{
        
// certs can be null, indicating no certs.
        
if ((certs == null) || (certs.length == 0)) {
            
return pcerts.length == 0;
        
}

        
// the length must be the same at this point
        
if (certs.length != pcerts.length)
            
return false;

        
// go through and make sure all the certs in one array
        
// are in the other and vice-versa.
        
boolean match;
        
for (int i = 0; i < certs.length; i++) {
            
match = false;
            
for (int j = 0; j < pcerts.length; j++) {
                
if (certs[i].equals(pcerts[j])) {
                    
match = true;
                    
break;
                
}
            
}
            
if (!match) return false;
        
}

        
// now do the same for pcerts
        
for (int i = 0; i < pcerts.length; i++) {
            
match = false;
            
for (int j = 0; j < certs.length; j++) {
                
if (pcerts[i].equals(certs[j])) {
                    
match = true;
                    
break;
                
}
            
}
            
if (!match) return false;
        
}

        
return true;
    
}

    
/**
     
* Links the specified class.
  
This (misleadingly named) method may be
     
* used by a class loader to link a class.
  
If the class <tt>c</tt> has
     
* already been linked, then this method simply returns. Otherwise, the
     
* class is linked as described in the "Execution" chapter of
     
* <cite>The Java&trade; Language Specification</cite>.
     
*
     
* @param
  
c
     
*
         
The class to link
     
*
     
* @throws
  
NullPointerException
     
*
          
If <tt>c</tt> is <tt>null</tt>.
     
*
     
* @see
  
#defineClass(String, byte[], int, int)
     
*/

    
protected final void resolveClass(Class<?> c) {
        
resolveClass0(c);
    
}

    
private native void resolveClass0(Class<?> c);

    
/**
     
* Finds a class with the specified
 
<a href="#name">binary name</a>,
     
* loading it if necessary.
     
*
     
* <p> This method loads the class through the system class loader (see
     
*
 
).
  
The <tt>Class</tt> object returned
     
* might have more than one <tt>ClassLoader</tt> associated with it.
     
* Subclasses of <tt>ClassLoader</tt> need not usually invoke this method,
     
* because most class loaders need to override just {@link
     
* #findClass(String)}.
  
</p>
     
*
     
* @param
  
name
     
*
         
The
 
<a href="#name">binary name</a>
 
of the class
     
*
     
* @return
  
The <tt>Class</tt> object for the specified <tt>name</tt>
     
*
     
* @throws
  
ClassNotFoundException
     
*
          
If the class could not be found
     
*
     
* @see
  
#ClassLoader(ClassLoader)
     
* @see
  
#getParent()
     
*/

    
protected final Class<?> findSystemClass(String name)
        
throws ClassNotFoundException
    
{
        
ClassLoader system = getSystemClassLoader();
        
if (system == null) {
            
if (!checkName(name))
                
throw new ClassNotFoundException(name);
            
Class<?> cls = findBootstrapClass(name);
            
if (cls == null) {
                
throw new ClassNotFoundException(name);
            
}
            
return cls;
        
}
        
return system.loadClass(name);
    
}

    
/**
     
* Returns a class loaded by the bootstrap class loader;
     
* or return null if not found.
     
*/

    
private Class<?> findBootstrapClassOrNull(String name)
    
{
        
if (!checkName(name)) return null;

        
return findBootstrapClass(name);
    
}

    
// return null if not found
    
private native Class<?> findBootstrapClass(String name);

    
/**
     
* Returns the class with the given
 
<a href="#name">binary name</a>
 
if this
     
* loader has been recorded by the Java virtual machine as an initiating
     
* loader of a class with that
 
<a href="#name">binary name</a>.
  
Otherwise
     
* <tt>null</tt> is returned.
     
*
     
* @param
  
name
     
*
         
The
 
<a href="#name">binary name</a>
 
of the class
     
*
     
* @return
  
The <tt>Class</tt> object, or <tt>null</tt> if the class has
     
*
          
not been loaded
     
*
     
* @since
  
1.1
     
*/

    
protected final Class<?> findLoadedClass(String name) {
        
if (!checkName(name))
            
return null;
        
return findLoadedClass0(name);
    
}

    
private native final Class<?> findLoadedClass0(String name);

    
/**
     
* Sets the signers of a class.
  
This should be invoked after defining a
     
* class.
     
