001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 * 017 */ 018package org.apache.commons.compress.utils; 019 020import java.io.IOException; 021import java.io.InputStream; 022import java.util.zip.Checksum; 023 024/** 025 * A stream that calculates the checksum of the data read. 026 * @NotThreadSafe 027 * @since 1.14 028 */ 029public class ChecksumCalculatingInputStream extends InputStream { 030 private final InputStream in; 031 private final Checksum checksum; 032 033 public ChecksumCalculatingInputStream(final Checksum checksum, final InputStream in) { 034 035 if ( checksum == null ){ 036 throw new NullPointerException("Parameter checksum must not be null"); 037 } 038 039 if ( in == null ){ 040 throw new NullPointerException("Parameter in must not be null"); 041 } 042 043 this.checksum = checksum; 044 this.in = in; 045 } 046 047 /** 048 * Reads a single byte from the stream 049 * @throws IOException if the underlying stream throws or the 050 * stream is exhausted and the Checksum doesn't match the expected 051 * value 052 */ 053 @Override 054 public int read() throws IOException { 055 final int ret = in.read(); 056 if (ret >= 0) { 057 checksum.update(ret); 058 } 059 return ret; 060 } 061 062 /** 063 * Reads a byte array from the stream 064 * @throws IOException if the underlying stream throws or the 065 * stream is exhausted and the Checksum doesn't match the expected 066 * value 067 */ 068 @Override 069 public int read(final byte[] b) throws IOException { 070 return read(b, 0, b.length); 071 } 072 073 /** 074 * Reads from the stream into a byte array. 075 * @throws IOException if the underlying stream throws or the 076 * stream is exhausted and the Checksum doesn't match the expected 077 * value 078 */ 079 @Override 080 public int read(final byte[] b, final int off, final int len) throws IOException { 081 final int ret = in.read(b, off, len); 082 if (ret >= 0) { 083 checksum.update(b, off, ret); 084 } 085 return ret; 086 } 087 088 @Override 089 public long skip(final long n) throws IOException { 090 // Can't really skip, we have to hash everything to verify the checksum 091 if (read() >= 0) { 092 return 1; 093 } 094 return 0; 095 } 096 097 /** 098 * Returns the calculated checksum. 099 * @return the calculated checksum. 100 */ 101 public long getValue() { 102 return checksum.getValue(); 103 } 104 105}