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	/*
	* Copyright (c) 1996, 2020, 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 java.util.zip;

	import java.io.InputStream;
	import java.io.IOException;
	import java.io.EOFException;
	import java.io.PushbackInputStream;
	import java.nio.charset.Charset;

	import sun.nio.cs.UTF_8;

	import static java.util.zip.ZipConstants64.*;
	import static java.util.zip.ZipUtils.*;

	/**
	* This class implements an input stream filter for reading files in the
	* ZIP file format. Includes support for both compressed and uncompressed
	* entries.
	*
	* @author David Connelly
	* @since 1.1
	*/
	public class ZipInputStream extends InflaterInputStream implements ZipConstants {
	private ZipEntry entry;
	private int flag;
	private CRC32 crc = new CRC32();
	private long remaining;
	private byte[] tmpbuf = new byte[512];

	private static final int STORED = ZipEntry.STORED;
	private static final int DEFLATED = ZipEntry.DEFLATED;

	private boolean closed = false;
	// this flag is set to true after EOF has reached for
	// one entry
	private boolean entryEOF = false;

	private ZipCoder zc;

	/**
	* Check to make sure that this stream has not been closed
	*/
	private void ensureOpen() throws IOException {
	if (closed) {
	throw new IOException("Stream closed");
	}
	}

	/**
	* Creates a new ZIP input stream.
	*
	* <p>The UTF-8 {@link java.nio.charset.Charset charset} is used to
	* decode the entry names.
	*
	* @param in the actual input stream
	*/
	public ZipInputStream(InputStream in) {
	this(in, UTF_8.INSTANCE);
	}

	/**
	* Creates a new ZIP input stream.
	*
	* @param in the actual input stream
	*
	* @param charset
	* The {@linkplain java.nio.charset.Charset charset} to be
	* used to decode the ZIP entry name (ignored if the
	* <a href="package-summary.html#lang_encoding"> language
	* encoding bit</a> of the ZIP entry's general purpose bit
	* flag is set).
	*
	* @since 1.7
	*/
	public ZipInputStream(InputStream in, Charset charset) {
	super(new PushbackInputStream(in, 512), new Inflater(true), 512);
	usesDefaultInflater = true;
	if (in == null) {
	throw new NullPointerException("in is null");
	}
	if (charset == null)
	throw new NullPointerException("charset is null");
	this.zc = ZipCoder.get(charset);
	}

	/**
	* Reads the next ZIP file entry and positions the stream at the
	* beginning of the entry data.
	* @return the next ZIP file entry, or null if there are no more entries
	* @throws ZipException if a ZIP file error has occurred
	* @throws IOException if an I/O error has occurred
	*/
	public ZipEntry getNextEntry() throws IOException {
	ensureOpen();
	if (entry != null) {
	closeEntry();
	}
	crc.reset();
	inf.reset();
	if ((entry = readLOC()) == null) {
	return null;
	}
	if (entry.method == STORED) {
	remaining = entry.size;
	}
	entryEOF = false;
	return entry;
	}

	/**
	* Closes the current ZIP entry and positions the stream for reading the
	* next entry.
	* @throws ZipException if a ZIP file error has occurred
	* @throws IOException if an I/O error has occurred
	*/
	public void closeEntry() throws IOException {
	ensureOpen();
	while (read(tmpbuf, 0, tmpbuf.length) != -1) ;
	entryEOF = true;
	}

	/**
	* Returns 0 after EOF has reached for the current entry data,
	* otherwise always return 1.
	* <p>
	* Programs should not count on this method to return the actual number
	* of bytes that could be read without blocking.
	*
	* @return 1 before EOF and 0 after EOF has reached for current entry.
	* @throws IOException if an I/O error occurs.
	*
	*/
	public int available() throws IOException {
	ensureOpen();
	if (entryEOF) {
	return 0;
	} else {
	return 1;
	}
	}

