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	/*
	* Copyright (c) 2003, 2015, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code 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
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package javax.sql.rowset.serial;

	import java.sql.*;
	import java.io.*;
	import java.lang.reflect.*;
	import java.util.Arrays;


	/**
	* A serialized mapping in the Java programming language of an SQL
	* <code>BLOB</code> value.
	* <P>
	* The <code>SerialBlob</code> class provides a constructor for creating
	* an instance from a <code>Blob</code> object. Note that the
	* <code>Blob</code>
	* object should have brought the SQL <code>BLOB</code> value's data over
	* to the client before a <code>SerialBlob</code> object
	* is constructed from it. The data of an SQL <code>BLOB</code> value can
	* be materialized on the client as an array of bytes (using the method
	* <code>Blob.getBytes</code>) or as a stream of uninterpreted bytes
	* (using the method <code>Blob.getBinaryStream</code>).
	* <P>
	* <code>SerialBlob</code> methods make it possible to make a copy of a
	* <code>SerialBlob</code> object as an array of bytes or as a stream.
	* They also make it possible to locate a given pattern of bytes or a
	* <code>Blob</code> object within a <code>SerialBlob</code> object
	* and to update or truncate a <code>Blob</code> object.
	*
	* <h3> Thread safety </h3>
	*
	* <p> A SerialBlob is not safe for use by multiple concurrent threads. If a
	* SerialBlob is to be used by more than one thread then access to the SerialBlob
	* should be controlled by appropriate synchronization.
	*
	* @author Jonathan Bruce
	*/
	public class SerialBlob implements Blob, Serializable, Cloneable {

	/**
	* A serialized array of uninterpreted bytes representing the
	* value of this <code>SerialBlob</code> object.
	* @serial
	*/
	private byte[] buf;

	/**
	* The internal representation of the <code>Blob</code> object on which this
	* <code>SerialBlob</code> object is based.
	*/
	private Blob blob;

	/**
	* The number of bytes in this <code>SerialBlob</code> object's
	* array of bytes.
	* @serial
	*/
	private long len;

	/**
	* The original number of bytes in this <code>SerialBlob</code> object's
	* array of bytes when it was first established.
	* @serial
	*/
	private long origLen;

	/**
	* Constructs a <code>SerialBlob</code> object that is a serialized version of
	* the given <code>byte</code> array.
	* <p>
	* The new <code>SerialBlob</code> object is initialized with the data from the
	* <code>byte</code> array, thus allowing disconnected <code>RowSet</code>
	* objects to establish serialized <code>Blob</code> objects without
	* touching the data source.
	*
	* @param b the <code>byte</code> array containing the data for the
	* <code>Blob</code> object to be serialized
	* @throws SerialException if an error occurs during serialization
	* @throws SQLException if a SQL errors occurs
	*/
	public SerialBlob(byte[] b)
	throws SerialException, SQLException {

	len = b.length;
	buf = new byte[(int)len];
	for(int i = 0; i < len; i++) {
	buf[i] = b[i];
	}
	origLen = len;
	}


	/**
	* Constructs a <code>SerialBlob</code> object that is a serialized
	* version of the given <code>Blob</code> object.
	* <P>
	* The new <code>SerialBlob</code> object is initialized with the
	* data from the <code>Blob</code> object; therefore, the
	* <code>Blob</code> object should have previously brought the
	* SQL <code>BLOB</code> value's data over to the client from
	* the database. Otherwise, the new <code>SerialBlob</code> object
	* will contain no data.
	*
	* @param blob the <code>Blob</code> object from which this
	* <code>SerialBlob</code> object is to be constructed;
	* cannot be null.
	* @throws SerialException if an error occurs during serialization
	* @throws SQLException if the <code>Blob</code> passed to this
	* to this constructor is a <code>null</code>.
	* @see java.sql.Blob
	*/
	public SerialBlob (Blob blob)
	throws SerialException, SQLException {

	if (blob == null) {
	throw new SQLException(
	"Cannot instantiate a SerialBlob object with a null Blob object");
	}

	len = blob.length();
	buf = blob.getBytes(1, (int)len );
	this.blob = blob;
	origLen = len;
	}

