/*
 * Copyright (c) 2009, 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 jdk.nio.zipfs;

import java.io.BufferedOutputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.EOFException;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.Runtime.Version;
import java.nio.ByteBuffer;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileLock;
import java.nio.channels.ReadableByteChannel;
import java.nio.channels.SeekableByteChannel;
import java.nio.channels.WritableByteChannel;
import java.nio.file.*;
import java.nio.file.attribute.*;
import java.nio.file.spi.FileSystemProvider;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.*;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.jar.Attributes;
import java.util.jar.Manifest;
import java.util.regex.Pattern;
import java.util.zip.CRC32;
import java.util.zip.Deflater;
import java.util.zip.DeflaterOutputStream;
import java.util.zip.Inflater;
import java.util.zip.InflaterInputStream;
import java.util.zip.ZipException;

import static java.lang.Boolean.TRUE;
import static java.nio.file.StandardCopyOption.COPY_ATTRIBUTES;
import static java.nio.file.StandardCopyOption.REPLACE_EXISTING;
import static java.nio.file.StandardOpenOption.APPEND;
import static java.nio.file.StandardOpenOption.CREATE;
import static java.nio.file.StandardOpenOption.CREATE_NEW;
import static java.nio.file.StandardOpenOption.READ;
import static java.nio.file.StandardOpenOption.TRUNCATE_EXISTING;
import static java.nio.file.StandardOpenOption.WRITE;
import static jdk.nio.zipfs.ZipConstants.*;
import static jdk.nio.zipfs.ZipUtils.*;

A FileSystem built on a zip file
Author:
Xueming Shen/**
 * A FileSystem built on a zip file
 *
 * @author Xueming Shen
 */
class ZipFileSystem extends FileSystem {
    // statics
    private static final boolean isWindows = AccessController.doPrivileged(
        (PrivilegedAction<Boolean>)()->System.getProperty("os.name")
                                             .startsWith("Windows"));
    private static final byte[] ROOTPATH = new byte[] { '/' };
    private static final String PROPERTY_POSIX = "enablePosixFileAttributes";
    private static final String PROPERTY_DEFAULT_OWNER = "defaultOwner";
    private static final String PROPERTY_DEFAULT_GROUP = "defaultGroup";
    private static final String PROPERTY_DEFAULT_PERMISSIONS = "defaultPermissions";
    // Property used to specify the entry version to use for a multi-release JAR
    private static final String PROPERTY_RELEASE_VERSION = "releaseVersion";
    // Original property used to specify the entry version to use for a
    // multi-release JAR which is kept for backwards compatibility.
    private static final String PROPERTY_MULTI_RELEASE = "multi-release";

    private static final Set<PosixFilePermission> DEFAULT_PERMISSIONS =
        PosixFilePermissions.fromString("rwxrwxrwx");
    // Property used to specify the compression mode to use
    private static final String PROPERTY_COMPRESSION_METHOD = "compressionMethod";
    // Value specified for compressionMethod property to compress Zip entries
    private static final String COMPRESSION_METHOD_DEFLATED = "DEFLATED";
    // Value specified for compressionMethod property to not compress Zip entries
    private static final String COMPRESSION_METHOD_STORED = "STORED";

    private final ZipFileSystemProvider provider;
    private final Path zfpath;
    final ZipCoder zc;
    private final ZipPath rootdir;
    private boolean readOnly; // readonly file system, false by default

    // default time stamp for pseudo entries
    private final long zfsDefaultTimeStamp = System.currentTimeMillis();

    // configurable by env map
    private final boolean noExtt;        // see readExtra()
    private final boolean useTempFile;   // use a temp file for newOS, default
                                         // is to use BAOS for better performance
    private final boolean forceEnd64;
    private final int defaultCompressionMethod; // METHOD_STORED if "noCompression=true"
                                                // METHOD_DEFLATED otherwise

    // entryLookup is identity by default, will be overridden for multi-release jars
    private Function<byte[], byte[]> entryLookup = Function.identity();

    // POSIX support
    final boolean supportPosix;
    private final UserPrincipal defaultOwner;
    private final GroupPrincipal defaultGroup;
    private final Set<PosixFilePermission> defaultPermissions;

    private final Set<String> supportedFileAttributeViews;

    ZipFileSystem(ZipFileSystemProvider provider,
                  Path zfpath,
                  Map<String, ?> env) throws IOException
    {
        // default encoding for name/comment
        String nameEncoding = env.containsKey("encoding") ?
            (String)env.get("encoding") : "UTF-8";
        this.noExtt = "false".equals(env.get("zipinfo-time"));
        this.useTempFile  = isTrue(env, "useTempFile");
        this.forceEnd64 = isTrue(env, "forceZIP64End");
        this.defaultCompressionMethod = getDefaultCompressionMethod(env);
        this.supportPosix = isTrue(env, PROPERTY_POSIX);
        this.defaultOwner = initOwner(zfpath, env);
        this.defaultGroup = initGroup(zfpath, env);
        this.defaultPermissions = initPermissions(env);
        this.supportedFileAttributeViews = supportPosix ?
            Set.of("basic", "posix", "zip") : Set.of("basic", "zip");
        if (Files.notExists(zfpath)) {
            // create a new zip if it doesn't exist
            if (isTrue(env, "create")) {
                try (OutputStream os = Files.newOutputStream(zfpath, CREATE_NEW, WRITE)) {
                    new END().write(os, 0, forceEnd64);
                }
            } else {
                throw new NoSuchFileException(zfpath.toString());
            }
        }
        // sm and existence check
        zfpath.getFileSystem().provider().checkAccess(zfpath, AccessMode.READ);
        boolean writeable = AccessController.doPrivileged(
            (PrivilegedAction<Boolean>)()->Files.isWritable(zfpath));
        this.readOnly = !writeable;
        this.zc = ZipCoder.get(nameEncoding);
        this.rootdir = new ZipPath(this, new byte[]{'/'});
        this.ch = Files.newByteChannel(zfpath, READ);
        try {
            this.cen = initCEN();
        } catch (IOException x) {
            try {
                this.ch.close();
            } catch (IOException xx) {
                x.addSuppressed(xx);
            }
            throw x;
        }
        this.provider = provider;
        this.zfpath = zfpath;

