    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 : 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 : 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     * EOF
    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     * @since 1.15
    297     */
    298    protected static final CodecPolicy DECODING_POLICY_DEFAULT = CodecPolicy.LENIENT;
    299
    300    /**
    301     * Chunk separator per RFC 2045 section 2.1.
    302     *
    303     * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 2.1</a>
    304     */
    305    static final byte[] CHUNK_SEPARATOR = {'\r', '\n'};
    306
    307    /**
    308     * Create a positive capacity at least as large the minimum required capacity.
    309     * If the minimum capacity is negative then this throws an OutOfMemoryError as no array
    310     * can be allocated.
    311     *
    312     * @param minCapacity the minimum capacity
    313     * @return the capacity
    314     * @throws OutOfMemoryError if the {@code minCapacity} is negative
    315     */
    316    private static int createPositiveCapacity(final int minCapacity) {
    317        if (minCapacity < 0) {
    318            // overflow
    319            throw new OutOfMemoryError("Unable to allocate array size: " + (minCapacity & 0xffffffffL));
    320        }
    321        // This is called when we require buffer expansion to a very big array.
    322        // Use the conservative maximum buffer size if possible, otherwise the biggest required.
    323        //
    324        // Note: In this situation JDK 1.8 java.util.ArrayList returns Integer.MAX_VALUE.
    325        // This excludes some VMs that can exceed MAX_BUFFER_SIZE but not allocate a full
    326        // Integer.MAX_VALUE length array.
    327        // The result is that we may have to allocate an array of this size more than once if
    328        // the capacity must be expanded again.
    329        return Math.max(minCapacity, MAX_BUFFER_SIZE);
    330    }
    331
    332    /**
    333     * Gets a copy of the chunk separator per RFC 2045 section 2.1.
    334     *
    335     * @return the chunk separator
    336     * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 2.1</a>
    337     * @since 1.15
    338     */
    339    public static byte[] getChunkSeparator() {
    340        return CHUNK_SEPARATOR.clone();
    341    }
    342
    343    /**
    344     * Checks if a byte value is whitespace or not.
    345     * @param byteToCheck
    346     *            the byte to check
    347     * @return true if byte is whitespace, false otherwise
    348     * @see Character#isWhitespace(int)
    349     * @deprecated Use {@link Character#isWhitespace(int)}.
    350     */
    351    @Deprecated
    352    protected static boolean isWhiteSpace(final byte byteToCheck) {
    353        return Character.isWhitespace(byteToCheck);
    354    }
    355
    356    /**
    357     * Increases our buffer by the {@link #DEFAULT_BUFFER_RESIZE_FACTOR}.
    358     * @param context the context to be used
    359     * @param minCapacity the minimum required capacity
    360     * @return the resized byte[] buffer
    361     * @throws OutOfMemoryError if the {@code minCapacity} is negative
    362     */
    363    private static byte[] resizeBuffer(final Context context, final int minCapacity) {
    364        // Overflow-conscious code treats the min and new capacity as unsigned.
    365        final int oldCapacity = context.buffer.length;
    366        int newCapacity = oldCapacity * DEFAULT_BUFFER_RESIZE_FACTOR;
    367        if (Integer.compareUnsigned(newCapacity, minCapacity) < 0) {
    368            newCapacity = minCapacity;
    369        }
    370        if (Integer.compareUnsigned(newCapacity, MAX_BUFFER_SIZE) > 0) {
    371            newCapacity = createPositiveCapacity(minCapacity);
    372        }
    373        final byte[] b = Arrays.copyOf(context.buffer, newCapacity);
    374        context.buffer = b;
    375        return b;
    376    }
    377
    378    /**
    379     * Gets the array length or 0 if null.
    380     *
    381     * @param array the array or null.
    382     * @return the array length or 0 if null.
    383     */
    384    static int toLength(final byte[] array) {
    385        return array == null ? 0 : array.length;
    386    }
    387
    388    /**
    389     * @deprecated Use {@link #pad}. Will be removed in 2.0.
    390     */
    391    @Deprecated
    392    protected final byte PAD = PAD_DEFAULT; // instance variable just in case it needs to vary later
    393
    394    /** Pad byte. Instance variable just in case it needs to vary later. */
    395    protected final byte pad;
    396
    397    /** Number of bytes in each full block of unencoded data, for example 4 for Base64 and 5 for Base32 */
    398    private final int unencodedBlockSize;
    399
    400    /** Number of bytes in each full block of encoded data, for example 3 for Base64 and 8 for Base32 */
    401    private final int encodedBlockSize;
    402
    403    /**
    404     * Chunksize for encoding. Not used when decoding.
