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.FilterInputStream;
20 import java.io.IOException;
21 import java.io.InputStream;
22
23 /**
24 * A wrapper that overwrites {@link #skip} and delegates to {@link #read} instead.
25 *
26 * <p>
27 * Some implementations of {@link InputStream} implement {@link InputStream#skip} in a way that throws an exception if the stream is not seekable -
28 * {@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
29 * 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
30 * you can wrap your own {@link InputStream} in it if you encounter problems with {@code skip} throwing an exception.
31 * </p>
32 *
33 * @since 1.17
34 * @deprecated No longer used.
35 */
36 @Deprecated
37 public class SkipShieldingInputStream extends FilterInputStream {
38 private static final int SKIP_BUFFER_SIZE = 8192;
39 // we can use a shared buffer as the content is discarded anyway
40 private static final byte[] SKIP_BUFFER = new byte[SKIP_BUFFER_SIZE];
41
42 public SkipShieldingInputStream(final InputStream in) {
43 super(in);
44 }
45
46 @Override
47 public long skip(final long n) throws IOException {
48 return n < 0 ? 0 : read(SKIP_BUFFER, 0, (int) Math.min(n, SKIP_BUFFER_SIZE));
49 }
50 }