    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 *      https://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.util.Arrays;
    021import java.util.Objects;
    022import java.util.function.Supplier;
    023
    024import org.apache.commons.codec.BinaryDecoder;
    025import org.apache.commons.codec.BinaryEncoder;
    026import org.apache.commons.codec.CodecPolicy;
    027import org.apache.commons.codec.DecoderException;
    028import org.apache.commons.codec.EncoderException;
    029
    030/**
    031 * Abstract superclass for Base-N encoders and decoders.
    032 *
    033 * <p>
    034 * This class is thread-safe.
    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
    038 * valid 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 */
    053public abstract class BaseNCodec implements BinaryEncoder, BinaryDecoder {
    054
    055    /**
    056     * Builds {@link Base64} instances.
    057     *
    058     * @param <T> the codec type to build.
    059     * @param <B> the codec builder subtype.
    060     * @since 1.17.0
    061     */
    062    public abstract static class AbstractBuilder<T, B extends AbstractBuilder<T, B>> implements Supplier<T> {
    063
    064        private CodecPolicy decodingPolicy = DECODING_POLICY_DEFAULT;
    065        private int lineLength;
    066        private byte[] lineSeparator = CHUNK_SEPARATOR;
    067        private final byte[] defaultEncodeTable;
    068        private byte[] encodeTable;
    069        /** Padding byte. */
    070        private byte padding = PAD_DEFAULT;
    071
    072        AbstractBuilder(final byte[] defaultEncodeTable) {
    073            this.defaultEncodeTable = defaultEncodeTable;
    074            this.encodeTable = defaultEncodeTable;
    075        }
    076
    077        /**
    078         * Returns this instance typed as the subclass type {@code B}.
    079         * <p>
    080         * This is the same as the expression:
    081         * </p>
    082         * <pre>
    083         * (B) this
    084         * </pre>
    085         *
    086         * @return this instance typed as the subclass type {@code B}.
    087         */
    088        @SuppressWarnings("unchecked")
    089        B asThis() {
    090            return (B) this;
    091        }
    092
    093        CodecPolicy getDecodingPolicy() {
    094            return decodingPolicy;
    095        }
    096
    097        byte[] getEncodeTable() {
    098            return encodeTable;
    099        }
    100
    101        int getLineLength() {
    102            return lineLength;
    103        }
    104
    105        byte[] getLineSeparator() {
    106            return lineSeparator;
    107        }
    108
    109        byte getPadding() {
    110            return padding;
    111        }
    112
    113        /**
    114         * Sets the decoding policy.
    115         *
    116         * @param decodingPolicy the decoding policy, null resets to the default.
    117         * @return {@code this} instance.
    118         */
    119        public B setDecodingPolicy(final CodecPolicy decodingPolicy) {
    120            this.decodingPolicy = decodingPolicy != null ? decodingPolicy : DECODING_POLICY_DEFAULT;
    121            return asThis();
    122        }
    123
    124        /**
    125         * Sets the encode table.
    126         *
    127         * @param encodeTable the encode table, null resets to the default.
    128         * @return {@code this} instance.
    129         */
    130        public B setEncodeTable(final byte... encodeTable) {
    131            this.encodeTable = encodeTable != null ? encodeTable.clone() : defaultEncodeTable;
    132            return asThis();
    133        }
    134
    135        /**
    136         * Sets the line length.
    137         *
    138         * @param lineLength the line length, less than 0 resets to the default.
    139         * @return {@code this} instance.
    140         */
    141        public B setLineLength(final int lineLength) {
    142            this.lineLength = Math.max(0, lineLength);
    143            return asThis();
    144        }
    145
    146        /**
    147         * Sets the line separator.
    148         *
    149         * @param lineSeparator the line separator, null resets to the default.
    150         * @return {@code this} instance.
    151         */
    152        public B setLineSeparator(final byte... lineSeparator) {
    153            this.lineSeparator = lineSeparator != null ? lineSeparator.clone() : CHUNK_SEPARATOR;
    154            return asThis();
    155        }
    156
    157        /**
    158         * Sets the padding byte.
    159         *
    160         * @param padding the padding byte.
    161         * @return {@code this} instance.
    162         */
    163        public B setPadding(final byte padding) {
    164            this.padding = padding;
    165            return asThis();
    166        }
    167
    168    }
    169
    170    /**
    171     * Holds thread context so classes can be thread-safe.
