https://tomcat.apache.org/: Common code shared by multiple Tomcat components 
/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.apache.tomcat.util.buf;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;

/*
 * In a server it is very important to be able to operate on
 * the original byte[] without converting everything to chars.
 * Some protocols are ASCII only, and some allow different
 * non-UNICODE encodings. The encoding is not known beforehand,
 * and can even change during the execution of the protocol.
 * ( for example a multipart message may have parts with different
 *  encoding )
 *
 * For HTTP it is not very clear how the encoding of RequestURI
 * and mime values can be determined, but it is a great advantage
 * to be able to parse the request without converting to string.
 */

// TODO: This class could either extend ByteBuffer, or better a ByteBuffer
// inside this way it could provide the search/etc on ByteBuffer, as a helper.


This class is used to represent a chunk of bytes, and utilities to manipulate
byte[].
The buffer can be modified and used for both input and output.
There are 2 modes: The chunk can be associated with a sink - ByteInputChannel
or ByteOutputChannel, which will be used when the buffer is empty (on input)
or filled (on output). For output, it can also grow. This operating mode is
selected by calling setLimit() or allocate(initial, limit) with limit != -1.
Various search and append method are defined - similar with String and
StringBuffer, but operating on bytes.
This is important because it allows processing the http headers directly on
the received bytes, without converting to chars and Strings until the strings
are needed. In addition, the charset is determined later, from headers or
user code.

Author:dac@sun.com, James Todd [gonzo@sun.com], Costin Manolache, Remy Maucherat
/**
 * This class is used to represent a chunk of bytes, and utilities to manipulate
 * byte[].
 *
 * The buffer can be modified and used for both input and output.
 *
 * There are 2 modes: The chunk can be associated with a sink - ByteInputChannel
 * or ByteOutputChannel, which will be used when the buffer is empty (on input)
 * or filled (on output). For output, it can also grow. This operating mode is
 * selected by calling setLimit() or allocate(initial, limit) with limit != -1.
 *
 * Various search and append method are defined - similar with String and
 * StringBuffer, but operating on bytes.
 *
 * This is important because it allows processing the http headers directly on
 * the received bytes, without converting to chars and Strings until the strings
 * are needed. In addition, the charset is determined later, from headers or
 * user code.
 *
 * @author dac@sun.com
 * @author James Todd [gonzo@sun.com]
 * @author Costin Manolache
 * @author Remy Maucherat
 */
public final class ByteChunk extends AbstractChunk {

    private static final long serialVersionUID = 1L;

    
Input interface, used when the buffer is empty.
Same as java.nio.channels.ReadableByteChannel

/**
     * Input interface, used when the buffer is empty.
     *
     * Same as java.nio.channels.ReadableByteChannel
     */
    public static interface ByteInputChannel {

        
Read new bytes.

Throws:
Returns:The number of bytes read
/**
         * Read new bytes.
         *
         * @return The number of bytes read
         *
         * @throws IOException If an I/O error occurs during reading
         */
        public int realReadBytes() throws IOException;
    }

    
When we need more space we'll either grow the buffer ( up to the limit )
or send it to a channel.
Same as java.nio.channel.WritableByteChannel.

/**
     * When we need more space we'll either grow the buffer ( up to the limit )
     * or send it to a channel.
     *
     * Same as java.nio.channel.WritableByteChannel.
     */
    public static interface ByteOutputChannel {

        
Send the bytes ( usually the internal conversion buffer ). Expect 8k
output if the buffer is full.

Params:
  • buf – bytes that will be written
  • off – offset in the bytes array
  • len – length that will be written
Throws:
  • IOException – If an I/O occurs while writing the bytes
/**
         * Send the bytes ( usually the internal conversion buffer ). Expect 8k
         * output if the buffer is full.
         *
         * @param buf bytes that will be written
         * @param off offset in the bytes array
         * @param len length that will be written
         * @throws IOException If an I/O occurs while writing the bytes
         */
        public void realWriteBytes(byte buf[], int off, int len) throws IOException;


        
Send the bytes ( usually the internal conversion buffer ). Expect 8k
output if the buffer is full.

