| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package org.apache.hadoop.io.compress; |
| |
| import java.io.EOFException; |
| import java.io.IOException; |
| import java.io.InputStream; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| |
| /** |
| * A {@link org.apache.hadoop.io.compress.DecompressorStream} which works |
| * with 'block-based' based compression algorithms, as opposed to |
| * 'stream-based' compression algorithms. |
| * |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Evolving |
| public class BlockDecompressorStream extends DecompressorStream { |
| private int originalBlockSize = 0; |
| private int noUncompressedBytes = 0; |
| |
| /** |
| * Create a {@link BlockDecompressorStream}. |
| * |
| * @param in input stream |
| * @param decompressor decompressor to use |
| * @param bufferSize size of buffer |
| * @throws IOException |
| */ |
| public BlockDecompressorStream(InputStream in, Decompressor decompressor, |
| int bufferSize) throws IOException { |
| super(in, decompressor, bufferSize); |
| } |
| |
| /** |
| * Create a {@link BlockDecompressorStream}. |
| * |
| * @param in input stream |
| * @param decompressor decompressor to use |
| * @throws IOException |
| */ |
| public BlockDecompressorStream(InputStream in, Decompressor decompressor) throws IOException { |
| super(in, decompressor); |
| } |
| |
| protected BlockDecompressorStream(InputStream in) throws IOException { |
| super(in); |
| } |
| |
| @Override |
| protected int decompress(byte[] b, int off, int len) throws IOException { |
| // Check if we are the beginning of a block |
| if (noUncompressedBytes == originalBlockSize) { |
| // Get original data size |
| try { |
| originalBlockSize = rawReadInt(); |
| } catch (IOException ioe) { |
| return -1; |
| } |
| noUncompressedBytes = 0; |
| // EOF if originalBlockSize is 0 |
| // This will occur only when decompressing previous compressed empty file |
| if (originalBlockSize == 0) { |
| eof = true; |
| return -1; |
| } |
| } |
| |
| int n = 0; |
| while ((n = decompressor.decompress(b, off, len)) == 0) { |
| if (decompressor.finished() || decompressor.needsDictionary()) { |
| if (noUncompressedBytes >= originalBlockSize) { |
| eof = true; |
| return -1; |
| } |
| } |
| if (decompressor.needsInput()) { |
| int m; |
| try { |
| m = getCompressedData(); |
| } catch (EOFException e) { |
| eof = true; |
| return -1; |
| } |
| // Send the read data to the decompressor |
| decompressor.setInput(buffer, 0, m); |
| } |
| } |
| |
| // Note the no. of decompressed bytes read from 'current' block |
| noUncompressedBytes += n; |
| |
| return n; |
| } |
| |
| @Override |
| protected int getCompressedData() throws IOException { |
| checkStream(); |
| |
| // Get the size of the compressed chunk (always non-negative) |
| int len = rawReadInt(); |
| |
| // Read len bytes from underlying stream |
| if (len > buffer.length) { |
| buffer = new byte[len]; |
| } |
| int n = 0, off = 0; |
| while (n < len) { |
| int count = in.read(buffer, off + n, len - n); |
| if (count < 0) { |
| throw new EOFException("Unexpected end of block in input stream"); |
| } |
| n += count; |
| } |
| |
| return len; |
| } |
| |
| @Override |
| public void resetState() throws IOException { |
| originalBlockSize = 0; |
| noUncompressedBytes = 0; |
| super.resetState(); |
| } |
| |
| private int rawReadInt() throws IOException { |
| int b1 = in.read(); |
| int b2 = in.read(); |
| int b3 = in.read(); |
| int b4 = in.read(); |
| if ((b1 | b2 | b3 | b4) < 0) |
| throw new EOFException(); |
| return ((b1 << 24) + (b2 << 16) + (b3 << 8) + (b4 << 0)); |
| } |
| } |