	/**
	* Reads from the current ZIP entry into an array of bytes.
	* If {@code len} is not zero, the method
	* blocks until some input is available; otherwise, no
	* bytes are read and {@code 0} is returned.
	* @param b the buffer into which the data is read
	* @param off the start offset in the destination array {@code b}
	* @param len the maximum number of bytes read
	* @return the actual number of bytes read, or -1 if the end of the
	* entry is reached
	* @throws NullPointerException if {@code b} is {@code null}.
	* @throws IndexOutOfBoundsException if {@code off} is negative,
	* {@code len} is negative, or {@code len} is greater than
	* {@code b.length - off}
	* @throws ZipException if a ZIP file error has occurred
	* @throws IOException if an I/O error has occurred
	*/
	public int read(byte[] b, int off, int len) throws IOException {
	ensureOpen();
	if (off < 0 \|\| len < 0 \|\| off > b.length - len) {
	throw new IndexOutOfBoundsException();
	} else if (len == 0) {
	return 0;
	}

	if (entry == null) {
	return -1;
	}
	switch (entry.method) {
	case DEFLATED:
	len = super.read(b, off, len);
	if (len == -1) {
	readEnd(entry);
	entryEOF = true;
	entry = null;
	} else {
	crc.update(b, off, len);
	}
	return len;
	case STORED:
	if (remaining <= 0) {
	entryEOF = true;
	entry = null;
	return -1;
	}
	if (len > remaining) {
	len = (int)remaining;
	}
	len = in.read(b, off, len);
	if (len == -1) {
	throw new ZipException("unexpected EOF");
	}
	crc.update(b, off, len);
	remaining -= len;
	if (remaining == 0 && entry.crc != crc.getValue()) {
	throw new ZipException(
	"invalid entry CRC (expected 0x" + Long.toHexString(entry.crc) +
	" but got 0x" + Long.toHexString(crc.getValue()) + ")");
	}
	return len;
	default:
	throw new ZipException("invalid compression method");
	}
	}

	/**
	* Skips specified number of bytes in the current ZIP entry.
	* @param n the number of bytes to skip
	* @return the actual number of bytes skipped
	* @throws ZipException if a ZIP file error has occurred
	* @throws IOException if an I/O error has occurred
	* @throws IllegalArgumentException if {@code n < 0}
	*/
	public long skip(long n) throws IOException {
	if (n < 0) {
	throw new IllegalArgumentException("negative skip length");
	}
	ensureOpen();
	int max = (int)Math.min(n, Integer.MAX_VALUE);
	int total = 0;
	while (total < max) {
	int len = max - total;
	if (len > tmpbuf.length) {
	len = tmpbuf.length;
	}
	len = read(tmpbuf, 0, len);
	if (len == -1) {
	entryEOF = true;
	break;
	}
	total += len;
	}
	return total;
	}

	/**
	* Closes this input stream and releases any system resources associated
	* with the stream.
	* @throws IOException if an I/O error has occurred
	*/
	public void close() throws IOException {
	if (!closed) {
	super.close();
	closed = true;
	}
	}

	private byte[] b = new byte[256];

	/*
	* Reads local file (LOC) header for next entry.
	*/
	private ZipEntry readLOC() throws IOException {
	try {
	readFully(tmpbuf, 0, LOCHDR);
	} catch (EOFException e) {
	return null;
	}
	if (get32(tmpbuf, 0) != LOCSIG) {
	return null;
	}
	// get flag first, we need check USE_UTF8.
	flag = get16(tmpbuf, LOCFLG);
	// get the entry name and create the ZipEntry first
	int len = get16(tmpbuf, LOCNAM);
	int blen = b.length;
	if (len > blen) {
	do {
	blen = blen * 2;
	} while (len > blen);
	b = new byte[blen];
	}
	readFully(b, 0, len);
	// Force to use UTF-8 if the USE_UTF8 bit is ON
	ZipEntry e = createZipEntry(((flag & USE_UTF8) != 0)
	? ZipCoder.toStringUTF8(b, len)
	: zc.toString(b, len));
	// now get the remaining fields for the entry
	if ((flag & 1) == 1) {
	throw new ZipException("encrypted ZIP entry not supported");
	}
	e.method = get16(tmpbuf, LOCHOW);
	e.xdostime = get32(tmpbuf, LOCTIM);
	if ((flag & 8) == 8) {
	/* "Data Descriptor" present */
	if (e.method != DEFLATED) {
	throw new ZipException(
	"only DEFLATED entries can have EXT descriptor");
	}
	} else {
	e.crc = get32(tmpbuf, LOCCRC);
	e.csize = get32(tmpbuf, LOCSIZ);
	e.size = get32(tmpbuf, LOCLEN);
	}
	len = get16(tmpbuf, LOCEXT);
	if (len > 0) {
	byte[] extra = new byte[len];
	readFully(extra, 0, len);
	e.setExtra0(extra,
	e.csize == ZIP64_MAGICVAL \|\| e.size == ZIP64_MAGICVAL, true);
	}
	return e;
	}

