content: // Protocol Buffers - Google's data interchange format
  // Copyright 2008 Google Inc.  All rights reserved.
  // https://developers.google.com/protocol-buffers/
  //
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  // modification, are permitted provided that the following conditions are
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  // 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
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  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);
    }
  
  }
  