	/**
	* Copies the specified number of bytes, starting at the given
	* position, from this <code>SerialBlob</code> object to
	* another array of bytes.
	* <P>
	* Note that if the given number of bytes to be copied is larger than
	* the length of this <code>SerialBlob</code> object's array of
	* bytes, the given number will be shortened to the array's length.
	*
	* @param pos the ordinal position of the first byte in this
	* <code>SerialBlob</code> object to be copied;
	* numbering starts at <code>1</code>; must not be less
	* than <code>1</code> and must be less than or equal
	* to the length of this <code>SerialBlob</code> object
	* @param length the number of bytes to be copied
	* @return an array of bytes that is a copy of a region of this
	* <code>SerialBlob</code> object, starting at the given
	* position and containing the given number of consecutive bytes
	* @throws SerialException if the given starting position is out of bounds;
	* if {@code free} had previously been called on this object
	*/
	public byte[] getBytes(long pos, int length) throws SerialException {
	isValid();
	if (length > len) {
	length = (int)len;
	}

	if (pos < 1 \|\| len - pos < 0 ) {
	throw new SerialException("Invalid arguments: position cannot be "
	+ "less than 1 or greater than the length of the SerialBlob");
	}

	pos--; // correct pos to array index

	byte[] b = new byte[length];

	for (int i = 0; i < length; i++) {
	b[i] = this.buf[(int)pos];
	pos++;
	}
	return b;
	}

	/**
	* Retrieves the number of bytes in this <code>SerialBlob</code>
	* object's array of bytes.
	*
	* @return a <code>long</code> indicating the length in bytes of this
	* <code>SerialBlob</code> object's array of bytes
	* @throws SerialException if an error occurs;
	* if {@code free} had previously been called on this object
	*/
	public long length() throws SerialException {
	isValid();
	return len;
	}

	/**
	* Returns this <code>SerialBlob</code> object as an input stream.
	* Unlike the related method, <code>setBinaryStream</code>,
	* a stream is produced regardless of whether the <code>SerialBlob</code>
	* was created with a <code>Blob</code> object or a <code>byte</code> array.
	*
	* @return a <code>java.io.InputStream</code> object that contains
	* this <code>SerialBlob</code> object's array of bytes
	* @throws SerialException if an error occurs;
	* if {@code free} had previously been called on this object
	* @see #setBinaryStream
	*/
	public java.io.InputStream getBinaryStream() throws SerialException {
	isValid();
	InputStream stream = new ByteArrayInputStream(buf);
	return stream;
	}

	/**
	* Returns the position in this <code>SerialBlob</code> object where
	* the given pattern of bytes begins, starting the search at the
	* specified position.
	*
	* @param pattern the pattern of bytes for which to search
	* @param start the position of the byte in this
	* <code>SerialBlob</code> object from which to begin
	* the search; the first position is <code>1</code>;
	* must not be less than <code>1</code> nor greater than
	* the length of this <code>SerialBlob</code> object
	* @return the position in this <code>SerialBlob</code> object
	* where the given pattern begins, starting at the specified
	* position; <code>-1</code> if the pattern is not found
	* or the given starting position is out of bounds; position
	* numbering for the return value starts at <code>1</code>
	* @throws SerialException if an error occurs when serializing the blob;
	* if {@code free} had previously been called on this object
	* @throws SQLException if there is an error accessing the <code>BLOB</code>
	* value from the database
	*/
	public long position(byte[] pattern, long start)
	throws SerialException, SQLException {

	isValid();
	if (start < 1 \|\| start > len) {
	return -1;
	}

	int pos = (int)start-1; // internally Blobs are stored as arrays.
	int i = 0;
	long patlen = pattern.length;

	while (pos < len) {
	if (pattern[i] == buf[pos]) {
	if (i + 1 == patlen) {
	return (pos + 1) - (patlen - 1);
	}
	i++; pos++; // increment pos, and i
	} else if (pattern[i] != buf[pos]) {
	pos++; // increment pos only
	}
	}
	return -1; // not found
	}