*
     
* @param
  
c
     
*
         
The <tt>Class</tt> object
     
*
     
* @param
  
signers
     
*
         
The signers for the class
     
*
     
* @since
  
1.1
     
*/

    
protected final void setSigners(Class<?> c, Object[] signers) {
        
c.setSigners(signers);
    
}


    
// -- Resource --

    
/**
     
* Finds the resource with the given name.
  
A resource is some data
     
* (images, audio, text, etc) that can be accessed by class code in a way
     
* that is independent of the location of the code.
     
*
     
* <p> The name of a resource is a '<tt>/</tt>'-separated path name that
     
* identifies the resource.
     
*
     
* <p> This method will first search the parent class loader for the
     
* resource; if the parent is <tt>null</tt> the path of the class loader
     
* built-in to the virtual machine is searched.
  
That failing, this method
     
* will invoke {@link #findResource(String)} to find the resource.
  
</p>
     
*
     
* @apiNote When overriding this method it is recommended that an
     
* implementation ensures that any delegation is consistent with the {@link
     
* #getResources(java.lang.String) getResources(String)} method.
     
*
     
* @param
  
name
     
*
         
The resource name
     
*
     
* @return
  
A <tt>URL</tt> object for reading the resource, or
     
*
          
<tt>null</tt> if the resource could not be found or the invoker
     
*
          
doesn't have adequate
  
privileges to get the resource.
     
*
     
* @since
  
1.1
     
*/

    
public URL getResource(String name) {
        
URL url;
        
if (parent != null) {
            
url = parent.getResource(name);
        
} else {
            
url = getBootstrapResource(name);
        
}
        
if (url == null) {
            
url = findResource(name);
        
}
        
return url;
    
}

    
/**
     
* Finds all the resources with the given name. A resource is some data
     
* (images, audio, text, etc) that can be accessed by class code in a way
     
* that is independent of the location of the code.
     
*
     
* <p>The name of a resource is a <tt>/</tt>-separated path name that
     
* identifies the resource.
     
*
     
* <p> The search order is described in the documentation for {@link
     
* #getResource(String)}.
  
</p>
     
*
     
* @apiNote When overriding this method it is recommended that an
     
* implementation ensures that any delegation is consistent with the {@link
     
* #getResource(java.lang.String) getResource(String)} method. This should
     
* ensure that the first element returned by the Enumeration's
     
* {@code nextElement} method is the same resource that the
     
* {@code getResource(String)} method would return.
     
*
     
* @param
  
name
     
*
         
The resource name
     
*
     
* @return
  
An enumeration of {@link java.net.URL <tt>URL</tt>} objects for
     
*
          
the resource.
  
If no resources couldbe found, the enumeration
     
*
          
will be empty.
  
Resources that the class loader doesn't have
     
*
          
access to will not be in the enumeration.
     
*
     
* @throws
  
IOException
     
*
          
If I/O errors occur
     
*
     
* @see
  
#findResources(String)
     
*
     
* @since
  
1.2
     
*/

    
public Enumeration<URL> getResources(String name) throws IOException {
        
@SuppressWarnings("unchecked")
        
Enumeration<URL>[] tmp = (Enumeration<URL>[]) new Enumeration<?>[2];
        
if (parent != null) {
            
tmp[0] = parent.getResources(name);
        
} else {
            
tmp[0] = getBootstrapResources(name);
        
}
        
tmp[1] = findResources(name);

        
return new CompoundEnumeration<>(tmp);
    
}

    
/**
     
* Finds the resource with the given name. Class loader implementations
     
* should override this method to specify where to find resources.
     
*
     
* @param
  
name
     
*
         
The resource name
     
*
     
* @return
  
A <tt>URL</tt> object for reading the resource, or
     
*
          
<tt>null</tt> if the resource could not be found
     
*
     
* @since
  
1.2
     
*/

    
protected URL findResource(String name) {
        
return null;
    
}

    
/**
     
* Returns an enumeration of {@link java.net.URL <tt>URL</tt>} objects
     
* representing all the resources with the given name. Class loader
     
* implementations should override this method to specify where to load
     
* resources from.
     
*
     
* @param
  
name
     
*
         
The resource name
     
*
     
* @return
  
An enumeration of {@link java.net.URL <tt>URL</tt>} objects for
     
*
          
the resources
     
*
     
* @throws
  
IOException
     
*
          
If I/O errors occur
     
*
     
* @since
  
1.2
     
*/

    
protected Enumeration<URL> findResources(String name) throws IOException {
        
return java.util.Collections.emptyEnumeration();
    
}

    
/**
     
* Registers the caller as parallel capable.
     
