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 verifies the checksum of the data read once the stream is 026 * exhausted. 027 * @NotThreadSafe 028 * @since 1.7 029 */ 030public class ChecksumVerifyingInputStream extends InputStream { 031 private final InputStream in; 032 private long bytesRemaining; 033 private final long expectedChecksum; 034 private final Checksum checksum; 035 036 public ChecksumVerifyingInputStream(final Checksum checksum, final InputStream in, 037 final long size, final long expectedChecksum) { 038 this.checksum = checksum; 039 this.in = in; 040 this.expectedChecksum = expectedChecksum; 041 this.bytesRemaining = size; 042 } 043 044 /** 045 * Reads a single byte from the stream 046 * @throws IOException if the underlying stream throws or the 047 * stream is exhausted and the Checksum doesn't match the expected 048 * value 049 */ 050 @Override 051 public int read() throws IOException { 052 if (bytesRemaining <= 0) { 053 return -1; 054 } 055 final int ret = in.read(); 056 if (ret >= 0) { 057 checksum.update(ret); 058 --bytesRemaining; 059 } 060 if (bytesRemaining == 0 && expectedChecksum != checksum.getValue()) { 061 throw new IOException("Checksum verification failed"); 062 } 063 return ret; 064 } 065 066 /** 067 * Reads a byte array from the stream 068 * @throws IOException if the underlying stream throws or the 069 * stream is exhausted and the Checksum doesn't match the expected 070 * value 071 */ 072 @Override 073 public int read(final byte[] b) throws IOException { 074 return read(b, 0, b.length); 075 } 076 077 /** 078 * Reads from the stream into a byte array. 079 * @throws IOException if the underlying stream throws or the 080 * stream is exhausted and the Checksum doesn't match the expected 081 * value 082 */ 083 @Override 084 public int read(final byte[] b, final int off, final int len) throws IOException { 085 final int ret = in.read(b, off, len); 086 if (ret >= 0) { 087 checksum.update(b, off, ret); 088 bytesRemaining -= ret; 089 } 090 if (bytesRemaining <= 0 && expectedChecksum != checksum.getValue()) { 091 throw new IOException("Checksum verification failed"); 092 } 093 return ret; 094 } 095 096 @Override 097 public long skip(final long n) throws IOException { 098 // Can't really skip, we have to hash everything to verify the checksum 099 if (read() >= 0) { 100 return 1; 101 } 102 return 0; 103 } 104 105 @Override 106 public void close() throws IOException { 107 in.close(); 108 } 109}