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	/*
	* Copyright (c) 2000, 2017, 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.logging;

	import static java.nio.file.StandardOpenOption.APPEND;
	import static java.nio.file.StandardOpenOption.CREATE_NEW;
	import static java.nio.file.StandardOpenOption.WRITE;

	import java.io.BufferedOutputStream;
	import java.io.File;
	import java.io.FileOutputStream;
	import java.io.IOException;
	import java.io.OutputStream;
	import java.nio.channels.FileChannel;
	import java.nio.channels.OverlappingFileLockException;
	import java.nio.file.FileAlreadyExistsException;
	import java.nio.file.Files;
	import java.nio.file.LinkOption;
	import java.nio.file.NoSuchFileException;
	import java.nio.file.Path;
	import java.nio.file.Paths;
	import java.security.AccessController;
	import java.security.PrivilegedAction;
	import java.util.HashSet;
	import java.util.Set;

	/**
	* Simple file logging <tt>Handler</tt>.
	* <p>
	* The <tt>FileHandler</tt> can either write to a specified file,
	* or it can write to a rotating set of files.
	* <p>
	* For a rotating set of files, as each file reaches a given size
	* limit, it is closed, rotated out, and a new file opened.
	* Successively older files are named by adding "0", "1", "2",
	* etc. into the base filename.
	* <p>
	* By default buffering is enabled in the IO libraries but each log
	* record is flushed out when it is complete.
	* <p>
	* By default the <tt>XMLFormatter</tt> class is used for formatting.
	* <p>
	* <b>Configuration:</b>
	* By default each <tt>FileHandler</tt> is initialized using the following
	* <tt>LogManager</tt> configuration properties where <tt><handler-name></tt>
	* refers to the fully-qualified class name of the handler.
	* If properties are not defined
	* (or have invalid values) then the specified default values are used.
	* <ul>
	* <li> <handler-name>.level
	* specifies the default level for the <tt>Handler</tt>
	* (defaults to <tt>Level.ALL</tt>). </li>
	* <li> <handler-name>.filter
	* specifies the name of a <tt>Filter</tt> class to use
	* (defaults to no <tt>Filter</tt>). </li>
	* <li> <handler-name>.formatter
	* specifies the name of a <tt>Formatter</tt> class to use
	* (defaults to <tt>java.util.logging.XMLFormatter</tt>) </li>
	* <li> <handler-name>.encoding
	* the name of the character set encoding to use (defaults to
	* the default platform encoding). </li>
	* <li> <handler-name>.limit
	* specifies an approximate maximum amount to write (in bytes)
	* to any one file. If this is zero, then there is no limit.
	* (Defaults to no limit). </li>
	* <li> <handler-name>.count
	* specifies how many output files to cycle through (defaults to 1). </li>
	* <li> <handler-name>.pattern
	* specifies a pattern for generating the output file name. See
	* below for details. (Defaults to "%h/java%u.log"). </li>
	* <li> <handler-name>.append
	* specifies whether the FileHandler should append onto
	* any existing files (defaults to false). </li>
	* </ul>
	* <p>
	* For example, the properties for {@code FileHandler} would be:
	* <ul>
	* <li> java.util.logging.FileHandler.level=INFO </li>
	* <li> java.util.logging.FileHandler.formatter=java.util.logging.SimpleFormatter </li>
	* </ul>
	* <p>
	* For a custom handler, e.g. com.foo.MyHandler, the properties would be:
	* <ul>
	* <li> com.foo.MyHandler.level=INFO </li>
	* <li> com.foo.MyHandler.formatter=java.util.logging.SimpleFormatter </li>
	* </ul>
	* <p>
	* A pattern consists of a string that includes the following special
	* components that will be replaced at runtime:
	* <ul>
	* <li> "/" the local pathname separator </li>
	* <li> "%t" the system temporary directory </li>
	* <li> "%h" the value of the "user.home" system property </li>
	* <li> "%g" the generation number to distinguish rotated logs </li>
	* <li> "%u" a unique number to resolve conflicts </li>
	* <li> "%%" translates to a single percent sign "%" </li>
	* </ul>
	* If no "%g" field has been specified and the file count is greater
	* than one, then the generation number will be added to the end of
	* the generated filename, after a dot.
	* <p>
	* Thus for example a pattern of "%t/java%g.log" with a count of 2
	* would typically cause log files to be written on Solaris to
	* /var/tmp/java0.log and /var/tmp/java1.log whereas on Windows 95 they
	* would be typically written to C:\TEMP\java0.log and C:\TEMP\java1.log
	* <p>
	* Generation numbers follow the sequence 0, 1, 2, etc.
	* <p>
	* Normally the "%u" unique field is set to 0. However, if the <tt>FileHandler</tt>
	* tries to open the filename and finds the file is currently in use by
	* another process it will increment the unique number field and try
	* again. This will be repeated until <tt>FileHandler</tt> finds a file name that
	* is not currently in use. If there is a conflict and no "%u" field has
	* been specified, it will be added at the end of the filename after a dot.
	* (This will be after any automatically added generation number.)
	* <p>
	* Thus if three processes were all trying to log to fred%u.%g.txt then
	* they might end up using fred0.0.txt, fred1.0.txt, fred2.0.txt as
	* the first file in their rotating sequences.
	* <p>
	* Note that the use of unique ids to avoid conflicts is only guaranteed
	* to work reliably when using a local disk file system.
	*
	* @since 1.4
	*/