* The registration succeeds if and only if all of the following
     
* conditions are met:
     
* <ol>
     
* <li> no instance of the caller has been created</li>
     
* <li> all of the super classes (except class Object) of the caller are
     
* registered as parallel capable</li>
     
* </ol>
     
* <p>Note that once a class loader is registered as parallel capable, there
     
* is no way to change it back.</p>
     
*
     
* @return
  
true if the caller is successfully registered as
     
*
          
parallel capable and false if otherwise.
     
*
     
* @since
   
1.7
     
*/

    
@CallerSensitive
    
protected static boolean registerAsParallelCapable() {
        
Class<? extends ClassLoader> callerClass =
            
Reflection.getCallerClass().asSubclass(ClassLoader.class);
        
return ParallelLoaders.register(callerClass);
    
}

    
/**
     
* Find a resource of the specified name from the search path used to load
     
* classes.
  
This method locates the resource through the system class
     
* loader (see
 
).
     
*
     
* @param
  
name
     
*
         
The resource name
     
*
     
* @return
  
A {@link java.net.URL <tt>URL</tt>} object for reading the
     
*
          
resource, or <tt>null</tt> if the resource could not be found
     
*
     
* @since
  
1.1
     
*/

    
public static URL getSystemResource(String name) {
        
ClassLoader system = getSystemClassLoader();
        
if (system == null) {
            
return getBootstrapResource(name);
        
}
        
return system.getResource(name);
    
}

    
/**
     
* Finds all resources of the specified name from the search path used to
     
* load classes.
  
The resources thus found are returned as an
     
* {@link java.util.Enumeration <tt>Enumeration</tt>} of {@link
     
* java.net.URL <tt>URL</tt>} objects.
     
*
     
* <p> The search order is described in the documentation for {@link
     
* #getSystemResource(String)}.
  
</p>
     
*
     
* @param
  
name
     
*
         
The resource name
     
*
     
* @return
  
An enumeration of resource {@link java.net.URL <tt>URL</tt>}
     
*
          
objects
     
*
     
* @throws
  
IOException
     
*
          
If I/O errors occur

     
* @since
  
1.2
     
*/

    
public static Enumeration<URL> getSystemResources(String name)
        
throws IOException
    
{
        
ClassLoader system = getSystemClassLoader();
        
if (system == null) {
            
return getBootstrapResources(name);
        
}
        
return system.getResources(name);
    
}

    
/**
     
* Find resources from the VM's built-in classloader.
     
*/
    
private static URL getBootstrapResource(String name) {
        
URLClassPath ucp = getBootstrapClassPath();
        
Resource res = ucp.getResource(name);
        
return res != null ? res.getURL() : null;
    
}

    
/**
     
* Find resources from the VM's built-in classloader.
     
*/
    
private static Enumeration<URL> getBootstrapResources(String name)
        
throws IOException
    
{
        
final Enumeration<Resource> e =
            
getBootstrapClassPath().getResources(name);
        
return new Enumeration<URL> () {
            
public URL nextElement() {
                
return e.nextElement().getURL();
            
}
            
public boolean hasMoreElements() {
                
return e.hasMoreElements();
            
}
        
};
    
}

    
// Returns the URLClassPath that is used for finding system resources.
    
static URLClassPath getBootstrapClassPath() {
        
return sun.misc.Launcher.getBootstrapClassPath();
    
}


    
/**
     
* Returns an input stream for reading the specified resource.
     
*
     
* <p> The search order is described in the documentation for {@link
     
* #getResource(String)}.
  
</p>
     
*
     
* @param
  
name
     
*
         
The resource name
     
*
     
* @return
  
An input stream for reading the resource, or <tt>null</tt>
     
*
          
if the resource could not be found
     
*
     
* @since
  
1.1
     
*/

    
public InputStream getResourceAsStream(String name) {
        
URL url = getResource(name);
        
try {
            
return url != null ? url.openStream() : null;
        
} catch (IOException e) {
            
return null;
        
}
    
}

    
/**
     
* Open for reading, a resource of the specified name from the search path
     
* used to load classes.
  
This method locates the resource through the
     
* system class loader (see
 
).
     
*
     
* @param
  
name
     
*
         
The resource name
     
*
     
* @return
  
An input stream for reading the resource, or <tt>null</tt>
     
*
          
if the resource could not be found
     
*
     
* @since
  
1.1
     
*/

    
public static InputStream getSystemResourceAsStream(String name) {
        
URL url = getSystemResource(name);
        
try {
            
return url != null ? url.openStream() : null;
        
} catch (IOException e) {
            
return null;
        
}
    
}


    
// -- Hierarchy --

    
/**
     
* Returns the parent class loader for delegation. Some implementations may
     
* use <tt>null</tt> to represent the bootstrap class loader. This method
     
* will return <tt>null</tt> in such implementations if this class loader's
     
* parent is the bootstrap class loader.
     