Params:
  • from – bytes that will be written
Throws:
  • IOException – If an I/O occurs while writing the bytes
/**
         * Send the bytes ( usually the internal conversion buffer ). Expect 8k
         * output if the buffer is full.
         *
         * @param from bytes that will be written
         * @throws IOException If an I/O occurs while writing the bytes
         */
        public void realWriteBytes(ByteBuffer from) throws IOException;
    }

    // --------------------

    
Default encoding used to convert to strings. It should be UTF8, as most
standards seem to converge, but the servlet API requires 8859_1, and this
object is used mostly for servlets.

/**
     * Default encoding used to convert to strings. It should be UTF8, as most
     * standards seem to converge, but the servlet API requires 8859_1, and this
     * object is used mostly for servlets.
     */
    public static final Charset DEFAULT_CHARSET = StandardCharsets.ISO_8859_1;

    private transient Charset charset;

    // byte[]
    private byte[] buff;

    // transient as serialization is primarily for values via, e.g. JMX
    private transient ByteInputChannel in = null;
    private transient ByteOutputChannel out = null;


    
Creates a new, uninitialized ByteChunk object.

/**
     * Creates a new, uninitialized ByteChunk object.
     */
    public ByteChunk() {
    }


    public ByteChunk(int initial) {
        allocate(initial, -1);
    }


    private void writeObject(ObjectOutputStream oos) throws IOException {
        oos.defaultWriteObject();
        oos.writeUTF(getCharset().name());
    }


    private void readObject(ObjectInputStream ois) throws ClassNotFoundException, IOException {
        ois.defaultReadObject();
        this.charset = Charset.forName(ois.readUTF());
    }


    @Override
    public Object clone() throws CloneNotSupportedException {
        return super.clone();
    }


    @Override
    public void recycle() {
        super.recycle();
        charset = null;
    }


    // -------------------- Setup --------------------

    public void allocate(int initial, int limit) {
        if (buff == null || buff.length < initial) {
            buff = new byte[initial];
        }
        setLimit(limit);
        start = 0;
        end = 0;
        isSet = true;
        hasHashCode = false;
    }


    
Sets the buffer to the specified subarray of bytes.

Params:
  • b – the ascii bytes
  • off – the start offset of the bytes
  • len – the length of the bytes
/**
     * Sets the buffer to the specified subarray of bytes.
     *
     * @param b the ascii bytes
     * @param off the start offset of the bytes
     * @param len the length of the bytes
     */
    public void setBytes(byte[] b, int off, int len) {
        buff = b;
        start = off;
        end = start + len;
        isSet = true;
        hasHashCode = false;
    }


    public void setCharset(Charset charset) {
        this.charset = charset;
    }


    public Charset getCharset() {
        if (charset == null) {
            charset = DEFAULT_CHARSET;
        }
        return charset;
    }


    
Returns:the buffer.
/**
     * @return the buffer.
     */
    public byte[] getBytes() {
        return getBuffer();
    }


    
Returns:the buffer.
/**
     * @return the buffer.
     */
    public byte[] getBuffer() {
        return buff;
    }


    
When the buffer is empty, read the data from the input channel.

Params:
  • in – The input channel
/**
     * When the buffer is empty, read the data from the input channel.
     *
     * @param in The input channel
     */
    public void setByteInputChannel(ByteInputChannel in) {
        this.in = in;
    }


    
When the buffer is full, write the data to the output channel. Also used
when large amount of data is appended. If not set, the buffer will grow
to the limit.

Params:
  • out – The output channel
/**
     * When the buffer is full, write the data to the output channel. Also used
     * when large amount of data is appended. If not set, the buffer will grow
     * to the limit.
     *
     * @param out The output channel
     */
    public void setByteOutputChannel(ByteOutputChannel out) {
        this.out = out;
    }


    // -------------------- Adding data to the buffer --------------------

    public void append(byte b) throws IOException {
        makeSpace(1);
        int limit = getLimitInternal();

        // couldn't make space
        if (end >= limit) {
            flushBuffer();
        }
        buff[end++] = b;
    }


    public void append(ByteChunk src) throws IOException {
        append(src.getBytes(), src.getStart(), src.getLength());
    }


    
Add data to the buffer.

