1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * https://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19 package org.apache.commons.compress.utils;
20
21 import java.io.FilterInputStream;
22 import java.io.IOException;
23 import java.io.InputStream;
24
25 /**
26 * A wrapper that overwrites {@link #skip} and delegates to {@link #read} instead.
27 *
28 * <p>
29 * Some implementations of {@link InputStream} implement {@link InputStream#skip} in a way that throws an exception if the stream is not seekable -
30 * {@link System#in System.in} is known to behave that way. For such a stream it is impossible to invoke skip at all and you have to read from the stream (and
31 * discard the data read) instead. Skipping is potentially much faster than reading so we do want to invoke {@code skip} when possible. We provide this class so
32 * you can wrap your own {@link InputStream} in it if you encounter problems with {@code skip} throwing an exception.
33 * </p>
34 *
35 * @since 1.17
36 * @deprecated No longer used.
37 */
38 @Deprecated
39 public class SkipShieldingInputStream extends FilterInputStream {
40
41 private static final int SKIP_BUFFER_SIZE = 8192;
42
43 /** We can use a shared buffer as the content is discarded anyway. */
44 private static final byte[] SKIP_BUFFER = new byte[SKIP_BUFFER_SIZE];
45
46 /**
47 * Creates a {@code SkipShieldingInputStream} by assigning the argument {@code in} to the field {@code this.in} so as to remember it for later use.
48 *
49 * @param in the underlying input stream, or {@code null} if this instance is to be created without an underlying stream.
50 */
51 public SkipShieldingInputStream(final InputStream in) {
52 super(in);
53 }
54
55 @Override
56 public long skip(final long n) throws IOException {
57 return n < 0 ? 0 : read(SKIP_BUFFER, 0, (int) Math.min(n, SKIP_BUFFER_SIZE));
58 }
59 }