*
     
* <p> If a security manager is present, and the invoker's class loader is
     
* not <tt>null</tt> and is not an ancestor of this class loader, then this
     
* method invokes the security manager's {@link
     
* SecurityManager#checkPermission(java.security.Permission)
     
* <tt>checkPermission</tt>} method with a {@link
     
* RuntimePermission#RuntimePermission(String)
     
* <tt>RuntimePermission("getClassLoader")</tt>} permission to verify
     
* access to the parent class loader is permitted.
  
If not, a
     
* <tt>SecurityException</tt> will be thrown.
  
</p>
     
*
     
* @return
  
The parent <tt>ClassLoader</tt>
     
*
     
* @throws
  
SecurityException
     
*
          
If a security manager exists and its <tt>checkPermission</tt>
     
*
          
method doesn't allow access to this class loader's parent class
     
*
          
loader.
     
*
     
* @since
  
1.2
     
*/

    
@CallerSensitive
    
public final ClassLoader getParent() {
        
if (parent == null)
            
return null;
        
SecurityManager sm = System.getSecurityManager();
        
if (sm != null) {
            
// Check access to the parent class loader
            
// If the caller's class loader is same as this class loader,
            
// permission check is performed.
            
checkClassLoaderPermission(parent, Reflection.getCallerClass());
        
}
        
return parent;
    
}

    
/**
     
* Returns the system class loader for delegation.
  
This is the default
     
* delegation parent for new <tt>ClassLoader</tt> instances, and is
     
* typically the class loader used to start the application.
     
*
     
* <p> This method is first invoked early in the runtime's startup
     
* sequence, at which point it creates the system class loader and sets it
     
* as the context class loader of the invoking <tt>Thread</tt>.
     
*
     
* <p> The default system class loader is an implementation-dependent
     
* instance of this class.
     
*
     
* <p> If the system property "<tt>java.system.class.loader</tt>" is defined
     
* when this method is first invoked then the value of that property is
     
* taken to be the name of a class that will be returned as the system
     
* class loader.
  
The class is loaded using the default system class loader
     
* and must define a public constructor that takes a single parameter of
     
* type <tt>ClassLoader</tt> which is used as the delegation parent.
  
An
     
* instance is then created using this constructor with the default system
     
* class loader as the parameter.
  
The resulting class loader is defined
     
* to be the system class loader.
     
*
     
* <p> If a security manager is present, and the invoker's class loader is
     
* not <tt>null</tt> and the invoker's class loader is not the same as or
     
* an ancestor of the system class loader, then this method invokes the
     
* security manager's {@link
     
* SecurityManager#checkPermission(java.security.Permission)
     
* <tt>checkPermission</tt>} method with a {@link
     
* RuntimePermission#RuntimePermission(String)
     
* <tt>RuntimePermission("getClassLoader")</tt>} permission to verify
     
* access to the system class loader.
  
If not, a
     
* <tt>SecurityException</tt> will be thrown.
  
</p>
     
*
     
* @return
  
The system <tt>ClassLoader</tt> for delegation, or
     
*
          
<tt>null</tt> if none
     
*
     
* @throws
  
SecurityException
     
*
          
If a security manager exists and its <tt>checkPermission</tt>
     
*
          
method doesn't allow access to the system class loader.
     
*
     
* @throws
  
IllegalStateException
     
*
          
If invoked recursively during the construction of the class
     
*
          
loader specified by the "<tt>java.system.class.loader</tt>"
     
*
          
property.
     
*
     
* @throws
  
Error
     
*
          
If the system property "<tt>java.system.class.loader</tt>"
     
*
          
is defined but the named class could not be loaded, the
     
*
          
provider class does not define the required constructor, or an
     
*
          
exception is thrown by that constructor when it is invoked. The
     
*
          
underlying cause of the error can be retrieved via the
     
*
          
{@link Throwable#getCause()} method.
     
