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/*
 * Copyright (c) 2004, 2010, 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 sun.corba ;

import java.lang.reflect.Field ;
import java.lang.reflect.Method ;
import java.lang.reflect.Constructor ;
import java.lang.reflect.InvocationTargetException ;

import java.io.ObjectInputStream ;

import java.security.AccessController;
import java.security.Permission;
import java.security.PrivilegedAction;

import sun.misc.Unsafe ;
import sun.reflect.ReflectionFactory ;

/** This class provides the methods for fundamental JVM operations
 * needed in the ORB that are not part of the public Java API.  This includes:
 * 
    *
  • throwException, which can throw undeclared checked exceptions. * This is needed to handle throwing arbitrary exceptions across a standardized OMG interface that (incorrectly) does not specify appropriate exceptions.
  • *
  • putXXX/getXXX methods that allow unchecked access to fields of objects. * This is used for setting uninitialzed non-static final fields (which is * impossible with reflection) and for speed.
  • *
  • objectFieldOffset to obtain the field offsets for use in the putXXX/getXXX methods
  • *
  • newConstructorForSerialization to get the special constructor required for a * Serializable class
  • *
  • latestUserDefinedLoader to get the latest user defined class loader from * the call stack as required by the RMI-IIOP specification (really from the * JDK 1.1 days)
  • *
* The code that calls Bridge.get() must have the following Permissions: *
    *
  • RuntimePermission "reflectionFactoryAccess"
  • *
  • BridgePermission "getBridge"
  • *
  • ReflectPermission "suppressAccessChecks"
  • *
*

* All of these permissions are required to obtain and correctly initialize * the instance of Bridge. No security checks are performed on calls * made to Bridge instance methods, so access to the Bridge instance * must be protected. *

* This class is a singleton (per ClassLoader of course). Access to the * instance is obtained through the Bridge.get() method. */ public final class Bridge { private static final Class[] NO_ARGS = new Class[] {}; private static final Permission getBridgePermission = new BridgePermission( "getBridge" ) ; private static Bridge bridge = null ; // latestUserDefinedLoader() is a private static method // in ObjectInputStream in JDK 1.3 through 1.5. // We use reflection in a doPrivileged block to get a // Method reference and make it accessible. private final Method latestUserDefinedLoaderMethod ; private final Unsafe unsafe ; private final ReflectionFactory reflectionFactory ; private Method getLatestUserDefinedLoaderMethod() { return (Method) AccessController.doPrivileged( new PrivilegedAction() { public Object run() { Method result = null; try { Class io = ObjectInputStream.class; result = io.getDeclaredMethod( "latestUserDefinedLoader", NO_ARGS); result.setAccessible(true); } catch (NoSuchMethodException nsme) { Error err = new Error( "java.io.ObjectInputStream" + " latestUserDefinedLoader " + nsme ); err.initCause(nsme) ; throw err ; } return result; } } ); } private Unsafe getUnsafe() { Field fld = (Field)AccessController.doPrivileged( new PrivilegedAction() { public Object run() { Field fld = null ; try { Class unsafeClass = sun.misc.Unsafe.class ; fld = unsafeClass.getDeclaredField( "theUnsafe" ) ; fld.setAccessible( true ) ; return fld ; } catch (NoSuchFieldException exc) { Error err = new Error( "Could not access Unsafe" ) ; err.initCause( exc ) ; throw err ; } } } ) ; Unsafe unsafe = null; try { unsafe = (Unsafe)(fld.get( null )) ; } catch (Throwable t) { Error err = new Error( "Could not access Unsafe" ) ; err.initCause( t ) ; throw err ; } return unsafe ; } private Bridge() { latestUserDefinedLoaderMethod = getLatestUserDefinedLoaderMethod(); unsafe = getUnsafe() ; reflectionFactory = ReflectionFactory.getReflectionFactory(); } /** Fetch the Bridge singleton. This requires the following * permissions: *

