001/* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, 013 * software distributed under the License is distributed on an 014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 015 * KIND, either express or implied. See the License for the 016 * specific language governing permissions and limitations 017 * under the License. 018 */ 019package org.apache.commons.compress.compressors.deflate; 020 021import java.io.IOException; 022import java.io.InputStream; 023import java.util.zip.Inflater; 024import java.util.zip.InflaterInputStream; 025 026import org.apache.commons.compress.compressors.CompressorInputStream; 027import org.apache.commons.compress.utils.CountingInputStream; 028import org.apache.commons.compress.utils.IOUtils; 029import org.apache.commons.compress.utils.InputStreamStatistics; 030 031/** 032 * Deflate decompressor. 033 * @since 1.9 034 */ 035public class DeflateCompressorInputStream extends CompressorInputStream 036 implements InputStreamStatistics { 037 038 private static final int MAGIC_1 = 0x78; 039 private static final int MAGIC_2a = 0x01; 040 private static final int MAGIC_2b = 0x5e; 041 private static final int MAGIC_2c = 0x9c; 042 private static final int MAGIC_2d = 0xda; 043 044 private final CountingInputStream countingStream; 045 private final InputStream in; 046 private final Inflater inflater; 047 048 /** 049 * Creates a new input stream that decompresses Deflate-compressed data 050 * from the specified input stream. 051 * 052 * @param inputStream where to read the compressed data 053 * 054 */ 055 public DeflateCompressorInputStream(final InputStream inputStream) { 056 this(inputStream, new DeflateParameters()); 057 } 058 059 /** 060 * Creates a new input stream that decompresses Deflate-compressed data 061 * from the specified input stream. 062 * 063 * @param inputStream where to read the compressed data 064 * @param parameters parameters 065 */ 066 public DeflateCompressorInputStream(final InputStream inputStream, 067 final DeflateParameters parameters) { 068 inflater = new Inflater(!parameters.withZlibHeader()); 069 in = new InflaterInputStream(countingStream = new CountingInputStream(inputStream), inflater); 070 } 071 072 /** {@inheritDoc} */ 073 @Override 074 public int read() throws IOException { 075 final int ret = in.read(); 076 count(ret == -1 ? 0 : 1); 077 return ret; 078 } 079 080 /** {@inheritDoc} */ 081 @Override 082 public int read(final byte[] buf, final int off, final int len) throws IOException { 083 final int ret = in.read(buf, off, len); 084 count(ret); 085 return ret; 086 } 087 088 /** {@inheritDoc} */ 089 @Override 090 public long skip(final long n) throws IOException { 091 return IOUtils.skip(in, n); 092 } 093 094 /** {@inheritDoc} */ 095 @Override 096 public int available() throws IOException { 097 return in.available(); 098 } 099 100 /** {@inheritDoc} */ 101 @Override 102 public void close() throws IOException { 103 try { 104 in.close(); 105 } finally { 106 inflater.end(); 107 } 108 } 109 110 /** 111 * @since 1.17 112 */ 113 @Override 114 public long getCompressedCount() { 115 return countingStream.getBytesRead(); 116 } 117 118 /** 119 * Checks if the signature matches what is expected for a zlib / deflated file 120 * with the zlib header. 121 * 122 * @param signature 123 * the bytes to check 124 * @param length 125 * the number of bytes to check 126 * @return true, if this stream is zlib / deflate compressed with a header 127 * stream, false otherwise 128 * 129 * @since 1.10 130 */ 131 public static boolean matches(final byte[] signature, final int length) { 132 return length > 3 && signature[0] == MAGIC_1 && ( 133 signature[1] == (byte) MAGIC_2a || 134 signature[1] == (byte) MAGIC_2b || 135 signature[1] == (byte) MAGIC_2c || 136 signature[1] == (byte) MAGIC_2d); 137 } 138}