*
     
* @revised
  
1.4
     
*/

    
@CallerSensitive
    
public static ClassLoader getSystemClassLoader() {
        
initSystemClassLoader();
        
if (scl == null) {
            
return null;
        
}
        
SecurityManager sm = System.getSecurityManager();
        
if (sm != null) {
            
checkClassLoaderPermission(scl, Reflection.getCallerClass());
        
}
        
return scl;
    
}

    
private static synchronized void initSystemClassLoader() {
        
if (!sclSet) {
            
if (scl != null)
                
throw new IllegalStateException("recursive invocation");
            
sun.misc.Launcher l = sun.misc.Launcher.getLauncher();
            
if (l != null) {
                
Throwable oops = null;
                
scl = l.getClassLoader();
                
try {
                    
scl = AccessController.doPrivileged(
                        
new SystemClassLoaderAction(scl));
                
} catch (PrivilegedActionException pae) {
                    
oops = pae.getCause();
                    
if (oops instanceof InvocationTargetException) {
                        
oops = oops.getCause();
                    
}
                
}
                
if (oops != null) {
                    
if (oops instanceof Error) {
                        
throw (Error) oops;
                    
} else {
                        
// wrap the exception
                        
throw new Error(oops);
                    
}
                
}
            
}
            
sclSet = true;
        
}
    
}

    
// Returns true if the specified class loader can be found in this class
    
// loader's delegation chain.
    
boolean isAncestor(ClassLoader cl) {
        
ClassLoader acl = this;
        
do {
            
acl = acl.parent;
            
if (cl == acl) {
                
return true;
            
}
        
} while (acl != null);
        
return false;
    
}

    
// Tests if class loader access requires "getClassLoader" permission
    
// check.
  
A class loader 'from' can access class loader 'to' if

    
// class loader 'from' is same as class loader 'to' or an ancestor
    
// of 'to'.
  
The class loader in a system domain can access

    
// any class loader.
    
private static boolean needsClassLoaderPermissionCheck(ClassLoader from,
                                                           
ClassLoader to)
    
{
        
if (from == to)
            
return false;

        
if (from == null)
            
return false;

        
return !to.isAncestor(from);
    
}

    
// Returns the class's class loader, or null if none.
    
static ClassLoader getClassLoader(Class<?> caller) {
        
// This can be null if the VM is requesting it
        
if (caller == null) {
            
return null;
        
}
        
// Circumvent security check since this is package-private
        
return caller.getClassLoader0();
    
}

    
/*
     
* Checks RuntimePermission("getClassLoader") permission
     
* if caller's class loader is not null and caller's class loader
     
* is not the same as or an ancestor of the given cl argument.
     
*/

    
static void checkClassLoaderPermission(ClassLoader cl, Class<?> caller) {
        
SecurityManager sm = System.getSecurityManager();
        
if (sm != null) {
            
// caller can be null if the VM is requesting it
            
ClassLoader ccl = getClassLoader(caller);
            
if (needsClassLoaderPermissionCheck(ccl, cl)) {
                
sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
            
}
        
}
    
}

    
// The class loader for the system
    
// @GuardedBy("ClassLoader.class")
    
private static ClassLoader scl;

    
// Set to true once the system class loader has been set
    
// @GuardedBy("ClassLoader.class")
    
private static boolean sclSet;


    
// -- Package --

    
/**
     
* Defines a package by name in this <tt>ClassLoader</tt>.
  
This allows
     
* class loaders to define the packages for their classes. Packages must
     
* be created before the class is defined, and package names must be
     
* unique within a class loader and cannot be redefined or changed once
     
* created.
     
*
     
* @param
  
name
     
*
         
The package name
     
*
     
* @param
  
specTitle
     
*
         
The specification title
     
*
     
* @param
  
specVersion
     
*
         
The specification version
     
*
     
* @param
  
specVendor
     
*
         
The specification vendor
     
*
     
* @param
  
implTitle
     
*
         
The implementation title
     
*
     
* @param
  
implVersion
     
*
         
The implementation version
     
*
     
* @param
  
implVendor
     
*
         
The implementation vendor
     
*
     
* @param
  
sealBase
     
*
         
If not <tt>null</tt>, then this package is sealed with
     
*
         
respect to the given code source {@link java.net.URL
     
*
         
<tt>URL</tt>}
  
object.Otherwise, the package is not sealed.
     
