doug daniels

package com.webwars.logging;

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.FileLock;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.logging.ErrorManager;
import java.util.logging.Filter;
import java.util.logging.Formatter;
import java.util.logging.Level;
import java.util.logging.LogManager;
import java.util.logging.LogRecord;
import java.util.logging.StreamHandler;
import java.util.logging.XMLFormatter;

/**
 * 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. If
 * properties are not defined (or have invalid values) then the specified
 * default values are used.
 * <ul>
 * <li>java.util.logging.FileHandler.level specifies the default level for the
 * <tt>Handler</tt> (defaults to <tt>Level.ALL</tt>).
 * <li>java.util.logging.FileHandler.filter specifies the name of a
 * <tt>Filter</tt> class to use (defaults to no <tt>Filter</tt>).
 * <li>java.util.logging.FileHandler.formatter specifies the name of a
 * <tt>Formatter</tt> class to use (defaults to
 * <tt>java.util.logging.XMLFormatter</tt>)
 * <li>java.util.logging.FileHandler.encoding the name of the character set
 * encoding to use (defaults to the default platform encoding).
 * <li>java.util.logging.FileHandler.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>java.util.logging.FileHandler.count specifies how many output files to
 * cycle through (defaults to 1).
 * <li>java.util.logging.FileHandler.pattern specifies a pattern for generating
 * the output file name. See below for details. (Defaults to "%h/java%u.log").
 * <li>java.util.logging.FileHandler.append specifies whether the FileHandler
 * should append onto any existing files (defaults to false).
 * </ul>
 * <p>
 * <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>"%t" the system temporary directory
 * <li>"%h" the value of the "user.home" system property
 * <li>"%g" the generation number to distinguish rotated logs
 * <li>"%u" a unique number to resolve conflicts
 * <li>"%%" translates to a single percent sign "%"
 * </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.
 *
 * @version 1.36, 04/07/06
 * @since 1.4
 */

public class WebwarsFileHandler extends StreamHandler {
    private LogManager manager = LogManager.getLogManager();

    private MeteredStream meter;

    private boolean append;

    private int limit; // zero => no limit.

    private int count;

    private String pattern;

    private String lockFileName;

    private FileOutputStream lockStream;

    private File files[];

    private static final int MAX_LOCKS = 100;

    private static java.util.HashMap locks = new java.util.HashMap();

    // 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 {
        OutputStream out;

        int written;

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

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

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

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

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

        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);
    }

    // Private method to 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 = getStringProperty(cname + ".pattern", "%h/java%u.log");
        limit = getIntProperty(cname + ".limit", 0);
        if (limit < 0) {
            limit = 0;
        }
        count = getIntProperty(cname + ".count", 1);
        if (count <= 0) {
            count = 1;
        }
        append = getBooleanProperty(cname + ".append", false);
        setLevel(getLevelProperty(cname + ".level", Level.ALL));
        setFilter(getFilterProperty(cname + ".filter", null));
        setFormatter(getFormatterProperty(cname + ".formatter",
                new XMLFormatter()));
        try {
            setEncoding(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 WebwarsFileHandler() throws IOException, SecurityException {
        // checkAccess();
        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 WebwarsFileHandler(String pattern) throws IOException,
            SecurityException {
        if (pattern.length() < 1) {
            throw new IllegalArgumentException();
        }
        // checkAccess();
        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 WebwarsFileHandler(String pattern, boolean append)
            throws IOException, SecurityException {
        if (pattern.length() < 1) {
            throw new IllegalArgumentException();
        }
        // checkAccess();
        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 limit < 0, or count < 1.
     * @exception IllegalArgumentException
     *                if pattern is an empty string
     */
    public WebwarsFileHandler(String pattern, int limit, int count)
            throws IOException, SecurityException {
        if (limit < 0 || count < 1 || pattern.length() < 1) {
            throw new IllegalArgumentException();
        }
        // checkAccess();
        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 limit < 0, or count < 1.
     * @exception IllegalArgumentException
     *                if pattern is an empty string
     *
     */
    public WebwarsFileHandler(String pattern, int limit, int count,
            boolean append) throws IOException, SecurityException {
        if (limit < 0 || count < 1 || pattern.length() < 1) {
            throw new IllegalArgumentException();
        }
        // checkAccess();
        configure();
        this.pattern = pattern;
        this.limit = limit;
        this.count = count;
        this.append = append;
        openFiles();
    }