    172     *
    173     * This class is not itself thread-safe; each thread must allocate its own copy.
    174     */
    175    static class Context {
    176
    177        /**
    178         * Placeholder for the bytes we're dealing with for our based logic.
    179         * Bitwise operations store and extract the encoding or decoding from this variable.
    180         */
    181        int ibitWorkArea;
    182
    183        /**
    184         * Placeholder for the bytes we're dealing with for our based logic.
    185         * Bitwise operations store and extract the encoding or decoding from this variable.
    186         */
    187        long lbitWorkArea;
    188
    189        /**
    190         * Buffer for streaming.
    191         */
    192        byte[] buffer;
    193
    194        /**
    195         * Position where next character should be written in the buffer.
    196         */
    197        int pos;
    198
    199        /**
    200         * Position where next character should be read from the buffer.
    201         */
    202        int readPos;
    203
    204        /**
    205         * Boolean flag to indicate the EOF has been reached. Once EOF has been reached, this object becomes useless,
    206         * and must be thrown away.
    207         */
    208        boolean eof;
    209
    210        /**
    211         * Variable tracks how many characters have been written to the current line. Only used when encoding. We use
    212         * it to make sure each encoded line never goes beyond lineLength (if lineLength &gt; 0).
    213         */
    214        int currentLinePos;
    215
    216        /**
    217         * Writes to the buffer only occur after every 3/5 reads when encoding, and every 4/8 reads when decoding. This
    218         * variable helps track that.
    219         */
    220        int modulus;
    221
    222        /**
    223         * Returns a String useful for debugging (especially within a debugger.)
    224         *
    225         * @return a String useful for debugging.
    226         */
    227        @Override
    228        public String toString() {
    229            return String.format("%s[buffer=%s, currentLinePos=%s, eof=%s, ibitWorkArea=%s, lbitWorkArea=%s, " +
    230                    "modulus=%s, pos=%s, readPos=%s]", this.getClass().getSimpleName(), Arrays.toString(buffer),
    231                    currentLinePos, eof, ibitWorkArea, lbitWorkArea, modulus, pos, readPos);
    232        }
    233    }
    234
    235    /**
    236     * End-of-file marker.
    237     *
    238     * @since 1.7
    239     */
    240    static final int EOF = -1;
    241
    242    /**
    243     *  MIME chunk size per RFC 2045 section 6.8.
    244     *
    245     * <p>
    246     * The {@value} character limit does not count the trailing CRLF, but counts all other characters, including any
    247     * equal signs.
    248     * </p>
    249     *
    250     * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 6.8</a>
    251     */
    252    public static final int MIME_CHUNK_SIZE = 76;
    253
    254    /**
    255     * PEM chunk size per RFC 1421 section 4.3.2.4.
    256     *
    257     * <p>
    258     * The {@value} character limit does not count the trailing CRLF, but counts all other characters, including any
    259     * equal signs.
    260     * </p>
    261     *
    262     * @see <a href="https://tools.ietf.org/html/rfc1421">RFC 1421 section 4.3.2.4</a>
    263     */
    264    public static final int PEM_CHUNK_SIZE = 64;
    265
    266    private static final int DEFAULT_BUFFER_RESIZE_FACTOR = 2;
    267
    268    /**
    269     * Defines the default buffer size - currently {@value}
    270     * - must be large enough for at least one encoded block+separator
    271     */
    272    private static final int DEFAULT_BUFFER_SIZE = 8192;
    273
    274    /**
    275     * The maximum size buffer to allocate.
    276     *
    277     * <p>This is set to the same size used in the JDK {@link java.util.ArrayList}:</p>
    278     * <blockquote>
    279     * Some VMs reserve some header words in an array.
    280     * Attempts to allocate larger arrays may result in
    281     * OutOfMemoryError: Requested array size exceeds VM limit.
    282     * </blockquote>
    283     */
    284    private static final int MAX_BUFFER_SIZE = Integer.MAX_VALUE - 8;
    285
    286    /** Mask used to extract 8 bits, used in decoding bytes */
    287    protected static final int MASK_8BITS = 0xff;
    288
    289    /**
    290     * Byte used to pad output.
    291     */
    292    protected static final byte PAD_DEFAULT = '='; // Allow static access to default
    293
    294    /**
    295     * The default decoding policy.
