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	/*
	* Copyright (c) 2003, 2021, 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.
	*/

	/*
	*******************************************************************************
	* Copyright (C) 1996-2014, International Business Machines Corporation and
	* others. All Rights Reserved.
	*******************************************************************************
	*/

	package jdk.internal.icu.impl;

	import java.io.DataInputStream;
	import java.io.InputStream;
	import java.io.IOException;
	import java.io.UncheckedIOException;
	import java.nio.ByteBuffer;
	import java.nio.ByteOrder;
	import java.util.Arrays;
	import java.security.AccessController;
	import java.security.PrivilegedAction;

	import jdk.internal.icu.util.VersionInfo;

	public final class ICUBinary {

	private static final class IsAcceptable implements Authenticate {
	@Override
	public boolean isDataVersionAcceptable(byte version[]) {
	return version[0] == 1;
	}
	}

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

	/**
	* Loads an ICU binary data file and returns it as a ByteBuffer.
	* The buffer contents is normally read-only, but its position etc. can be modified.
	*
	* @param itemPath Relative ICU data item path, for example "root.res" or "coll/ucadata.icu".
	* @return The data as a read-only ByteBuffer.
	*/
	public static ByteBuffer getRequiredData(String itemPath) {
	final Class<ICUBinary> root = ICUBinary.class;

	try (@SuppressWarnings("removal") InputStream is = AccessController.doPrivileged(new PrivilegedAction<InputStream>() {
	public InputStream run() {
	return root.getResourceAsStream(itemPath);
	}
	})) {

	// is.available() may return 0, or 1, or the total number of bytes in the stream,
	// or some other number.
	// Do not try to use is.available() == 0 to find the end of the stream!
	byte[] bytes;
	int avail = is.available();
	if (avail > 32) {
	// There are more bytes available than just the ICU data header length.
	// With luck, it is the total number of bytes.
	bytes = new byte[avail];
	} else {
	bytes = new byte[128]; // empty .res files are even smaller
	}
	// Call is.read(...) until one returns a negative value.
	int length = 0;
	for(;;) {
	if (length < bytes.length) {
	int numRead = is.read(bytes, length, bytes.length - length);
	if (numRead < 0) {
	break; // end of stream
	}
	length += numRead;
	} else {
	// See if we are at the end of the stream before we grow the array.
	int nextByte = is.read();
	if (nextByte < 0) {
	break;
	}
	int capacity = 2 * bytes.length;
	if (capacity < 128) {
	capacity = 128;
	} else if (capacity < 0x4000) {
	capacity *= 2; // Grow faster until we reach 16kB.
	}
	bytes = Arrays.copyOf(bytes, capacity);
	bytes[length++] = (byte) nextByte;
	}
	}
	return ByteBuffer.wrap(bytes, 0, length);
	}
	catch (IOException e) {
	throw new UncheckedIOException(e);
	}
	}

	/**
	* Same as readHeader(), but returns a VersionInfo rather than a compact int.
	*/
	public static VersionInfo readHeaderAndDataVersion(ByteBuffer bytes,
	int dataFormat,
	Authenticate authenticate)
	throws IOException {
	return getVersionInfoFromCompactInt(readHeader(bytes, dataFormat, authenticate));
	}

	private static final byte BIG_ENDIAN_ = 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;
	}

	/**
	* Reads an ICU data header, checks the data format, and returns the data version.
	*
	* <p>Assumes that the ByteBuffer position is 0 on input.
	* The buffer byte order is set according to the data.
	* The buffer position is advanced past the header (including UDataInfo and comment).
	*
	* <p>See C++ ucmndata.h and unicode/udata.h.
	*
	* @return dataVersion
	* @throws IOException if this is not a valid ICU data item of the expected dataFormat
	*/
	public static int readHeader(ByteBuffer bytes, int dataFormat, Authenticate authenticate)
	throws IOException {
	assert bytes.position() == 0;
	byte magic1 = bytes.get(2);
	byte magic2 = bytes.get(3);
	if (magic1 != MAGIC1 \|\| magic2 != MAGIC2) {
	throw new IOException(MAGIC_NUMBER_AUTHENTICATION_FAILED_);
	}