    405     * A value of zero or less implies no chunking of the encoded data.
    406     * Rounded down to the nearest multiple of encodedBlockSize.
    407     */
    408    protected final int lineLength;
    409
    410    /**
    411     * Size of chunk separator. Not used unless {@link #lineLength} &gt; 0.
    412     */
    413    private final int chunkSeparatorLength;
    414
    415    /**
    416     * Defines the decoding behavior when the input bytes contain leftover trailing bits that
    417     * cannot be created by a valid encoding. These can be bits that are unused from the final
    418     * character or entire characters. The default mode is lenient decoding. Set this to
    419     * {@code true} to enable strict decoding.
    420     * <ul>
    421     * <li>Lenient: Any trailing bits are composed into 8-bit bytes where possible.
    422     *     The remainder are discarded.
    423     * <li>Strict: The decoding will raise an {@link IllegalArgumentException} if trailing bits
    424     *     are not part of a valid encoding. Any unused bits from the final character must
    425     *     be zero. Impossible counts of entire final characters are not allowed.
    426     * </ul>
    427     * <p>
    428     * When strict decoding is enabled it is expected that the decoded bytes will be re-encoded
    429     * to a byte array that matches the original, i.e. no changes occur on the final
    430     * character. This requires that the input bytes use the same padding and alphabet
    431     * as the encoder.
    432     * </p>
    433     */
    434    private final CodecPolicy decodingPolicy;
    435
    436    /**
    437     * Constructs a new instance.
    438     * <p>
    439     * Note {@code lineLength} is rounded down to the nearest multiple of the encoded block size.
    440     * If {@code chunkSeparatorLength} is zero, then chunking is disabled.
    441     * </p>
    442     *
    443     * @param unencodedBlockSize the size of an unencoded block (for example Base64 = 3)
    444     * @param encodedBlockSize the size of an encoded block (for example Base64 = 4)
    445     * @param lineLength if &gt; 0, use chunking with a length {@code lineLength}
    446     * @param chunkSeparatorLength the chunk separator length, if relevant
    447     */
    448    protected BaseNCodec(final int unencodedBlockSize, final int encodedBlockSize, final int lineLength, final int chunkSeparatorLength) {
    449        this(unencodedBlockSize, encodedBlockSize, lineLength, chunkSeparatorLength, PAD_DEFAULT);
    450    }
    451
    452    /**
    453     * Constructs a new instance.
    454     * <p>
    455     * Note {@code lineLength} is rounded down to the nearest multiple of the encoded block size.
    456     * If {@code chunkSeparatorLength} is zero, then chunking is disabled.
    457     * </p>
    458     *
    459     * @param unencodedBlockSize the size of an unencoded block (for example Base64 = 3)
    460     * @param encodedBlockSize the size of an encoded block (for example Base64 = 4)
    461     * @param lineLength if &gt; 0, use chunking with a length {@code lineLength}
    462     * @param chunkSeparatorLength the chunk separator length, if relevant
    463     * @param pad byte used as padding byte.
    464     */
    465    protected BaseNCodec(final int unencodedBlockSize, final int encodedBlockSize, final int lineLength, final int chunkSeparatorLength, final byte pad) {
    466        this(unencodedBlockSize, encodedBlockSize, lineLength, chunkSeparatorLength, pad, DECODING_POLICY_DEFAULT);
    467    }
    468
    469    /**
    470     * Constructs a new instance.
    471     * <p>
    472     * Note {@code lineLength} is rounded down to the nearest multiple of the encoded block size.
    473     * If {@code chunkSeparatorLength} is zero, then chunking is disabled.
    474     * </p>
    475     *
    476     * @param unencodedBlockSize the size of an unencoded block (for example Base64 = 3)
    477     * @param encodedBlockSize the size of an encoded block (for example Base64 = 4)
    478     * @param lineLength if &gt; 0, use chunking with a length {@code lineLength}
    479     * @param chunkSeparatorLength the chunk separator length, if relevant
    480     * @param pad byte used as padding byte.
    481     * @param decodingPolicy Decoding policy.