    296     *
    297     * @since 1.15
    298     */
    299    protected static final CodecPolicy DECODING_POLICY_DEFAULT = CodecPolicy.LENIENT;
    300
    301    /**
    302     * Chunk separator per RFC 2045 section 2.1.
    303     *
    304     * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 2.1</a>
    305     */
    306    static final byte[] CHUNK_SEPARATOR = {'\r', '\n'};
    307
    308    /**
    309     * Create a positive capacity at least as large the minimum required capacity.
    310     * If the minimum capacity is negative then this throws an OutOfMemoryError as no array
    311     * can be allocated.
    312     *
    313     * @param minCapacity the minimum capacity
    314     * @return the capacity
    315     * @throws OutOfMemoryError if the {@code minCapacity} is negative
    316     */
    317    private static int createPositiveCapacity(final int minCapacity) {
    318        if (minCapacity < 0) {
    319            // overflow
    320            throw new OutOfMemoryError("Unable to allocate array size: " + (minCapacity & 0xffffffffL));
    321        }
    322        // This is called when we require buffer expansion to a very big array.
    323        // Use the conservative maximum buffer size if possible, otherwise the biggest required.
    324        //
    325        // Note: In this situation JDK 1.8 java.util.ArrayList returns Integer.MAX_VALUE.
    326        // This excludes some VMs that can exceed MAX_BUFFER_SIZE but not allocate a full
    327        // Integer.MAX_VALUE length array.
    328        // The result is that we may have to allocate an array of this size more than once if
    329        // the capacity must be expanded again.
    330        return Math.max(minCapacity, MAX_BUFFER_SIZE);
    331    }
    332
    333    /**
    334     * Gets a copy of the chunk separator per RFC 2045 section 2.1.
    335     *
    336     * @return the chunk separator
    337     * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 2.1</a>
    338     * @since 1.15
    339     */
    340    public static byte[] getChunkSeparator() {
    341        return CHUNK_SEPARATOR.clone();
    342    }
    343
    344    /**
    345     * Checks if a byte value is whitespace or not.
    346     *
    347     * @param byteToCheck the byte to check
    348     * @return true if byte is whitespace, false otherwise
    349     * @see Character#isWhitespace(int)
    350     * @deprecated Use {@link Character#isWhitespace(int)}.
    351     */
    352    @Deprecated
    353    protected static boolean isWhiteSpace(final byte byteToCheck) {
    354        return Character.isWhitespace(byteToCheck);
    355    }
    356
    357    /**
    358     * Increases our buffer by the {@link #DEFAULT_BUFFER_RESIZE_FACTOR}.
    359     *
    360     * @param context the context to be used
    361     * @param minCapacity the minimum required capacity
    362     * @return the resized byte[] buffer
    363     * @throws OutOfMemoryError if the {@code minCapacity} is negative
    364     */
    365    private static byte[] resizeBuffer(final Context context, final int minCapacity) {
    366        // Overflow-conscious code treats the min and new capacity as unsigned.
    367        final int oldCapacity = context.buffer.length;
    368        int newCapacity = oldCapacity * DEFAULT_BUFFER_RESIZE_FACTOR;
    369        if (Integer.compareUnsigned(newCapacity, minCapacity) < 0) {
    370            newCapacity = minCapacity;
    371        }
    372        if (Integer.compareUnsigned(newCapacity, MAX_BUFFER_SIZE) > 0) {
    373            newCapacity = createPositiveCapacity(minCapacity);
    374        }
    375        final byte[] b = Arrays.copyOf(context.buffer, newCapacity);
    376        context.buffer = b;
    377        return b;
    378    }
    379
    380    /**
    381     * Gets the array length or 0 if null.
    382     *
    383     * @param array the array or null.
    384     * @return the array length or 0 if null.
    385     */
    386    static int toLength(final byte[] array) {
    387        return array == null ? 0 : array.length;
    388    }
    389
    390    /**
    391     * Deprecated: Will be removed in 2.0.
    392     * <p>
    393     * Instance variable just in case it needs to vary later
    394     * </p>
    395     *
    396     * @deprecated Use {@link #pad}. Will be removed in 2.0.
    397     */
    398    @Deprecated
    399    protected final byte PAD = PAD_DEFAULT;
    400
    401    /** Pad byte. Instance variable just in case it needs to vary later. */
    402    protected final byte pad;
    403
    404    /** Number of bytes in each full block of unencoded data, for example 4 for Base64 and 5 for Base32 */
    405    private final int unencodedBlockSize;
    406
    407    /** Number of bytes in each full block of encoded data, for example 3 for Base64 and 8 for Base32 */
    408    private final int encodedBlockSize;
    409
    410    /**
    411     * Chunksize for encoding. Not used when decoding.