*
     
* @return
  
The newly defined <tt>Package</tt> object
     
*
     
* @throws
  
IllegalArgumentException
     
*
          
If package name duplicates an existing package either in this
     
*
          
class loader or one of its ancestors
     
*
     
* @since
  
1.2
     
*/

    
protected Package definePackage(String name, String specTitle,
                                    
String specVersion, String specVendor,
                                    
String implTitle, String implVersion,
                                    
String implVendor, URL sealBase)
        
throws IllegalArgumentException
    
{
        
synchronized (packages) {
            
Package pkg = getPackage(name);
            
if (pkg != null) {
                
throw new IllegalArgumentException(name);
            
}
            
pkg = new Package(name, specTitle, specVersion, specVendor,
                              
implTitle, implVersion, implVendor,
                              
sealBase, this);
            
packages.put(name, pkg);
            
return pkg;
        
}
    
}

    
/**
     
* Returns a <tt>Package</tt> that has been defined by this class loader
     
* or any of its ancestors.
     
*
     
* @param
  
name
     
*
         
The package name
     
*
     
* @return
  
The <tt>Package</tt> corresponding to the given name, or
     
*
          
<tt>null</tt> if not found
     
*
     
* @since
  
1.2
     
*/

    
protected Package getPackage(String name) {
        
Package pkg;
        
synchronized (packages) {
            
pkg = packages.get(name);
        
}
        
if (pkg == null) {
            
if (parent != null) {
                
pkg = parent.getPackage(name);
            
} else {
                
pkg = Package.getSystemPackage(name);
            
}
            
if (pkg != null) {
                
synchronized (packages) {
                    
Package pkg2 = packages.get(name);
                    
if (pkg2 == null) {
                        
packages.put(name, pkg);
                    
} else {
                        
pkg = pkg2;
                    
}
                
}
            
}
        
}
        
return pkg;
    
}

    
/**
     
* Returns all of the <tt>Packages</tt> defined by this class loader and
     
* its ancestors.
     
*
     
* @return
  
The array of <tt>Package</tt> objects defined by this
     
*
          
<tt>ClassLoader</tt>
     
*
     
* @since
  
1.2
     
*/

    
protected Package[] getPackages() {
        
Map<String, Package> map;
        
synchronized (packages) {
            
map = new HashMap<>(packages);
        
}
        
Package[] pkgs;
        
if (parent != null) {
            
pkgs = parent.getPackages();
        
} else {
            
pkgs = Package.getSystemPackages();
        
}
        
if (pkgs != null) {
            
for (int i = 0; i < pkgs.length; i++) {
                
String pkgName = pkgs[i].getName();
                
if (map.get(pkgName) == null) {
                    
map.put(pkgName, pkgs[i]);
                
}
            
}
        
}
        
return map.values().toArray(new Package[map.size()]);
    
}


    
// -- Native library access --

    
/**
     
* Returns the absolute path name of a native library.
  
The VM invokes this
     
* method to locate the native libraries that belong to classes loaded with
     
* this class loader. If this method returns <tt>null</tt>, the VM
     
* searches the library along the path specified as the
     
* "<tt>java.library.path</tt>" property.
     
*
     
* @param
  
libname
     
*
         
The library name
     
*
     
* @return
  
The absolute path of the native library
     
*
     
* @see
  
System#loadLibrary(String)
     
* @see
  
System#mapLibraryName(String)
     
*
     
* @since
  
1.2
     
*/

    
protected String findLibrary(String libname) {
        
return null;
    
}

    
/**
     
* The inner class NativeLibrary denotes a loaded native library instance.
     
* Every classloader contains a vector of loaded native libraries in the
     
* private field <tt>nativeLibraries</tt>.
  
The native libraries loaded
     
* into the system are entered into the <tt>systemNativeLibraries</tt>
     
* vector.
     
*
     
* <p> Every native library requires a particular version of JNI. This is
     
* denoted by the private <tt>jniVersion</tt> field.
  
This field is set by
     
* the VM when it loads the library, and used by the VM to pass the correct
     
* version of JNI to the native methods.
  
</p>
     
*
     
* @see
      
ClassLoader
     
* @since
    
1.2
     
*/

    
static class NativeLibrary {
        
// opaque handle to native library, used in native code.
        
long handle;
        
// the version of JNI environment the native library requires.
        
private int jniVersion;
        
// the class from which the library is loaded, also indicates
        
// the loader this native library belongs.
        
private final Class<?> fromClass;
        
// the canonicalized name of the native library.
        