        initializeReleaseVersion(env);
    }

    
Return the compression method to use (STORED or DEFLATED). If the property commpressionMethod is set use its value to determine the compression method to use. If the property is not set, then the default compression is DEFLATED unless the property noCompression is set which is supported for backwards compatibility. 
Params:
env – Zip FS map of properties
Returns:
The Compression method to use/**
     * Return the compression method to use (STORED or DEFLATED).  If the
     * property {@code commpressionMethod} is set use its value to determine
     * the compression method to use.  If the property is not set, then the
     * default compression is DEFLATED unless the property {@code noCompression}
     * is set which is supported for backwards compatibility.
     * @param env Zip FS map of properties
     * @return The Compression method to use
     */
    private int getDefaultCompressionMethod(Map<String, ?> env) {
        int result =
                isTrue(env, "noCompression") ? METHOD_STORED : METHOD_DEFLATED;
        if (env.containsKey(PROPERTY_COMPRESSION_METHOD)) {
            Object compressionMethod =  env.get(PROPERTY_COMPRESSION_METHOD);
            if (compressionMethod != null) {
                if (compressionMethod instanceof String) {
                    switch (((String) compressionMethod).toUpperCase()) {
                        case COMPRESSION_METHOD_STORED:
                            result = METHOD_STORED;
                            break;
                        case COMPRESSION_METHOD_DEFLATED:
                            result = METHOD_DEFLATED;
                            break;
                        default:
                            throw new IllegalArgumentException(String.format(
                                    "The value for the %s property must be %s or %s",
                                    PROPERTY_COMPRESSION_METHOD, COMPRESSION_METHOD_STORED,
                                    COMPRESSION_METHOD_DEFLATED));
                    }
                } else {
                    throw new IllegalArgumentException(String.format(
                            "The Object type for the %s property must be a String",
                            PROPERTY_COMPRESSION_METHOD));
                }
            } else {
                throw new IllegalArgumentException(String.format(
                        "The value for the %s property must be %s or %s",
                        PROPERTY_COMPRESSION_METHOD, COMPRESSION_METHOD_STORED,
                        COMPRESSION_METHOD_DEFLATED));
            }
        }
        return result;
    }

    // returns true if there is a name=true/"true" setting in env
    private static boolean isTrue(Map<String, ?> env, String name) {
        return "true".equals(env.get(name)) || TRUE.equals(env.get(name));
    }

    // Initialize the default owner for files inside the zip archive.
    // If not specified in env, it is the owner of the archive. If no owner can
    // be determined, we try to go with system property "user.name". If that's not
    // accessible, we return "<zipfs_default>".
    private UserPrincipal initOwner(Path zfpath, Map<String, ?> env) throws IOException {
        Object o = env.get(PROPERTY_DEFAULT_OWNER);
        if (o == null) {
            try {
                PrivilegedExceptionAction<UserPrincipal> pa = ()->Files.getOwner(zfpath);
                return AccessController.doPrivileged(pa);
            } catch (UnsupportedOperationException | PrivilegedActionException e) {
                if (e instanceof UnsupportedOperationException ||
                    e.getCause() instanceof NoSuchFileException)
                {
                    PrivilegedAction<String> pa = ()->System.getProperty("user.name");
                    String userName = AccessController.doPrivileged(pa);
                    return ()->userName;
                } else {
                    throw new IOException(e);
                }
            }
        }
        if (o instanceof String) {
            if (((String)o).isEmpty()) {
                throw new IllegalArgumentException("Value for property " +
                        PROPERTY_DEFAULT_OWNER + " must not be empty.");
            }
            return ()->(String)o;
        }
        if (o instanceof UserPrincipal) {
            return (UserPrincipal)o;
        }
        throw new IllegalArgumentException("Value for property " +
                PROPERTY_DEFAULT_OWNER + " must be of type " + String.class +
            " or " + UserPrincipal.class);
    }

    // Initialize the default group for files inside the zip archive.
    // If not specified in env, we try to determine the group of the zip archive itself.
    // If this is not possible/unsupported, we will return a group principal going by
    // the same name as the default owner.
    private GroupPrincipal initGroup(Path zfpath, Map<String, ?> env) throws IOException {
        Object o = env.get(PROPERTY_DEFAULT_GROUP);
        if (o == null) {
            try {
                PosixFileAttributeView zfpv = Files.getFileAttributeView(zfpath, PosixFileAttributeView.class);
                if (zfpv == null) {
                    return defaultOwner::getName;
                }
                PrivilegedExceptionAction<GroupPrincipal> pa = ()->zfpv.readAttributes().group();
                return AccessController.doPrivileged(pa);
            } catch (UnsupportedOperationException | PrivilegedActionException e) {
                if (e instanceof UnsupportedOperationException ||
                    e.getCause() instanceof NoSuchFileException)
                {
                    return defaultOwner::getName;
                } else {
                    throw new IOException(e);
                }
            }
        }
        if (o instanceof String) {
            if (((String)o).isEmpty()) {
                throw new IllegalArgumentException("Value for property " +
                        PROPERTY_DEFAULT_GROUP + " must not be empty.");
            }
            return ()->(String)o;
        }
        if (o instanceof GroupPrincipal) {
            return (GroupPrincipal)o;
        }
        throw new IllegalArgumentException("Value for property " +
                PROPERTY_DEFAULT_GROUP + " must be of type " + String.class +
            " or " + GroupPrincipal.class);
    }

    // Initialize the default permissions for files inside the zip archive.
    // If not specified in env, it will return 777.
    private Set<PosixFilePermission> initPermissions(Map<String, ?> env) {
        Object o = env.get(PROPERTY_DEFAULT_PERMISSIONS);
        if (o == null) {
            return DEFAULT_PERMISSIONS;
        }
        if (o instanceof String) {
            return PosixFilePermissions.fromString((String)o);
        }
        if (!(o instanceof Set)) {
            throw new IllegalArgumentException("Value for property " +
                PROPERTY_DEFAULT_PERMISSIONS + " must be of type " + String.class +
                " or " + Set.class);
        }
        Set<PosixFilePermission> perms = new HashSet<>();
        for (Object o2 : (Set<?>)o) {
            if (o2 instanceof PosixFilePermission) {
                perms.add((PosixFilePermission)o2);
            } else {
                throw new IllegalArgumentException(PROPERTY_DEFAULT_PERMISSIONS +
                    " must only contain objects of type " + PosixFilePermission.class);
            }
        }
        return perms;
    }

