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 */ 017package org.apache.commons.compress.utils; 018 019import java.io.FilterInputStream; 020import java.io.IOException; 021import java.io.InputStream; 022import java.util.Objects; 023import java.util.zip.Checksum; 024 025/** 026 * Calculates the checksum of the data read. 027 * 028 * @NotThreadSafe 029 * @since 1.14 030 */ 031public class ChecksumCalculatingInputStream extends FilterInputStream { 032 private final Checksum checksum; 033 034 public ChecksumCalculatingInputStream(final Checksum checksum, final InputStream inputStream) { 035 super(Objects.requireNonNull(inputStream, "inputStream")); 036 this.checksum = Objects.requireNonNull(checksum, "checksum"); 037 } 038 039 /** 040 * Returns the calculated checksum. 041 * @return the calculated checksum. 042 */ 043 public long getValue() { 044 return checksum.getValue(); 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 from the stream into a byte array. 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, final int off, final int len) throws IOException { 070 if (len == 0) { 071 return 0; 072 } 073 final int ret = in.read(b, off, len); 074 if (ret >= 0) { 075 checksum.update(b, off, ret); 076 } 077 return ret; 078 } 079 080 @Override 081 public long skip(final long n) throws IOException { 082 // Can't really skip, we have to hash everything to verify the checksum 083 if (read() >= 0) { 084 return 1; 085 } 086 return 0; 087 } 088 089}