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Apache Commons Compress defines an API for working with compression and archive formats. These include bzip2, gzip, pack200, LZMA, XZ, Snappy, traditional Unix Compress, DEFLATE, DEFLATE64, LZ4, Brotli, Zstandard and ar, cpio, jar, tar, zip, dump, 7z, arj.

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/*
 *  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.IOException;
import java.io.InputStream;

/**
 * A stream that limits reading from a wrapped stream to a given number of bytes.
 * @NotThreadSafe
 * @since 1.6
 */
public class BoundedInputStream extends InputStream {
    private final InputStream in;
    private long bytesRemaining;

    /**
     * Creates the stream that will at most read the given amount of
     * bytes from the given stream.
     * @param in the stream to read from
     * @param size the maximum amount of bytes to read
     */
    public BoundedInputStream(final InputStream in, final long size) {
        this.in = in;
        bytesRemaining = size;
    }

    @Override
    public int read() throws IOException {
        if (bytesRemaining > 0) {
            --bytesRemaining;
            return in.read();
        }
        return -1;
    }

    @Override
    public int read(final byte[] b, final int off, final int len) throws IOException {
        if (bytesRemaining == 0) {
            return -1;
        }
        int bytesToRead = len;
        if (bytesToRead > bytesRemaining) {
            bytesToRead = (int) bytesRemaining;
        }
        final int bytesRead = in.read(b, off, bytesToRead);
        if (bytesRead >= 0) {
            bytesRemaining -= bytesRead;
        }
        return bytesRead;
    }

    @Override
    public void close() {
        // there isn't anything to close in this stream and the nested
        // stream is controlled externally
    }
}