    // Private method to open the set of output files, based on the
    // configured instance variables.
    private void openFiles() throws IOException {
        LogManager manager = LogManager.getLogManager();
        manager.checkAccess();
        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 > MAX_LOCKS) {
                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.get(lockFileName) != null) {
                    // We already own this lock, for a different FileHandler
                    // object. Try again.
                    continue;
                }
                FileChannel fc;
                try {
                    File lockFile = new File(lockFileName);
                    if (lockFile.getParent() != null) {
                        File lockParentDir = new File(lockFile.getParent());
                        // create the log dir if it does not exist
                        if (!lockParentDir.exists()) {
                            lockParentDir.mkdirs();
                        }
                    }

                    lockStream = new FileOutputStream(lockFileName);
                    fc = lockStream.getChannel();
                } catch (IOException ix) {
                    // We got an IOException while trying to open the file.
                    // Try the next file.
                    continue;
                }
                try {
                    FileLock fl = fc.tryLock();
                    if (fl == null) {
                        // We failed to get the lock. Try next file.
                        continue;
                    }
                    // We got the lock OK.
                } 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.
                }
                // We got the lock. Remember it.
                locks.put(lockFileName, lockFileName);
                break;
            }
        }

        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 filename from a pattern.
    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
     */
    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() {
                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>.
     */
    public synchronized void close() throws SecurityException {
        super.close();
        // Unlock any lock file.
        if (lockFileName == null) {
            return;
        }
        try {
            // Closing the lock file's FileOutputStream will close
            // the underlying channel and free any locks.
            lockStream.close();
        } catch (Exception ex) {
            // Problems closing the stream. Punt.
        }
        synchronized (locks) {
            locks.remove(lockFileName);
        }
        new File(lockFileName).delete();
        lockFileName = null;
        lockStream = null;
    }

    private static class InitializationErrorManager extends ErrorManager {
        Exception lastException;

        public void error(String msg, Exception ex, int code) {
            lastException = ex;
        }
    }

    // Package private method to get a String property.
    // If the property is not defined we return the given
    // default value.
    protected String getStringProperty(String name, String defaultValue) {
        String val = manager.getProperty(name);
        if (val == null) {
            return defaultValue;
        }
        return val.trim();
    }

    // Package private method to get an integer property.
    // If the property is not defined or cannot be parsed
    // we return the given default value.
    protected int getIntProperty(String name, int defaultValue) {
        String val = manager.getProperty(name);
        if (val == null) {
            return defaultValue;
        }
        try {
            return Integer.parseInt(val.trim());
        } catch (Exception ex) {
            return defaultValue;
        }
    }

    // Package private method to get a boolean property.
    // If the property is not defined or cannot be parsed
    // we return the given default value.
    protected boolean getBooleanProperty(String name, boolean defaultValue) {
        String val = manager.getProperty(name);
        if (val == null) {
            return defaultValue;
        }
        val = val.toLowerCase();
        if (val.equals("true") || val.equals("1")) {
            return true;
        } else if (val.equals("false") || val.equals("0")) {
            return false;
        }
        return defaultValue;
    }

    // Package private method to get a Level property.
    // If the property is not defined or cannot be parsed
    // we return the given default value.
    protected Level getLevelProperty(String name, Level defaultValue) {
        String val = manager.getProperty(name);
        if (val == null) {
            return defaultValue;
        }
        try {
            return Level.parse(val.trim());
        } catch (Exception ex) {
            return defaultValue;
        }
    }

    // Package private method to get a filter property.
    // We return an instance of the class named by the "name"
    // property. If the property is not defined or has problems
    // we return the defaultValue.
    protected Filter getFilterProperty(String name, Filter defaultValue) {
        String val = manager.getProperty(name);
        try {
            if (val != null) {
                Class clz = ClassLoader.getSystemClassLoader().loadClass(val);
                return (Filter) clz.newInstance();
            }
        } catch (Exception ex) {
            // We got one of a variety of exceptions in creating the
            // class or creating an instance.
            // Drop through.
        }
        // We got an exception. Return the defaultValue.
        return defaultValue;
    }

    // Package private method to get a formatter property.
    // We return an instance of the class named by the "name"
    // property. If the property is not defined or has problems
    // we return the defaultValue.
    protected Formatter getFormatterProperty(String name, Formatter defaultValue) {
        String val = manager.getProperty(name);
        try {
            if (val != null) {
                Class clz = ClassLoader.getSystemClassLoader().loadClass(val);
                return (Formatter) clz.newInstance();
            }
        } catch (Exception ex) {
            // We got one of a variety of exceptions in creating the
            // class or creating an instance.
            // Drop through.
        }
        // We got an exception. Return the defaultValue.
        return defaultValue;
    }
}