	/**
	* Returns the position in this <code>SerialBlob</code> object where
	* the given <code>Blob</code> object begins, starting the search at the
	* specified position.
	*
	* @param pattern the <code>Blob</code> object for which to search;
	* @param start the position of the byte in this
	* <code>SerialBlob</code> object from which to begin
	* the search; the first position is <code>1</code>;
	* must not be less than <code>1</code> nor greater than
	* the length of this <code>SerialBlob</code> object
	* @return the position in this <code>SerialBlob</code> object
	* where the given <code>Blob</code> object begins, starting
	* at the specified position; <code>-1</code> if the pattern is
	* not found or the given starting position is out of bounds;
	* position numbering for the return value starts at <code>1</code>
	* @throws SerialException if an error occurs when serializing the blob;
	* if {@code free} had previously been called on this object
	* @throws SQLException if there is an error accessing the <code>BLOB</code>
	* value from the database
	*/
	public long position(Blob pattern, long start)
	throws SerialException, SQLException {
	isValid();
	return position(pattern.getBytes(1, (int)(pattern.length())), start);
	}

	/**
	* Writes the given array of bytes to the <code>BLOB</code> value that
	* this <code>Blob</code> object represents, starting at position
	* <code>pos</code>, and returns the number of bytes written.
	*
	* @param pos the position in the SQL <code>BLOB</code> value at which
	* to start writing. The first position is <code>1</code>;
	* must not be less than <code>1</code> nor greater than
	* the length of this <code>SerialBlob</code> object.
	* @param bytes the array of bytes to be written to the <code>BLOB</code>
	* value that this <code>Blob</code> object represents
	* @return the number of bytes written
	* @throws SerialException if there is an error accessing the
	* <code>BLOB</code> value; or if an invalid position is set; if an
	* invalid offset value is set;
	* if {@code free} had previously been called on this object
	* @throws SQLException if there is an error accessing the <code>BLOB</code>
	* value from the database
	* @see #getBytes
	*/
	public int setBytes(long pos, byte[] bytes)
	throws SerialException, SQLException {
	return setBytes(pos, bytes, 0, bytes.length);
	}

	/**
	* Writes all or part of the given <code>byte</code> array to the
	* <code>BLOB</code> value that this <code>Blob</code> object represents
	* and returns the number of bytes written.
	* Writing starts at position <code>pos</code> in the <code>BLOB</code>
	* value; <i>len</i> bytes from the given byte array are written.
	*
	* @param pos the position in the <code>BLOB</code> object at which
	* to start writing. The first position is <code>1</code>;
	* must not be less than <code>1</code> nor greater than
	* the length of this <code>SerialBlob</code> object.
	* @param bytes the array of bytes to be written to the <code>BLOB</code>
	* value
	* @param offset the offset in the <code>byte</code> array at which
	* to start reading the bytes. The first offset position is
	* <code>0</code>; must not be less than <code>0</code> nor greater
	* than the length of the <code>byte</code> array
	* @param length the number of bytes to be written to the
	* <code>BLOB</code> value from the array of bytes <i>bytes</i>.
	*
	* @return the number of bytes written
	* @throws SerialException if there is an error accessing the
	* <code>BLOB</code> value; if an invalid position is set; if an
	* invalid offset value is set; if number of bytes to be written
	* is greater than the <code>SerialBlob</code> length; or the combined
	* values of the length and offset is greater than the Blob buffer;
	* if {@code free} had previously been called on this object
	* @throws SQLException if there is an error accessing the <code>BLOB</code>
	* value from the database.
	* @see #getBytes
	*/
	public int setBytes(long pos, byte[] bytes, int offset, int length)
	throws SerialException, SQLException {

