    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one
    003 * or more contributor license agreements.  See the NOTICE file
    004 * distributed with this work for additional information
    005 * regarding copyright ownership.  The ASF licenses this file
    006 * to you under the Apache License, Version 2.0 (the
    007 * "License"); you may not use this file except in compliance
    008 * with the License.  You may obtain a copy of the License at
    009 *
    010 * http://www.apache.org/licenses/LICENSE-2.0
    011 *
    012 * Unless required by applicable law or agreed to in writing,
    013 * software distributed under the License is distributed on an
    014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    015 * KIND, either express or implied.  See the License for the
    016 * specific language governing permissions and limitations
    017 * under the License.
    018 */
    019package org.apache.commons.compress.utils;
    020
    021import java.io.ByteArrayOutputStream;
    022import java.io.Closeable;
    023import java.io.IOException;
    024import java.io.InputStream;
    025import java.io.OutputStream;
    026
    027/**
    028 * Utility functions
    029 * @Immutable (has mutable data but it is write-only)
    030 */
    031public final class IOUtils {
    032
    033    private static final int COPY_BUF_SIZE = 8024;
    034    private static final int SKIP_BUF_SIZE = 4096;
    035
    036    // This buffer does not need to be synchronised because it is write only; the contents are ignored
    037    // Does not affect Immutability
    038    private static final byte[] SKIP_BUF = new byte[SKIP_BUF_SIZE];
    039
    040    /** Private constructor to prevent instantiation of this utility class. */
    041    private IOUtils(){
    042    }
    043
    044    /**
    045     * Copies the content of a InputStream into an OutputStream.
    046     * Uses a default buffer size of 8024 bytes.
    047     *
    048     * @param input
    049     *            the InputStream to copy
    050     * @param output
    051     *            the target Stream
    052     * @return the number of bytes copied
    053     * @throws IOException
    054     *             if an error occurs
    055     */
    056    public static long copy(final InputStream input, final OutputStream output) throws IOException {
    057        return copy(input, output, COPY_BUF_SIZE);
    058    }
    059
    060    /**
    061     * Copies the content of a InputStream into an OutputStream
    062     *
    063     * @param input
    064     *            the InputStream to copy
    065     * @param output
    066     *            the target Stream
    067     * @param buffersize
    068     *            the buffer size to use
    069     * @return the number of bytes copied
    070     * @throws IOException
    071     *             if an error occurs
    072     */
    073    public static long copy(final InputStream input, final OutputStream output, final int buffersize) throws IOException {
    074        final byte[] buffer = new byte[buffersize];
    075        int n = 0;
    076        long count=0;
    077        while (-1 != (n = input.read(buffer))) {
    078            output.write(buffer, 0, n);
    079            count += n;
    080        }
    081        return count;
    082    }
    083
    084    /**
    085     * Skips the given number of bytes by repeatedly invoking skip on
    086     * the given input stream if necessary.
    087     *
    088     * <p>In a case where the stream's skip() method returns 0 before
    089     * the requested number of bytes has been skip this implementation
    090     * will fall back to using the read() method.</p>
    091     *
    092     * <p>This method will only skip less than the requested number of
    093     * bytes if the end of the input stream has been reached.</p>
    094     *
    095     * @param input stream to skip bytes in
    096     * @param numToSkip the number of bytes to skip
    097     * @return the number of bytes actually skipped
    098     * @throws IOException on error
    099     */
    100    public static long skip(final InputStream input, long numToSkip) throws IOException {
    101        final long available = numToSkip;
    102        while (numToSkip > 0) {
    103            final long skipped = input.skip(numToSkip);
    104            if (skipped == 0) {
    105                break;
    106            }
    107            numToSkip -= skipped;
    108        }
    109
    110        while (numToSkip > 0) {
    111            final int read = readFully(input, SKIP_BUF, 0,
    112                                 (int) Math.min(numToSkip, SKIP_BUF_SIZE));
    113            if (read < 1) {
    114                break;
    115            }
    116            numToSkip -= read;
    117        }
    118        return available - numToSkip;
    119    }
    120
    121    /**
    122     * Reads as much from input as possible to fill the given array.
    123     *
    124     * <p>This method may invoke read repeatedly to fill the array and
    125     * only read less bytes than the length of the array if the end of
    126     * the stream has been reached.</p>
    127     *
    128     * @param input stream to read from
    129     * @param b buffer to fill
    130     * @return the number of bytes actually read
    131     * @throws IOException on error
    132     */
    133    public static int readFully(final InputStream input, final byte[] b) throws IOException {
    134        return readFully(input, b, 0, b.length);
    135    }
    136
    137    /**
    138     * Reads as much from input as possible to fill the given array
    139     * with the given amount of bytes.
    140     *
    141     * <p>This method may invoke read repeatedly to read the bytes and
    142     * only read less bytes than the requested length if the end of
    143     * the stream has been reached.</p>
    144     *
    145     * @param input stream to read from
    146     * @param b buffer to fill
    147     * @param offset offset into the buffer to start filling at
    148     * @param len of bytes to read
    149     * @return the number of bytes actually read
    150     * @throws IOException
    151     *             if an I/O error has occurred
    152     */
    153    public static int readFully(final InputStream input, final byte[] b, final int offset, final int len)
    154        throws IOException {
    155        if (len < 0 || offset < 0 || len + offset > b.length) {
    156            throw new IndexOutOfBoundsException();
    157        }
    158        int count = 0, x = 0;
    159        while (count != len) {
    160            x = input.read(b, offset + count, len - count);
    161            if (x == -1) {
    162                break;
    163            }
    164            count += x;
    165        }
    166        return count;
    167    }
    168
    169    // toByteArray(InputStream) copied from:
    170    // commons/proper/io/trunk/src/main/java/org/apache/commons/io/IOUtils.java?revision=1428941
    171    // January 8th, 2013
    172    //
    173    // Assuming our copy() works just as well as theirs!  :-)
    174
    175    /**
    176     * Gets the contents of an <code>InputStream</code> as a <code>byte[]</code>.
    177     * <p>
    178     * This method buffers the input internally, so there is no need to use a
    179     * <code>BufferedInputStream</code>.
    180     *
    181     * @param input  the <code>InputStream</code> to read from
    182     * @return the requested byte array
    183     * @throws NullPointerException if the input is null
    184     * @throws IOException if an I/O error occurs
    185     * @since 1.5
    186     */
    187    public static byte[] toByteArray(final InputStream input) throws IOException {
    188        final ByteArrayOutputStream output = new ByteArrayOutputStream();
    189        copy(input, output);
    190        return output.toByteArray();
    191    }
    192
    193    /**
    194     * Closes the given Closeable and swallows any IOException that may occur.
    195     * @param c Closeable to close, can be null
    196     * @since 1.7
    197     */
    198    public static void closeQuietly(final Closeable c) {
    199        if (c != null) {
    200            try {
    201                c.close();
    202            } catch (final IOException ignored) { // NOPMD
    203            }
    204        }
    205    }
    206}