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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 java.io.IOException;
import java.nio.ByteBuffer;
/**
* Provides a number of unsafe byte operations to be used by advanced applications with high
* performance requirements. These methods are referred to as "unsafe" due to the fact that they
* potentially expose the backing buffer of a {@link ByteString} to the application.
*
* <p><strong>DISCLAIMER:</strong> The methods in this class should only be called if it is
* guaranteed that the buffer backing the {@link ByteString} will never change! Mutation of a {@link
* ByteString} can lead to unexpected and undesirable consequences in your application, and will
* likely be difficult to debug. Proceed with caution!
*
* <p>This can have a number of significant side affects that have spooky-action-at-a-distance-like
* behavior. In particular, if the bytes value changes out from under a Protocol Buffer:
*
* <ul>
* <li>serialization may throw
* <li>serialization may succeed but the wrong bytes may be written out
* <li>messages are no longer threadsafe
* <li>hashCode may be incorrect
* <ul>
* <li>can result in a permanent memory leak when used as a key in a long-lived HashMap
* <li>the semantics of many programs may be violated if this is the case
* </ul>
* </ul>
*
* Each of these issues will occur in parts of the code base that are entirely distinct from the
* parts of the code base modifying the buffer. In fact, both parts of the code base may be correct
* - it is the bridging with the unsafe operations that was in error!
*/
@ExperimentalApi
public final class UnsafeByteOperations {
private UnsafeByteOperations() {}
/**
* An unsafe operation that returns a {@link ByteString} that is backed by the provided buffer.
*
* @param buffer the buffer to be wrapped
* @return a {@link ByteString} backed by the provided buffer
*/
public static ByteString unsafeWrap(byte[] buffer) {
return ByteString.wrap(buffer);
}
/**
* An unsafe operation that returns a {@link ByteString} that is backed by a subregion of the
* provided buffer.
*
* @param buffer the buffer to be wrapped
* @param offset the offset of the wrapped region
* @param length the number of bytes of the wrapped region
* @return a {@link ByteString} backed by the provided buffer
*/
public static ByteString unsafeWrap(byte[] buffer, int offset, int length) {
return ByteString.wrap(buffer, offset, length);
}
/**
* An unsafe operation that returns a {@link ByteString} that is backed by the provided buffer.
*
* @param buffer the Java NIO buffer to be wrapped
* @return a {@link ByteString} backed by the provided buffer
*/
public static ByteString unsafeWrap(ByteBuffer buffer) {
return ByteString.wrap(buffer);
}
/**
* Writes the given {@link ByteString} to the provided {@link ByteOutput}. Calling this method may
* result in multiple operations on the target {@link ByteOutput} (i.e. for roped {@link
* ByteString}s).
*
* <p>This method exposes the internal backing buffer(s) of the {@link ByteString} to the {@link
* ByteOutput} in order to avoid additional copying overhead. It would be possible for a malicious
* {@link ByteOutput} to corrupt the {@link ByteString}. Use with caution!
*
* <p>NOTE: The {@link ByteOutput} <strong>MUST NOT</strong> modify the provided buffers. Doing so
* may result in corrupted data, which would be difficult to debug.
*
* @param bytes the {@link ByteString} to be written
* @param output the output to receive the bytes
* @throws IOException if an I/O error occurs
*/
public static void unsafeWriteTo(ByteString bytes, ByteOutput output) throws IOException {
bytes.writeTo(output);
}
}
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