    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017
    018package org.apache.commons.codec.binary;
    019
    020import java.io.InputStream;
    021
    022import org.apache.commons.codec.CodecPolicy;
    023
    024/**
    025 * Provides Base32 encoding and decoding in a streaming fashion (unlimited size). When encoding the default lineLength
    026 * is 76 characters and the default lineEnding is CRLF, but these can be overridden by using the appropriate
    027 * constructor.
    028 * <p>
    029 * The default behavior of the Base32InputStream is to DECODE, whereas the default behavior of the Base32OutputStream
    030 * is to ENCODE, but this behavior can be overridden by using a different constructor.
    031 * </p>
    032 * <p>
    033 * Since this class operates directly on byte streams, and not character streams, it is hard-coded to only encode/decode
    034 * character encodings which are compatible with the lower 127 ASCII chart (ISO-8859-1, Windows-1252, UTF-8, etc).
    035 * </p>
    036 * <p>
    037 * You can set the decoding behavior when the input bytes contain leftover trailing bits that cannot be created by a valid
    038 * encoding. These can be bits that are unused from the final character or entire characters. The default mode is
    039 * lenient decoding.
    040 * </p>
    041 * <ul>
    042 * <li>Lenient: Any trailing bits are composed into 8-bit bytes where possible. The remainder are discarded.
    043 * <li>Strict: The decoding will raise an {@link IllegalArgumentException} if trailing bits are not part of a valid
    044 * encoding. Any unused bits from the final character must be zero. Impossible counts of entire final characters are not
    045 * allowed.
    046 * </ul>
    047 * <p>
    048 * When strict decoding is enabled it is expected that the decoded bytes will be re-encoded to a byte array that matches
    049 * the original, i.e. no changes occur on the final character. This requires that the input bytes use the same padding
    050 * and alphabet as the encoder.
    051 * </p>
    052 * @see <a href="http://www.ietf.org/rfc/rfc4648.txt">RFC 4648</a>
    053 * @since 1.5
    054 */
    055public class Base32InputStream extends BaseNCodecInputStream {
    056
    057    /**
    058     * Creates a Base32InputStream such that all data read is Base32-decoded from the original provided InputStream.
    059     *
    060     * @param in
    061     *            InputStream to wrap.
    062     */
    063    public Base32InputStream(final InputStream in) {
    064        this(in, false);
    065    }
    066
    067    /**
    068     * Creates a Base32InputStream such that all data read is either Base32-encoded or Base32-decoded from the original
    069     * provided InputStream.
    070     *
    071     * @param in
    072     *            InputStream to wrap.
    073     * @param doEncode
    074     *            true if we should encode all data read from us, false if we should decode.
    075     */
    076    public Base32InputStream(final InputStream in, final boolean doEncode) {
    077        super(in, new Base32(false), doEncode);
    078    }
    079
    080    /**
    081     * Creates a Base32InputStream such that all data read is either Base32-encoded or Base32-decoded from the original
    082     * provided InputStream.
    083     *
    084     * @param input
    085     *            InputStream to wrap.
    086     * @param doEncode
    087     *            true if we should encode all data read from us, false if we should decode.
    088     * @param lineLength
    089     *            If doEncode is true, each line of encoded data will contain lineLength characters (rounded down to
    090     *            nearest multiple of 4). If lineLength &lt;= 0, the encoded data is not divided into lines. If doEncode
    091     *            is false, lineLength is ignored.
    092     * @param lineSeparator
    093     *            If doEncode is true, each line of encoded data will be terminated with this byte sequence (e.g. \r\n).
    094     *            If lineLength &lt;= 0, the lineSeparator is not used. If doEncode is false lineSeparator is ignored.
    095     */
    096    public Base32InputStream(final InputStream input, final boolean doEncode,
    097                             final int lineLength, final byte[] lineSeparator) {
    098        super(input, new Base32(lineLength, lineSeparator), doEncode);
    099    }
    100
    101    /**
    102     * Creates a Base32InputStream such that all data read is either Base32-encoded or Base32-decoded from the original
    103     * provided InputStream.
    104     *
    105     * @param input
    106     *            InputStream to wrap.
    107     * @param doEncode
    108     *            true if we should encode all data read from us, false if we should decode.
    109     * @param lineLength
    110     *            If doEncode is true, each line of encoded data will contain lineLength characters (rounded down to
    111     *            nearest multiple of 4). If lineLength &lt;= 0, the encoded data is not divided into lines. If doEncode
    112     *            is false, lineLength is ignored.
    113     * @param lineSeparator
    114     *            If doEncode is true, each line of encoded data will be terminated with this byte sequence (e.g. \r\n).
    115     *            If lineLength &lt;= 0, the lineSeparator is not used. If doEncode is false lineSeparator is ignored.
    116     * @param decodingPolicy
    117     *            The decoding policy.
    118     * @since 1.15
    119     */
    120    public Base32InputStream(final InputStream input, final boolean doEncode,
    121                             final int lineLength, final byte[] lineSeparator, final CodecPolicy decodingPolicy) {
    122        super(input, new Base32(lineLength, lineSeparator, false, BaseNCodec.PAD_DEFAULT, decodingPolicy), doEncode);
    123    }
    124
    125}