/*
* @(#)ICUBinary.java 1.5 05/11/17
*
* Portions Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
/*
*******************************************************************************
* (C) Copyright IBM Corp. 1996-2005 - All Rights Reserved *
* *
* The original version of this source code and documentation is copyrighted *
* and owned by IBM, These materials are provided under terms of a License *
* Agreement between IBM and Sun. This technology is protected by multiple *
* US and International patents. This notice and attribution to IBM may not *
* to removed. *
*******************************************************************************
*/
package jdk1_6.sun.text.normalizer;
import java.io.InputStream;
import java.io.DataInputStream;
import java.io.IOException;
import java.util.Arrays;
public final class ICUBinary
{
// public inner interface ------------------------------------------------
/**
* Special interface for data authentication
*/
public static interface Authenticate
{
/**
* Method used in ICUBinary.readHeader() to provide data format
* authentication.
* @param version version of the current data
* @return true if dataformat is an acceptable version, false otherwise
*/
public boolean isDataVersionAcceptable(byte version[]);
}
// public methods --------------------------------------------------------
/**
* <p>ICU data header reader method.
* Takes a ICU generated big-endian input stream, parse the ICU standard
* file header and authenticates them.</p>
* <p>Header format:
* <ul>
* <li> Header size (char)
* <li> Magic number 1 (byte)
* <li> Magic number 2 (byte)
* <li> Rest of the header size (char)
* <li> Reserved word (char)
* <li> Big endian indicator (byte)
* <li> Character set family indicator (byte)
* <li> Size of a char (byte) for c++ and c use
* <li> Reserved byte (byte)
* <li> Data format identifier (4 bytes), each ICU data has its own
* identifier to distinguish them. [0] major [1] minor
* [2] milli [3] micro
* <li> Data version (4 bytes), the change version of the ICU data
* [0] major [1] minor [2] milli [3] micro
* <li> Unicode version (4 bytes) this ICU is based on.
* </ul>
* </p>
* <p>
* Example of use:<br>
* <pre>
* try {
* FileInputStream input = new FileInputStream(filename);
* If (Utility.readICUDataHeader(input, dataformat, dataversion,
* unicode) {
* System.out.println("Verified file header, this is a ICU data file");
* }
* } catch (IOException e) {
* System.out.println("This is not a ICU data file");
* }
* </pre>
* </p>
* @param inputStream input stream that contains the ICU data header
* @param dataFormatIDExpected Data format expected. An array of 4 bytes
* information about the data format.
* E.g. data format ID 1.2.3.4. will became an array of
* {1, 2, 3, 4}
* @param authenticate user defined extra data authentication. This value
* can be null, if no extra authentication is needed.
* @exception IOException thrown if there is a read error or
* when header authentication fails.
* @draft 2.1
*/
public static final byte[] readHeader(InputStream inputStream,
byte dataFormatIDExpected[],
Authenticate authenticate)
throws IOException
{
DataInputStream input = new DataInputStream(inputStream);
char headersize = input.readChar();
int readcount = 2;
//reading the header format
byte magic1 = input.readByte();
readcount ++;
byte magic2 = input.readByte();
readcount ++;
if (magic1 != MAGIC1 || magic2 != MAGIC2) {
throw new IOException(MAGIC_NUMBER_AUTHENTICATION_FAILED_);
}
input.readChar(); // reading size
readcount += 2;
input.readChar(); // reading reserved word
readcount += 2;
byte bigendian = input.readByte();
readcount ++;
byte charset = input.readByte();
readcount ++;
byte charsize = input.readByte();
readcount ++;
input.readByte(); // reading reserved byte
readcount ++;
byte dataFormatID[] = new byte[4];
input.readFully(dataFormatID);
readcount += 4;
byte dataVersion[] = new byte[4];
input.readFully(dataVersion);
readcount += 4;
byte unicodeVersion[] = new byte[4];
input.readFully(unicodeVersion);
readcount += 4;
if (headersize < readcount) {
throw new IOException("Internal Error: Header size error");
}
input.skipBytes(headersize - readcount);
if (bigendian != BIG_ENDIAN_ || charset != CHAR_SET_
|| charsize != CHAR_SIZE_
|| !Arrays.equals(dataFormatIDExpected, dataFormatID)
|| (authenticate != null
&& !authenticate.isDataVersionAcceptable(dataVersion))) {
throw new IOException(HEADER_AUTHENTICATION_FAILED_);
}
return unicodeVersion;
}
// private variables -------------------------------------------------
/**
* Magic numbers to authenticate the data file
*/
private static final byte MAGIC1 = (byte)0xda;
private static final byte MAGIC2 = (byte)0x27;
/**
* File format authentication values
*/
private static final byte BIG_ENDIAN_ = 1;
private static final byte CHAR_SET_ = 0;
private static final byte CHAR_SIZE_ = 2;
/**
* Error messages
*/
private static final String MAGIC_NUMBER_AUTHENTICATION_FAILED_ =
"ICU data file error: Not an ICU data file";
private static final String HEADER_AUTHENTICATION_FAILED_ =
"ICU data file error: Header authentication failed, please check if you have a valid ICU data file";
}