    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.BufferedReader;
    022import java.io.IOException;
    023import java.io.InputStream;
    024import java.io.InputStreamReader;
    025import java.io.OutputStreamWriter;
    026import java.io.Reader;
    027import java.nio.ByteBuffer;
    028import java.nio.CharBuffer;
    029import java.nio.charset.Charset;
    030import java.nio.charset.CharsetEncoder;
    031import java.nio.charset.CoderResult;
    032import java.nio.charset.CodingErrorAction;
    033import java.util.Objects;
    034
    035import org.apache.commons.io.Charsets;
    036import org.apache.commons.io.IOUtils;
    037import org.apache.commons.io.build.AbstractStreamBuilder;
    038import org.apache.commons.io.charset.CharsetEncoders;
    039
    040/**
    041 * {@link InputStream} implementation that reads a character stream from a {@link Reader} and transforms it to a byte stream using a specified charset encoding.
    042 * The stream is transformed using a {@link CharsetEncoder} object, guaranteeing that all charset encodings supported by the JRE are handled correctly. In
    043 * particular for charsets such as UTF-16, the implementation ensures that one and only one byte order marker is produced.
    044 * <p>
    045 * Since in general it is not possible to predict the number of characters to be read from the {@link Reader} to satisfy a read request on the
    046 * {@link ReaderInputStream}, all reads from the {@link Reader} are buffered. There is therefore no well defined correlation between the current position of the
    047 * {@link Reader} and that of the {@link ReaderInputStream}. This also implies that in general there is no need to wrap the underlying {@link Reader} in a
    048 * {@link BufferedReader}.
    049 * </p>
    050 * <p>
    051 * {@link ReaderInputStream} implements the inverse transformation of {@link InputStreamReader}; in the following example, reading from {@code in2}
    052 * would return the same byte sequence as reading from {@code in} (provided that the initial byte sequence is legal with respect to the charset encoding):
    053 * </p>
    054 * <p>
    055 * To build an instance, use {@link Builder}.
    056 * </p>
    057 * <pre>
    058 * InputStream inputStream = ...
    059 * Charset cs = ...
    060 * InputStreamReader reader = new InputStreamReader(inputStream, cs);
    061 * ReaderInputStream in2 = ReaderInputStream.builder()
    062 *   .setReader(reader)
    063 *   .setCharset(cs)
    064 *   .get();
    065 * </pre>
    066 * <p>
    067 * {@link ReaderInputStream} implements the same transformation as {@link OutputStreamWriter}, except that the control flow is reversed: both classes
    068 * transform a character stream into a byte stream, but {@link OutputStreamWriter} pushes data to the underlying stream, while {@link ReaderInputStream}
    069 * pulls it from the underlying stream.
    070 * </p>
    071 * <p>
    072 * Note that while there are use cases where there is no alternative to using this class, very often the need to use this class is an indication of a flaw in
    073 * the design of the code. This class is typically used in situations where an existing API only accepts an {@link InputStream}, but where the most natural way
    074 * to produce the data is as a character stream, by providing a {@link Reader} instance. An example of a situation where this problem may appear is when
    075 * implementing the {@code javax.activation.DataSource} interface from the Java Activation Framework.
    076 * </p>
    077 * <p>
    078 * The {@link #available()} method of this class always returns 0. The methods {@link #mark(int)} and {@link #reset()} are not supported.
    079 * </p>
    080 * <p>
    081 * Instances of {@link ReaderInputStream} are not thread safe.
    082 * </p>
    083 *
    084 * @see Builder
    085 * @see org.apache.commons.io.output.WriterOutputStream
    086 * @since 2.0
    087 */
    088public class ReaderInputStream extends AbstractInputStream {
    089
    090    // @formatter:off
    091    /**
    092     * Builds a new {@link ReaderInputStream}.
    093     *
    094     * <p>
    095     * For example:
    096     * </p>
    097     * <pre>{@code
    098     * ReaderInputStream s = ReaderInputStream.builder()
    099     *   .setPath(path)
    100     *   .setCharsetEncoder(Charset.defaultCharset().newEncoder())
    101     *   .get();}
    102     * </pre>
    103     *
    104     * @see #get()
    105     * @since 2.12.0
    106     */
    107    // @formatter:on
    108    public static class Builder extends AbstractStreamBuilder<ReaderInputStream, Builder> {
    109
    110        private CharsetEncoder charsetEncoder = newEncoder(getCharset());
    111
    112        /**
    113         * Builds a new {@link ReaderInputStream}.
    114         *
    115         * <p>
    116         * You must set input that supports {@link #getReader()}, otherwise, this method throws an exception.