// or static library name
        
String name;
        
// Indicates if the native library is linked into the VM
        
boolean isBuiltin;
        
// Indicates if the native library is loaded
        
boolean loaded;
        
native void load(String name, boolean isBuiltin);

        
native long find(String name);
        
native void unload(String name, boolean isBuiltin);

        
public NativeLibrary(Class<?> fromClass, String name, boolean isBuiltin) {
            
this.name = name;
            
this.fromClass = fromClass;
            
this.isBuiltin = isBuiltin;
        
}

        
protected void finalize() {
            
synchronized (loadedLibraryNames) {
                
if (fromClass.getClassLoader() != null && loaded) {
                    
/* remove the native library name */
                    
int size = loadedLibraryNames.size();
                    
for (int i = 0; i < size; i++) {
                        
if (name.equals(loadedLibraryNames.elementAt(i))) {
                            
loadedLibraryNames.removeElementAt(i);
                            
break;
                        
}
                    
}
                    
/* unload the library. */
                    
ClassLoader.nativeLibraryContext.push(this);
                    
try {
                        
unload(name, isBuiltin);
                    
} finally {
                        
ClassLoader.nativeLibraryContext.pop();
                    
}
                
}
            
}
        
}
        
// Invoked in the VM to determine the context class in
        
// JNI_Load/JNI_Unload
        
static Class<?> getFromClass() {
            
return ClassLoader.nativeLibraryContext.peek().fromClass;
        
}
    
}

    
// All native library names we've loaded.
    
private static Vector<String> loadedLibraryNames = new Vector<>();

    
// Native libraries belonging to system classes.
    
private static Vector<NativeLibrary> systemNativeLibraries
        
= new Vector<>();

    
// Native libraries associated with the class loader.
    
private Vector<NativeLibrary> nativeLibraries = new Vector<>();

    
// native libraries being loaded/unloaded.
    
private static Stack<NativeLibrary> nativeLibraryContext = new Stack<>();

    
// The paths searched for libraries
    
private static String usr_paths[];
    
private static String sys_paths[];

    
private static String[] initializePath(String propname) {
        
String ldpath = System.getProperty(propname, "");
        
String ps = File.pathSeparator;
        
int ldlen = ldpath.length();
        
int i, j, n;
        
// Count the separators in the path
        
i = ldpath.indexOf(ps);
        
n = 0;
        
while (i >= 0) {
            
n++;
            
i = ldpath.indexOf(ps, i + 1);
        
}

        
// allocate the array of paths - n :'s = n + 1 path elements
        
String[] paths = new String[n + 1];

        
// Fill the array with paths from the ldpath
        
n = i = 0;
        
j = ldpath.indexOf(ps);
        
while (j >= 0) {
            
if (j - i > 0) {
                
paths[n++] = ldpath.substring(i, j);
            
} else if (j - i == 0) {
                
paths[n++] = ".";
            
}
            
i = j + 1;
            
j = ldpath.indexOf(ps, i);
        
}
        
paths[n] = ldpath.substring(i, ldlen);
        
return paths;
    
}

    
// Invoked in the java.lang.Runtime class to implement load and loadLibrary.
    
static void loadLibrary(Class<?> fromClass, String name,
                            
boolean isAbsolute) {
        
ClassLoader loader =
            
(fromClass == null) ? null : fromClass.getClassLoader();
        
if (sys_paths == null) {
            
usr_paths = initializePath("java.library.path");
            
sys_paths = initializePath("sun.boot.library.path");
        
}
        
if (isAbsolute) {
            
if (loadLibrary0(fromClass, new File(name))) {
                
return;
            
}
            
throw new UnsatisfiedLinkError("Can't load library: " + name);
        
}
        
if (loader != null) {
            
String libfilename = loader.findLibrary(name);
            
if (libfilename != null) {
                
File libfile = new File(libfilename);
                
if (!libfile.isAbsolute()) {
                    
throw new UnsatisfiedLinkError(
    
"ClassLoader.findLibrary failed to return an absolute path: " + libfilename);
                
}
                
if (loadLibrary0(fromClass, libfile)) {
                    
return;
                
}
                
throw new UnsatisfiedLinkError("Can't load " + libfilename);
            
}
        
}
        
for (int i = 0 ; i < sys_paths.length ; i++) {
            
File libfile = new File(sys_paths[i], System.mapLibraryName(name));
            
if (loadLibrary0(fromClass, libfile)) {
                
return;
            
}
            
libfile = ClassLoaderHelper.mapAlternativeName(libfile);
            
if (libfile != null && loadLibrary0(fromClass, libfile)) {
                
return;
            
}
        
}
        
if (loader != null) {
            
for (int i = 0 ; i < usr_paths.length ; i++) {
                
File libfile = new File(usr_paths[i],
                                        
System.mapLibraryName(name));
                
if (loadLibrary0(fromClass, libfile)) {
                    
return;
                
