/*

 * Copyright (c) 2000, 2013, 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

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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 {@code Handler}.

 * <p>

 * The {@code FileHandler} 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 {@code XMLFormatter} class is used for formatting.

 * <p>

 * <b>Configuration:</b>

 * By default each {@code FileHandler} is initialized using the following

 * {@code LogManager} configuration properties where {@code <handler-name>}

 * 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>   &lt;handler-name&gt;.level

 *        specifies the default level for the {@code Handler}

 *        (defaults to {@code Level.ALL}). </li>

 * <li>   &lt;handler-name&gt;.filter

 *        specifies the name of a {@code Filter} class to use

 *        (defaults to no {@code Filter}). </li>

 * <li>   &lt;handler-name&gt;.formatter

 *        specifies the name of a {@code Formatter} class to use

 *        (defaults to {@code java.util.logging.XMLFormatter}) </li>

 * <li>   &lt;handler-name&gt;.encoding

 *        the name of the character set encoding to use (defaults to

 *        the default platform encoding). </li>

 * <li>   &lt;handler-name&gt;.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>   &lt;handler-name&gt;.count

 *        specifies how many output files to cycle through (defaults to 1). </li>

 * <li>   &lt;handler-name&gt;.pattern

 *        specifies a pattern for generating the output file name.  See

 *        below for details. (Defaults to "%h/java%u.log"). </li>

 * <li>   &lt;handler-name&gt;.append

 *        specifies whether the FileHandler should append onto

 *        any existing files (defaults to false). </li>

 * <li>   &lt;handler-name&gt;.maxLocks

 *        specifies the maximum number of concurrent locks held by

 *        FileHandler (defaults to 100). </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 {@code FileHandler}

 * 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 {@code FileHandler} 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 long limit;       // zero => no limit.

    private int count;

    private String pattern;

    private String lockFileName;

    private FileChannel lockFileChannel;

    private File files[];

    private static final int MAX_LOCKS = 100;

    private int maxLocks = MAX_LOCKS;

    private static final Set<String> locks = new HashSet<>();

    /**

     * 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 static final class MeteredStream extends OutputStream {

        final OutputStream out;

        long written;

        MeteredStream(OutputStream out, long 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 {

        long len = 0;

        if (append) {

            len = 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.getLongProperty(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()));

        // Initialize maxLocks from the logging.properties file.

        // If invalid/no property is provided 100 will be used as a default value.

        maxLocks = manager.getIntProperty(cname + ".maxLocks", MAX_LOCKS);

        if(maxLocks <= 0) {

            maxLocks = MAX_LOCKS;

        }

        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 {@code FileHandler}.  This will be configured

     * entirely from {@code LogManager} properties (or their default values).

     *

     * @exception  IOException if there are IO problems opening the files.

     * @exception  SecurityException  if a security manager exists and if

     *             the caller does not have {@code LoggingPermission("control"))}.

     * @exception  NullPointerException if pattern property is an empty String.

     */

    public FileHandler() throws IOException, SecurityException {

        checkPermission();

        configure();

        // pattern will have been set by configure. check that it's not

        // empty.

        if (pattern.isEmpty()) {

            throw new NullPointerException();

        }

        openFiles();

    }

    /**

     * Initialize a {@code FileHandler} to write to the given filename.

     * <p>

     * The {@code FileHandler} is configured based on {@code LogManager}

     * 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 {@code LoggingPermission("control")}.

     * @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 {@code FileHandler} to write to the given filename,

     * with optional append.

     * <p>

     * The {@code FileHandler} is configured based on {@code LogManager}

     * 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 {@code append} 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 {@code LoggingPermission("control")}.

     * @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 {@code FileHandler} 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 {@code FileHandler} is configured based on {@code LogManager}

     * 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 {@code LoggingPermission("control")}.

     * @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 {@code FileHandler} 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 {@code FileHandler} is configured based on {@code LogManager}

     * 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

     * {@code append} 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 {@code LoggingPermission("control")}.

     * @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 {

        this(pattern, (long)limit, count, append);

    }

    /**

     * Initialize a {@code FileHandler} 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 {@code FileHandler} is configured based on {@code LogManager}

     * 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

     * {@code append} 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 {@code LoggingPermission("control")}.

     * @exception  IllegalArgumentException if {@code limit < 0}, or {@code count < 1}.

     * @exception  IllegalArgumentException if pattern is an empty string

     *

     * @since 9

     *

     */

    public FileHandler(String pattern, long limit, int count, boolean append)

                                        throws IOException {

        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;

        }

        // All constructors check that pattern is neither null nor empty.

        assert pattern != null : "pattern should not be null";

        assert !pattern.isEmpty() : "pattern should not be empty";

        // 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);

            }

            // 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);