    @Override
    public FileSystemProvider provider() {
        return provider;
    }

    @Override
    public String getSeparator() {
        return "/";
    }

    @Override
    public boolean isOpen() {
        return isOpen;
    }

    @Override
    public boolean isReadOnly() {
        return readOnly;
    }

    private void checkWritable() {
        if (readOnly) {
            throw new ReadOnlyFileSystemException();
        }
    }

    void setReadOnly() {
        this.readOnly = true;
    }

    @Override
    public Iterable<Path> getRootDirectories() {
        return List.of(rootdir);
    }

    ZipPath getRootDir() {
        return rootdir;
    }

    @Override
    public ZipPath getPath(String first, String... more) {
        if (more.length == 0) {
            return new ZipPath(this, first);
        }
        StringBuilder sb = new StringBuilder();
        sb.append(first);
        for (String path : more) {
            if (path.length() > 0) {
                if (sb.length() > 0) {
                    sb.append('/');
                }
                sb.append(path);
            }
        }
        return new ZipPath(this, sb.toString());
    }

    @Override
    public UserPrincipalLookupService getUserPrincipalLookupService() {
        throw new UnsupportedOperationException();
    }

    @Override
    public WatchService newWatchService() {
        throw new UnsupportedOperationException();
    }

    FileStore getFileStore(ZipPath path) {
        return new ZipFileStore(path);
    }

    @Override
    public Iterable<FileStore> getFileStores() {
        return List.of(new ZipFileStore(rootdir));
    }

    @Override
    public Set<String> supportedFileAttributeViews() {
        return supportedFileAttributeViews;
    }

    @Override
    public String toString() {
        return zfpath.toString();
    }

    Path getZipFile() {
        return zfpath;
    }

    private static final String GLOB_SYNTAX = "glob";
    private static final String REGEX_SYNTAX = "regex";

    @Override
    public PathMatcher getPathMatcher(String syntaxAndInput) {
        int pos = syntaxAndInput.indexOf(':');
        if (pos <= 0 || pos == syntaxAndInput.length()) {
            throw new IllegalArgumentException();
        }
        String syntax = syntaxAndInput.substring(0, pos);
        String input = syntaxAndInput.substring(pos + 1);
        String expr;
        if (syntax.equalsIgnoreCase(GLOB_SYNTAX)) {
            expr = toRegexPattern(input);
        } else {
            if (syntax.equalsIgnoreCase(REGEX_SYNTAX)) {
                expr = input;
            } else {
                throw new UnsupportedOperationException("Syntax '" + syntax +
                    "' not recognized");
            }
        }
        // return matcher
        final Pattern pattern = Pattern.compile(expr);
        return (path)->pattern.matcher(path.toString()).matches();
    }

    @Override
    public void close() throws IOException {
        beginWrite();
        try {
            if (!isOpen)
                return;
            isOpen = false;          // set closed
        } finally {
            endWrite();
        }
        if (!streams.isEmpty()) {    // unlock and close all remaining streams
            Set<InputStream> copy = new HashSet<>(streams);
            for (InputStream is : copy)
                is.close();
        }
        beginWrite();                // lock and sync
        try {
            AccessController.doPrivileged((PrivilegedExceptionAction<Void>)() -> {
                sync(); return null;
            });
            ch.close();              // close the ch just in case no update
                                     // and sync didn't close the ch
        } catch (PrivilegedActionException e) {
            throw (IOException)e.getException();
        } finally {
            endWrite();
        }

        synchronized (inflaters) {
            for (Inflater inf : inflaters)
                inf.end();
        }
        synchronized (deflaters) {
            for (Deflater def : deflaters)
                def.end();
        }

        beginWrite();                // lock and sync
        try {
            // Clear the map so that its keys & values can be garbage collected
            inodes = null;
        } finally {
            endWrite();
        }

        IOException ioe = null;
        synchronized (tmppaths) {
            for (Path p : tmppaths) {
                try {
                    AccessController.doPrivileged(
                        (PrivilegedExceptionAction<Boolean>)() -> Files.deleteIfExists(p));
                } catch (PrivilegedActionException e) {
                    IOException x = (IOException)e.getException();
                    if (ioe == null)
                        ioe = x;
                    else
                        ioe.addSuppressed(x);
                }
            }
        }
        provider.removeFileSystem(zfpath, this);
        if (ioe != null)
           throw ioe;
    }

    ZipFileAttributes getFileAttributes(byte[] path)
        throws IOException
    {
        beginRead();
        try {
            ensureOpen();
            IndexNode inode = getInode(path);
            if (inode == null) {
                return null;
            } else if (inode instanceof Entry) {
                return (Entry)inode;
            } else if (inode.pos == -1) {
                // pseudo directory, uses METHOD_STORED
                Entry e = supportPosix ?
                    new PosixEntry(inode.name, inode.isdir, METHOD_STORED) :
                    new Entry(inode.name, inode.isdir, METHOD_STORED);
                e.mtime = e.atime = e.ctime = zfsDefaultTimeStamp;
                return e;
            } else {
                return supportPosix ? new PosixEntry(this, inode) : new Entry(this, inode);
            }
        } finally {
            endRead();
        }
    }

    void checkAccess(byte[] path) throws IOException {
        beginRead();
        try {
            ensureOpen();
            // is it necessary to readCEN as a sanity check?
            if (getInode(path) == null) {
                throw new NoSuchFileException(toString());
            }

