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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.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * Utility functions
 * @Immutable
 */
public final class IOUtils {

    /** Private constructor to prevent instantiation of this utility class. */
    private IOUtils(){
    }

    /**
     * Copies the content of a InputStream into an OutputStream.
     * Uses a default buffer size of 8024 bytes.
     *
     * @param input
     *            the InputStream to copy
     * @param output
     *            the target Stream
     * @throws IOException
     *             if an error occurs
     */
    public static long copy(final InputStream input, final OutputStream output) throws IOException {
        return copy(input, output, 8024);
    }

    /**
     * Copies the content of a InputStream into an OutputStream
     *
     * @param input
     *            the InputStream to copy
     * @param output
     *            the target Stream
     * @param buffersize
     *            the buffer size to use
     * @throws IOException
     *             if an error occurs
     */
    public static long copy(final InputStream input, final OutputStream output, int buffersize) throws IOException {
        final byte[] buffer = new byte[buffersize];
        int n = 0;
        long count=0;
        while (-1 != (n = input.read(buffer))) {
            output.write(buffer, 0, n);
            count += n;
        }
        return count;
    }


    // toByteArray(InputStream) copied from:
    // commons/proper/io/trunk/src/main/java/org/apache/commons/io/IOUtils.java?revision=1428941
    // January 8th, 2013
    //
    // Assuming our copy() works just as well as theirs!  :-)

    /**
     * Gets the contents of an InputStream as a byte[].
     * 
     * This method buffers the input internally, so there is no need to use a
     * BufferedInputStream.
     *
     * @param input  the InputStream to read from
     * @return the requested byte array
     * @throws NullPointerException if the input is null
     * @throws IOException if an I/O error occurs
     * @since 1.5
     */
    public static byte[] toByteArray(final InputStream input) throws IOException {
        final ByteArrayOutputStream output = new ByteArrayOutputStream();
        copy(input, output);
        return output.toByteArray();
    }
}