| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * |
| */ |
| package org.apache.commons.compress.utils; |
| |
| import java.io.FilterInputStream; |
| import java.io.IOException; |
| import java.io.InputStream; |
| |
| /** |
| * A wrapper that overwrites {@link #skip} and delegates to {@link #read} instead. |
| * |
| * <p>Some implementations of {@link InputStream} implement {@link |
| * InputStream#skip} in a way that throws an exception if the stream |
| * is not seekable - {@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 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 |
| * you can wrap your own {@link InputStream} in it if you encounter |
| * problems with {@code skip} throwing an exception.</p> |
| * |
| * @since 1.17 |
| */ |
| public class SkipShieldingInputStream extends FilterInputStream { |
| private static final int SKIP_BUFFER_SIZE = 8192; |
| // we can use a shared buffer as the content is discarded anyway |
| private static final byte[] SKIP_BUFFER = new byte[SKIP_BUFFER_SIZE]; |
| public SkipShieldingInputStream(final InputStream in) { |
| super(in); |
| } |
| |
| @Override |
| public long skip(final long n) throws IOException { |
| return n < 0 ? 0 : read(SKIP_BUFFER, 0, (int) Math.min(n, SKIP_BUFFER_SIZE)); |
| } |
| } |