	public class FileHandler extends StreamHandler {
	private MeteredStream meter;
	private boolean append;
	private int limit; // zero => no limit.
	private int count;
	private String pattern;
	private String lockFileName;
	private FileChannel lockFileChannel;
	private File files[];
	private static final int DEFAULT_MAX_LOCKS = 100;
	private static int maxLocks;
	private static final Set<String> locks = new HashSet<>();

	/*
	* Initialize maxLocks from the System property if set.
	* If invalid/no property is provided 100 will be used as a default value.
	*/
	static {
	maxLocks = java.security.AccessController.doPrivileged(
	(PrivilegedAction<Integer>) () ->
	Integer.getInteger(
	"jdk.internal.FileHandlerLogging.maxLocks",
	DEFAULT_MAX_LOCKS)
	);

	if (maxLocks <= 0) {
	maxLocks = DEFAULT_MAX_LOCKS;
	}
	}

	/**
	* A metered stream is a subclass of OutputStream that
	* (a) forwards all its output to a target stream
	* (b) keeps track of how many bytes have been written
	*/
	private class MeteredStream extends OutputStream {
	final OutputStream out;
	int written;

	MeteredStream(OutputStream out, int written) {
	this.out = out;
	this.written = written;
	}

	@Override
	public void write(int b) throws IOException {
	out.write(b);
	written++;
	}

	@Override
	public void write(byte buff[]) throws IOException {
	out.write(buff);
	written += buff.length;
	}

	@Override
	public void write(byte buff[], int off, int len) throws IOException {
	out.write(buff,off,len);
	written += len;
	}

	@Override
	public void flush() throws IOException {
	out.flush();
	}

	@Override
	public void close() throws IOException {
	out.close();
	}
	}

	private void open(File fname, boolean append) throws IOException {
	int len = 0;
	if (append) {
	len = (int)fname.length();
	}
	FileOutputStream fout = new FileOutputStream(fname.toString(), append);
	BufferedOutputStream bout = new BufferedOutputStream(fout);
	meter = new MeteredStream(bout, len);
	setOutputStream(meter);
	}

	/**
	* Configure a FileHandler from LogManager properties and/or default values
	* as specified in the class javadoc.
	*/
	private void configure() {
	LogManager manager = LogManager.getLogManager();

	String cname = getClass().getName();

	pattern = manager.getStringProperty(cname + ".pattern", "%h/java%u.log");
	limit = manager.getIntProperty(cname + ".limit", 0);
	if (limit < 0) {
	limit = 0;
	}
	count = manager.getIntProperty(cname + ".count", 1);
	if (count <= 0) {
	count = 1;
	}
	append = manager.getBooleanProperty(cname + ".append", false);
	setLevel(manager.getLevelProperty(cname + ".level", Level.ALL));
	setFilter(manager.getFilterProperty(cname + ".filter", null));
	setFormatter(manager.getFormatterProperty(cname + ".formatter", new XMLFormatter()));
	try {
	setEncoding(manager.getStringProperty(cname +".encoding", null));
	} catch (Exception ex) {
	try {
	setEncoding(null);
	} catch (Exception ex2) {
	// doing a setEncoding with null should always work.
	// assert false;
	}
	}
	}


	/**
	* Construct a default <tt>FileHandler</tt>. This will be configured
	* entirely from <tt>LogManager</tt> properties (or their default values).
	* <p>
	* @exception IOException if there are IO problems opening the files.
	* @exception SecurityException if a security manager exists and if
	* the caller does not have <tt>LoggingPermission("control"))</tt>.
	* @exception NullPointerException if pattern property is an empty String.
	*/
	public FileHandler() throws IOException, SecurityException {
	checkPermission();
	configure();
	openFiles();
	}

