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	/*
	* Copyright (c) 2000, 2012, 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.imageio.stream;

	import java.io.File;
	import java.io.InputStream;
	import java.io.IOException;
	import java.io.RandomAccessFile;
	import java.nio.file.Files;
	import com.sun.imageio.stream.StreamCloser;
	import com.sun.imageio.stream.StreamFinalizer;
	import sun.java2d.Disposer;
	import sun.java2d.DisposerRecord;

	/**
	* An implementation of <code>ImageInputStream</code> that gets its
	* input from a regular <code>InputStream</code>. A file is used to
	* cache previously read data.
	*
	*/
	public class FileCacheImageInputStream extends ImageInputStreamImpl {

	private InputStream stream;

	private File cacheFile;

	private RandomAccessFile cache;

	private static final int BUFFER_LENGTH = 1024;

	private byte[] buf = new byte[BUFFER_LENGTH];

	private long length = 0L;

	private boolean foundEOF = false;

	/** The referent to be registered with the Disposer. */
	private final Object disposerReferent;

	/** The DisposerRecord that closes the underlying cache. */
	private final DisposerRecord disposerRecord;

	/** The CloseAction that closes the stream in
	* the StreamCloser's shutdown hook */
	private final StreamCloser.CloseAction closeAction;

	/**
	* Constructs a <code>FileCacheImageInputStream</code> that will read
	* from a given <code>InputStream</code>.
	*
	* <p> A temporary file is used as a cache. If
	* <code>cacheDir</code>is non-<code>null</code> and is a
	* directory, the file will be created there. If it is
	* <code>null</code>, the system-dependent default temporary-file
	* directory will be used (see the documentation for
	* <code>File.createTempFile</code> for details).
	*
	* @param stream an <code>InputStream</code> to read from.
	* @param cacheDir a <code>File</code> indicating where the
	* cache file should be created, or <code>null</code> to use the
	* system directory.
	*
	* @exception IllegalArgumentException if <code>stream</code> is
	* <code>null</code>.
	* @exception IllegalArgumentException if <code>cacheDir</code> is
	* non-<code>null</code> but is not a directory.
	* @exception IOException if a cache file cannot be created.
	*/
	public FileCacheImageInputStream(InputStream stream, File cacheDir)
	throws IOException {
	if (stream == null) {
	throw new IllegalArgumentException("stream == null!");
	}
	if ((cacheDir != null) && !(cacheDir.isDirectory())) {
	throw new IllegalArgumentException("Not a directory!");
	}
	this.stream = stream;
	if (cacheDir == null)
	this.cacheFile = Files.createTempFile("imageio", ".tmp").toFile();
	else
	this.cacheFile = Files.createTempFile(cacheDir.toPath(), "imageio", ".tmp")
	.toFile();
	this.cache = new RandomAccessFile(cacheFile, "rw");

	this.closeAction = StreamCloser.createCloseAction(this);
	StreamCloser.addToQueue(closeAction);

	disposerRecord = new StreamDisposerRecord(cacheFile, cache);
	if (getClass() == FileCacheImageInputStream.class) {
	disposerReferent = new Object();
	Disposer.addRecord(disposerReferent, disposerRecord);
	} else {
	disposerReferent = new StreamFinalizer(this);
	}
	}

	/**
	* Ensures that at least <code>pos</code> bytes are cached,
	* or the end of the source is reached. The return value
	* is equal to the smaller of <code>pos</code> and the
	* length of the source file.
	*/
	private long readUntil(long pos) throws IOException {
	// We've already got enough data cached
	if (pos < length) {
	return pos;
	}
	// pos >= length but length isn't getting any bigger, so return it
	if (foundEOF) {
	return length;
	}

	long len = pos - length;
	cache.seek(length);
	while (len > 0) {
	// Copy a buffer's worth of data from the source to the cache
	// BUFFER_LENGTH will always fit into an int so this is safe
	int nbytes =
	stream.read(buf, 0, (int)Math.min(len, (long)BUFFER_LENGTH));
	if (nbytes == -1) {
	foundEOF = true;
	return length;
	}

	cache.write(buf, 0, nbytes);
	len -= nbytes;
	length += nbytes;
	}

	return pos;
	}

	public int read() throws IOException {
	checkClosed();
	bitOffset = 0;
	long next = streamPos + 1;
	long pos = readUntil(next);
	if (pos >= next) {
	cache.seek(streamPos++);
	return cache.read();
	} else {
	return -1;
	}
	}

	public int read(byte[] b, int off, int len) throws IOException {
	checkClosed();

	if (b == null) {
	throw new NullPointerException("b == null!");
	}
	// Fix 4430357 - if off + len < 0, overflow occurred
	if (off < 0 \|\| len < 0 \|\| off + len > b.length \|\| off + len < 0) {
	throw new IndexOutOfBoundsException
	("off < 0 \|\| len < 0 \|\| off+len > b.length \|\| off+len < 0!");
	}

	bitOffset = 0;

	if (len == 0) {
	return 0;
	}

	long pos = readUntil(streamPos + len);

	// len will always fit into an int so this is safe
	len = (int)Math.min((long)len, pos - streamPos);
	if (len > 0) {
	cache.seek(streamPos);
	cache.readFully(b, off, len);
	streamPos += len;
	return len;
	} else {
	return -1;
	}
	}

	/**
	* Returns <code>true</code> since this
	* <code>ImageInputStream</code> caches data in order to allow
	* seeking backwards.
	*
	* @return <code>true</code>.
	*
	* @see #isCachedMemory
	* @see #isCachedFile
	*/
	public boolean isCached() {
	return true;
	}

	/**
	* Returns <code>true</code> since this
	* <code>ImageInputStream</code> maintains a file cache.
	*
	* @return <code>true</code>.
	*
	* @see #isCached
	* @see #isCachedMemory
	*/
	public boolean isCachedFile() {
	return true;
	}

	/**
	* Returns <code>false</code> since this
	* <code>ImageInputStream</code> does not maintain a main memory
	* cache.
	*
	* @return <code>false</code>.
	*
	* @see #isCached
	* @see #isCachedFile
	*/
	public boolean isCachedMemory() {
	return false;
	}

	/**
	* Closes this <code>FileCacheImageInputStream</code>, closing
	* and removing the cache file. The source <code>InputStream</code>
	* is not closed.
	*
	* @exception IOException if an error occurs.
	*/
	public void close() throws IOException {
	super.close();
	disposerRecord.dispose(); // this will close/delete the cache file
	stream = null;
	cache = null;
	cacheFile = null;
	StreamCloser.removeFromQueue(closeAction);
	}

	/**
	* {@inheritDoc}
	*/
	protected void finalize() throws Throwable {
	// Empty finalizer: for performance reasons we instead use the
	// Disposer mechanism for ensuring that the underlying
	// RandomAccessFile is closed/deleted prior to garbage collection
	}

	private static class StreamDisposerRecord implements DisposerRecord {
	private File cacheFile;
	private RandomAccessFile cache;

	public StreamDisposerRecord(File cacheFile, RandomAccessFile cache) {
	this.cacheFile = cacheFile;
	this.cache = cache;
	}

	public synchronized void dispose() {
	if (cache != null) {
	try {
	cache.close();
	} catch (IOException e) {
	} finally {
	cache = null;
	}
	}
	if (cacheFile != null) {
	cacheFile.delete();
	cacheFile = null;
	}
	// Note: Explicit removal of the stream from the StreamCloser
	// queue is not mandatory in this case, as it will be removed
	// automatically by GC shortly after this method is called.
	}
	}
	}

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