Params:
  • src – Bytes array
  • off – Offset
  • len – Length
Throws:
  • IOException – Writing overflow data to the output channel failed
/**
     * Add data to the buffer.
     *
     * @param src Bytes array
     * @param off Offset
     * @param len Length
     * @throws IOException Writing overflow data to the output channel failed
     */
    public void append(byte src[], int off, int len) throws IOException {
        // will grow, up to limit
        makeSpace(len);
        int limit = getLimitInternal();

        // Optimize on a common case.
        // If the buffer is empty and the source is going to fill up all the
        // space in buffer, may as well write it directly to the output,
        // and avoid an extra copy
        if (len == limit && end == start && out != null) {
            out.realWriteBytes(src, off, len);
            return;
        }

        // if we are below the limit
        if (len <= limit - end) {
            System.arraycopy(src, off, buff, end, len);
            end += len;
            return;
        }

        // Need more space than we can afford, need to flush buffer.

        // The buffer is already at (or bigger than) limit.

        // We chunk the data into slices fitting in the buffer limit, although
        // if the data is written directly if it doesn't fit.

        int avail = limit - end;
        System.arraycopy(src, off, buff, end, avail);
        end += avail;

        flushBuffer();

        int remain = len - avail;

        while (remain > (limit - end)) {
            out.realWriteBytes(src, (off + len) - remain, limit - end);
            remain = remain - (limit - end);
        }

        System.arraycopy(src, (off + len) - remain, buff, end, remain);
        end += remain;
    }


    
Add data to the buffer.

Params:
  • from – the ByteBuffer with the data
Throws:
  • IOException – Writing overflow data to the output channel failed
/**
     * Add data to the buffer.
     *
     * @param from the ByteBuffer with the data
     * @throws IOException Writing overflow data to the output channel failed
     */
    public void append(ByteBuffer from) throws IOException {
        int len = from.remaining();

        // will grow, up to limit
        makeSpace(len);
        int limit = getLimitInternal();

        // Optimize on a common case.
        // If the buffer is empty and the source is going to fill up all the
        // space in buffer, may as well write it directly to the output,
        // and avoid an extra copy
        if (len == limit && end == start && out != null) {
            out.realWriteBytes(from);
            from.position(from.limit());
            return;
        }
        // if we have limit and we're below
        if (len <= limit - end) {
            // makeSpace will grow the buffer to the limit,
            // so we have space
            from.get(buff, end, len);
            end += len;
            return;
        }

        // need more space than we can afford, need to flush
        // buffer

        // the buffer is already at ( or bigger than ) limit

        // We chunk the data into slices fitting in the buffer limit, although
        // if the data is written directly if it doesn't fit

        int avail = limit - end;
        from.get(buff, end, avail);
        end += avail;

        flushBuffer();

        int fromLimit = from.limit();
        int remain = len - avail;
        avail = limit - end;
        while (remain >= avail) {
            from.limit(from.position() + avail);
            out.realWriteBytes(from);
            from.position(from.limit());
            remain = remain - avail;
        }

        from.limit(fromLimit);
        from.get(buff, end, remain);
        end += remain;
    }


    // -------------------- Removing data from the buffer --------------------

    public int subtract() throws IOException {
        if (checkEof()) {
            return -1;
        }
        return buff[start++] & 0xFF;
    }

    public byte subtractB() throws IOException {
        if (checkEof()) {
            return -1;
        }
        return buff[start++];
    }


    public int subtract(byte dest[], int off, int len) throws IOException {
        if (checkEof()) {
            return -1;
        }
        int n = len;
        if (len > getLength()) {
            n = getLength();
        }
        System.arraycopy(buff, start, dest, off, n);
        start += n;
        return n;
    }


    
Transfers bytes from the buffer to the specified ByteBuffer. After the
operation the position of the ByteBuffer will be returned to the one
before the operation, the limit will be the position incremented by the
number of the transferred bytes.