	/**
	* Initialize a <tt>FileHandler</tt> to write to the given filename.
	* <p>
	* The <tt>FileHandler</tt> is configured based on <tt>LogManager</tt>
	* properties (or their default values) except that the given pattern
	* argument is used as the filename pattern, the file limit is
	* set to no limit, and the file count is set to one.
	* <p>
	* There is no limit on the amount of data that may be written,
	* so use this with care.
	*
	* @param pattern the name of the output file
	* @exception IOException if there are IO problems opening the files.
	* @exception SecurityException if a security manager exists and if
	* the caller does not have <tt>LoggingPermission("control")</tt>.
	* @exception IllegalArgumentException if pattern is an empty string
	*/
	public FileHandler(String pattern) throws IOException, SecurityException {
	if (pattern.length() < 1 ) {
	throw new IllegalArgumentException();
	}
	checkPermission();
	configure();
	this.pattern = pattern;
	this.limit = 0;
	this.count = 1;
	openFiles();
	}

	/**
	* Initialize a <tt>FileHandler</tt> to write to the given filename,
	* with optional append.
	* <p>
	* The <tt>FileHandler</tt> is configured based on <tt>LogManager</tt>
	* properties (or their default values) except that the given pattern
	* argument is used as the filename pattern, the file limit is
	* set to no limit, the file count is set to one, and the append
	* mode is set to the given <tt>append</tt> argument.
	* <p>
	* There is no limit on the amount of data that may be written,
	* so use this with care.
	*
	* @param pattern the name of the output file
	* @param append specifies append mode
	* @exception IOException if there are IO problems opening the files.
	* @exception SecurityException if a security manager exists and if
	* the caller does not have <tt>LoggingPermission("control")</tt>.
	* @exception IllegalArgumentException if pattern is an empty string
	*/
	public FileHandler(String pattern, boolean append) throws IOException,
	SecurityException {
	if (pattern.length() < 1 ) {
	throw new IllegalArgumentException();
	}
	checkPermission();
	configure();
	this.pattern = pattern;
	this.limit = 0;
	this.count = 1;
	this.append = append;
	openFiles();
	}

	/**
	* Initialize a <tt>FileHandler</tt> to write to a set of files. When
	* (approximately) the given limit has been written to one file,
	* another file will be opened. The output will cycle through a set
	* of count files.
	* <p>
	* The <tt>FileHandler</tt> is configured based on <tt>LogManager</tt>
	* properties (or their default values) except that the given pattern
	* argument is used as the filename pattern, the file limit is
	* set to the limit argument, and the file count is set to the
	* given count argument.
	* <p>
	* The count must be at least 1.
	*
	* @param pattern the pattern for naming the output file
	* @param limit the maximum number of bytes to write to any one file
	* @param count the number of files to use
	* @exception IOException if there are IO problems opening the files.
	* @exception SecurityException if a security manager exists and if
	* the caller does not have <tt>LoggingPermission("control")</tt>.
	* @exception IllegalArgumentException if {@code limit < 0}, or {@code count < 1}.
	* @exception IllegalArgumentException if pattern is an empty string
	*/
	public FileHandler(String pattern, int limit, int count)
	throws IOException, SecurityException {
	if (limit < 0 \|\| count < 1 \|\| pattern.length() < 1) {
	throw new IllegalArgumentException();
	}
	checkPermission();
	configure();
	this.pattern = pattern;
	this.limit = limit;
	this.count = count;
	openFiles();
	}

	/**
	* Initialize a <tt>FileHandler</tt> to write to a set of files
	* with optional append. When (approximately) the given limit has
	* been written to one file, another file will be opened. The
	* output will cycle through a set of count files.
	* <p>
	* The <tt>FileHandler</tt> is configured based on <tt>LogManager</tt>
	* properties (or their default values) except that the given pattern
	* argument is used as the filename pattern, the file limit is
	* set to the limit argument, and the file count is set to the
	* given count argument, and the append mode is set to the given
	* <tt>append</tt> argument.
	* <p>
	* The count must be at least 1.
	*
	* @param pattern the pattern for naming the output file
	* @param limit the maximum number of bytes to write to any one file
	* @param count the number of files to use
	* @param append specifies append mode
	* @exception IOException if there are IO problems opening the files.
	* @exception SecurityException if a security manager exists and if
	* the caller does not have <tt>LoggingPermission("control")</tt>.
	* @exception IllegalArgumentException if {@code limit < 0}, or {@code count < 1}.
	* @exception IllegalArgumentException if pattern is an empty string
	*
	*/
	public FileHandler(String pattern, int limit, int count, boolean append)
	throws IOException, SecurityException {
	if (limit < 0 \|\| count < 1 \|\| pattern.length() < 1) {
	throw new IllegalArgumentException();
	}
	checkPermission();
	configure();
	this.pattern = pattern;
	this.limit = limit;
	this.count = count;
	this.append = append;
	openFiles();
	}

	private boolean isParentWritable(Path path) {
	Path parent = path.getParent();
	if (parent == null) {
	parent = path.toAbsolutePath().getParent();
	}
	return parent != null && Files.isWritable(parent);
	}