    117         * </p>
    118         * <p>
    119         * This builder use the following aspects:
    120         * </p>
    121         * <ul>
    122         * <li>{@link #getReader()}</li>
    123         * <li>{@link #getBufferSize()}</li>
    124         * <li>{@link #getCharset()}</li>
    125         * <li>{@link CharsetEncoder}</li>
    126         * </ul>
    127         *
    128         * @return a new instance.
    129         * @throws UnsupportedOperationException if the origin cannot provide a Reader.
    130         * @throws IllegalStateException if the {@code origin} is {@code null}.
    131         * @see #getReader()
    132         * @see CharsetEncoder
    133         * @see #getBufferSize()
    134         */
    135        @SuppressWarnings("resource")
    136        @Override
    137        public ReaderInputStream get() throws IOException {
    138            return new ReaderInputStream(getReader(), charsetEncoder, getBufferSize());
    139        }
    140
    141        CharsetEncoder getCharsetEncoder() {
    142            return charsetEncoder;
    143        }
    144
    145        @Override
    146        public Builder setCharset(final Charset charset) {
    147            super.setCharset(charset);
    148            charsetEncoder = newEncoder(getCharset());
    149            return this;
    150        }
    151
    152        /**
    153         * Sets the charset encoder. Assumes that the caller has configured the encoder.
    154         *
    155         * @param newEncoder the charset encoder, null resets to a default encoder.
    156         * @return {@code this} instance.
    157         */
    158        public Builder setCharsetEncoder(final CharsetEncoder newEncoder) {
    159            charsetEncoder = CharsetEncoders.toCharsetEncoder(newEncoder, () -> newEncoder(getCharsetDefault()));
    160            super.setCharset(charsetEncoder.charset());
    161            return this;
    162        }
    163
    164    }
    165
    166    /**
    167     * Constructs a new {@link Builder}.
    168     *
    169     * @return a new {@link Builder}.
    170     * @since 2.12.0
    171     */
    172    public static Builder builder() {
    173        return new Builder();
    174    }
    175
    176    static int checkMinBufferSize(final CharsetEncoder charsetEncoder, final int bufferSize) {
    177        final float minRequired = minBufferSize(charsetEncoder);
    178        if (bufferSize < minRequired) {
    179            throw new IllegalArgumentException(String.format("Buffer size %,d must be at least %s for a CharsetEncoder %s.", bufferSize, minRequired,
    180                    charsetEncoder.charset().displayName()));
    181        }
    182        return bufferSize;
    183    }
    184
    185    static float minBufferSize(final CharsetEncoder charsetEncoder) {
    186        return charsetEncoder.maxBytesPerChar() * 2;
    187    }
    188
    189    private static CharsetEncoder newEncoder(final Charset charset) {
    190        // @formatter:off
    191        return Charsets.toCharset(charset).newEncoder()
    192                .onMalformedInput(CodingErrorAction.REPLACE)
    193                .onUnmappableCharacter(CodingErrorAction.REPLACE);
    194        // @formatter:on
    195    }
    196
    197    private final Reader reader;
    198
    199    private final CharsetEncoder charsetEncoder;
    200
    201    /**
    202     * CharBuffer used as input for the decoder. It should be reasonably large as we read data from the underlying Reader into this buffer.
    203     */
    204    private final CharBuffer encoderIn;
    205    /**
    206     * ByteBuffer used as output for the decoder. This buffer can be small as it is only used to transfer data from the decoder to the buffer provided by the
    207     * caller.
    208     */
    209    private final ByteBuffer encoderOut;
    210
    211    private CoderResult lastCoderResult;
    212
    213    private boolean endOfInput;
    214
    215    /**
    216     * Constructs a new {@link ReaderInputStream} that uses the default character encoding with a default input buffer size of
    217     * {@value IOUtils#DEFAULT_BUFFER_SIZE} characters.
    218     *
    219     * @param reader the target {@link Reader}
    220     * @deprecated Use {@link ReaderInputStream#builder()} instead
    221     */
    222    @Deprecated
    223    public ReaderInputStream(final Reader reader) {
    224        this(reader, Charset.defaultCharset());
    225    }
    226
    227    /**
    228     * Constructs a new {@link ReaderInputStream} with a default input buffer size of {@value IOUtils#DEFAULT_BUFFER_SIZE} characters.
    229     *
    230     * <p>
    231     * The encoder created for the specified charset will use {@link CodingErrorAction#REPLACE} for malformed input and unmappable characters.
