/* Copyright (C) 2002-2005 MySQL AB This program is free software; you can redistribute it and/or modify it under the terms of version 2 of the GNU General Public License as  published by the Free Software Foundation. There are special exceptions to the terms and conditions of the GPL  as it is applied to this software. View the full text of the  exception in file EXCEPTIONS-CONNECTOR-J in the directory of this  software distribution. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */package com.mysql.jdbc;import java.io.UnsupportedEncodingException;import java.nio.ByteBuffer;import java.sql.SQLException;/** * Buffer contains code to read and write packets from/to the MySQL server. *  * @version $Id: Buffer.java 5417 2006-06-20 21:33:56Z mmatthews $ * @author Mark Matthews */class Buffer {	static final int MAX_BYTES_TO_DUMP = 512;	static final int NO_LENGTH_LIMIT = -1;	static final long NULL_LENGTH = -1;	private int bufLength = 0;	private byte[] byteBuffer;	private int position = 0;	protected boolean wasMultiPacket = false;	Buffer(byte[] buf) {		this.byteBuffer = buf;		setBufLength(buf.length);	}	Buffer(int size) {		this.byteBuffer = new byte[size];		setBufLength(this.byteBuffer.length);		this.position = MysqlIO.HEADER_LENGTH;	}	final void clear() {		this.position = MysqlIO.HEADER_LENGTH;	}	final void dump() {		dump(getBufLength());	}	final String dump(int numBytes) {		return StringUtils.dumpAsHex(getBytes(0,				numBytes > getBufLength() ? getBufLength() : numBytes),				numBytes > getBufLength() ? getBufLength() : numBytes);	}	final String dumpClampedBytes(int numBytes) {		int numBytesToDump = numBytes < MAX_BYTES_TO_DUMP ? numBytes				: MAX_BYTES_TO_DUMP;		String dumped = StringUtils.dumpAsHex(getBytes(0,				numBytesToDump > getBufLength() ? getBufLength()						: numBytesToDump),				numBytesToDump > getBufLength() ? getBufLength()						: numBytesToDump);		if (numBytesToDump < numBytes) {			return dumped + " ....(packet exceeds max. dump length)";		}		return dumped;	}	final void dumpHeader() {		for (int i = 0; i < MysqlIO.HEADER_LENGTH; i++) {			String hexVal = Integer.toHexString(readByte(i) & 0xff);			if (hexVal.length() == 1) {				hexVal = "0" + hexVal; //$NON-NLS-1$			}			System.out.print(hexVal + " "); //$NON-NLS-1$		}	}	final void dumpNBytes(int start, int nBytes) {		StringBuffer asciiBuf = new StringBuffer();		for (int i = start; (i < (start + nBytes)) && (i < getBufLength()); i++) {			String hexVal = Integer.toHexString(readByte(i) & 0xff);			if (hexVal.length() == 1) {				hexVal = "0" + hexVal; //$NON-NLS-1$			}			System.out.print(hexVal + " "); //$NON-NLS-1$			if ((readByte(i) > 32) && (readByte(i) < 127)) {				asciiBuf.append((char) readByte(i));			} else {				asciiBuf.append("."); //$NON-NLS-1$			}			asciiBuf.append(" "); //$NON-NLS-1$		}		System.out.println("    " + asciiBuf.toString()); //$NON-NLS-1$	}	final void ensureCapacity(int additionalData) throws SQLException {		if ((this.position + additionalData) > getBufLength()) {			if ((this.position + additionalData) < this.byteBuffer.length) {				// byteBuffer.length is != getBufLength() all of the time				// due to re-using of packets (we don't shrink them)				//				// If we can, don't re-alloc, just set buffer length				// to size of current buffer				setBufLength(this.byteBuffer.length);			} else {				//				// Otherwise, re-size, and pad so we can avoid				// allocing again in the near future				//				int newLength = (int) (this.byteBuffer.length * 1.25);				if (newLength < (this.byteBuffer.length + additionalData)) {					newLength = this.byteBuffer.length							+ (int) (additionalData * 1.25);				}				if (newLength < this.byteBuffer.length) {					newLength = this.byteBuffer.length + additionalData;				}				byte[] newBytes = new byte[newLength];				System.arraycopy(this.byteBuffer, 0, newBytes, 0,						this.byteBuffer.length);				this.byteBuffer = newBytes;				setBufLength(this.byteBuffer.length);			}		}	}	/**	 * Skip over a length-encoded string	 * 	 * @return The position past the end of the string	 */	public int fastSkipLenString() {		long len = this.readFieldLength();		this.position += len;		return (int) len; // this is safe, as this is only	}	protected final byte[] getBufferSource() {		return this.byteBuffer;	}	int getBufLength() {		return this.bufLength;	}	/**	 * Returns the array of bytes this Buffer is using to read from.	 * 	 * @return byte array being read from	 */	public byte[] getByteBuffer() {		return this.byteBuffer;	}	final byte[] getBytes(int len) {		byte[] b = new byte[len];		System.arraycopy(this.byteBuffer, this.position, b, 0, len);		this.position += len; // update cursor		return b;	}	/*	 * (non-Javadoc)	 * 	 * @see com.mysql.jdbc.Buffer#getBytes(int, int)	 */	byte[] getBytes(int offset, int len) {		byte[] dest = new byte[len];		System.arraycopy(this.byteBuffer, offset, dest, 0, len);		return dest;	}	int getCapacity() {		return this.byteBuffer.length;	}	public ByteBuffer getNioBuffer() {		throw new IllegalArgumentException(Messages				.getString("ByteArrayBuffer.0")); //$NON-NLS-1$	}	/**	 * Returns the current position to write to/ read from	 * 	 * @return the current position to write to/ read from	 */	public int getPosition() {		return this.position;	}	// 2000-06-05 Changed	final boolean isLastDataPacket() {		return ((getBufLength() < 9) && ((this.byteBuffer[0] & 0xff) == 254));	}	final long newReadLength() {		int sw = this.byteBuffer[this.position++] & 0xff;		switch (sw) {		case 251:			return 0;		case 252:			return readInt();		case 253:			return readLongInt();		case 254: // changed for 64 bit lengths			return readLongLong();		default:			return sw;		}	}	final byte readByte() {		return this.byteBuffer[this.position++];	}	final byte readByte(int readAt) {		return this.byteBuffer[readAt];	}	final long readFieldLength() {		int sw = this.byteBuffer[this.position++] & 0xff;		switch (sw) {		case 251:			return NULL_LENGTH;		case 252:			return readInt();		case 253:			return readLongInt();		case 254:			return readLongLong();		default:			return sw;		}	}	// 2000-06-05 Changed	final int readInt() {		byte[] b = this.byteBuffer; // a little bit optimization		return (b[this.position++] & 0xff) | ((b[this.position++] & 0xff) << 8);	}	final int readIntAsLong() {		byte[] b = this.byteBuffer;		return (b[this.position++] & 0xff) | ((b[this.position++] & 0xff) << 8)				| ((b[this.position++] & 0xff) << 16)				| ((b[this.position++] & 0xff) << 24);	}	final byte[] readLenByteArray(int offset) {		long len = this.readFieldLength();		if (len == NULL_LENGTH) {			return null;		}		if (len == 0) {			return Constants.EMPTY_BYTE_ARRAY;		}		this.position += offset;		return getBytes((int) len);	}	final long readLength() {		int sw = this.byteBuffer[this.position++] & 0xff;		switch (sw) {		case 251:			return 0;		case 252:			return readInt();		case 253:			return readLongInt();