}
                
libfile = ClassLoaderHelper.mapAlternativeName(libfile);
                
if (libfile != null && loadLibrary0(fromClass, libfile)) {
                    
return;
                
}
            
}
        
}
        
// Oops, it failed
        
throw new UnsatisfiedLinkError("no " + name + " in java.library.path");
    
}

    
private static native String findBuiltinLib(String name);

    
private static boolean loadLibrary0(Class<?> fromClass, final File file) {
        
// Check to see if we're attempting to access a static library
        
String name = findBuiltinLib(file.getName());
        
boolean isBuiltin = (name != null);
        
if (!isBuiltin) {
            
boolean exists = AccessController.doPrivileged(
                
new PrivilegedAction<Object>() {
                    
public Object run() {
                        
return file.exists() ? Boolean.TRUE : null;
                    
}})
                
!= null;
            
if (!exists) {
                
return false;
            
}
            
try {
                
name = file.getCanonicalPath();
            
} catch (IOException e) {
                
return false;
            
}
        
}
        
ClassLoader loader =
            
(fromClass == null) ? null : fromClass.getClassLoader();
        
Vector<NativeLibrary> libs =
            
loader != null ? loader.nativeLibraries : systemNativeLibraries;
        
synchronized (libs) {
            
int size = libs.size();
            
for (int i = 0; i < size; i++) {
                
NativeLibrary lib = libs.elementAt(i);
                
if (name.equals(lib.name)) {
                    
return true;
                
}
            
}

            
synchronized (loadedLibraryNames) {
                
if (loadedLibraryNames.contains(name)) {
                    
throw new UnsatisfiedLinkError
                        
("Native Library " +
                         
name +
                         
" already loaded in another classloader");
                
}
                
/* If the library is being loaded (must be by the same thread,
                 
* because Runtime.load and Runtime.loadLibrary are
                 
* synchronous). The reason is can occur is that the JNI_OnLoad
                 
* function can cause another loadLibrary invocation.
                 
*
                 
* Thus we can use a static stack to hold the list of libraries
                 
* we are loading.
                 
*
                 
* If there is a pending load operation for the library, we
                 
* immediately return success; otherwise, we raise
                 
* UnsatisfiedLinkError.
                 
*/

                
int n = nativeLibraryContext.size();
                
for (int i = 0; i < n; i++) {
                    
NativeLibrary lib = nativeLibraryContext.elementAt(i);
                    
if (name.equals(lib.name)) {
                        
if (loader == lib.fromClass.getClassLoader()) {
                            
return true;
                        
} else {
                            
throw new UnsatisfiedLinkError
                                
("Native Library " +
                                 
name +
                                 
" is being loaded in another classloader");
                        
}
                    
}
                
}
                
NativeLibrary lib = new NativeLibrary(fromClass, name, isBuiltin);
                
nativeLibraryContext.push(lib);
                
try {
                    
lib.load(name, isBuiltin);
                
} finally {
                    
nativeLibraryContext.pop();
                
}
                
if (lib.loaded) {
                    
loadedLibraryNames.addElement(name);
                    
libs.addElement(lib);
                    
return true;
                
}
                
return false;
            
}
        
}
    
}

    
// Invoked in the VM class linking code.
    
static long findNative(ClassLoader loader, String name) {
        
Vector<NativeLibrary> libs =
            
loader != null ? loader.nativeLibraries : systemNativeLibraries;
        
synchronized (libs) {
            
int size = libs.size();
            
for (int i = 0; i < size; i++) {
                
NativeLibrary lib = libs.elementAt(i);
                
long entry = lib.find(name);
                
if (entry != 0)
                    
return entry;
            
}
        
}
        
return 0;
    
}


    
// -- Assertion management --

    
final Object assertionLock;

    
// The default toggle for assertion checking.
    
// @GuardedBy("assertionLock")
    
private boolean defaultAssertionStatus = false;

    
// Maps String packageName to Boolean package default assertion status Note
    
// that the default package is placed under a null map key.
  
If this field

    
// is null then we are delegating assertion status queries to the VM, i.e.,
    
// none of this ClassLoader's assertion status modification methods have
    
// been invoked.
    
// @GuardedBy("assertionLock")
    
private Map<String, Boolean> packageAssertionStatus = null;

    
// Maps String fullyQualifiedClassName to Boolean assertionStatus If this
    
// field is null then we are delegating assertion status queries to the VM,
    
// i.e., none of this ClassLoader's assertion status modification methods
    
// have been invoked.
    
// @GuardedBy("assertionLock")
    
Map<String, Boolean