    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 */
    017package org.apache.commons.io.input;
    018
    019import static org.apache.commons.io.IOUtils.EOF;
    020
    021import java.io.IOException;
    022import java.io.InputStream;
    023import java.util.Arrays;
    024import java.util.Comparator;
    025import java.util.List;
    026import java.util.Objects;
    027
    028import org.apache.commons.io.ByteOrderMark;
    029import org.apache.commons.io.IOUtils;
    030
    031/**
    032 * This class is used to wrap a stream that includes an encoded {@link ByteOrderMark} as its first bytes.
    033 * <p>
    034 * This class detects these bytes and, if required, can automatically skip them and return the subsequent byte as the
    035 * first byte in the stream.
    036 * </p>
    037 * <p>
    038 * The {@link ByteOrderMark} implementation has the following predefined BOMs:
    039 * </p>
    040 * <ul>
    041 * <li>UTF-8 - {@link ByteOrderMark#UTF_8}</li>
    042 * <li>UTF-16BE - {@link ByteOrderMark#UTF_16LE}</li>
    043 * <li>UTF-16LE - {@link ByteOrderMark#UTF_16BE}</li>
    044 * <li>UTF-32BE - {@link ByteOrderMark#UTF_32LE}</li>
    045 * <li>UTF-32LE - {@link ByteOrderMark#UTF_32BE}</li>
    046 * </ul>
    047 * <p>
    048 * To build an instance, use {@link Builder}.
    049 * </p>
    050 * <h2>Example 1 - Detecting and excluding a UTF-8 BOM</h2>
    051 *
    052 * <pre>
    053 * BOMInputStream bomIn = BOMInputStream.builder().setInputStream(in).get();
    054 * if (bomIn.hasBOM()) {
    055 *     // has a UTF-8 BOM
    056 * }
    057 * </pre>
    058 *
    059 * <h2>Example 2 - Detecting a UTF-8 BOM without excluding it</h2>
    060 *
    061 * <pre>
    062 * boolean include = true;
    063 * BOMInputStream bomIn = BOMInputStream.builder()
    064 *     .setInputStream(in)
    065 *     .setInclude(include)
    066 *     .get();
    067 * if (bomIn.hasBOM()) {
    068 *     // has a UTF-8 BOM
    069 * }
    070 * </pre>
    071 *
    072 * <h2>Example 3 - Detecting Multiple BOMs</h2>
    073 *
    074 * <pre>
    075 * BOMInputStream bomIn = BOMInputStream.builder()
    076 *   .setInputStream(in)
    077 *   .setByteOrderMarks(ByteOrderMark.UTF_16LE, ByteOrderMark.UTF_16BE, ByteOrderMark.UTF_32LE, ByteOrderMark.UTF_32BE)
    078 *   .get();
    079 * if (bomIn.hasBOM() == false) {
    080 *     // No BOM found
    081 * } else if (bomIn.hasBOM(ByteOrderMark.UTF_16LE)) {
    082 *     // has a UTF-16LE BOM
    083 * } else if (bomIn.hasBOM(ByteOrderMark.UTF_16BE)) {
    084 *     // has a UTF-16BE BOM
    085 * } else if (bomIn.hasBOM(ByteOrderMark.UTF_32LE)) {
    086 *     // has a UTF-32LE BOM
    087 * } else if (bomIn.hasBOM(ByteOrderMark.UTF_32BE)) {
    088 *     // has a UTF-32BE BOM
    089 * }
    090 * </pre>
    091 * <p>
    092 * To build an instance, use {@link Builder}.
    093 * </p>
    094 *
    095 * @see Builder
    096 * @see org.apache.commons.io.ByteOrderMark
    097 * @see <a href="https://en.wikipedia.org/wiki/Byte_order_mark">Wikipedia - Byte Order Mark</a>
    098 * @since 2.0
    099 */
    100public class BOMInputStream extends ProxyInputStream {
    101
    102    // @formatter:off
    103    /**
    104     * Builds a new {@link BOMInputStream}.
    105     *
    106     * <h2>Using NIO</h2>
    107     * <pre>{@code
    108     * BOMInputStream s = BOMInputStream.builder()
    109     *   .setPath(Paths.get("MyFile.xml"))
    110     *   .setByteOrderMarks(ByteOrderMark.UTF_8)
    111     *   .setInclude(false)
    112     *   .get();}
    113     * </pre>
    114     * <h2>Using IO</h2>
    115     * <pre>{@code
    116     * BOMInputStream s = BOMInputStream.builder()
    117     *   .setFile(new File("MyFile.xml"))
    118     *   .setByteOrderMarks(ByteOrderMark.UTF_8)
    119     *   .setInclude(false)
    120     *   .get();}
    121     * </pre>
    122     *
    123     * @see #get()
    124     * @since 2.12.0
    125     */
    126    // @formatter:on
    127    public static class Builder extends AbstractBuilder<BOMInputStream, Builder> {
    128
    129        private static final ByteOrderMark[] DEFAULT = { ByteOrderMark.UTF_8 };
    130
    131        /**
    132         * For test access.