        } finally {
            endRead();
        }
    }

    void setTimes(byte[] path, FileTime mtime, FileTime atime, FileTime ctime)
        throws IOException
    {
        checkWritable();
        beginWrite();
        try {
            ensureOpen();
            Entry e = getEntry(path);    // ensureOpen checked
            if (e == null)
                throw new NoSuchFileException(getString(path));
            if (e.type == Entry.CEN)
                e.type = Entry.COPY;     // copy e
            if (mtime != null)
                e.mtime = mtime.toMillis();
            if (atime != null)
                e.atime = atime.toMillis();
            if (ctime != null)
                e.ctime = ctime.toMillis();
            update(e);
        } finally {
            endWrite();
        }
    }

    void setOwner(byte[] path, UserPrincipal owner) throws IOException {
        checkWritable();
        beginWrite();
        try {
            ensureOpen();
            Entry e = getEntry(path);    // ensureOpen checked
            if (e == null) {
                throw new NoSuchFileException(getString(path));
            }
            // as the owner information is not persistent, we don't need to
            // change e.type to Entry.COPY
            if (e instanceof PosixEntry) {
                ((PosixEntry)e).owner = owner;
                update(e);
            }
        } finally {
            endWrite();
        }
    }

    void setGroup(byte[] path, GroupPrincipal group) throws IOException {
        checkWritable();
        beginWrite();
        try {
            ensureOpen();
            Entry e = getEntry(path);    // ensureOpen checked
            if (e == null) {
                throw new NoSuchFileException(getString(path));
            }
            // as the group information is not persistent, we don't need to
            // change e.type to Entry.COPY
            if (e instanceof PosixEntry) {
                ((PosixEntry)e).group = group;
                update(e);
            }
        } finally {
            endWrite();
        }
    }

    void setPermissions(byte[] path, Set<PosixFilePermission> perms) throws IOException {
        checkWritable();
        beginWrite();
        try {
            ensureOpen();
            Entry e = getEntry(path);    // ensureOpen checked
            if (e == null) {
                throw new NoSuchFileException(getString(path));
            }
            if (e.type == Entry.CEN) {
                e.type = Entry.COPY;     // copy e
            }
            e.posixPerms = perms == null ? -1 : ZipUtils.permsToFlags(perms);
            update(e);
        } finally {
            endWrite();
        }
    }

    boolean exists(byte[] path) {
        beginRead();
        try {
            ensureOpen();
            return getInode(path) != null;
        } finally {
            endRead();
        }
    }

    boolean isDirectory(byte[] path) {
        beginRead();
        try {
            IndexNode n = getInode(path);
            return n != null && n.isDir();
        } finally {
            endRead();
        }
    }

    // returns the list of child paths of "path"
    Iterator<Path> iteratorOf(ZipPath dir,
                              DirectoryStream.Filter<? super Path> filter)
        throws IOException
    {
        beginWrite();    // iteration of inodes needs exclusive lock
        try {
            ensureOpen();
            byte[] path = dir.getResolvedPath();
            IndexNode inode = getInode(path);
            if (inode == null)
                throw new NotDirectoryException(getString(path));
            List<Path> list = new ArrayList<>();
            IndexNode child = inode.child;
            while (child != null) {
                // (1) Assume each path from the zip file itself is "normalized"
                // (2) IndexNode.name is absolute. see IndexNode(byte[],int,int)
                // (3) If parent "dir" is relative when ZipDirectoryStream
                //     is created, the returned child path needs to be relative
                //     as well.
                ZipPath childPath = new ZipPath(this, child.name, true);
                ZipPath childFileName = childPath.getFileName();
                ZipPath zpath = dir.resolve(childFileName);
                if (filter == null || filter.accept(zpath))
                    list.add(zpath);
                child = child.sibling;
            }
            return list.iterator();
        } finally {
            endWrite();
        }
    }

    void createDirectory(byte[] dir, FileAttribute<?>... attrs) throws IOException {
        checkWritable();
        beginWrite();
        try {
            ensureOpen();
            if (dir.length == 0 || exists(dir))  // root dir, or existing dir
                throw new FileAlreadyExistsException(getString(dir));
            checkParents(dir);
            Entry e = supportPosix ?
                new PosixEntry(dir, Entry.NEW, true, METHOD_STORED, attrs) :
                new Entry(dir, Entry.NEW, true, METHOD_STORED, attrs);
            update(e);
        } finally {
            endWrite();
        }
    }

    void copyFile(boolean deletesrc, byte[]src, byte[] dst, CopyOption... options)
        throws IOException
    {
        checkWritable();
        if (Arrays.equals(src, dst))
            return;    // do nothing, src and dst are the same

        beginWrite();
        try {
            ensureOpen();
            Entry eSrc = getEntry(src);  // ensureOpen checked

            if (eSrc == null)
                throw new NoSuchFileException(getString(src));
            if (eSrc.isDir()) {    // spec says to create dst dir
                createDirectory(dst);
                return;
            }
            boolean hasReplace = false;
            boolean hasCopyAttrs = false;
            for (CopyOption opt : options) {
                if (opt == REPLACE_EXISTING)
                    hasReplace = true;
                else if (opt == COPY_ATTRIBUTES)
                    hasCopyAttrs = true;
            }
            Entry eDst = getEntry(dst);
            if (eDst != null) {
                if (!hasReplace)
                    throw new FileAlreadyExistsException(getString(dst));
            } else {
                checkParents(dst);
            }
            // copy eSrc entry and change name
            Entry u = supportPosix ?
                new PosixEntry((PosixEntry)eSrc, Entry.COPY) :
                new Entry(eSrc, Entry.COPY);
            u.name(dst);
            if (eSrc.type == Entry.NEW || eSrc.type == Entry.FILECH) {
                u.type = eSrc.type;    // make it the same type
                if (deletesrc) {       // if it's a "rename", take the data
                    u.bytes = eSrc.bytes;
                    u.file = eSrc.file;
                } else {               // if it's not "rename", copy the data
                    if (eSrc.bytes != null)
                        u.bytes = Arrays.copyOf(eSrc.bytes, eSrc.bytes.length);
                    else if (eSrc.file != null) {
                        u.file = getTempPathForEntry(null);
                        Files.copy(eSrc.file, u.file, REPLACE_EXISTING);
                    }
                }
            } else if (eSrc.type == Entry.CEN && eSrc.method != defaultCompressionMethod) {

                /**
                 * We are copying a file within the same Zip file using a
                 * different compression method.
                 */
                try (InputStream in = newInputStream(src);
                     OutputStream out = newOutputStream(dst,
                             CREATE, TRUNCATE_EXISTING, WRITE)) {
                    in.transferTo(out);
                }
                u = getEntry(dst);
            }

            if (!hasCopyAttrs)
                u.mtime = u.atime= u.ctime = System.currentTimeMillis();
            update(u);
            if (deletesrc)
                updateDelete(eSrc);
        } finally {
            endWrite();
        }
    }