	byte isBigEndian = bytes.get(8);
	byte charsetFamily = bytes.get(9);
	byte sizeofUChar = bytes.get(10);
	if (isBigEndian < 0 \|\| 1 < isBigEndian \|\|
	charsetFamily != CHAR_SET_ \|\| sizeofUChar != CHAR_SIZE_) {
	throw new IOException(HEADER_AUTHENTICATION_FAILED_);
	}
	bytes.order(isBigEndian != 0 ? ByteOrder.BIG_ENDIAN : ByteOrder.LITTLE_ENDIAN);

	int headerSize = bytes.getChar(0);
	int sizeofUDataInfo = bytes.getChar(4);
	if (sizeofUDataInfo < 20 \|\| headerSize < (sizeofUDataInfo + 4)) {
	throw new IOException("Internal Error: Header size error");
	}
	// TODO: Change Authenticate to take int major, int minor, int milli, int micro
	// to avoid array allocation.
	byte[] formatVersion = new byte[] {
	bytes.get(16), bytes.get(17), bytes.get(18), bytes.get(19)
	};
	if (bytes.get(12) != (byte)(dataFormat >> 24) \|\|
	bytes.get(13) != (byte)(dataFormat >> 16) \|\|
	bytes.get(14) != (byte)(dataFormat >> 8) \|\|
	bytes.get(15) != (byte)dataFormat \|\|
	(authenticate != null && !authenticate.isDataVersionAcceptable(formatVersion))) {
	throw new IOException(HEADER_AUTHENTICATION_FAILED_ +
	String.format("; data format %02x%02x%02x%02x, format version %d.%d.%d.%d",
	bytes.get(12), bytes.get(13), bytes.get(14), bytes.get(15),
	formatVersion[0] & 0xff, formatVersion[1] & 0xff,
	formatVersion[2] & 0xff, formatVersion[3] & 0xff));
	}

	bytes.position(headerSize);
	return // dataVersion
	((int)bytes.get(20) << 24) \|
	((bytes.get(21) & 0xff) << 16) \|
	((bytes.get(22) & 0xff) << 8) \|
	(bytes.get(23) & 0xff);
	}

	public static void skipBytes(ByteBuffer bytes, int skipLength) {
	if (skipLength > 0) {
	bytes.position(bytes.position() + skipLength);
	}
	}

	public static byte[] getBytes(ByteBuffer bytes, int length, int additionalSkipLength) {
	byte[] dest = new byte[length];
	bytes.get(dest);
	if (additionalSkipLength > 0) {
	skipBytes(bytes, additionalSkipLength);
	}
	return dest;
	}

	public static String getString(ByteBuffer bytes, int length, int additionalSkipLength) {
	CharSequence cs = bytes.asCharBuffer();
	String s = cs.subSequence(0, length).toString();
	skipBytes(bytes, length * 2 + additionalSkipLength);
	return s;
	}

	public static char[] getChars(ByteBuffer bytes, int length, int additionalSkipLength) {
	char[] dest = new char[length];
	bytes.asCharBuffer().get(dest);
	skipBytes(bytes, length * 2 + additionalSkipLength);
	return dest;
	}

	public static int[] getInts(ByteBuffer bytes, int length, int additionalSkipLength) {
	int[] dest = new int[length];
	bytes.asIntBuffer().get(dest);
	skipBytes(bytes, length * 4 + additionalSkipLength);
	return dest;
	}

	/**
	* Returns a VersionInfo for the bytes in the compact version integer.
	*/
	public static VersionInfo getVersionInfoFromCompactInt(int version) {
	return VersionInfo.getInstance(
	version >>> 24, (version >> 16) & 0xff, (version >> 8) & 0xff, version & 0xff);
	}

	// 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 CHAR_SET_ = 0;
	private static final byte CHAR_SIZE_ = 2;

	/**
	* Error messages
	*/
	private static final String MAGIC_NUMBER_AUTHENTICATION_FAILED_ =
	"ICUBinary data file error: Magic number authentication failed";
	private static final String HEADER_AUTHENTICATION_FAILED_ =
	"ICUBinary data file error: Header authentication failed";
	}

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