	/**
	* Open the set of output files, based on the configured
	* instance variables.
	*/
	private void openFiles() throws IOException {
	LogManager manager = LogManager.getLogManager();
	manager.checkPermission();
	if (count < 1) {
	throw new IllegalArgumentException("file count = " + count);
	}
	if (limit < 0) {
	limit = 0;
	}

	// We register our own ErrorManager during initialization
	// so we can record exceptions.
	InitializationErrorManager em = new InitializationErrorManager();
	setErrorManager(em);

	// Create a lock file. This grants us exclusive access
	// to our set of output files, as long as we are alive.
	int unique = -1;
	for (;;) {
	unique++;
	if (unique > maxLocks) {
	throw new IOException("Couldn't get lock for " + pattern
	+ ", maxLocks: " + maxLocks);
	}
	// Generate a lock file name from the "unique" int.
	lockFileName = generate(pattern, 0, unique).toString() + ".lck";
	// Now try to lock that filename.
	// Because some systems (e.g., Solaris) can only do file locks
	// between processes (and not within a process), we first check
	// if we ourself already have the file locked.
	synchronized(locks) {
	if (locks.contains(lockFileName)) {
	// We already own this lock, for a different FileHandler
	// object. Try again.
	continue;
	}

	final Path lockFilePath = Paths.get(lockFileName);
	FileChannel channel = null;
	int retries = -1;
	boolean fileCreated = false;
	while (channel == null && retries++ < 1) {
	try {
	channel = FileChannel.open(lockFilePath,
	CREATE_NEW, WRITE);
	fileCreated = true;
	} catch (FileAlreadyExistsException ix) {
	// This may be a zombie file left over by a previous
	// execution. Reuse it - but only if we can actually
	// write to its directory.
	// Note that this is a situation that may happen,
	// but not too frequently.
	if (Files.isRegularFile(lockFilePath, LinkOption.NOFOLLOW_LINKS)
	&& isParentWritable(lockFilePath)) {
	try {
	channel = FileChannel.open(lockFilePath,
	WRITE, APPEND);
	} catch (NoSuchFileException x) {
	// Race condition - retry once, and if that
	// fails again just try the next name in
	// the sequence.
	continue;
	} catch(IOException x) {
	// the file may not be writable for us.
	// try the next name in the sequence
	break;
	}
	} else {
	// at this point channel should still be null.
	// break and try the next name in the sequence.
	break;
	}
	}
	}

	if (channel == null) continue; // try the next name;
	lockFileChannel = channel;

	boolean available;
	try {
	available = lockFileChannel.tryLock() != null;
	// We got the lock OK.
	// At this point we could call File.deleteOnExit().
	// However, this could have undesirable side effects
	// as indicated by JDK-4872014. So we will instead
	// rely on the fact that close() will remove the lock
	// file and that whoever is creating FileHandlers should
	// be responsible for closing them.
	} catch (IOException ix) {
	// We got an IOException while trying to get the lock.
	// This normally indicates that locking is not supported
	// on the target directory. We have to proceed without
	// getting a lock. Drop through, but only if we did
	// create the file...
	available = fileCreated;
	} catch (OverlappingFileLockException x) {
	// someone already locked this file in this VM, through
	// some other channel - that is - using something else
	// than new FileHandler(...);
	// continue searching for an available lock.
	available = false;
	}
	if (available) {
	// We got the lock. Remember it.
	locks.add(lockFileName);
	break;
	}

	// We failed to get the lock. Try next file.
	lockFileChannel.close();
	}
	}

	files = new File[count];
	for (int i = 0; i < count; i++) {
	files[i] = generate(pattern, i, unique);
	}

	// Create the initial log file.
	if (append) {
	open(files[0], true);
	} else {
	rotate();
	}

	// Did we detect any exceptions during initialization?
	Exception ex = em.lastException;
	if (ex != null) {
	if (ex instanceof IOException) {
	throw (IOException) ex;
	} else if (ex instanceof SecurityException) {
	throw (SecurityException) ex;
	} else {
	throw new IOException("Exception: " + ex);
	}
	}