	isValid();
	if (offset < 0 \|\| offset > bytes.length) {
	throw new SerialException("Invalid offset in byte array set");
	}

	if (pos < 1 \|\| pos > this.length()) {
	throw new SerialException("Invalid position in BLOB object set");
	}

	if ((long)(length) > origLen) {
	throw new SerialException("Buffer is not sufficient to hold the value");
	}

	if ((length + offset) > bytes.length) {
	throw new SerialException("Invalid OffSet. Cannot have combined offset " +
	"and length that is greater that the Blob buffer");
	}

	int i = 0;
	pos--; // correct to array indexing
	while ( i < length \|\| (offset + i +1) < (bytes.length-offset) ) {
	this.buf[(int)pos + i] = bytes[offset + i ];
	i++;
	}
	return i;
	}

	/**
	* Retrieves a stream that can be used to write to the <code>BLOB</code>
	* value that this <code>Blob</code> object represents. The stream begins
	* at position <code>pos</code>. This method forwards the
	* <code>setBinaryStream()</code> call to the underlying <code>Blob</code> in
	* the event that this <code>SerialBlob</code> object is instantiated with a
	* <code>Blob</code>. If this <code>SerialBlob</code> is instantiated with
	* a <code>byte</code> array, a <code>SerialException</code> is thrown.
	*
	* @param pos the position in the <code>BLOB</code> value at which
	* to start writing
	* @return a <code>java.io.OutputStream</code> object to which data can
	* be written
	* @throws SQLException if there is an error accessing the
	* <code>BLOB</code> value
	* @throws SerialException if the SerialBlob in not instantiated with a
	* <code>Blob</code> object that supports <code>setBinaryStream()</code>;
	* if {@code free} had previously been called on this object
	* @see #getBinaryStream
	*/
	public java.io.OutputStream setBinaryStream(long pos)
	throws SerialException, SQLException {

	isValid();
	if (this.blob != null) {
	return this.blob.setBinaryStream(pos);
	} else {
	throw new SerialException("Unsupported operation. SerialBlob cannot " +
	"return a writable binary stream, unless instantiated with a Blob object " +
	"that provides a setBinaryStream() implementation");
	}
	}

	/**
	* Truncates the <code>BLOB</code> value that this <code>Blob</code>
	* object represents to be <code>len</code> bytes in length.
	*
	* @param length the length, in bytes, to which the <code>BLOB</code>
	* value that this <code>Blob</code> object represents should be
	* truncated
	* @throws SerialException if there is an error accessing the Blob value;
	* or the length to truncate is greater that the SerialBlob length;
	* if {@code free} had previously been called on this object
	*/
	public void truncate(long length) throws SerialException {
	isValid();
	if (length > len) {
	throw new SerialException(
	"Length more than what can be truncated");
	} else if((int)length == 0) {
	buf = new byte[0];
	len = length;
	} else {
	len = length;
	buf = this.getBytes(1, (int)len);
	}
	}


	/**
	* Returns an
	* <code>InputStream</code> object that contains a partial
	* {@code Blob} value, starting with the byte specified by pos, which is
	* length bytes in length.
	*
	* @param pos the offset to the first byte of the partial value to be
	* retrieved. The first byte in the {@code Blob} is at position 1
	* @param length the length in bytes of the partial value to be retrieved
	* @return
	* <code>InputStream</code> through which the partial {@code Blob} value can
	* be read.
	* @throws SQLException if pos is less than 1 or if pos is greater than the
	* number of bytes in the {@code Blob} or if pos + length is greater than
	* the number of bytes in the {@code Blob}
	* @throws SerialException if the {@code free} method had been previously
	* called on this object
	*
	* @since 1.6
	*/
	public InputStream getBinaryStream(long pos, long length) throws SQLException {
	isValid();
	if (pos < 1 \|\| pos > this.length()) {
	throw new SerialException("Invalid position in BLOB object set");
	}
	if (length < 1 \|\| length > len - pos + 1) {
	throw new SerialException(
	"length is < 1 or pos + length > total number of bytes");
	}
	return new ByteArrayInputStream(buf, (int) pos - 1, (int) length);
	}