    *
  • RuntimePermission "reflectionFactoryAccess"
  • *
  • BridgePermission "getBridge"
  • *
  • ReflectPermission "suppressAccessChecks"
  • *
* @return The singleton instance of the Bridge class * @throws SecurityException if the caller does not have the * required permissions and the caller has a non-null security manager. */ public static final synchronized Bridge get() { SecurityManager sman = System.getSecurityManager() ; if (sman != null) sman.checkPermission( getBridgePermission ) ; if (bridge == null) { bridge = new Bridge() ; } return bridge ; } /** Obtain the latest user defined ClassLoader from the call stack. * This is required by the RMI-IIOP specification. */ public final ClassLoader getLatestUserDefinedLoader() { try { // Invoke the ObjectInputStream.latestUserDefinedLoader method return (ClassLoader)latestUserDefinedLoaderMethod.invoke(null, (Object[])NO_ARGS); } catch (InvocationTargetException ite) { Error err = new Error( "sun.corba.Bridge.latestUserDefinedLoader: " + ite ) ; err.initCause( ite ) ; throw err ; } catch (IllegalAccessException iae) { Error err = new Error( "sun.corba.Bridge.latestUserDefinedLoader: " + iae ) ; err.initCause( iae ) ; throw err ; } } /** * Fetches a field element within the given * object o at the given offset. * The result is undefined unless the offset was obtained from * {@link #objectFieldOffset} on the {@link java.lang.reflect.Field} * of some Java field and the object referred to by o * is of a class compatible with that field's class. * @param o Java heap object in which the field from which the offset * was obtained resides * @param offset indication of where the field resides in a Java heap * object * @return the value fetched from the indicated Java field * @throws RuntimeException No defined exceptions are thrown, not even * {@link NullPointerException} */ public final int getInt(Object o, long offset) { return unsafe.getInt( o, offset ) ; } /** * Stores a value into a given Java field. *

* The first two parameters are interpreted exactly as with * {@link #getInt(Object, long)} to refer to a specific * Java field. The given value is stored into that field. *

* The field must be of the same type as the method * parameter x. * * @param o Java heap object in which the field resides, if any, else * null * @param offset indication of where the field resides in a Java heap * object. * @param x the value to store into the indicated Java field * @throws RuntimeException No defined exceptions are thrown, not even * {@link NullPointerException} */ public final void putInt(Object o, long offset, int x) { unsafe.putInt( o, offset, x ) ; } /** * @see #getInt(Object, long) */ public final Object getObject(Object o, long offset) { return unsafe.getObject( o, offset ) ; } /** * @see #putInt(Object, long, int) */ public final void putObject(Object o, long offset, Object x) { unsafe.putObject( o, offset, x ) ; } /** @see #getInt(Object, long) */ public final boolean getBoolean(Object o, long offset) { return unsafe.getBoolean( o, offset ) ; } /** @see #putInt(Object, long, int) */ public final void putBoolean(Object o, long offset, boolean x) { unsafe.putBoolean( o, offset, x ) ; } /** @see #getInt(Object, long) */ public final byte getByte(Object o, long offset) { return unsafe.getByte( o, offset ) ; } /** @see #putInt(Object, long, int) */ public final void putByte(Object o, long offset, byte x) { unsafe.putByte( o, offset, x ) ; } /** @see #getInt(Object, long) */ public final short getShort(Object o, long offset) { return unsafe.getShort( o, offset ) ; } /** @see #putInt(Object, long, int) */ public final void putShort(Object o, long offset, short x) { unsafe.putShort( o, offset, x ) ; } /** @see #getInt(Object, long) */ public final char getChar(Object o, long offset) { return unsafe.getChar( o, offset ) ; } /** @see #putInt(Object, long, int) */ public final void putChar(Object o, long offset, char x) { unsafe.putChar( o, offset, x ) ; } /** @see #getInt(Object, long) */ public final long getLong(Object o, long offset) { return unsafe.getLong( o, offset ) ; } /** @see #putInt(Object, long, int) */ public final void putLong(Object o, long offset, long x) { unsafe.putLong( o, offset, x ) ; } /** @see #getInt(Object, long) */ public final float getFloat(Object o, long offset) { return unsafe.getFloat( o, offset ) ; } /** @see #putInt(Object, long, int) */ public final void putFloat(Object o, long offset, float x) { unsafe.putFloat( o, offset, x ) ; } /** @see #getInt(Object, long) */ public final double getDouble(Object o, long offset) { return unsafe.getDouble( o, offset ) ; } /** @see #putInt(Object, long, int) */ public final void putDouble(Object o, long offset, double x) { unsafe.putDouble( o, offset, x ) ; } /** * This constant differs from all results that will ever be returned from * {@link #objectFieldOffset}. */ public static final long INVALID_FIELD_OFFSET = -1; /** * Returns the offset of a non-static field. */ public final long objectFieldOffset(Field f) { return unsafe.objectFieldOffset( f ) ; } /** Throw the exception. * The exception may be an undeclared checked exception. */ public final void throwException(Throwable ee) { unsafe.throwException( ee ) ; } /** Obtain a constructor for Class cl using constructor cons which * may be the constructor defined in a superclass of cl. This is * used to create a constructor for Serializable classes that * constructs an instance of the Serializable class using the * no args constructor of the first non-Serializable superclass * of the Serializable class. */ public final Constructor newConstructorForSerialization( Class cl, Constructor cons ) { return reflectionFactory.newConstructorForSerialization( cl, cons ) ; } }





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