/* * Copyright (c) 2000, 2009, 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.misc; import java.security.*;import java.lang.reflect.*;  /** * A collection of methods for performing low-level, unsafe operations. * Although the class and all methods are public, use of this class is * limited because only trusted code can obtain instances of it. * * @author John R. Rose * @see #getUnsafe */ public final class Unsafe {     private static native void registerNatives();    static {        registerNatives();        //sun.reflect.Reflection.registerMethodsToFilter(Unsafe.class, "getUnsafe");    }     private Unsafe() {}     private static final Unsafe theUnsafe = new Unsafe();     /**     * Provides the caller with the capability of performing unsafe     * operations.     *     * <p> The returned <code>Unsafe</code> object should be carefully guarded     * by the caller, since it can be used to read and write data at arbitrary     * memory addresses.  It must never be passed to untrusted code.     *     * <p> Most methods in this class are very low-level, and correspond to a     * small number of hardware instructions (on typical machines).  Compilers     * are encouraged to optimize these methods accordingly.     *     * <p> Here is a suggested idiom for using unsafe operations:     *     * <blockquote><pre>     * class MyTrustedClass {     *   private static final Unsafe unsafe = Unsafe.getUnsafe();     *   ...     *   private long myCountAddress = ...;     *   public int getCount() { return unsafe.getByte(myCountAddress); }     * }     * </pre></blockquote>     *     * (It may assist compilers to make the local variable be     * <code>final</code>.)     *     * @exception  SecurityException  if a security manager exists and its     *             <code>checkPropertiesAccess</code> method doesn't allow     *             access to the system properties.     */    public static Unsafe getUnsafe() {        // [Infenro] TODO: uncomment this! IMPORTANT        //Class cc = sun.reflect.Reflection.getCallerClass(2);        //if (cc.getClassLoader() != null)        //    throw new SecurityException("Unsafe");        return theUnsafe;    }     /// peek and poke operations    /// (compilers should optimize these to memory ops)     // These work on object fields in the Java heap.    // They will not work on elements of packed arrays.     /**     * Fetches a value from a given Java variable.     * More specifically, fetches a field or array element within the given     * object <code>o</code> at the given offset, or (if <code>o</code> is     * null) from the memory address whose numerical value is the given     * offset.     * <p>     * The results are undefined unless one of the following cases is true:     * <ul>     * <li>The offset was obtained from {@link #objectFieldOffset} on     * the {@link java.lang.reflect.Field} of some Java field and the object     * referred to by <code>o</code> is of a class compatible with that     * field's class.     *     * <li>The offset and object reference <code>o</code> (either null or     * non-null) were both obtained via {@link #staticFieldOffset}     * and {@link #staticFieldBase} (respectively) from the     * reflective {@link Field} representation of some Java field.     *     * <li>The object referred to by <code>o</code> is an array, and the offset     * is an integer of the form <code>B+N*S</code>, where <code>N</code> is     * a valid index into the array, and <code>B</code> and <code>S</code> are     * the values obtained by {@link #arrayBaseOffset} and {@link     * #arrayIndexScale} (respectively) from the array's class.  The value     * referred to is the <code>N</code><em>th</em> element of the array.     *     * </ul>     * <p>     * If one of the above cases is true, the call references a specific Java     * variable (field or array element).  However, the results are undefined     * if that variable is not in fact of the type returned by this method.     * <p>     * This method refers to a variable by means of two parameters, and so     * it provides (in effect) a <em>double-register</em> addressing mode     * for Java variables.  When the object reference is null, this method     * uses its offset as an absolute address.  This is similar in operation     * to methods such as {@link #getInt(long)}, which provide (in effect) a     * <em>single-register</em> addressing mode for non-Java variables.     * However, because Java variables may have a different layout in memory     * from non-Java variables, programmers should not assume that these     * two addressing modes are ever equivalent.  Also, programmers should     * remember that offsets from the double-register addressing mode cannot     * be portably confused with longs used in the single-register addressing     * mode.     *     * @param o Java heap object in which the variable resides, if any, else     *        null     * @param offset indication of where the variable resides in a Java heap     *        object, if any, else a memory address locating the variable     *        statically     * @return the value fetched from the indicated Java variable     * @throws RuntimeException No defined exceptions are thrown, not even     *         {@link NullPointerException}     */    public native int getInt(Object o, long offset);     /**     * Stores a value into a given Java variable.     * <p>     * The first two parameters are interpreted exactly as with     * {@link #getInt(Object, long)} to refer to a specific     * Java variable (field or array element).  The given value     * is stored into that variable.     * <p>     * The variable must be of the same type as the method     * parameter <code>x</code>.     *     * @param o Java heap object in which the variable resides, if any, else     *        null     * @param offset indication of where the variable resides in a Java heap     *        object, if any, else a memory address locating the variable     *        statically     * @param x the value to store into the indicated Java variable     * @throws RuntimeException No defined exceptions are thrown, not even     *         {@link NullPointerException}     */    public native void putInt(Object o, long offset, int x);     /**     * Fetches a reference value from a given Java variable.     * @see #getInt(Object, long)     */    public native Object getObject(Object o, long offset);     /**     * Stores a reference value into a given Java variable.     * <p>     * Unless the reference <code>x</code> being stored is either null     * or matches the field type, the results are undefined.     * If the reference <code>o</code> is non-null, car marks or     * other store barriers for that object (if the VM requires them)     * are updated.     * @see #putInt(Object, int, int)     */    public native void putObject(Object o, long offset, Object x);     /** @see #getInt(Object, long) */    public native boolean getBoolean(Object o, long offset);    /** @see #putInt(Object, int, int) */    public native void    putBoolean(Object o, long offset, boolean x);    /** @see #getInt(Object, long) */    public native byte    getByte(Object o, long offset);    /** @see #putInt(Object, int, int) */    public native void    putByte(Object o, long offset, byte x);    /** @see #getInt(Object, long) */    public native short   getShort(Object o, long offset);    /** @see #putInt(Object, int, int) */    public native void    putShort(Object o, long offset, short x);    /** @see #getInt(Object, long) */    public native char    getChar(Object o, long offset);    /** @see #putInt(Object, int, int) */    public native void    putChar(Object o, long offset, char x);    /** @see #getInt(Object, long) */    public native long    getLong(Object o, long offset);    /** @see #putInt(Object, int, int) */    public native void    putLong(Object o, long offset, long x);    /** @see #getInt(Object, long) */    public native float   getFloat(Object o, long offset);    /** @see #putInt(Object, int, int) */    public native void    putFloat(Object o, long offset, float x);    /** @see #getInt(Object, long) */    public native double  getDouble(Object o, long offset);    /** @see #putInt(Object, int, int) */    public native void    putDouble(Object o, long offset, double x);     /**     * This method, like all others with 32-bit offsets, was native     * in a previous release but is now a wrapper which simply casts     * the offset to a long value.  It provides backward compatibility     * with bytecodes compiled against 1.4.     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.     * See {@link #staticFieldOffset}.     */    @Deprecated    public int getInt(Object o, int offset) {        return getInt(o, (long)offset);    }     /**     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.     * See {@link #staticFieldOffset}.     */    @Deprecated    public void putInt(Object o, int offset, int x) {        putInt(o, (long)offset, x);    }     /**     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.     * See {@link #staticFieldOffset}.     */    @Deprecated    public Object getObject(Object o, int offset) {        return getObject(o, (long)offset);    }     /**     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.     * See {@link #staticFieldOffset}.     */    @Deprecated    public void putObject(Object o, int offset, Object x) {        putObject(o, (long)offset, x);    }     /**     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.     * See {@link #staticFieldOffset}.     */    @Deprecated    public boolean getBoolean(Object o, int offset) {        return getBoolean(o, (long)offset);    }     /**     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.     * See {@link #staticFieldOffset}.     */    @Deprecated    public void putBoolean(Object o, int offset, boolean x) {        putBoolean(o, (long)offset, x);    }     /**     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.     * See {@link #staticFieldOffset}.     */    @Deprecated    public byte getByte(Object o, int offset) {        return getByte(o, (long)offset);    }     /**     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.     * See {@link #staticFieldOffset}.     */    @Deprecated    public void putByte(Object o, int offset, byte x) {        putByte(o, (long)offset, x);    }     /**     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.     * See {@link #staticFieldOffset}.     */    @Deprecated    public short getShort(Object o, int offset) {        return getShort(o, (long)offset);    }     /**     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.     * See {@link #staticFieldOffset}.     */    @Deprecated    public void putShort(Object o, int offset, short x) {        putShort(o, (long)offset, x);    }     /**     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.     * See {@link #staticFieldOffset}.     */    @Deprecated    public char getChar(Object o, int offset) {        return getChar(o, (long)offset);    }     /**     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.     * See {@link #staticFieldOffset}.     */    @Deprecated    public void putChar(Object o, int offset, char x) {        putChar(o, (long)offset, x);    }     /**     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.     * See {@link #staticFieldOffset}.     */    @Deprecated    public long getLong(Object o, int offset) {        return getLong(o, (long)offset);    }     /**     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.     * See {@link #staticFieldOffset}.     */    @Deprecated    public void putLong(Object o, int offset, long x) {        putLong(o, (long)offset, x);    }     /**     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.     * See {@link #staticFieldOffset}.     */    @Deprecated    public float getFloat(Object o, int offset) {        return getFloat(o, (long)offset);    }     /**     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.     * See {@link #staticFieldOffset}.     */    @Deprecated    public void putFloat(Object o, int offset, float x) {        putFloat(o, (long)offset, x);    }     /**     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.     * See {@link #staticFieldOffset}.     */    @Deprecated    public double getDouble(Object o, int offset) {        return getDouble(o, (long)offset);    }     /**     * @deprecated As of 1.4.1, cast the 32-bit offset argument to a long.     * See {@link #staticFieldOffset}.     */    @Deprecated    public void putDouble(Object o, int offset, double x) {        putDouble(o, (long)offset, x);    }     // These work on values in the C heap.     /**     * Fetches a value from a given memory address.  If the address is zero, or     * does not point into a block obtained from {@link #allocateMemory}, the     * results are undefined.     *     * @see #allocateMemory     */    public native byte    getByte(long address);     /**     * Stores a value into a given memory address.  If the address is zero, or     * does not point into a block obtained from {@link #allocateMemory}, the     * results are undefined.     *     * @see #getByte(long)     */    public native void    putByte(long address, byte x);     /** @see #getByte(long) */    public native short   getShort(long address);    /** @see #putByte(long, byte) */    public native void    putShort(long address, short x);    /** @see #getByte(long) */    public native char    getChar(long address);    /** @see #putByte(long, byte) */    public native void    putChar(long address, char x);    /** @see #getByte(long) */    public native int     getInt(long address);    /** @see #putByte(long, byte) */    public native void    putInt(long address, int x);    /** @see #getByte(long) */    public native long    getLong(long address);    /** @see #putByte(long, byte) */    public native void    putLong(long address, long x);    /** @see #getByte(long) */    public native float   getFloat(long address);    /** @see #putByte(long, byte) */    public native void    putFloat(long address, float x);    /** @see #getByte(long) */    public native double  getDouble(long address);    /** @see #putByte(long, byte) */    public native void    putDouble(long address, double x);     /**     * Fetches a native pointer from a given memory address.  If the address is     * zero, or does not point into a block obtained from {@link     * #allocateMemory}, the results are undefined.     *     * <p> If the native pointer is less than 64 bits wide, it is extended as     * an unsigned number to a Java long.  The pointer may be indexed by any     * given byte offset, simply by adding that offset (as a simple integer) to     * the long representing the pointer.  The number of bytes actually read     * from the target address maybe determined by consulting {@link     * #addressSize}.     *     * @see #allocateMemory     */    public native long getAddress(long address);     /**     * Stores a native pointer into a given memory address.  If the address is     * zero, or does not point into a block obtained from {@link     * #allocateMemory}, the results are undefined.     *     * <p> The number of bytes actually written at the target address maybe     * determined by consulting {@link #addressSize}.     *     * @see #getAddress(long)     */    public native void putAddress(long address, long x);     /// wrappers for malloc, realloc, free:     /**     * Allocates a new block of native memory, of the given size in bytes.  The     * contents of the memory are uninitialized; they will generally be     * garbage.  The resulting native pointer will never be zero, and will be     * aligned for all value types.  Dispose of this memory by calling {@link     * #freeMemory}, or resize it with {@link #reallocateMemory}.     *     * @throws IllegalArgumentException if the size is negative or too large     *         for the native size_t type     *     * @throws OutOfMemoryError if the allocation is refused by the system     *     * @see #getByte(long)     * @see #putByte(long, byte)     */    public native long allocateMemory(long bytes);     /**     * Resizes a new block of native memory, to the given size in bytes.  The     * contents of the new block past the size of the old block are     * uninitialized; they will generally be garbage.  The resulting native     * pointer will be zero if and only if the requested size is zero.  The     * resulting native pointer will be aligned for all value types.  Dispose     * of this memory by calling {@link #freeMemory}, or resize it with {@link     * #reallocateMemory}.  The address passed to this method may be null, in     * which case an allocation will be performed.     *     * @throws IllegalArgumentException if the size is negative or too large     *         for the native size_t type     *     * @throws OutOfMemoryError if the allocation is refused by the system     *     * @see #allocateMemory     */    public native long reallocateMemory(long address, long bytes);     /**     * Sets all bytes in a given block of memory to a fixed value

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