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.Objects; 023import java.util.zip.Checksum; 024 025/** 026 * A stream that calculates the checksum of the data read. 027 * @NotThreadSafe 028 * @since 1.14 029 */ 030public class ChecksumCalculatingInputStream extends InputStream { 031 private final InputStream in; 032 private final Checksum checksum; 033 034 public ChecksumCalculatingInputStream(final Checksum checksum, final InputStream inputStream) { 035 036 Objects.requireNonNull(checksum, "checksum"); 037 Objects.requireNonNull(inputStream, "in"); 038 039 this.checksum = checksum; 040 this.in = inputStream; 041 } 042 043 /** 044 * Reads a single byte from the stream 045 * @throws IOException if the underlying stream throws or the 046 * stream is exhausted and the Checksum doesn't match the expected 047 * value 048 */ 049 @Override 050 public int read() throws IOException { 051 final int ret = in.read(); 052 if (ret >= 0) { 053 checksum.update(ret); 054 } 055 return ret; 056 } 057 058 /** 059 * Reads a byte array from the stream 060 * @throws IOException if the underlying stream throws or the 061 * stream is exhausted and the Checksum doesn't match the expected 062 * value 063 */ 064 @Override 065 public int read(final byte[] b) throws IOException { 066 return read(b, 0, b.length); 067 } 068 069 /** 070 * Reads from the stream into a byte array. 071 * @throws IOException if the underlying stream throws or the 072 * stream is exhausted and the Checksum doesn't match the expected 073 * value 074 */ 075 @Override 076 public int read(final byte[] b, final int off, final int len) throws IOException { 077 if (len == 0) { 078 return 0; 079 } 080 final int ret = in.read(b, off, len); 081 if (ret >= 0) { 082 checksum.update(b, off, ret); 083 } 084 return ret; 085 } 086 087 @Override 088 public long skip(final long n) throws IOException { 089 // Can't really skip, we have to hash everything to verify the checksum 090 if (read() >= 0) { 091 return 1; 092 } 093 return 0; 094 } 095 096 /** 097 * Returns the calculated checksum. 098 * @return the calculated checksum. 099 */ 100 public long getValue() { 101 return checksum.getValue(); 102 } 103 104}