Params:
  • to – the ByteBuffer into which bytes are to be written.
Throws:
  • IOException – if an input or output exception has occurred
Returns:an integer specifying the actual number of bytes read, or -1 if
        the end of the stream is reached
/**
     * Transfers bytes from the buffer to the specified ByteBuffer. After the
     * operation the position of the ByteBuffer will be returned to the one
     * before the operation, the limit will be the position incremented by the
     * number of the transferred bytes.
     *
     * @param to the ByteBuffer into which bytes are to be written.
     * @return an integer specifying the actual number of bytes read, or -1 if
     *         the end of the stream is reached
     * @throws IOException if an input or output exception has occurred
     */
    public int subtract(ByteBuffer to) throws IOException {
        if (checkEof()) {
            return -1;
        }
        int n = Math.min(to.remaining(), getLength());
        to.put(buff, start, n);
        to.limit(to.position());
        to.position(to.position() - n);
        start += n;
        return n;
    }


    private boolean checkEof() throws IOException {
        if ((end - start) == 0) {
            if (in == null) {
                return true;
            }
            int n = in.realReadBytes();
            if (n < 0) {
                return true;
            }
        }
        return false;
    }


    
Send the buffer to the sink. Called by append() when the limit is
reached. You can also call it explicitly to force the data to be written.

Throws:
  • IOException – Writing overflow data to the output channel failed
/**
     * Send the buffer to the sink. Called by append() when the limit is
     * reached. You can also call it explicitly to force the data to be written.
     *
     * @throws IOException Writing overflow data to the output channel failed
     */
    public void flushBuffer() throws IOException {
        // assert out!=null
        if (out == null) {
            throw new IOException(sm.getString(
                    "chunk.overflow", Integer.valueOf(getLimit()), Integer.valueOf(buff.length)));
        }
        out.realWriteBytes(buff, start, end - start);
        end = start;
    }


    
Make space for len bytes. If len is small, allocate a reserve space too. Never grow bigger than the limit or AbstractChunk.ARRAY_MAX_SIZE. 
Params:
  • count – The size
/**
     * Make space for len bytes. If len is small, allocate a reserve space too.
     * Never grow bigger than the limit or {@link AbstractChunk#ARRAY_MAX_SIZE}.
     *
     * @param count The size
     */
    public void makeSpace(int count) {
        byte[] tmp = null;

        int limit = getLimitInternal();

        long newSize;
        long desiredSize = end + count;

        // Can't grow above the limit
        if (desiredSize > limit) {
            desiredSize = limit;
        }

        if (buff == null) {
            if (desiredSize < 256) {
                desiredSize = 256; // take a minimum
            }
            buff = new byte[(int) desiredSize];
        }

        // limit < buf.length (the buffer is already big)
        // or we already have space XXX
        if (desiredSize <= buff.length) {
            return;
        }
        // grow in larger chunks
        if (desiredSize < 2L * buff.length) {
            newSize = buff.length * 2L;
        } else {
            newSize = buff.length * 2L + count;
        }

        if (newSize > limit) {
            newSize = limit;
        }
        tmp = new byte[(int) newSize];

        // Compacts buffer
        System.arraycopy(buff, start, tmp, 0, end - start);
        buff = tmp;
        tmp = null;
        end = end - start;
        start = 0;
    }


    // -------------------- Conversion and getters --------------------

    @Override
    public String toString() {
        if (isNull()) {
            return null;
        } else if (end - start == 0) {
            return "";
        }
        return StringCache.toString(this);
    }


    public String toStringInternal() {
        if (charset == null) {
            charset = DEFAULT_CHARSET;
        }
        // new String(byte[], int, int, Charset) takes a defensive copy of the
        // entire byte array. This is expensive if only a small subset of the
        // bytes will be used. The code below is from Apache Harmony.
        CharBuffer cb = charset.decode(ByteBuffer.wrap(buff, start, end - start));
        return new String(cb.array(), cb.arrayOffset(), cb.length());
    }


    public long getLong() {
        return Ascii.parseLong(buff, start, end - start);
    }


    // -------------------- equals --------------------

    @Override
    public boolean equals(Object obj) {
        if (obj instanceof ByteChunk) {
            return equals((ByteChunk) obj);
        }
        return false;
    }


    
Compares the message bytes to the specified String object.