    482     * @since 1.15
    483     */
    484    protected BaseNCodec(final int unencodedBlockSize, final int encodedBlockSize, final int lineLength, final int chunkSeparatorLength, final byte pad,
    485            final CodecPolicy decodingPolicy) {
    486        this.unencodedBlockSize = unencodedBlockSize;
    487        this.encodedBlockSize = encodedBlockSize;
    488        final boolean useChunking = lineLength > 0 && chunkSeparatorLength > 0;
    489        this.lineLength = useChunking ? lineLength / encodedBlockSize * encodedBlockSize : 0;
    490        this.chunkSeparatorLength = chunkSeparatorLength;
    491        this.pad = pad;
    492        this.decodingPolicy = Objects.requireNonNull(decodingPolicy, "codecPolicy");
    493    }
    494
    495    /**
    496     * Returns the amount of buffered data available for reading.
    497     *
    498     * @param context the context to be used
    499     * @return The amount of buffered data available for reading.
    500     */
    501    int available(final Context context) {  // package protected for access from I/O streams
    502        return hasData(context) ? context.pos - context.readPos : 0;
    503    }
    504
    505    /**
    506     * Tests a given byte array to see if it contains any characters within the alphabet or PAD.
    507     *
    508     * Intended for use in checking line-ending arrays
    509     *
    510     * @param arrayOctet
    511     *            byte array to test
    512     * @return {@code true} if any byte is a valid character in the alphabet or PAD; {@code false} otherwise
    513     */
    514    protected boolean containsAlphabetOrPad(final byte[] arrayOctet) {
    515        if (arrayOctet != null) {
    516            for (final byte element : arrayOctet) {
    517                if (pad == element || isInAlphabet(element)) {
    518                    return true;
    519                }
    520            }
    521        }
    522        return false;
    523    }
    524
    525    /**
    526     * Decodes a byte[] containing characters in the Base-N alphabet.
    527     *
    528     * @param pArray
    529     *            A byte array containing Base-N character data
    530     * @return a byte array containing binary data
    531     */
    532    @Override
    533    public byte[] decode(final byte[] pArray) {
    534        if (BinaryCodec.isEmpty(pArray)) {
    535            return pArray;
    536        }
    537        final Context context = new Context();
    538        decode(pArray, 0, pArray.length, context);
    539        decode(pArray, 0, EOF, context); // Notify decoder of EOF.
    540        final byte[] result = new byte[context.pos];
    541        readResults(result, 0, result.length, context);
    542        return result;
    543    }
    544
    545    // package protected for access from I/O streams
    546    abstract void decode(byte[] pArray, int i, int length, Context context);
    547
    548    /**
    549     * Decodes an Object using the Base-N algorithm. This method is provided in order to satisfy the requirements of
    550     * the Decoder interface, and will throw a DecoderException if the supplied object is not of type byte[] or String.
    551     *
    552     * @param obj
    553     *            Object to decode
    554     * @return An object (of type byte[]) containing the binary data which corresponds to the byte[] or String
    555     *         supplied.
    556     * @throws DecoderException
    557     *             if the parameter supplied is not of type byte[]
    558     */
    559    @Override
    560    public Object decode(final Object obj) throws DecoderException {
    561        if (obj instanceof byte[]) {
    562            return decode((byte[]) obj);
    563        }
    564        if (obj instanceof String) {
    565            return decode((String) obj);
    566        }
    567        throw new DecoderException("Parameter supplied to Base-N decode is not a byte[] or a String");
    568    }
    569
    570    /**
    571     * Decodes a String containing characters in the Base-N alphabet.
    572     *
    573     * @param pArray
    574     *            A String containing Base-N character data
    575     * @return a byte array containing binary data
    576     */
    577    public byte[] decode(final String pArray) {
    578        return decode(StringUtils.getBytesUtf8(pArray));
    579    }
    580
    581    /**
    582     * Encodes a byte[] containing binary data, into a byte[] containing characters in the alphabet.
    583     *
    584     * @param pArray
    585     *            a byte array containing binary data
    586     * @return A byte array containing only the base N alphabetic character data
    587     */
    588    @Override
    589    public byte[] encode(final byte[] pArray) {
    590        if (BinaryCodec.isEmpty(pArray)) {
    591            return pArray;
    592        }
    593        return encode(pArray, 0, pArray.length);
    594    }
    595
    596    /**
    597     * Encodes a byte[] containing binary data, into a byte[] containing
    598     * characters in the alphabet.
    599     *
    600     * @param pArray
    601     *            a byte array containing binary data
    602     * @param offset
    603     *            initial offset of the subarray.