    133         *
    134         * @return the default byte order mark
    135         */
    136        static ByteOrderMark getDefaultByteOrderMark() {
    137            return DEFAULT[0];
    138        }
    139
    140        private ByteOrderMark[] byteOrderMarks = DEFAULT;
    141
    142        private boolean include;
    143
    144        /**
    145         * Builds a new {@link BOMInputStream}.
    146         * <p>
    147         * You must set input that supports {@link #getInputStream()}, otherwise, this method throws an exception.
    148         * </p>
    149         * <p>
    150         * This builder use the following aspects: InputStream, OpenOption[], include, and ByteOrderMark[].
    151         * </p>
    152         * <p>
    153         * This builder use the following aspects:
    154         * </p>
    155         * <ul>
    156         * <li>{@link #getInputStream()}</li>
    157         * <li>include}</li>
    158         * <li>byteOrderMarks</li>
    159         * </ul>
    160         *
    161         * @return a new instance.
    162         * @throws IllegalStateException         if the {@code origin} is {@code null}.
    163         * @throws UnsupportedOperationException if the origin cannot be converted to an {@link InputStream}.
    164         * @throws IOException                   if an I/O error occurs.
    165         * @see #getInputStream()
    166         */
    167        @Override
    168        public BOMInputStream get() throws IOException {
    169            return new BOMInputStream(this);
    170        }
    171
    172        /**
    173         * Sets the ByteOrderMarks to detect and optionally exclude.
    174         * <p>
    175         * The default is {@link ByteOrderMark#UTF_8}.
    176         * </p>
    177         *
    178         * @param byteOrderMarks the ByteOrderMarks to detect and optionally exclude.
    179         * @return {@code this} instance.
    180         */
    181        public Builder setByteOrderMarks(final ByteOrderMark... byteOrderMarks) {
    182            this.byteOrderMarks = byteOrderMarks != null ? byteOrderMarks.clone() : DEFAULT;
    183            return this;
    184        }
    185
    186        /**
    187         * Sets whether to include the UTF-8 BOM (true) or to exclude it (false).
    188         * <p>
    189         * The default is false.
    190         * </p>
    191         *
    192         * @param include true to include the UTF-8 BOM or false to exclude it. return this;
    193         * @return {@code this} instance.
    194         */
    195        public Builder setInclude(final boolean include) {
    196            this.include = include;
    197            return this;
    198        }
    199
    200    }
    201
    202    /**
    203     * Compares ByteOrderMark objects in descending length order.
    204     */
    205    private static final Comparator<ByteOrderMark> ByteOrderMarkLengthComparator = Comparator.comparing(ByteOrderMark::length).reversed();
    206
    207    /**
    208     * Constructs a new {@link Builder}.
    209     *
    210     * @return a new {@link Builder}.
    211     * @since 2.12.0
    212     */
    213    public static Builder builder() {
    214        return new Builder();
    215    }
    216
    217    /**
    218     * BOMs are sorted from longest to shortest.
    219     */
    220    private final List<ByteOrderMark> boms;
    221
    222    private ByteOrderMark byteOrderMark;
    223    private int fbIndex;
    224    private int fbLength;
    225    private int[] firstBytes;
    226    private final boolean include;
    227    private boolean markedAtStart;
    228    private int markFbIndex;
    229
    230    private BOMInputStream(final Builder builder) throws IOException {
    231        super(builder);
    232        if (IOUtils.length(builder.byteOrderMarks) == 0) {
    233            throw new IllegalArgumentException("No BOMs specified");
    234        }
    235        this.include = builder.include;
    236        final List<ByteOrderMark> list = Arrays.asList(builder.byteOrderMarks);
    237        // Sort the BOMs to match the longest BOM first because some BOMs have the same starting two bytes.
    238        list.sort(ByteOrderMarkLengthComparator);
    239        this.boms = list;
    240    }
    241
    242    /**
    243     * Constructs a new BOM InputStream that excludes a {@link ByteOrderMark#UTF_8} BOM.
    244     *
    245     * @param delegate
    246     *            the InputStream to delegate to
    247     * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
    248     */
    249    @Deprecated
    250    public BOMInputStream(final InputStream delegate) {
    251        this(delegate, false, Builder.DEFAULT);
    252    }
    253
    254    /**
    255     * Constructs a new BOM InputStream that detects a {@link ByteOrderMark#UTF_8} and optionally includes it.