    232     * </p>
    233     *
    234     * @param reader  the target {@link Reader}
    235     * @param charset the charset encoding
    236     * @deprecated Use {@link ReaderInputStream#builder()} instead, will be protected for subclasses.
    237     */
    238    @Deprecated
    239    public ReaderInputStream(final Reader reader, final Charset charset) {
    240        this(reader, charset, IOUtils.DEFAULT_BUFFER_SIZE);
    241    }
    242
    243    /**
    244     * Constructs a new {@link ReaderInputStream}.
    245     *
    246     * <p>
    247     * The encoder created for the specified charset will use {@link CodingErrorAction#REPLACE} for malformed input and unmappable characters.
    248     * </p>
    249     *
    250     * @param reader     the target {@link Reader}.
    251     * @param charset    the charset encoding.
    252     * @param bufferSize the size of the input buffer in number of characters.
    253     * @deprecated Use {@link ReaderInputStream#builder()} instead
    254     */
    255    @Deprecated
    256    public ReaderInputStream(final Reader reader, final Charset charset, final int bufferSize) {
    257        // @formatter:off
    258        this(reader,
    259            Charsets.toCharset(charset).newEncoder()
    260                    .onMalformedInput(CodingErrorAction.REPLACE)
    261                    .onUnmappableCharacter(CodingErrorAction.REPLACE),
    262             bufferSize);
    263        // @formatter:on
    264    }
    265
    266    /**
    267     * Constructs a new {@link ReaderInputStream}.
    268     *
    269     * <p>
    270     * This constructor does not call {@link CharsetEncoder#reset() reset} on the provided encoder. The caller of this constructor should do this when providing
    271     * an encoder which had already been in use.
    272     * </p>
    273     *
    274     * @param reader         the target {@link Reader}
    275     * @param charsetEncoder the charset encoder
    276     * @since 2.1
    277     * @deprecated Use {@link ReaderInputStream#builder()} instead
    278     */
    279    @Deprecated
    280    public ReaderInputStream(final Reader reader, final CharsetEncoder charsetEncoder) {
    281        this(reader, charsetEncoder, IOUtils.DEFAULT_BUFFER_SIZE);
    282    }
    283
    284    /**
    285     * Constructs a new {@link ReaderInputStream}.
    286     *
    287     * <p>
    288     * This constructor does not call {@link CharsetEncoder#reset() reset} on the provided encoder. The caller of this constructor should do this when providing
    289     * an encoder which had already been in use.
    290     * </p>
    291     *
    292     * @param reader         the target {@link Reader}
    293     * @param charsetEncoder the charset encoder, null defaults to the default Charset encoder.
    294     * @param bufferSize     the size of the input buffer in number of characters
    295     * @since 2.1
    296     * @deprecated Use {@link ReaderInputStream#builder()} instead
    297     */
    298    @Deprecated
    299    public ReaderInputStream(final Reader reader, final CharsetEncoder charsetEncoder, final int bufferSize) {
    300        this.reader = reader;
    301        this.charsetEncoder = CharsetEncoders.toCharsetEncoder(charsetEncoder);
    302        this.encoderIn = CharBuffer.allocate(checkMinBufferSize(this.charsetEncoder, bufferSize));
    303        this.encoderIn.flip();
    304        this.encoderOut = ByteBuffer.allocate(128);
    305        this.encoderOut.flip();
    306    }
    307
    308    /**
    309     * Constructs a new {@link ReaderInputStream} with a default input buffer size of {@value IOUtils#DEFAULT_BUFFER_SIZE} characters.
    310     *
    311     * <p>
    312     * The encoder created for the specified charset will use {@link CodingErrorAction#REPLACE} for malformed input and unmappable characters.
    313     * </p>
    314     *
    315     * @param reader      the target {@link Reader}
    316     * @param charsetName the name of the charset encoding
    317     * @deprecated Use {@link ReaderInputStream#builder()} instead
    318     */
    319    @Deprecated
    320    public ReaderInputStream(final Reader reader, final String charsetName) {
    321        this(reader, charsetName, IOUtils.DEFAULT_BUFFER_SIZE);
    322    }
    323
    324    /**
    325     * Constructs a new {@link ReaderInputStream}.
    326     *
    327     * <p>
    328     * The encoder created for the specified charset will use {@link CodingErrorAction#REPLACE} for malformed input and unmappable characters.
    329     * </p>
    330     *
    331     * @param reader      the target {@link Reader}
    332     * @param charsetName the name of the charset encoding, null maps to the default Charset.
