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 /** 045 * Checks if the signature matches what is expected for a zlib / deflated file 046 * with the zlib header. 047 * 048 * @param signature 049 * the bytes to check 050 * @param length 051 * the number of bytes to check 052 * @return true, if this stream is zlib / deflate compressed with a header 053 * stream, false otherwise 054 * 055 * @since 1.10 056 */ 057 public static boolean matches(final byte[] signature, final int length) { 058 return length > 3 && signature[0] == MAGIC_1 && ( 059 signature[1] == (byte) MAGIC_2a || 060 signature[1] == (byte) MAGIC_2b || 061 signature[1] == (byte) MAGIC_2c || 062 signature[1] == (byte) MAGIC_2d); 063 } 064 private final CountingInputStream countingStream; 065 private final InputStream in; 066 067 private final Inflater inflater; 068 069 /** 070 * Creates a new input stream that decompresses Deflate-compressed data 071 * from the specified input stream. 072 * 073 * @param inputStream where to read the compressed data 074 * 075 */ 076 public DeflateCompressorInputStream(final InputStream inputStream) { 077 this(inputStream, new DeflateParameters()); 078 } 079 080 /** 081 * Creates a new input stream that decompresses Deflate-compressed data 082 * from the specified input stream. 083 * 084 * @param inputStream where to read the compressed data 085 * @param parameters parameters 086 */ 087 public DeflateCompressorInputStream(final InputStream inputStream, 088 final DeflateParameters parameters) { 089 inflater = new Inflater(!parameters.withZlibHeader()); 090 in = new InflaterInputStream(countingStream = new CountingInputStream(inputStream), inflater); 091 } 092 093 /** {@inheritDoc} */ 094 @Override 095 public int available() throws IOException { 096 return in.available(); 097 } 098 099 /** {@inheritDoc} */ 100 @Override 101 public void close() throws IOException { 102 try { 103 in.close(); 104 } finally { 105 inflater.end(); 106 } 107 } 108 109 /** 110 * @since 1.17 111 */ 112 @Override 113 public long getCompressedCount() { 114 return countingStream.getBytesRead(); 115 } 116 117 /** {@inheritDoc} */ 118 @Override 119 public int read() throws IOException { 120 final int ret = in.read(); 121 count(ret == -1 ? 0 : 1); 122 return ret; 123 } 124 125 /** {@inheritDoc} */ 126 @Override 127 public int read(final byte[] buf, final int off, final int len) throws IOException { 128 if (len == 0) { 129 return 0; 130 } 131 final int ret = in.read(buf, off, len); 132 count(ret); 133 return ret; 134 } 135 136 /** {@inheritDoc} */ 137 @Override 138 public long skip(final long n) throws IOException { 139 return IOUtils.skip(in, n); 140 } 141}