    256     *
    257     * @param delegate
    258     *            the InputStream to delegate to
    259     * @param include
    260     *            true to include the UTF-8 BOM or false to exclude it
    261     * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
    262     */
    263    @Deprecated
    264    public BOMInputStream(final InputStream delegate, final boolean include) {
    265        this(delegate, include, Builder.DEFAULT);
    266    }
    267
    268    /**
    269     * Constructs a new BOM InputStream that detects the specified BOMs and optionally includes them.
    270     *
    271     * @param delegate
    272     *            the InputStream to delegate to
    273     * @param include
    274     *            true to include the specified BOMs or false to exclude them
    275     * @param boms
    276     *            The BOMs to detect and optionally exclude
    277     * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
    278     */
    279    @Deprecated
    280    public BOMInputStream(final InputStream delegate, final boolean include, final ByteOrderMark... boms) {
    281        super(delegate);
    282        if (IOUtils.length(boms) == 0) {
    283            throw new IllegalArgumentException("No BOMs specified");
    284        }
    285        this.include = include;
    286        final List<ByteOrderMark> list = Arrays.asList(boms);
    287        // Sort the BOMs to match the longest BOM first because some BOMs have the same starting two bytes.
    288        list.sort(ByteOrderMarkLengthComparator);
    289        this.boms = list;
    290    }
    291
    292    /**
    293     * Constructs a new BOM InputStream that excludes the specified BOMs.
    294     *
    295     * @param delegate
    296     *            the InputStream to delegate to
    297     * @param boms
    298     *            The BOMs to detect and exclude
    299     * @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}
    300     */
    301    @Deprecated
    302    public BOMInputStream(final InputStream delegate, final ByteOrderMark... boms) {
    303        this(delegate, false, boms);
    304    }
    305
    306    /**
    307     * Find a BOM with the specified bytes.
    308     *
    309     * @return The matched BOM or null if none matched
    310     */
    311    private ByteOrderMark find() {
    312        return boms.stream().filter(this::matches).findFirst().orElse(null);
    313    }
    314
    315    /**
    316     * Gets the BOM (Byte Order Mark).
    317     *
    318     * @return The BOM or null if none
    319     * @throws IOException
    320     *             if an error reading the first bytes of the stream occurs
    321     */
    322    public ByteOrderMark getBOM() throws IOException {
    323        if (firstBytes == null) {
    324            fbLength = 0;
    325            // BOMs are sorted from longest to shortest
    326            final int maxBomSize = boms.get(0).length();
    327            firstBytes = new int[maxBomSize];
    328            // Read first maxBomSize bytes
    329            for (int i = 0; i < firstBytes.length; i++) {
    330                firstBytes[i] = in.read();
    331                afterRead(firstBytes[i]);
    332                fbLength++;
    333                if (firstBytes[i] < 0) {
    334                    break;
    335                }
    336            }
    337            // match BOM in firstBytes
    338            byteOrderMark = find();
    339            if (byteOrderMark != null && !include) {
    340                if (byteOrderMark.length() < firstBytes.length) {
    341                    fbIndex = byteOrderMark.length();
    342                } else {
    343                    fbLength = 0;
    344                }
    345            }
    346        }
    347        return byteOrderMark;
    348    }
    349
    350    /**
    351     * Gets the BOM charset Name - {@link ByteOrderMark#getCharsetName()}.
    352     *
    353     * @return The BOM charset Name or null if no BOM found
    354     * @throws IOException
    355     *             if an error reading the first bytes of the stream occurs
    356     */
    357    public String getBOMCharsetName() throws IOException {
    358        getBOM();
    359        return byteOrderMark == null ? null : byteOrderMark.getCharsetName();
    360    }
    361
    362    /**
    363     * Tests whether the stream contains one of the specified BOMs.
    364     *
    365     * @return true if the stream has one of the specified BOMs, otherwise false if it does not
    366     * @throws IOException
    367     *             if an error reading the first bytes of the stream occurs
    368     */
    369    public boolean hasBOM() throws IOException {
    370        return getBOM() != null;
    371    }
    372
    373    /**
    374     * Tests whether the stream contains the specified BOM.
    375     *
    376     * @param bom
    377     *            The BOM to check for
    378     * @return true if the stream has the specified BOM, otherwise false if it does not
    379     * @throws IllegalArgumentException
    380     *             if the BOM is not one the stream is configured to detect
    381     * @throws IOException
    382     *             if an error reading the first bytes of the stream occurs
    383     */
    384    public boolean hasBOM(final ByteOrderMark bom) throws IOException {
    385        if (!boms.contains(bom)) {
    386            throw new IllegalArgumentException("Stream not configured to detect " + bom);
    387        }
    388        return Objects.equals(getBOM(), bom);
    389    }
    390
    391    /**
    392     * Invokes the delegate's {@code mark(int)} method.