    // Returns an output stream for writing the contents into the specified
    // entry.
    OutputStream newOutputStream(byte[] path, OpenOption... options)
        throws IOException
    {
        checkWritable();
        boolean hasCreateNew = false;
        boolean hasCreate = false;
        boolean hasAppend = false;
        boolean hasTruncate = false;
        for (OpenOption opt : options) {
            if (opt == READ)
                throw new IllegalArgumentException("READ not allowed");
            if (opt == CREATE_NEW)
                hasCreateNew = true;
            if (opt == CREATE)
                hasCreate = true;
            if (opt == APPEND)
                hasAppend = true;
            if (opt == TRUNCATE_EXISTING)
                hasTruncate = true;
        }
        if (hasAppend && hasTruncate)
            throw new IllegalArgumentException("APPEND + TRUNCATE_EXISTING not allowed");
        beginRead();                 // only need a readlock, the "update()" will
        try {                        // try to obtain a writelock when the os is
            ensureOpen();            // being closed.
            Entry e = getEntry(path);
            if (e != null) {
                if (e.isDir() || hasCreateNew)
                    throw new FileAlreadyExistsException(getString(path));
                if (hasAppend) {
                    OutputStream os = getOutputStream(new Entry(e, Entry.NEW));
                    try (InputStream is = getInputStream(e)) {
                        is.transferTo(os);
                    }
                    return os;
                }
                return getOutputStream(supportPosix ?
                    new PosixEntry((PosixEntry)e, Entry.NEW, defaultCompressionMethod)
                        : new Entry(e, Entry.NEW, defaultCompressionMethod));
            } else {
                if (!hasCreate && !hasCreateNew)
                    throw new NoSuchFileException(getString(path));
                checkParents(path);
                return getOutputStream(supportPosix ?
                    new PosixEntry(path, Entry.NEW, false, defaultCompressionMethod) :
                    new Entry(path, Entry.NEW, false, defaultCompressionMethod));
            }
        } finally {
            endRead();
        }
    }

    // Returns an input stream for reading the contents of the specified
    // file entry.
    InputStream newInputStream(byte[] path) throws IOException {
        beginRead();
        try {
            ensureOpen();
            Entry e = getEntry(path);
            if (e == null)
                throw new NoSuchFileException(getString(path));
            if (e.isDir())
                throw new FileSystemException(getString(path), "is a directory", null);
            return getInputStream(e);
        } finally {
            endRead();
        }
    }

    private void checkOptions(Set<? extends OpenOption> options) {
        // check for options of null type and option is an intance of StandardOpenOption
        for (OpenOption option : options) {
            if (option == null)
                throw new NullPointerException();
            if (!(option instanceof StandardOpenOption))
                throw new IllegalArgumentException();
        }
        if (options.contains(APPEND) && options.contains(TRUNCATE_EXISTING))
            throw new IllegalArgumentException("APPEND + TRUNCATE_EXISTING not allowed");
    }

    // Returns an output SeekableByteChannel for either
    // (1) writing the contents of a new entry, if the entry doesn't exist, or
    // (2) updating/replacing the contents of an existing entry.
    // Note: The content of the channel is not compressed until the
    // channel is closed
    private class EntryOutputChannel extends ByteArrayChannel {
        final Entry e;

        EntryOutputChannel(Entry e) {
            super(e.size > 0? (int)e.size : 8192, false);
            this.e = e;
            if (e.mtime == -1)
                e.mtime = System.currentTimeMillis();
            if (e.method == -1)
                e.method = defaultCompressionMethod;
            // store size, compressed size, and crc-32 in datadescriptor
            e.flag = FLAG_DATADESCR;
            if (zc.isUTF8())
                e.flag |= FLAG_USE_UTF8;
        }

        @Override
        public void close() throws IOException {
            super.beginWrite();
            try {
                if (!isOpen())
                    return;
                // will update the entry
                try (OutputStream os = getOutputStream(e)) {
                    os.write(toByteArray());
                }
                super.close();
            } finally {
                super.endWrite();
            }
        }
    }

    // Returns a Writable/ReadByteChannel for now. Might consider to use
    // newFileChannel() instead, which dump the entry data into a regular
    // file on the default file system and create a FileChannel on top of it.
    SeekableByteChannel newByteChannel(byte[] path,
                                       Set<? extends OpenOption> options,
                                       FileAttribute<?>... attrs)
        throws IOException
    {
        checkOptions(options);
        if (options.contains(StandardOpenOption.WRITE) ||
            options.contains(StandardOpenOption.APPEND)) {
            checkWritable();
            beginRead();    // only need a read lock, the "update()" will obtain
                            // the write lock when the channel is closed
            ensureOpen();
            try {
                Entry e = getEntry(path);
                if (e != null) {
                    if (e.isDir() || options.contains(CREATE_NEW))
                        throw new FileAlreadyExistsException(getString(path));
                    SeekableByteChannel sbc =
                            new EntryOutputChannel(supportPosix ?
                                new PosixEntry((PosixEntry)e, Entry.NEW) :
                                new Entry(e, Entry.NEW));
                    if (options.contains(APPEND)) {
                        try (InputStream is = getInputStream(e)) {  // copyover
                            byte[] buf = new byte[8192];
                            ByteBuffer bb = ByteBuffer.wrap(buf);
                            int n;
                            while ((n = is.read(buf)) != -1) {
                                bb.position(0);
                                bb.limit(n);
                                sbc.write(bb);
                            }
                        }
                    }
                    return sbc;
                }
                if (!options.contains(CREATE) && !options.contains(CREATE_NEW))
                    throw new NoSuchFileException(getString(path));
                checkParents(path);
                return new EntryOutputChannel(
                    supportPosix ?
                        new PosixEntry(path, Entry.NEW, false, defaultCompressionMethod, attrs) :
                        new Entry(path, Entry.NEW, false, defaultCompressionMethod, attrs));
            } finally {
                endRead();
            }
        } else {
            beginRead();
            try {
                ensureOpen();
                Entry e = getEntry(path);
                if (e == null || e.isDir())
                    throw new NoSuchFileException(getString(path));
                try (InputStream is = getInputStream(e)) {
                    // TBD: if (e.size < NNNNN);
                    return new ByteArrayChannel(is.readAllBytes(), true);
                }
            } finally {
                endRead();
            }
        }
    }