Params:
  • s – the String to compare
Returns:true if the comparison succeeded, false
        otherwise
/**
     * Compares the message bytes to the specified String object.
     *
     * @param s the String to compare
     * @return <code>true</code> if the comparison succeeded, <code>false</code>
     *         otherwise
     */
    public boolean equals(String s) {
        // XXX ENCODING - this only works if encoding is UTF8-compat
        // ( ok for tomcat, where we compare ascii - header names, etc )!!!

        byte[] b = buff;
        int len = end - start;
        if (b == null || len != s.length()) {
            return false;
        }
        int off = start;
        for (int i = 0; i < len; i++) {
            if (b[off++] != s.charAt(i)) {
                return false;
            }
        }
        return true;
    }


    
Compares the message bytes to the specified String object.

Params:
  • s – the String to compare
Returns:true if the comparison succeeded, false
        otherwise
/**
     * Compares the message bytes to the specified String object.
     *
     * @param s the String to compare
     * @return <code>true</code> if the comparison succeeded, <code>false</code>
     *         otherwise
     */
    public boolean equalsIgnoreCase(String s) {
        byte[] b = buff;
        int len = end - start;
        if (b == null || len != s.length()) {
            return false;
        }
        int off = start;
        for (int i = 0; i < len; i++) {
            if (Ascii.toLower(b[off++]) != Ascii.toLower(s.charAt(i))) {
                return false;
            }
        }
        return true;
    }


    public boolean equals(ByteChunk bb) {
        return equals(bb.getBytes(), bb.getStart(), bb.getLength());
    }


    public boolean equals(byte b2[], int off2, int len2) {
        byte b1[] = buff;
        if (b1 == null && b2 == null) {
            return true;
        }

        int len = end - start;
        if (len != len2 || b1 == null || b2 == null) {
            return false;
        }

        int off1 = start;

        while (len-- > 0) {
            if (b1[off1++] != b2[off2++]) {
                return false;
            }
        }
        return true;
    }


    public boolean equals(CharChunk cc) {
        return equals(cc.getChars(), cc.getStart(), cc.getLength());
    }


    public boolean equals(char c2[], int off2, int len2) {
        // XXX works only for enc compatible with ASCII/UTF !!!
        byte b1[] = buff;
        if (c2 == null && b1 == null) {
            return true;
        }

        if (b1 == null || c2 == null || end - start != len2) {
            return false;
        }
        int off1 = start;
        int len = end - start;

        while (len-- > 0) {
            if ((char) b1[off1++] != c2[off2++]) {
                return false;
            }
        }
        return true;
    }


    
Returns true if the buffer starts with the specified string when tested
in a case sensitive manner.

Params:
  • s – the string
  • pos – The position
Returns:true if the start matches
/**
     * Returns true if the buffer starts with the specified string when tested
     * in a case sensitive manner.
     *
     * @param s the string
     * @param pos The position
     *
     * @return <code>true</code> if the start matches
     */
    public boolean startsWith(String s, int pos) {
        byte[] b = buff;
        int len = s.length();
        if (b == null || len + pos > end - start) {
            return false;
        }
        int off = start + pos;
        for (int i = 0; i < len; i++) {
            if (b[off++] != s.charAt(i)) {
                return false;
            }
        }
        return true;
    }


    
Returns true if the buffer starts with the specified string when tested
in a case insensitive manner.

Params:
  • s – the string
  • pos – The position
Returns:true if the start matches
/**
     * Returns true if the buffer starts with the specified string when tested
     * in a case insensitive manner.
     *
     * @param s the string
     * @param pos The position
     *
     * @return <code>true</code> if the start matches
     */
    public boolean startsWithIgnoreCase(String s, int pos) {
        byte[] b = buff;
        int len = s.length();
        if (b == null || len + pos > end - start) {
            return false;
        }
        int off = start + pos;
        for (int i = 0; i < len; i++) {
            if (Ascii.toLower(b[off++]) != Ascii.toLower(s.charAt(i))) {
                return false;
            }
        }
        return true;
    }


    @Override
    protected int getBufferElement(int index) {
        return buff[index];
    }


    
Returns the first instance of the given character in this ByteChunk
starting at the specified byte. If the character is not found, -1 is
returned. 