    333     * @param bufferSize  the size of the input buffer in number of characters
    334     * @deprecated Use {@link ReaderInputStream#builder()} instead
    335     */
    336    @Deprecated
    337    public ReaderInputStream(final Reader reader, final String charsetName, final int bufferSize) {
    338        this(reader, Charsets.toCharset(charsetName), bufferSize);
    339    }
    340
    341    @Override
    342    public int available() throws IOException {
    343        if (encoderOut.hasRemaining()) {
    344            return encoderOut.remaining();
    345        }
    346        return 0;
    347    }
    348
    349    /**
    350     * Closes the stream. This method will cause the underlying {@link Reader} to be closed.
    351     *
    352     * @throws IOException if an I/O error occurs.
    353     */
    354    @Override
    355    public void close() throws IOException {
    356        reader.close();
    357        super.close();
    358    }
    359
    360    /**
    361     * Fills the internal char buffer from the reader.
    362     *
    363     * @throws IOException If an I/O error occurs
    364     */
    365    private void fillBuffer() throws IOException {
    366        if (endOfInput) {
    367            return;
    368        }
    369        if (!endOfInput && (lastCoderResult == null || lastCoderResult.isUnderflow())) {
    370            encoderIn.compact();
    371            final int position = encoderIn.position();
    372            // We don't use Reader#read(CharBuffer) here because it is more efficient
    373            // to write directly to the underlying char array (the default implementation
    374            // copies data to a temporary char array).
    375            final int c = reader.read(encoderIn.array(), position, encoderIn.remaining());
    376            if (c == EOF) {
    377                endOfInput = true;
    378            } else {
    379                encoderIn.position(position + c);
    380            }
    381            encoderIn.flip();
    382        }
    383        encoderOut.compact();
    384        lastCoderResult = charsetEncoder.encode(encoderIn, encoderOut, endOfInput);
    385        if (endOfInput) {
    386            lastCoderResult = charsetEncoder.flush(encoderOut);
    387        }
    388        if (lastCoderResult.isError()) {
    389            lastCoderResult.throwException();
    390        }
    391        encoderOut.flip();
    392    }
    393
    394    /**
    395     * Gets the CharsetEncoder.
    396     *
    397     * @return the CharsetEncoder.
    398     */
    399    CharsetEncoder getCharsetEncoder() {
    400        return charsetEncoder;
    401    }
    402
    403    /**
    404     * Reads a single byte.
    405     *
    406     * @return either the byte read or {@code -1} if the end of the stream has been reached
    407     * @throws IOException if an I/O error occurs.
    408     */
    409    @Override
    410    public int read() throws IOException {
    411        checkOpen();
    412        for (;;) {
    413            if (encoderOut.hasRemaining()) {
    414                return encoderOut.get() & 0xFF;
    415            }
    416            fillBuffer();
    417            if (endOfInput && !encoderOut.hasRemaining()) {
    418                return EOF;
    419            }
    420        }
    421    }
    422
    423    /**
    424     * Reads the specified number of bytes into an array.
    425     *
    426     * @param b the byte array to read into
    427     * @return the number of bytes read or {@code -1} if the end of the stream has been reached
    428     * @throws IOException if an I/O error occurs.
    429     */
    430    @Override
    431    public int read(final byte[] b) throws IOException {
    432        return read(b, 0, b.length);
    433    }
    434
    435    /**
    436     * Reads the specified number of bytes into an array.
    437     *
    438     * @param array the byte array to read into
    439     * @param off   the offset to start reading bytes into
    440     * @param len   the number of bytes to read
    441     * @return the number of bytes read or {@code -1} if the end of the stream has been reached
    442     * @throws IOException if an I/O error occurs.
    443     */
    444    @Override
    445    public int read(final byte[] array, int off, int len) throws IOException {
    446        Objects.requireNonNull(array, "array");
    447        if (len < 0 || off < 0 || off + len > array.length) {
    448            throw new IndexOutOfBoundsException("Array size=" + array.length + ", offset=" + off + ", length=" + len);
    449        }
    450        int read = 0;
    451        if (len == 0) {
    452            return 0; // Always return 0 if len == 0
    453        }
    454        while (len > 0) {
    455            if (encoderOut.hasRemaining()) { // Data from the last read not fully copied
    456                final int c = Math.min(encoderOut.remaining(), len);
    457                encoderOut.get(array, off, c);
    458                off += c;
    459                len -= c;
    460                read += c;
    461            } else if (endOfInput) { // Already reach EOF in the last read
    462                break;
    463            } else { // Read again
    464                fillBuffer();
    465            }
    466        }
    467        return read == 0 && endOfInput ? EOF : read;
    468    }
    469}