    // Returns a FileChannel of the specified entry.
    //
    // This implementation creates a temporary file on the default file system,
    // copy the entry data into it if the entry exists, and then create a
    // FileChannel on top of it.
    FileChannel newFileChannel(byte[] path,
                               Set<? extends OpenOption> options,
                               FileAttribute<?>... attrs)
        throws IOException
    {
        checkOptions(options);
        final  boolean forWrite = (options.contains(StandardOpenOption.WRITE) ||
                                   options.contains(StandardOpenOption.APPEND));
        beginRead();
        try {
            ensureOpen();
            Entry e = getEntry(path);
            if (forWrite) {
                checkWritable();
                if (e == null) {
                    if (!options.contains(StandardOpenOption.CREATE) &&
                        !options.contains(StandardOpenOption.CREATE_NEW)) {
                        throw new NoSuchFileException(getString(path));
                    }
                } else {
                    if (options.contains(StandardOpenOption.CREATE_NEW)) {
                        throw new FileAlreadyExistsException(getString(path));
                    }
                    if (e.isDir())
                        throw new FileAlreadyExistsException("directory <"
                            + getString(path) + "> exists");
                }
                options = new HashSet<>(options);
                options.remove(StandardOpenOption.CREATE_NEW); // for tmpfile
            } else if (e == null || e.isDir()) {
                throw new NoSuchFileException(getString(path));
            }

            final boolean isFCH = (e != null && e.type == Entry.FILECH);
            final Path tmpfile = isFCH ? e.file : getTempPathForEntry(path);
            final FileChannel fch = tmpfile.getFileSystem()
                                           .provider()
                                           .newFileChannel(tmpfile, options, attrs);
            final Entry u = isFCH ? e : (
                supportPosix ?
                new PosixEntry(path, tmpfile, Entry.FILECH, attrs) :
                new Entry(path, tmpfile, Entry.FILECH, attrs));
            if (forWrite) {
                u.flag = FLAG_DATADESCR;
                u.method = defaultCompressionMethod;
            }
            // is there a better way to hook into the FileChannel's close method?
            return new FileChannel() {
                public int write(ByteBuffer src) throws IOException {
                    return fch.write(src);
                }
                public long write(ByteBuffer[] srcs, int offset, int length)
                    throws IOException
                {
                    return fch.write(srcs, offset, length);
                }
                public long position() throws IOException {
                    return fch.position();
                }
                public FileChannel position(long newPosition)
                    throws IOException
                {
                    fch.position(newPosition);
                    return this;
                }
                public long size() throws IOException {
                    return fch.size();
                }
                public FileChannel truncate(long size)
                    throws IOException
                {
                    fch.truncate(size);
                    return this;
                }
                public void force(boolean metaData)
                    throws IOException
                {
                    fch.force(metaData);
                }
                public long transferTo(long position, long count,
                                       WritableByteChannel target)
                    throws IOException
                {
                    return fch.transferTo(position, count, target);
                }
                public long transferFrom(ReadableByteChannel src,
                                         long position, long count)
                    throws IOException
                {
                    return fch.transferFrom(src, position, count);
                }
                public int read(ByteBuffer dst) throws IOException {
                    return fch.read(dst);
                }
                public int read(ByteBuffer dst, long position)
                    throws IOException
                {
                    return fch.read(dst, position);
                }
                public long read(ByteBuffer[] dsts, int offset, int length)
                    throws IOException
                {
                    return fch.read(dsts, offset, length);
                }
                public int write(ByteBuffer src, long position)
                    throws IOException
                {
                   return fch.write(src, position);
                }
                public MappedByteBuffer map(MapMode mode,
                                            long position, long size)
                {
                    throw new UnsupportedOperationException();
                }
                public FileLock lock(long position, long size, boolean shared)
                    throws IOException
                {
                    return fch.lock(position, size, shared);
                }
                public FileLock tryLock(long position, long size, boolean shared)
                    throws IOException
                {
                    return fch.tryLock(position, size, shared);
                }
                protected void implCloseChannel() throws IOException {
                    fch.close();
                    if (forWrite) {
                        u.mtime = System.currentTimeMillis();
                        u.size = Files.size(u.file);
                        update(u);
                    } else {
                        if (!isFCH)    // if this is a new fch for reading
                            removeTempPathForEntry(tmpfile);
                    }
               }
            };
        } finally {
            endRead();
        }
    }

    // the outstanding input streams that need to be closed
    private Set<InputStream> streams =
        Collections.synchronizedSet(new HashSet<>());

    private final Set<Path> tmppaths = Collections.synchronizedSet(new HashSet<>());
    private Path getTempPathForEntry(byte[] path) throws IOException {
        Path tmpPath = createTempFileInSameDirectoryAs(zfpath);
        if (path != null) {
            Entry e = getEntry(path);
            if (e != null) {
                try (InputStream is = newInputStream(path)) {
                    Files.copy(is, tmpPath, REPLACE_EXISTING);
                }
            }
        }
        return tmpPath;
    }

    private void removeTempPathForEntry(Path path) throws IOException {
        Files.delete(path);
        tmppaths.remove(path);
    }

    // check if all parents really exist. ZIP spec does not require
    // the existence of any "parent directory".
    private void checkParents(byte[] path) throws IOException {
        beginRead();
        try {
            while ((path = getParent(path)) != null &&
                    path != ROOTPATH) {
                if (!inodes.containsKey(IndexNode.keyOf(path))) {
                    throw new NoSuchFileException(getString(path));
                }
            }
        } finally {
            endRead();
        }
    }

    private static byte[] getParent(byte[] path) {
        int off = getParentOff(path);
        if (off <= 1)
            return ROOTPATH;
        return Arrays.copyOf(path, off);
    }

    private static int getParentOff(byte[] path) {
        int off = path.length - 1;
        if (off > 0 && path[off] == '/')  // isDirectory
            off--;
        while (off > 0 && path[off] != '/') { off--; }
        return off;
    }

    private void beginWrite() {
        rwlock.writeLock().lock();
    }

    private void endWrite() {
        rwlock.writeLock().unlock();
    }

    private void beginRead() {
        rwlock.readLock().lock();
    }

    private void endRead() {
        rwlock.readLock().unlock();
    }

    ///////////////////////////////////////////////////////////////////

    private volatile boolean isOpen = true;
    private final SeekableByteChannel ch; // channel to the zipfile
    final byte[]  cen;     // CEN & ENDHDR
    private END  end;
    private long locpos;   // position of first LOC header (usually 0)

    private final ReadWriteLock rwlock = new ReentrantReadWriteLock();