	// Install the normal default ErrorManager.
	setErrorManager(new ErrorManager());
	}

	/**
	* Generate a file based on a user-supplied pattern, generation number,
	* and an integer uniqueness suffix
	* @param pattern the pattern for naming the output file
	* @param generation the generation number to distinguish rotated logs
	* @param unique a unique number to resolve conflicts
	* @return the generated File
	* @throws IOException
	*/
	private File generate(String pattern, int generation, int unique)
	throws IOException {
	File file = null;
	String word = "";
	int ix = 0;
	boolean sawg = false;
	boolean sawu = false;
	while (ix < pattern.length()) {
	char ch = pattern.charAt(ix);
	ix++;
	char ch2 = 0;
	if (ix < pattern.length()) {
	ch2 = Character.toLowerCase(pattern.charAt(ix));
	}
	if (ch == '/') {
	if (file == null) {
	file = new File(word);
	} else {
	file = new File(file, word);
	}
	word = "";
	continue;
	} else if (ch == '%') {
	if (ch2 == 't') {
	String tmpDir = System.getProperty("java.io.tmpdir");
	if (tmpDir == null) {
	tmpDir = System.getProperty("user.home");
	}
	file = new File(tmpDir);
	ix++;
	word = "";
	continue;
	} else if (ch2 == 'h') {
	file = new File(System.getProperty("user.home"));
	if (isSetUID()) {
	// Ok, we are in a set UID program. For safety's sake
	// we disallow attempts to open files relative to %h.
	throw new IOException("can't use %h in set UID program");
	}
	ix++;
	word = "";
	continue;
	} else if (ch2 == 'g') {
	word = word + generation;
	sawg = true;
	ix++;
	continue;
	} else if (ch2 == 'u') {
	word = word + unique;
	sawu = true;
	ix++;
	continue;
	} else if (ch2 == '%') {
	word = word + "%";
	ix++;
	continue;
	}
	}
	word = word + ch;
	}
	if (count > 1 && !sawg) {
	word = word + "." + generation;
	}
	if (unique > 0 && !sawu) {
	word = word + "." + unique;
	}
	if (word.length() > 0) {
	if (file == null) {
	file = new File(word);
	} else {
	file = new File(file, word);
	}
	}
	return file;
	}

	/**
	* Rotate the set of output files
	*/
	private synchronized void rotate() {
	Level oldLevel = getLevel();
	setLevel(Level.OFF);

	super.close();
	for (int i = count-2; i >= 0; i--) {
	File f1 = files[i];
	File f2 = files[i+1];
	if (f1.exists()) {
	if (f2.exists()) {
	f2.delete();
	}
	f1.renameTo(f2);
	}
	}
	try {
	open(files[0], false);
	} catch (IOException ix) {
	// We don't want to throw an exception here, but we
	// report the exception to any registered ErrorManager.
	reportError(null, ix, ErrorManager.OPEN_FAILURE);

	}
	setLevel(oldLevel);
	}

	/**
	* Format and publish a <tt>LogRecord</tt>.
	*
	* @param record description of the log event. A null record is
	* silently ignored and is not published
	*/
	@Override
	public synchronized void publish(LogRecord record) {
	if (!isLoggable(record)) {
	return;
	}
	super.publish(record);
	flush();
	if (limit > 0 && meter.written >= limit) {
	// We performed access checks in the "init" method to make sure
	// we are only initialized from trusted code. So we assume
	// it is OK to write the target files, even if we are
	// currently being called from untrusted code.
	// So it is safe to raise privilege here.
	AccessController.doPrivileged(new PrivilegedAction<Object>() {
	@Override
	public Object run() {
	rotate();
	return null;
	}
	});
	}
	}

	/**
	* Close all the files.
	*
	* @exception SecurityException if a security manager exists and if
	* the caller does not have <tt>LoggingPermission("control")</tt>.
	*/
	@Override
	public synchronized void close() throws SecurityException {
	super.close();
	// Unlock any lock file.
	if (lockFileName == null) {
	return;
	}
	try {
	// Close the lock file channel (which also will free any locks)
	lockFileChannel.close();
	} catch (Exception ex) {
	// Problems closing the stream. Punt.
	}
	synchronized(locks) {
	locks.remove(lockFileName);
	}
	new File(lockFileName).delete();
	lockFileName = null;
	lockFileChannel = null;
	}

	private static class InitializationErrorManager extends ErrorManager {
	Exception lastException;
	@Override
	public void error(String msg, Exception ex, int code) {
	lastException = ex;
	}
	}

	/**
	* check if we are in a set UID program.
	*/
	private static native boolean isSetUID();
	}

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