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// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
// https://developers.google.com/protocol-buffers/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
package com.google.protobuf;
import sun.misc.Unsafe;
import java.lang.reflect.Field;
import java.nio.Buffer;
import java.nio.ByteBuffer;
import java.security.AccessController;
import java.security.PrivilegedExceptionAction;
/**
* Utility class for working with unsafe operations.
*/
// TODO(nathanmittler): Add support for Android Memory/MemoryBlock
final class UnsafeUtil {
private static final sun.misc.Unsafe UNSAFE = getUnsafe();
private static final boolean HAS_UNSAFE_BYTEBUFFER_OPERATIONS =
supportsUnsafeByteBufferOperations();
private static final boolean HAS_UNSAFE_ARRAY_OPERATIONS = supportsUnsafeArrayOperations();
private static final long ARRAY_BASE_OFFSET = byteArrayBaseOffset();
private static final long BUFFER_ADDRESS_OFFSET = fieldOffset(field(Buffer.class, "address"));
private UnsafeUtil() {
}
static boolean hasUnsafeArrayOperations() {
return HAS_UNSAFE_ARRAY_OPERATIONS;
}
static boolean hasUnsafeByteBufferOperations() {
return HAS_UNSAFE_BYTEBUFFER_OPERATIONS;
}
static long getArrayBaseOffset() {
return ARRAY_BASE_OFFSET;
}
static byte getByte(byte[] target, long offset) {
return UNSAFE.getByte(target, offset);
}
static void putByte(byte[] target, long offset, byte value) {
UNSAFE.putByte(target, offset, value);
}
// BEGIN Android-removed
// This method doesn't exist in sun.misc.Unsafe in Android, and leaving the
// dangling reference causes soft-verification errors when a jarjar'd version
// of libprotobuf-java-lite is included in the bootclasspath:
// Soft verification failures in void com.android.framework.protobuf.UnsafeUtil.copyMemory(byte[], long, byte[], long, long)
// void com.android.framework.protobuf.UnsafeUtil.copyMemory(byte[], long, byte[], long, long): [0x7] couldn't find method sun.misc.Unsafe.copyMemory ([BJ[BJJ)V
// This method is unused in the current open-source implementation of the
// protobuf lite runtime, so just remove it for now.
//static void copyMemory(
// byte[] src, long srcOffset, byte[] target, long targetOffset, long length) {
// UNSAFE.copyMemory(src, srcOffset, target, targetOffset, length);
//}
// END Android-removed
static long getLong(byte[] target, long offset) {
return UNSAFE.getLong(target, offset);
}
static byte getByte(long address) {
return UNSAFE.getByte(address);
}
static void putByte(long address, byte value) {
UNSAFE.putByte(address, value);
}
static long getLong(long address) {
return UNSAFE.getLong(address);
}
static void copyMemory(long srcAddress, long targetAddress, long length) {
UNSAFE.copyMemory(srcAddress, targetAddress, length);
}
/**
* Gets the offset of the {@code address} field of the given direct {@link ByteBuffer}.
*/
static long addressOffset(ByteBuffer buffer) {
return UNSAFE.getLong(buffer, BUFFER_ADDRESS_OFFSET);
}
/**
* Gets the {@code sun.misc.Unsafe} instance, or {@code null} if not available on this platform.
*/
private static sun.misc.Unsafe getUnsafe() {
sun.misc.Unsafe unsafe = null;
try {
unsafe =
AccessController.doPrivileged(
new PrivilegedExceptionAction<Unsafe>() {
@Override
public sun.misc.Unsafe run() throws Exception {
Class<sun.misc.Unsafe> k = sun.misc.Unsafe.class;
for (Field f : k.getDeclaredFields()) {
f.setAccessible(true);
Object x = f.get(null);
if (k.isInstance(x)) {
return k.cast(x);
}
}
// The sun.misc.Unsafe field does not exist.
return null;
}
});
} catch (Throwable e) {
// Catching Throwable here due to the fact that Google AppEngine raises NoClassDefFoundError
// for Unsafe.
}
return unsafe;
}
/**
* Indicates whether or not unsafe array operations are supported on this platform.
*/
private static boolean supportsUnsafeArrayOperations() {
boolean supported = false;
if (UNSAFE != null) {
try {
Class<?> clazz = UNSAFE.getClass();
clazz.getMethod("arrayBaseOffset", Class.class);
clazz.getMethod("getByte", Object.class, long.class);
clazz.getMethod("putByte", Object.class, long.class, byte.class);
clazz.getMethod("getLong", Object.class, long.class);
clazz.getMethod(
"copyMemory", Object.class, long.class, Object.class, long.class, long.class);
supported = true;
} catch (Throwable e) {
// Do nothing.
}
}
return supported;
}
private static boolean supportsUnsafeByteBufferOperations() {
boolean supported = false;
if (UNSAFE != null) {
try {
Class<?> clazz = UNSAFE.getClass();
clazz.getMethod("objectFieldOffset", Field.class);
clazz.getMethod("getByte", long.class);
clazz.getMethod("getLong", Object.class, long.class);
clazz.getMethod("putByte", long.class, byte.class);
clazz.getMethod("getLong", long.class);
clazz.getMethod("copyMemory", long.class, long.class, long.class);
supported = true;
} catch (Throwable e) {
// Do nothing.
}
}
return supported;
}
/**
* Get the base offset for byte arrays, or {@code -1} if {@code sun.misc.Unsafe} is not available.
*/
private static int byteArrayBaseOffset() {
return HAS_UNSAFE_ARRAY_OPERATIONS ? UNSAFE.arrayBaseOffset(byte[].class) : -1;
}
/**
* Returns the offset of the provided field, or {@code -1} if {@code sun.misc.Unsafe} is not
* available.
*/
private static long fieldOffset(Field field) {
return field == null || UNSAFE == null ? -1 : UNSAFE.objectFieldOffset(field);
}
/**
* Gets the field with the given name within the class, or {@code null} if not found. If found,
* the field is made accessible.
*/
private static Field field(Class<?> clazz, String fieldName) {
Field field;
try {
field = clazz.getDeclaredField(fieldName);
field.setAccessible(true);
} catch (Throwable t) {
// Failed to access the fields.
field = null;
}
return field;
}
}
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