    412     * A value of zero or less implies no chunking of the encoded data.
    413     * Rounded down to the nearest multiple of encodedBlockSize.
    414     */
    415    protected final int lineLength;
    416
    417    /**
    418     * Size of chunk separator. Not used unless {@link #lineLength} &gt; 0.
    419     */
    420    private final int chunkSeparatorLength;
    421
    422    /**
    423     * Defines the decoding behavior when the input bytes contain leftover trailing bits that
    424     * cannot be created by a valid encoding. These can be bits that are unused from the final
    425     * character or entire characters. The default mode is lenient decoding. Set this to
    426     * {@code true} to enable strict decoding.
    427     * <ul>
    428     * <li>Lenient: Any trailing bits are composed into 8-bit bytes where possible.
    429     *     The remainder are discarded.
    430     * <li>Strict: The decoding will raise an {@link IllegalArgumentException} if trailing bits
    431     *     are not part of a valid encoding. Any unused bits from the final character must
    432     *     be zero. Impossible counts of entire final characters are not allowed.
    433     * </ul>
    434     * <p>
    435     * When strict decoding is enabled it is expected that the decoded bytes will be re-encoded
    436     * to a byte array that matches the original, i.e. no changes occur on the final
    437     * character. This requires that the input bytes use the same padding and alphabet
    438     * as the encoder.
    439     * </p>
    440     */
    441    private final CodecPolicy decodingPolicy;
    442
    443    /**
    444     * Constructs a new instance.
    445     * <p>
    446     * Note {@code lineLength} is rounded down to the nearest multiple of the encoded block size.
    447     * If {@code chunkSeparatorLength} is zero, then chunking is disabled.
    448     * </p>
    449     *
    450     * @param unencodedBlockSize the size of an unencoded block (for example Base64 = 3)
    451     * @param encodedBlockSize the size of an encoded block (for example Base64 = 4)
    452     * @param lineLength if &gt; 0, use chunking with a length {@code lineLength}
    453     * @param chunkSeparatorLength the chunk separator length, if relevant
    454     */
    455    protected BaseNCodec(final int unencodedBlockSize, final int encodedBlockSize, final int lineLength, final int chunkSeparatorLength) {
    456        this(unencodedBlockSize, encodedBlockSize, lineLength, chunkSeparatorLength, PAD_DEFAULT);
    457    }
    458
    459    /**
    460     * Constructs a new instance.
    461     * <p>
    462     * Note {@code lineLength} is rounded down to the nearest multiple of the encoded block size.
    463     * If {@code chunkSeparatorLength} is zero, then chunking is disabled.
    464     * </p>
    465     *
    466     * @param unencodedBlockSize the size of an unencoded block (for example Base64 = 3)
    467     * @param encodedBlockSize the size of an encoded block (for example Base64 = 4)
    468     * @param lineLength if &gt; 0, use chunking with a length {@code lineLength}
    469     * @param chunkSeparatorLength the chunk separator length, if relevant
    470     * @param pad byte used as padding byte.
    471     */
    472    protected BaseNCodec(final int unencodedBlockSize, final int encodedBlockSize, final int lineLength, final int chunkSeparatorLength, final byte pad) {
    473        this(unencodedBlockSize, encodedBlockSize, lineLength, chunkSeparatorLength, pad, DECODING_POLICY_DEFAULT);
    474    }
    475
    476    /**
    477     * Constructs a new instance.
    478     * <p>
    479     * Note {@code lineLength} is rounded down to the nearest multiple of the encoded block size.
    480     * If {@code chunkSeparatorLength} is zero, then chunking is disabled.
    481     * </p>
    482     *
    483     * @param unencodedBlockSize the size of an unencoded block (for example Base64 = 3)
    484     * @param encodedBlockSize the size of an encoded block (for example Base64 = 4)
    485     * @param lineLength if &gt; 0, use chunking with a length {@code lineLength}
    486     * @param chunkSeparatorLength the chunk separator length, if relevant
    487     * @param pad byte used as padding byte.
    488     * @param decodingPolicy Decoding policy.