	/**
	* Creates a new {@code ZipEntry} object for the specified
	* entry name.
	*
	* @param name the ZIP file entry name
	* @return the ZipEntry just created
	*/
	protected ZipEntry createZipEntry(String name) {
	return new ZipEntry(name);
	}

	/**
	* Reads end of deflated entry as well as EXT descriptor if present.
	*
	* Local headers for DEFLATED entries may optionally be followed by a
	* data descriptor, and that data descriptor may optionally contain a
	* leading signature (EXTSIG).
	*
	* From the zip spec http://www.pkware.com/documents/casestudies/APPNOTE.TXT
	*
	* """Although not originally assigned a signature, the value 0x08074b50
	* has commonly been adopted as a signature value for the data descriptor
	* record. Implementers should be aware that ZIP files may be
	* encountered with or without this signature marking data descriptors
	* and should account for either case when reading ZIP files to ensure
	* compatibility."""
	*/
	private void readEnd(ZipEntry e) throws IOException {
	int n = inf.getRemaining();
	if (n > 0) {
	((PushbackInputStream)in).unread(buf, len - n, n);
	}
	if ((flag & 8) == 8) {
	/* "Data Descriptor" present */
	if (inf.getBytesWritten() > ZIP64_MAGICVAL \|\|
	inf.getBytesRead() > ZIP64_MAGICVAL) {
	// ZIP64 format
	readFully(tmpbuf, 0, ZIP64_EXTHDR);
	long sig = get32(tmpbuf, 0);
	if (sig != EXTSIG) { // no EXTSIG present
	e.crc = sig;
	e.csize = get64(tmpbuf, ZIP64_EXTSIZ - ZIP64_EXTCRC);
	e.size = get64(tmpbuf, ZIP64_EXTLEN - ZIP64_EXTCRC);
	((PushbackInputStream)in).unread(
	tmpbuf, ZIP64_EXTHDR - ZIP64_EXTCRC, ZIP64_EXTCRC);
	} else {
	e.crc = get32(tmpbuf, ZIP64_EXTCRC);
	e.csize = get64(tmpbuf, ZIP64_EXTSIZ);
	e.size = get64(tmpbuf, ZIP64_EXTLEN);
	}
	} else {
	readFully(tmpbuf, 0, EXTHDR);
	long sig = get32(tmpbuf, 0);
	if (sig != EXTSIG) { // no EXTSIG present
	e.crc = sig;
	e.csize = get32(tmpbuf, EXTSIZ - EXTCRC);
	e.size = get32(tmpbuf, EXTLEN - EXTCRC);
	((PushbackInputStream)in).unread(
	tmpbuf, EXTHDR - EXTCRC, EXTCRC);
	} else {
	e.crc = get32(tmpbuf, EXTCRC);
	e.csize = get32(tmpbuf, EXTSIZ);
	e.size = get32(tmpbuf, EXTLEN);
	}
	}
	}
	if (e.size != inf.getBytesWritten()) {
	throw new ZipException(
	"invalid entry size (expected " + e.size +
	" but got " + inf.getBytesWritten() + " bytes)");
	}
	if (e.csize != inf.getBytesRead()) {
	throw new ZipException(
	"invalid entry compressed size (expected " + e.csize +
	" but got " + inf.getBytesRead() + " bytes)");
	}
	if (e.crc != crc.getValue()) {
	throw new ZipException(
	"invalid entry CRC (expected 0x" + Long.toHexString(e.crc) +
	" but got 0x" + Long.toHexString(crc.getValue()) + ")");
	}
	}

	/*
	* Reads bytes, blocking until all bytes are read.
	*/
	private void readFully(byte[] b, int off, int len) throws IOException {
	while (len > 0) {
	int n = in.read(b, off, len);
	if (n == -1) {
	throw new EOFException();
	}
	off += n;
	len -= n;
	}
	}

	}

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