1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.compress.utils;
18
19 import java.io.IOException;
20 import java.io.InputStream;
21 import java.util.zip.CheckedInputStream;
22 import java.util.zip.Checksum;
23
24 /**
25 * Verifies the checksum of the data read once the stream is exhausted.
26 *
27 * @NotThreadSafe
28 * @since 1.7
29 */
30 public class ChecksumVerifyingInputStream extends CheckedInputStream {
31 // TODO Use Commons IO 2.16.0 ChecksumInputStream
32
33 private long remaining;
34 private final long expected;
35
36 /**
37 * Constructs a new instance.
38 *
39 * @param checksum Checksum implementation.
40 * @param in the stream to wrap
41 * @param size the of the stream's content
42 * @param expectedChecksum the expected checksum
43 */
44 public ChecksumVerifyingInputStream(final Checksum checksum, final InputStream in, final long size, final long expectedChecksum) {
45 super(in, checksum);
46 this.expected = expectedChecksum;
47 this.remaining = size;
48 }
49
50 /**
51 * Gets the byte count remaining to read.
52 *
53 * @return bytes remaining to read.
54 * @since 1.21
55 */
56 public long getBytesRemaining() {
57 return remaining;
58 }
59
60 /**
61 * Reads a single byte from the stream
62 *
63 * @throws IOException if the underlying stream throws or the stream is exhausted and the Checksum doesn't match the expected value
64 */
65 @Override
66 public int read() throws IOException {
67 if (remaining <= 0) {
68 return -1;
69 }
70 final int data = super.read();
71 if (data >= 0) {
72 --remaining;
73 }
74 verify();
75 return data;
76 }
77
78 /**
79 * Reads from the stream into a byte array.
80 *
81 * @throws IOException if the underlying stream throws or the stream is exhausted and the Checksum doesn't match the expected value
82 */
83 @Override
84 public int read(final byte[] b, final int off, final int len) throws IOException {
85 if (len == 0) {
86 return 0;
87 }
88 final int readCount = super.read(b, off, len);
89 if (readCount >= 0) {
90 remaining -= readCount;
91 }
92 verify();
93 return readCount;
94 }
95
96 private void verify() throws IOException {
97 if (remaining <= 0 && expected != getChecksum().getValue()) {
98 throw new IOException("Checksum verification failed");
99 }
100 }
101 }