    // name -> pos (in cen), IndexNode itself can be used as a "key"
    private LinkedHashMap<IndexNode, IndexNode> inodes;

    final byte[] getBytes(String name) {
        return zc.getBytes(name);
    }

    final String getString(byte[] name) {
        return zc.toString(name);
    }

    @SuppressWarnings("deprecation")
    protected void finalize() throws IOException {
        close();
    }

    // Reads len bytes of data from the specified offset into buf.
    // Returns the total number of bytes read.
    // Each/every byte read from here (except the cen, which is mapped).
    final long readFullyAt(byte[] buf, int off, long len, long pos)
        throws IOException
    {
        ByteBuffer bb = ByteBuffer.wrap(buf);
        bb.position(off);
        bb.limit((int)(off + len));
        return readFullyAt(bb, pos);
    }

    private long readFullyAt(ByteBuffer bb, long pos) throws IOException {
        synchronized(ch) {
            return ch.position(pos).read(bb);
        }
    }

    // Searches for end of central directory (END) header. The contents of
    // the END header will be read and placed in endbuf. Returns the file
    // position of the END header, otherwise returns -1 if the END header
    // was not found or an error occurred.
    private END findEND() throws IOException {
        byte[] buf = new byte[READBLOCKSZ];
        long ziplen = ch.size();
        long minHDR = (ziplen - END_MAXLEN) > 0 ? ziplen - END_MAXLEN : 0;
        long minPos = minHDR - (buf.length - ENDHDR);

        for (long pos = ziplen - buf.length; pos >= minPos; pos -= (buf.length - ENDHDR)) {
            int off = 0;
            if (pos < 0) {
                // Pretend there are some NUL bytes before start of file
                off = (int)-pos;
                Arrays.fill(buf, 0, off, (byte)0);
            }
            int len = buf.length - off;
            if (readFullyAt(buf, off, len, pos + off) != len)
                throw new ZipException("zip END header not found");

            // Now scan the block backwards for END header signature
            for (int i = buf.length - ENDHDR; i >= 0; i--) {
                if (buf[i]   == (byte)'P'    &&
                    buf[i+1] == (byte)'K'    &&
                    buf[i+2] == (byte)'\005' &&
                    buf[i+3] == (byte)'\006' &&
                    (pos + i + ENDHDR + ENDCOM(buf, i) == ziplen)) {
                    // Found END header
                    buf = Arrays.copyOfRange(buf, i, i + ENDHDR);
                    END end = new END();
                    // end.endsub = ENDSUB(buf); // not used
                    end.centot = ENDTOT(buf);
                    end.cenlen = ENDSIZ(buf);
                    end.cenoff = ENDOFF(buf);
                    // end.comlen = ENDCOM(buf); // not used
                    end.endpos = pos + i;
                    // try if there is zip64 end;
                    byte[] loc64 = new byte[ZIP64_LOCHDR];
                    if (end.endpos < ZIP64_LOCHDR ||
                        readFullyAt(loc64, 0, loc64.length, end.endpos - ZIP64_LOCHDR)
                        != loc64.length ||
                        !locator64SigAt(loc64, 0)) {
                        return end;
                    }
                    long end64pos = ZIP64_LOCOFF(loc64);
                    byte[] end64buf = new byte[ZIP64_ENDHDR];
                    if (readFullyAt(end64buf, 0, end64buf.length, end64pos)
                        != end64buf.length ||
                        !end64SigAt(end64buf, 0)) {
                        return end;
                    }
                    // end64 found,
                    long cenlen64 = ZIP64_ENDSIZ(end64buf);
                    long cenoff64 = ZIP64_ENDOFF(end64buf);
                    long centot64 = ZIP64_ENDTOT(end64buf);
                    // double-check
                    if (cenlen64 != end.cenlen && end.cenlen != ZIP64_MINVAL ||
                        cenoff64 != end.cenoff && end.cenoff != ZIP64_MINVAL ||
                        centot64 != end.centot && end.centot != ZIP64_MINVAL32) {
                        return end;
                    }
                    // to use the end64 values
                    end.cenlen = cenlen64;
                    end.cenoff = cenoff64;
                    end.centot = (int)centot64; // assume total < 2g
                    end.endpos = end64pos;
                    return end;
                }
            }
        }
        throw new ZipException("zip END header not found");
    }

    private void makeParentDirs(IndexNode node, IndexNode root) {
        IndexNode parent;
        ParentLookup lookup = new ParentLookup();
        while (true) {
            int off = getParentOff(node.name);
            // parent is root
            if (off <= 1) {
                node.sibling = root.child;
                root.child = node;
                break;
            }
            // parent exists
            lookup = lookup.as(node.name, off);
            if (inodes.containsKey(lookup)) {
                parent = inodes.get(lookup);
                node.sibling = parent.child;
                parent.child = node;
                break;
            }
            // parent does not exist, add new pseudo directory entry
            parent = new IndexNode(Arrays.copyOf(node.name, off), true);
            inodes.put(parent, parent);
            node.sibling = parent.child;
            parent.child = node;
            node = parent;
        }
    }

    // ZIP directory has two issues:
    // (1) ZIP spec does not require the ZIP file to include
    //     directory entry
    // (2) all entries are not stored/organized in a "tree"
    //     structure.
    // A possible solution is to build the node tree ourself as
    // implemented below.
    private void buildNodeTree() {
        beginWrite();
        try {
            IndexNode root = inodes.remove(LOOKUPKEY.as(ROOTPATH));
            if (root == null) {
                root = new IndexNode(ROOTPATH, true);
            }
            IndexNode[] nodes = inodes.values().toArray(new IndexNode[0]);
            inodes.put(root, root);
            for (IndexNode node : nodes) {
                makeParentDirs(node, root);
            }
        } finally {
            endWrite();
        }
    }

    private void removeFromTree(IndexNode inode) {
        IndexNode parent = inodes.get(LOOKUPKEY.as(getParent(inode.name)));
        IndexNode child = parent.child;
        if (child.equals(inode)) {
            parent.child = child.sibling;
        } else {
            IndexNode last = child;
            while ((child = child.sibling) != null) {
                if (child.equals(inode)) {
                    last.sibling = child.sibling;
                    break;
                } else {
                    last = child;
                }
            }
        }
    }

