1 // Protocol Buffers - Google's data interchange format 2 // Copyright 2008 Google Inc. All rights reserved. 3 // https://developers.google.com/protocol-buffers/ 4 // 5 // Redistribution and use in source and binary forms, with or without 6 // modification, are permitted provided that the following conditions are 7 // met: 8 // 9 // * Redistributions of source code must retain the above copyright 10 // notice, this list of conditions and the following disclaimer. 11 // * Redistributions in binary form must reproduce the above 12 // copyright notice, this list of conditions and the following disclaimer 13 // in the documentation and/or other materials provided with the 14 // distribution. 15 // * Neither the name of Google Inc. nor the names of its 16 // contributors may be used to endorse or promote products derived from 17 // this software without specific prior written permission. 18 // 19 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 20 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 21 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 22 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 23 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 24 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 25 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 29 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 31 package com.google.protobuf; 32 33 import java.io.IOException; 34 import java.nio.ByteBuffer; 35 36 /** 37 * Provides a number of unsafe byte operations to be used by advanced applications with high 38 * performance requirements. These methods are referred to as "unsafe" due to the fact that they 39 * potentially expose the backing buffer of a {@link ByteString} to the application. 40 * 41 * <p><strong>DISCLAIMER:</strong> The methods in this class should only be called if it is 42 * guaranteed that the buffer backing the {@link ByteString} will never change! Mutation of a 43 * {@link ByteString} can lead to unexpected and undesirable consequences in your application, 44 * and will likely be difficult to debug. Proceed with caution! 45 */ 46 @ExperimentalApi 47 public final class UnsafeByteOperations { UnsafeByteOperations()48 private UnsafeByteOperations() {} 49 50 /** 51 * An unsafe operation that returns a {@link ByteString} that is backed by the provided buffer. 52 * 53 * @param buffer the Java NIO buffer to be wrapped 54 * @return a {@link ByteString} backed by the provided buffer 55 */ unsafeWrap(ByteBuffer buffer)56 public static ByteString unsafeWrap(ByteBuffer buffer) { 57 if (buffer.hasArray()) { 58 final int offset = buffer.arrayOffset(); 59 return ByteString.wrap(buffer.array(), offset + buffer.position(), buffer.remaining()); 60 } else { 61 return new NioByteString(buffer); 62 } 63 } 64 65 /** 66 * Writes the given {@link ByteString} to the provided {@link ByteOutput}. Calling this method may 67 * result in multiple operations on the target {@link ByteOutput} 68 * (i.e. for roped {@link ByteString}s). 69 * 70 * <p>This method exposes the internal backing buffer(s) of the {@link ByteString} to the {@link 71 * ByteOutput} in order to avoid additional copying overhead. It would be possible for a malicious 72 * {@link ByteOutput} to corrupt the {@link ByteString}. Use with caution! 73 * 74 * <p> NOTE: The {@link ByteOutput} <strong>MUST NOT</strong> modify the provided buffers. Doing 75 * so may result in corrupted data, which would be difficult to debug. 76 * 77 * @param bytes the {@link ByteString} to be written 78 * @param output the output to receive the bytes 79 * @throws IOException if an I/O error occurs 80 */ unsafeWriteTo(ByteString bytes, ByteOutput output)81 public static void unsafeWriteTo(ByteString bytes, ByteOutput output) throws IOException { 82 bytes.writeTo(output); 83 } 84 } 85