    604     * @param length
    605     *            length of the subarray.
    606     * @return A byte array containing only the base N alphabetic character data
    607     * @since 1.11
    608     */
    609    public byte[] encode(final byte[] pArray, final int offset, final int length) {
    610        if (BinaryCodec.isEmpty(pArray)) {
    611            return pArray;
    612        }
    613        final Context context = new Context();
    614        encode(pArray, offset, length, context);
    615        encode(pArray, offset, EOF, context); // Notify encoder of EOF.
    616        final byte[] buf = new byte[context.pos - context.readPos];
    617        readResults(buf, 0, buf.length, context);
    618        return buf;
    619    }
    620
    621    // package protected for access from I/O streams
    622    abstract void encode(byte[] pArray, int i, int length, Context context);
    623
    624    /**
    625     * Encodes an Object using the Base-N algorithm. This method is provided in order to satisfy the requirements of
    626     * the Encoder interface, and will throw an EncoderException if the supplied object is not of type byte[].
    627     *
    628     * @param obj
    629     *            Object to encode
    630     * @return An object (of type byte[]) containing the Base-N encoded data which corresponds to the byte[] supplied.
    631     * @throws EncoderException
    632     *             if the parameter supplied is not of type byte[]
    633     */
    634    @Override
    635    public Object encode(final Object obj) throws EncoderException {
    636        if (!(obj instanceof byte[])) {
    637            throw new EncoderException("Parameter supplied to Base-N encode is not a byte[]");
    638        }
    639        return encode((byte[]) obj);
    640    }
    641
    642    /**
    643     * Encodes a byte[] containing binary data, into a String containing characters in the appropriate alphabet.
    644     * Uses UTF8 encoding.
    645     * <p>
    646     * This is a duplicate of {@link #encodeToString(byte[])}; it was merged during refactoring.
    647     * </p>
    648     *
    649     * @param pArray a byte array containing binary data
    650     * @return String containing only character data in the appropriate alphabet.
    651     * @since 1.5
    652    */
    653    public String encodeAsString(final byte[] pArray) {
    654        return StringUtils.newStringUtf8(encode(pArray));
    655    }
    656
    657    /**
    658     * Encodes a byte[] containing binary data, into a String containing characters in the Base-N alphabet.
    659     * Uses UTF8 encoding.
    660     *
    661     * @param pArray
    662     *            a byte array containing binary data
    663     * @return A String containing only Base-N character data
    664     */
    665    public String encodeToString(final byte[] pArray) {
    666        return StringUtils.newStringUtf8(encode(pArray));
    667    }
    668
    669    /**
    670     * Ensure that the buffer has room for {@code size} bytes
    671     *
    672     * @param size minimum spare space required
    673     * @param context the context to be used
    674     * @return the buffer
    675     */
    676    protected byte[] ensureBufferSize(final int size, final Context context) {
    677        if (context.buffer == null) {
    678            context.buffer = new byte[Math.max(size, getDefaultBufferSize())];
    679            context.pos = 0;
    680            context.readPos = 0;
    681            // Overflow-conscious:
    682            // x + y > z == x + y - z > 0
    683        } else if (context.pos + size - context.buffer.length > 0) {
    684            return resizeBuffer(context, context.pos + size);
    685        }
    686        return context.buffer;
    687    }
    688
    689    /**
    690     * Returns the decoding behavior policy.
    691     *
    692     * <p>
    693     * The default is lenient. If the decoding policy is strict, then decoding will raise an
    694     * {@link IllegalArgumentException} if trailing bits are not part of a valid encoding. Decoding will compose
    695     * trailing bits into 8-bit bytes and discard the remainder.
    696     * </p>
    697     *
    698     * @return true if using strict decoding
    699     * @since 1.15
    700     */
    701    public CodecPolicy getCodecPolicy() {
    702        return decodingPolicy;
    703    }
    704
    705    /**
    706     * Gets the default buffer size. Can be overridden.
    707     *
    708     * @return the default buffer size.
    709     */
    710    protected int getDefaultBufferSize() {
    711        return DEFAULT_BUFFER_SIZE;
    712    }
    713
    714    /**
    715     * Calculates the amount of space needed to encode the supplied array.
    716     *
    717     * @param pArray byte[] array which will later be encoded
    718     * @return amount of space needed to encode the supplied array.
