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1   /*
2    * Copyright 2016 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at:
7    *
8    *   http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package io.netty.handler.codec.compression;
17  
18  import io.netty.buffer.ByteBuf;
19  
20  import java.nio.ByteBuffer;
21  
22  final class CompressionUtil {
23  
24      private CompressionUtil() { }
25  
26      static void checkChecksum(ByteBufChecksum checksum, ByteBuf uncompressed, int currentChecksum) {
27          checksum.reset();
28          checksum.update(uncompressed,
29                  uncompressed.readerIndex(), uncompressed.readableBytes());
30  
31          final int checksumResult = (int) checksum.getValue();
32          if (checksumResult != currentChecksum) {
33              throw new DecompressionException(String.format(
34                      "stream corrupted: mismatching checksum: %d (expected: %d)",
35                      checksumResult, currentChecksum));
36          }
37      }
38  
39      static ByteBuffer safeNioBuffer(ByteBuf buffer) {
40          return buffer.nioBufferCount() == 1 ? buffer.internalNioBuffer(buffer.readerIndex(), buffer.readableBytes())
41                  : buffer.nioBuffer();
42      }
43  }