NOTE: This only works for characters in the range 0-127.

Params:
  • c – The character
  • starting – The start position
Returns:The position of the first instance of the character or -1 if the
        character is not found.
/**
     * Returns the first instance of the given character in this ByteChunk
     * starting at the specified byte. If the character is not found, -1 is
     * returned. <br>
     * NOTE: This only works for characters in the range 0-127.
     *
     * @param c The character
     * @param starting The start position
     * @return The position of the first instance of the character or -1 if the
     *         character is not found.
     */
    public int indexOf(char c, int starting) {
        int ret = indexOf(buff, start + starting, end, c);
        return (ret >= start) ? ret - start : -1;
    }


    
Returns the first instance of the given character in the given byte array
between the specified start and end. 

NOTE: This only works for characters in the range 0-127.

Params:
  • bytes – The array to search
  • start – The point to start searching from in the array
  • end – The point to stop searching in the array
  • s – The character to search for
Returns:The position of the first instance of the character or -1 if the
        character is not found.
/**
     * Returns the first instance of the given character in the given byte array
     * between the specified start and end. <br>
     * NOTE: This only works for characters in the range 0-127.
     *
     * @param bytes The array to search
     * @param start The point to start searching from in the array
     * @param end The point to stop searching in the array
     * @param s The character to search for
     * @return The position of the first instance of the character or -1 if the
     *         character is not found.
     */
    public static int indexOf(byte bytes[], int start, int end, char s) {
        int offset = start;

        while (offset < end) {
            byte b = bytes[offset];
            if (b == s) {
                return offset;
            }
            offset++;
        }
        return -1;
    }


    
Returns the first instance of the given byte in the byte array between
the specified start and end.

Params:
  • bytes – The byte array to search
  • start – The point to start searching from in the byte array
  • end – The point to stop searching in the byte array
  • b – The byte to search for
Returns:The position of the first instance of the byte or -1 if the byte
        is not found.
/**
     * Returns the first instance of the given byte in the byte array between
     * the specified start and end.
     *
     * @param bytes The byte array to search
     * @param start The point to start searching from in the byte array
     * @param end The point to stop searching in the byte array
     * @param b The byte to search for
     * @return The position of the first instance of the byte or -1 if the byte
     *         is not found.
     */
    public static int findByte(byte bytes[], int start, int end, byte b) {
        int offset = start;
        while (offset < end) {
            if (bytes[offset] == b) {
                return offset;
            }
            offset++;
        }
        return -1;
    }


    
Returns the first instance of any of the given bytes in the byte array
between the specified start and end.

Params:
  • bytes – The byte array to search
  • start – The point to start searching from in the byte array
  • end – The point to stop searching in the byte array
  • b – The array of bytes to search for
Returns:The position of the first instance of the byte or -1 if the byte
        is not found.
/**
     * Returns the first instance of any of the given bytes in the byte array
     * between the specified start and end.
     *
     * @param bytes The byte array to search
     * @param start The point to start searching from in the byte array
     * @param end The point to stop searching in the byte array
     * @param b The array of bytes to search for
     * @return The position of the first instance of the byte or -1 if the byte
     *         is not found.
     */
    public static int findBytes(byte bytes[], int start, int end, byte b[]) {
        int offset = start;
        while (offset < end) {
            for (byte value : b) {
                if (bytes[offset] == value) {
                    return offset;
                }
            }
            offset++;
        }
        return -1;
    }


    
Convert specified String to a byte array. This ONLY WORKS for ascii, UTF
chars will be truncated.

Params:
  • value – to convert to byte array
Returns:the byte array value
/**
     * Convert specified String to a byte array. This ONLY WORKS for ascii, UTF
     * chars will be truncated.
     *
     * @param value to convert to byte array
     * @return the byte array value
     */
    public static final byte[] convertToBytes(String value) {
        byte[] result = new byte[value.length()];
        for (int i = 0; i < value.length(); i++) {
            result[i] = (byte) value.charAt(i);
        }
        return result;
    }
}