    489     * @since 1.15
    490     */
    491    protected BaseNCodec(final int unencodedBlockSize, final int encodedBlockSize, final int lineLength, final int chunkSeparatorLength, final byte pad,
    492            final CodecPolicy decodingPolicy) {
    493        this.unencodedBlockSize = unencodedBlockSize;
    494        this.encodedBlockSize = encodedBlockSize;
    495        final boolean useChunking = lineLength > 0 && chunkSeparatorLength > 0;
    496        this.lineLength = useChunking ? lineLength / encodedBlockSize * encodedBlockSize : 0;
    497        this.chunkSeparatorLength = chunkSeparatorLength;
    498        this.pad = pad;
    499        this.decodingPolicy = Objects.requireNonNull(decodingPolicy, "codecPolicy");
    500    }
    501
    502    /**
    503     * Returns the amount of buffered data available for reading.
    504     *
    505     * @param context the context to be used
    506     * @return The amount of buffered data available for reading.
    507     */
    508    int available(final Context context) {  // package protected for access from I/O streams
    509        return hasData(context) ? context.pos - context.readPos : 0;
    510    }
    511
    512    /**
    513     * Tests a given byte array to see if it contains any characters within the alphabet or PAD.
    514     *
    515     * Intended for use in checking line-ending arrays
    516     *
    517     * @param arrayOctet
    518     *            byte array to test
    519     * @return {@code true} if any byte is a valid character in the alphabet or PAD; {@code false} otherwise
    520     */
    521    protected boolean containsAlphabetOrPad(final byte[] arrayOctet) {
    522        if (arrayOctet != null) {
    523            for (final byte element : arrayOctet) {
    524                if (pad == element || isInAlphabet(element)) {
    525                    return true;
    526                }
    527            }
    528        }
    529        return false;
    530    }
    531
    532    /**
    533     * Decodes a byte[] containing characters in the Base-N alphabet.
    534     *
    535     * @param array
    536     *            A byte array containing Base-N character data
    537     * @return a byte array containing binary data
    538     */
    539    @Override
    540    public byte[] decode(final byte[] array) {
    541        if (BinaryCodec.isEmpty(array)) {
    542            return array;
    543        }
    544        final Context context = new Context();
    545        decode(array, 0, array.length, context);
    546        decode(array, 0, EOF, context); // Notify decoder of EOF.
    547        final byte[] result = new byte[context.pos];
    548        readResults(result, 0, result.length, context);
    549        return result;
    550    }
    551
    552    // package protected for access from I/O streams
    553    abstract void decode(byte[] array, int i, int length, Context context);
    554
    555    /**
    556     * Decodes an Object using the Base-N algorithm. This method is provided in order to satisfy the requirements of
    557     * the Decoder interface, and will throw a DecoderException if the supplied object is not of type byte[] or String.
    558     *
    559     * @param obj
    560     *            Object to decode
    561     * @return An object (of type byte[]) containing the binary data which corresponds to the byte[] or String
    562     *         supplied.
    563     * @throws DecoderException
    564     *             if the parameter supplied is not of type byte[]
    565     */
    566    @Override
    567    public Object decode(final Object obj) throws DecoderException {
    568        if (obj instanceof byte[]) {
    569            return decode((byte[]) obj);
    570        }
    571        if (obj instanceof String) {
    572            return decode((String) obj);
    573        }
    574        throw new DecoderException("Parameter supplied to Base-N decode is not a byte[] or a String");
    575    }
    576
    577    /**
    578     * Decodes a String containing characters in the Base-N alphabet.
    579     *
    580     * @param array
    581     *            A String containing Base-N character data
    582     * @return a byte array containing binary data
    583     */
    584    public byte[] decode(final String array) {
    585        return decode(StringUtils.getBytesUtf8(array));
    586    }
    587
    588    /**
    589     * Encodes a byte[] containing binary data, into a byte[] containing characters in the alphabet.
    590     *
    591     * @param array
    592     *            a byte array containing binary data
    593     * @return A byte array containing only the base N alphabetic character data
    594     */
    595    @Override
    596    public byte[] encode(final byte[] array) {
    597        if (BinaryCodec.isEmpty(array)) {
    598            return array;
    599        }
    600        return encode(array, 0, array.length);
    601    }
    602
    603    /**
    604     * Encodes a byte[] containing binary data, into a byte[] containing
    605     * characters in the alphabet.
    606     *
    607     * @param array
    608     *            a byte array containing binary data
    609     * @param offset
    610     *            initial offset of the subarray.