	/**
	* This method frees the {@code SeriableBlob} object and releases the
	* resources that it holds. The object is invalid once the {@code free}
	* method is called. <p> If {@code free} is called multiple times, the
	* subsequent calls to {@code free} are treated as a no-op. </P>
	*
	* @throws SQLException if an error occurs releasing the Blob's resources
	* @since 1.6
	*/
	public void free() throws SQLException {
	if (buf != null) {
	buf = null;
	if (blob != null) {
	blob.free();
	}
	blob = null;
	}
	}

	/**
	* Compares this SerialBlob to the specified object. The result is {@code
	* true} if and only if the argument is not {@code null} and is a {@code
	* SerialBlob} object that represents the same sequence of bytes as this
	* object.
	*
	* @param obj The object to compare this {@code SerialBlob} against
	*
	* @return {@code true} if the given object represents a {@code SerialBlob}
	* equivalent to this SerialBlob, {@code false} otherwise
	*
	*/
	public boolean equals(Object obj) {
	if (this == obj) {
	return true;
	}
	if (obj instanceof SerialBlob) {
	SerialBlob sb = (SerialBlob)obj;
	if (this.len == sb.len) {
	return Arrays.equals(buf, sb.buf);
	}
	}
	return false;
	}

	/**
	* Returns a hash code for this {@code SerialBlob}.
	* @return a hash code value for this object.
	*/
	public int hashCode() {
	return ((31 + Arrays.hashCode(buf)) * 31 + (int)len) * 31 + (int)origLen;
	}

	/**
	* Returns a clone of this {@code SerialBlob}. The copy will contain a
	* reference to a clone of the internal byte array, not a reference
	* to the original internal byte array of this {@code SerialBlob} object.
	* The underlying {@code Blob} object will be set to null.
	*
	* @return a clone of this SerialBlob
	*/
	public Object clone() {
	try {
	SerialBlob sb = (SerialBlob) super.clone();
	sb.buf = (buf != null) ? Arrays.copyOf(buf, (int)len) : null;
	sb.blob = null;
	return sb;
	} catch (CloneNotSupportedException ex) {
	// this shouldn't happen, since we are Cloneable
	throw new InternalError();
	}
	}

	/**
	* readObject is called to restore the state of the SerialBlob from
	* a stream.
	*/
	private void readObject(ObjectInputStream s)
	throws IOException, ClassNotFoundException {

	ObjectInputStream.GetField fields = s.readFields();
	byte[] tmp = (byte[])fields.get("buf", null);
	if (tmp == null)
	throw new InvalidObjectException("buf is null and should not be!");
	buf = tmp.clone();
	len = fields.get("len", 0L);
	if (buf.length != len)
	throw new InvalidObjectException("buf is not the expected size");
	origLen = fields.get("origLen", 0L);
	blob = (Blob) fields.get("blob", null);
	}

	/**
	* writeObject is called to save the state of the SerialBlob
	* to a stream.
	*/
	private void writeObject(ObjectOutputStream s)
	throws IOException, ClassNotFoundException {

	ObjectOutputStream.PutField fields = s.putFields();
	fields.put("buf", buf);
	fields.put("len", len);
	fields.put("origLen", origLen);
	// Note: this check to see if it is an instance of Serializable
	// is for backwards compatibiity
	fields.put("blob", blob instanceof Serializable ? blob : null);
	s.writeFields();
	}

	/**
	* Check to see if this object had previously had its {@code free} method
	* called
	*
	* @throws SerialException
	*/
	private void isValid() throws SerialException {
	if (buf == null) {
	throw new SerialException("Error: You cannot call a method on a " +
	"SerialBlob instance once free() has been called.");
	}
	}

	/**
	* The identifier that assists in the serialization of this
	* {@code SerialBlob} object.
	*/
	static final long serialVersionUID = -8144641928112860441L;
	}

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