    393     *
    394     * @param readLimit
    395     *            read ahead limit
    396     */
    397    @Override
    398    public synchronized void mark(final int readLimit) {
    399        markFbIndex = fbIndex;
    400        markedAtStart = firstBytes == null;
    401        in.mark(readLimit);
    402    }
    403
    404    /**
    405     * Checks if the bytes match a BOM.
    406     *
    407     * @param bom
    408     *            The BOM
    409     * @return true if the bytes match the bom, otherwise false
    410     */
    411    private boolean matches(final ByteOrderMark bom) {
    412        // if (bom.length() != fbLength) {
    413        // return false;
    414        // }
    415        // firstBytes may be bigger than the BOM bytes
    416        for (int i = 0; i < bom.length(); i++) {
    417            if (bom.get(i) != firstBytes[i]) {
    418                return false;
    419            }
    420        }
    421        return true;
    422    }
    423
    424    /**
    425     * Invokes the delegate's {@code read()} method, detecting and optionally skipping BOM.
    426     *
    427     * @return the byte read (excluding BOM) or -1 if the end of stream
    428     * @throws IOException
    429     *             if an I/O error occurs
    430     */
    431    @Override
    432    public int read() throws IOException {
    433        checkOpen();
    434        final int b = readFirstBytes();
    435        return b >= 0 ? b : in.read();
    436    }
    437
    438    /**
    439     * Invokes the delegate's {@code read(byte[])} method, detecting and optionally skipping BOM.
    440     *
    441     * @param buf
    442     *            the buffer to read the bytes into
    443     * @return the number of bytes read (excluding BOM) or -1 if the end of stream
    444     * @throws IOException
    445     *             if an I/O error occurs
    446     */
    447    @Override
    448    public int read(final byte[] buf) throws IOException {
    449        return read(buf, 0, buf.length);
    450    }
    451
    452    /**
    453     * Invokes the delegate's {@code read(byte[], int, int)} method, detecting and optionally skipping BOM.
    454     *
    455     * @param buf
    456     *            the buffer to read the bytes into
    457     * @param off
    458     *            The start offset
    459     * @param len
    460     *            The number of bytes to read (excluding BOM)
    461     * @return the number of bytes read or -1 if the end of stream
    462     * @throws IOException
    463     *             if an I/O error occurs
    464     */
    465    @Override
    466    public int read(final byte[] buf, int off, int len) throws IOException {
    467        int firstCount = 0;
    468        int b = 0;
    469        while (len > 0 && b >= 0) {
    470            b = readFirstBytes();
    471            if (b >= 0) {
    472                buf[off++] = (byte) (b & 0xFF);
    473                len--;
    474                firstCount++;
    475            }
    476        }
    477        final int secondCount = in.read(buf, off, len);
    478        afterRead(secondCount);
    479        return secondCount < 0 ? firstCount > 0 ? firstCount : EOF : firstCount + secondCount;
    480    }
    481
    482    /**
    483     * This method reads and either preserves or skips the first bytes in the stream. It behaves like the single-byte
    484     * {@code read()} method, either returning a valid byte or -1 to indicate that the initial bytes have been
    485     * processed already.
    486     *
    487     * @return the byte read (excluding BOM) or -1 if the end of stream
    488     * @throws IOException
    489     *             if an I/O error occurs
    490     */
    491    private int readFirstBytes() throws IOException {
    492        getBOM();
    493        return fbIndex < fbLength ? firstBytes[fbIndex++] : EOF;
    494    }
    495
    496    /**
    497     * Invokes the delegate's {@code reset()} method.
    498     *
    499     * @throws IOException
    500     *             if an I/O error occurs
    501     */
    502    @Override
    503    public synchronized void reset() throws IOException {
    504        fbIndex = markFbIndex;
    505        if (markedAtStart) {
    506            firstBytes = null;
    507        }
    508        in.reset();
    509    }
    510
    511    /**
    512     * Invokes the delegate's {@code skip(long)} method, detecting and optionally skipping BOM.
    513     *
    514     * @param n
    515     *            the number of bytes to skip
    516     * @return the number of bytes to skipped or -1 if the end of stream
    517     * @throws IOException
    518     *             if an I/O error occurs
    519     */
    520    @Override
    521    public long skip(final long n) throws IOException {
    522        int skipped = 0;
    523        while (n > skipped && readFirstBytes() >= 0) {
    524            skipped++;
    525        }
    526        return in.skip(n - skipped) + skipped;
    527    }
    528}