    611     * @param length
    612     *            length of the subarray.
    613     * @return A byte array containing only the base N alphabetic character data
    614     * @since 1.11
    615     */
    616    public byte[] encode(final byte[] array, final int offset, final int length) {
    617        if (BinaryCodec.isEmpty(array)) {
    618            return array;
    619        }
    620        final Context context = new Context();
    621        encode(array, offset, length, context);
    622        encode(array, offset, EOF, context); // Notify encoder of EOF.
    623        final byte[] buf = new byte[context.pos - context.readPos];
    624        readResults(buf, 0, buf.length, context);
    625        return buf;
    626    }
    627
    628    // package protected for access from I/O streams
    629    abstract void encode(byte[] array, int i, int length, Context context);
    630
    631    /**
    632     * Encodes an Object using the Base-N algorithm. This method is provided in order to satisfy the requirements of
    633     * the Encoder interface, and will throw an EncoderException if the supplied object is not of type byte[].
    634     *
    635     * @param obj
    636     *            Object to encode
    637     * @return An object (of type byte[]) containing the Base-N encoded data which corresponds to the byte[] supplied.
    638     * @throws EncoderException
    639     *             if the parameter supplied is not of type byte[]
    640     */
    641    @Override
    642    public Object encode(final Object obj) throws EncoderException {
    643        if (!(obj instanceof byte[])) {
    644            throw new EncoderException("Parameter supplied to Base-N encode is not a byte[]");
    645        }
    646        return encode((byte[]) obj);
    647    }
    648
    649    /**
    650     * Encodes a byte[] containing binary data, into a String containing characters in the appropriate alphabet.
    651     * Uses UTF8 encoding.
    652     * <p>
    653     * This is a duplicate of {@link #encodeToString(byte[])}; it was merged during refactoring.
    654     * </p>
    655     *
    656     * @param array a byte array containing binary data
    657     * @return String containing only character data in the appropriate alphabet.
    658     * @since 1.5
    659    */
    660    public String encodeAsString(final byte[] array) {
    661        return StringUtils.newStringUtf8(encode(array));
    662    }
    663
    664    /**
    665     * Encodes a byte[] containing binary data, into a String containing characters in the Base-N alphabet.
    666     * Uses UTF8 encoding.
    667     *
    668     * @param array
    669     *            a byte array containing binary data
    670     * @return A String containing only Base-N character data
    671     */
    672    public String encodeToString(final byte[] array) {
    673        return StringUtils.newStringUtf8(encode(array));
    674    }
    675
    676    /**
    677     * Ensures that the buffer has room for {@code size} bytes
    678     *
    679     * @param size minimum spare space required
    680     * @param context the context to be used
    681     * @return the buffer
    682     */
    683    protected byte[] ensureBufferSize(final int size, final Context context) {
    684        if (context.buffer == null) {
    685            context.buffer = new byte[Math.max(size, getDefaultBufferSize())];
    686            context.pos = 0;
    687            context.readPos = 0;
    688            // Overflow-conscious:
    689            // x + y > z == x + y - z > 0
    690        } else if (context.pos + size - context.buffer.length > 0) {
    691            return resizeBuffer(context, context.pos + size);
    692        }
    693        return context.buffer;
    694    }
    695
    696    /**
    697     * Gets the decoding behavior policy.
    698     *
    699     * <p>
    700     * The default is lenient. If the decoding policy is strict, then decoding will raise an
    701     * {@link IllegalArgumentException} if trailing bits are not part of a valid encoding. Decoding will compose
    702     * trailing bits into 8-bit bytes and discard the remainder.
    703     * </p>
    704     *
    705     * @return true if using strict decoding
    706     * @since 1.15
    707     */
    708    public CodecPolicy getCodecPolicy() {
    709        return decodingPolicy;
    710    }
    711
    712    /**
    713     * Gets the default buffer size. Can be overridden.
    714     *
    715     * @return the default buffer size.
    716     */
    717    protected int getDefaultBufferSize() {
    718        return DEFAULT_BUFFER_SIZE;
    719    }
    720
    721    /**
    722     * Gets the amount of space needed to encode the supplied array.
    723     *
    724     * @param array byte[] array which will later be encoded
    725     * @return amount of space needed to encode the supplied array.