    719     * Returns a long since a max-len array will require &gt; Integer.MAX_VALUE
    720     */
    721    public long getEncodedLength(final byte[] pArray) {
    722        // Calculate non-chunked size - rounded up to allow for padding
    723        // cast to long is needed to avoid possibility of overflow
    724        long len = (pArray.length + unencodedBlockSize - 1) / unencodedBlockSize * (long) encodedBlockSize;
    725        if (lineLength > 0) { // We're using chunking
    726            // Round up to nearest multiple
    727            len += (len + lineLength - 1) / lineLength * chunkSeparatorLength;
    728        }
    729        return len;
    730    }
    731
    732    /**
    733     * Returns true if this object has buffered data for reading.
    734     *
    735     * @param context the context to be used
    736     * @return true if there is data still available for reading.
    737     */
    738    boolean hasData(final Context context) {  // package protected for access from I/O streams
    739        return context.pos > context.readPos;
    740    }
    741
    742    /**
    743     * Returns whether or not the {@code octet} is in the current alphabet.
    744     * Does not allow whitespace or pad.
    745     *
    746     * @param value The value to test
    747     * @return {@code true} if the value is defined in the current alphabet, {@code false} otherwise.
    748     */
    749    protected abstract boolean isInAlphabet(byte value);
    750
    751    /**
    752     * Tests a given byte array to see if it contains only valid characters within the alphabet.
    753     * The method optionally treats whitespace and pad as valid.
    754     *
    755     * @param arrayOctet byte array to test
    756     * @param allowWSPad if {@code true}, then whitespace and PAD are also allowed
    757     * @return {@code true} if all bytes are valid characters in the alphabet or if the byte array is empty;
    758     *         {@code false}, otherwise
    759     */
    760    public boolean isInAlphabet(final byte[] arrayOctet, final boolean allowWSPad) {
    761        for (final byte octet : arrayOctet) {
    762            if (!isInAlphabet(octet) && (!allowWSPad || octet != pad && !Character.isWhitespace(octet))) {
    763                return false;
    764            }
    765        }
    766        return true;
    767    }
    768
    769    /**
    770     * Tests a given String to see if it contains only valid characters within the alphabet.
    771     * The method treats whitespace and PAD as valid.
    772     *
    773     * @param basen String to test
    774     * @return {@code true} if all characters in the String are valid characters in the alphabet or if
    775     *         the String is empty; {@code false}, otherwise
    776     * @see #isInAlphabet(byte[], boolean)
    777     */
    778    public boolean isInAlphabet(final String basen) {
    779        return isInAlphabet(StringUtils.getBytesUtf8(basen), true);
    780    }
    781
    782    /**
    783     * Returns true if decoding behavior is strict. Decoding will raise an {@link IllegalArgumentException} if trailing
    784     * bits are not part of a valid encoding.
    785     *
    786     * <p>
    787     * The default is false for lenient decoding. Decoding will compose trailing bits into 8-bit bytes and discard the
    788     * remainder.
    789     * </p>
    790     *
    791     * @return true if using strict decoding
    792     * @since 1.15
    793     */
    794    public boolean isStrictDecoding() {
    795        return decodingPolicy == CodecPolicy.STRICT;
    796    }
    797
    798    /**
    799     * Extracts buffered data into the provided byte[] array, starting at position bPos, up to a maximum of bAvail
    800     * bytes. Returns how many bytes were actually extracted.
    801     * <p>
    802     * Package private for access from I/O streams.
    803     * </p>
    804     *
    805     * @param b
    806     *            byte[] array to extract the buffered data into.
    807     * @param bPos
    808     *            position in byte[] array to start extraction at.
    809     * @param bAvail
    810     *            amount of bytes we're allowed to extract. We may extract fewer (if fewer are available).
    811     * @param context
    812     *            the context to be used
    813     * @return The number of bytes successfully extracted into the provided byte[] array.
    814     */
    815    int readResults(final byte[] b, final int bPos, final int bAvail, final Context context) {
    816        if (hasData(context)) {
    817            final int len = Math.min(available(context), bAvail);
    818            System.arraycopy(context.buffer, context.readPos, b, bPos, len);
    819            context.readPos += len;
    820            if (!hasData(context)) {
    821                // All data read.
    822                // Reset position markers but do not set buffer to null to allow its reuse.
    823                // hasData(context) will still return false, and this method will return 0 until
    824                // more data is available, or -1 if EOF.
    825                context.pos = context.readPos = 0;
    826            }
    827            return len;
    828        }
    829        return context.eof ? EOF : 0;
    830    }
    831}