    726     * Returns a long since a max-len array will require &gt; Integer.MAX_VALUE
    727     */
    728    public long getEncodedLength(final byte[] array) {
    729        // Calculate non-chunked size - rounded up to allow for padding
    730        // cast to long is needed to avoid possibility of overflow
    731        long len = (array.length + unencodedBlockSize - 1) / unencodedBlockSize * (long) encodedBlockSize;
    732        if (lineLength > 0) { // We're using chunking
    733            // Round up to nearest multiple
    734            len += (len + lineLength - 1) / lineLength * chunkSeparatorLength;
    735        }
    736        return len;
    737    }
    738
    739    /**
    740     * Tests whether this object has buffered data for reading.
    741     *
    742     * @param context the context to be used
    743     * @return true if there is data still available for reading.
    744     */
    745    boolean hasData(final Context context) {  // package protected for access from I/O streams
    746        return context.pos > context.readPos;
    747    }
    748
    749    /**
    750     * Tests whether or not the {@code octet} is in the current alphabet.
    751     * Does not allow whitespace or pad.
    752     *
    753     * @param value The value to test
    754     * @return {@code true} if the value is defined in the current alphabet, {@code false} otherwise.
    755     */
    756    protected abstract boolean isInAlphabet(byte value);
    757
    758    /**
    759     * Tests a given byte array to see if it contains only valid characters within the alphabet.
    760     * The method optionally treats whitespace and pad as valid.
    761     *
    762     * @param arrayOctet byte array to test
    763     * @param allowWSPad if {@code true}, then whitespace and PAD are also allowed
    764     * @return {@code true} if all bytes are valid characters in the alphabet or if the byte array is empty;
    765     *         {@code false}, otherwise
    766     */
    767    public boolean isInAlphabet(final byte[] arrayOctet, final boolean allowWSPad) {
    768        for (final byte octet : arrayOctet) {
    769            if (!isInAlphabet(octet) && (!allowWSPad || octet != pad && !Character.isWhitespace(octet))) {
    770                return false;
    771            }
    772        }
    773        return true;
    774    }
    775
    776    /**
    777     * Tests a given String to see if it contains only valid characters within the alphabet.
    778     * The method treats whitespace and PAD as valid.
    779     *
    780     * @param basen String to test
    781     * @return {@code true} if all characters in the String are valid characters in the alphabet or if
    782     *         the String is empty; {@code false}, otherwise
    783     * @see #isInAlphabet(byte[], boolean)
    784     */
    785    public boolean isInAlphabet(final String basen) {
    786        return isInAlphabet(StringUtils.getBytesUtf8(basen), true);
    787    }
    788
    789    /**
    790     * Tests true if decoding behavior is strict. Decoding will raise an {@link IllegalArgumentException} if trailing
    791     * bits are not part of a valid encoding.
    792     *
    793     * <p>
    794     * The default is false for lenient decoding. Decoding will compose trailing bits into 8-bit bytes and discard the
    795     * remainder.
    796     * </p>
    797     *
    798     * @return true if using strict decoding
    799     * @since 1.15
    800     */
    801    public boolean isStrictDecoding() {
    802        return decodingPolicy == CodecPolicy.STRICT;
    803    }
    804
    805    /**
    806     * Reads buffered data into the provided byte[] array, starting at position bPos, up to a maximum of bAvail
    807     * bytes. Returns how many bytes were actually extracted.
    808     * <p>
    809     * Package private for access from I/O streams.
    810     * </p>
    811     *
    812     * @param b
    813     *            byte[] array to extract the buffered data into.
    814     * @param bPos
    815     *            position in byte[] array to start extraction at.
    816     * @param bAvail
    817     *            amount of bytes we're allowed to extract. We may extract fewer (if fewer are available).
    818     * @param context
    819     *            the context to be used
    820     * @return The number of bytes successfully extracted into the provided byte[] array.
    821     */
    822    int readResults(final byte[] b, final int bPos, final int bAvail, final Context context) {
    823        if (hasData(context)) {
    824            final int len = Math.min(available(context), bAvail);
    825            System.arraycopy(context.buffer, context.readPos, b, bPos, len);
    826            context.readPos += len;
    827            if (!hasData(context)) {
    828                // All data read.
    829                // Reset position markers but do not set buffer to null to allow its reuse.
    830                // hasData(context) will still return false, and this method will return 0 until
    831                // more data is available, or -1 if EOF.
    832                context.pos = context.readPos = 0;
    833            }
    834            return len;
    835        }
    836        return context.eof ? EOF : 0;
    837    }
    838}