    
If a version property has been specified and the file represents a multi-release JAR,
determine the requested runtime version and initialize the ZipFileSystem instance accordingly.
Checks if the Zip File System property "releaseVersion" has been specified. If it has,
use its value to determine the requested version. If not use the value of the "multi-release" property.
/**
     * If a version property has been specified and the file represents a multi-release JAR,
     * determine the requested runtime version and initialize the ZipFileSystem instance accordingly.
     *
     * Checks if the Zip File System property "releaseVersion" has been specified. If it has,
     * use its value to determine the requested version. If not use the value of the "multi-release" property.
     */
    private void initializeReleaseVersion(Map<String, ?> env) throws IOException {
        Object o = env.containsKey(PROPERTY_RELEASE_VERSION) ?
            env.get(PROPERTY_RELEASE_VERSION) :
            env.get(PROPERTY_MULTI_RELEASE);

        if (o != null && isMultiReleaseJar()) {
            int version;
            if (o instanceof String) {
                String s = (String)o;
                if (s.equals("runtime")) {
                    version = Runtime.version().feature();
                } else if (s.matches("^[1-9][0-9]*$")) {
                    version = Version.parse(s).feature();
                } else {
                    throw new IllegalArgumentException("Invalid runtime version");
                }
            } else if (o instanceof Integer) {
                version = Version.parse(((Integer)o).toString()).feature();
            } else if (o instanceof Version) {
                version = ((Version)o).feature();
            } else {
                throw new IllegalArgumentException("env parameter must be String, " +
                    "Integer, or Version");
            }
            createVersionedLinks(version < 0 ? 0 : version);
            setReadOnly();
        }
    }

    
Returns true if the Manifest main attribute "Multi-Release" is set to true; false otherwise.
/**
     * Returns true if the Manifest main attribute "Multi-Release" is set to true; false otherwise.
     */
    private boolean isMultiReleaseJar() throws IOException {
        try (InputStream is = newInputStream(getBytes("/META-INF/MANIFEST.MF"))) {
            String multiRelease = new Manifest(is).getMainAttributes()
                .getValue(Attributes.Name.MULTI_RELEASE);
            return "true".equalsIgnoreCase(multiRelease);
        } catch (NoSuchFileException x) {
            return false;
        }
    }

    
Create a map of aliases for versioned entries, for example:
  version/PackagePrivate.class -> META-INF/versions/9/version/PackagePrivate.class
  version/PackagePrivate.java -> META-INF/versions/9/version/PackagePrivate.java
  version/Version.class -> META-INF/versions/10/version/Version.class
  version/Version.java -> META-INF/versions/10/version/Version.java
Then wrap the map in a function that getEntry can use to override root
entry lookup for entries that have corresponding versioned entries.
/**
     * Create a map of aliases for versioned entries, for example:
     *   version/PackagePrivate.class -> META-INF/versions/9/version/PackagePrivate.class
     *   version/PackagePrivate.java -> META-INF/versions/9/version/PackagePrivate.java
     *   version/Version.class -> META-INF/versions/10/version/Version.class
     *   version/Version.java -> META-INF/versions/10/version/Version.java
     *
     * Then wrap the map in a function that getEntry can use to override root
     * entry lookup for entries that have corresponding versioned entries.
     */
    private void createVersionedLinks(int version) {
        IndexNode verdir = getInode(getBytes("/META-INF/versions"));
        // nothing to do, if no /META-INF/versions
        if (verdir == null) {
            return;
        }
        // otherwise, create a map and for each META-INF/versions/{n} directory
        // put all the leaf inodes, i.e. entries, into the alias map
        // possibly shadowing lower versioned entries
        HashMap<IndexNode, byte[]> aliasMap = new HashMap<>();
        getVersionMap(version, verdir).values().forEach(versionNode ->
            walk(versionNode.child, entryNode ->
                aliasMap.put(
                    getOrCreateInode(getRootName(entryNode, versionNode), entryNode.isdir),
                    entryNode.name))
        );
        entryLookup = path -> {
            byte[] entry = aliasMap.get(IndexNode.keyOf(path));
            return entry == null ? path : entry;
        };
    }

    
Create a sorted version map of version -> inode, for inodes <= max version.
  9 -> META-INF/versions/9
 10 -> META-INF/versions/10
/**
     * Create a sorted version map of version -> inode, for inodes <= max version.
     *   9 -> META-INF/versions/9
     *  10 -> META-INF/versions/10
     */
    private TreeMap<Integer, IndexNode> getVersionMap(int version, IndexNode metaInfVersions) {
        TreeMap<Integer,IndexNode> map = new TreeMap<>();
        IndexNode child = metaInfVersions.child;
        while (child != null) {
            Integer key = getVersion(child, metaInfVersions);
            if (key != null && key <= version) {
                map.put(key, child);
            }
            child = child.sibling;
        }
        return map;
    }

    
Extract the integer version number -- META-INF/versions/9 returns 9.
/**
     * Extract the integer version number -- META-INF/versions/9 returns 9.
     */
    private Integer getVersion(IndexNode inode, IndexNode metaInfVersions) {
        try {
            byte[] fullName = inode.name;
            return Integer.parseInt(getString(Arrays
                .copyOfRange(fullName, metaInfVersions.name.length + 1, fullName.length)));
        } catch (NumberFormatException x) {
            // ignore this even though it might indicate issues with the JAR structure
            return null;
        }
    }

    
Walk the IndexNode tree processing all leaf nodes.
/**
     * Walk the IndexNode tree processing all leaf nodes.
     */
    private void walk(IndexNode inode, Consumer<IndexNode> consumer) {
        if (inode == null) return;
        if (inode.isDir()) {
            walk(inode.child, consumer);
        } else {
            consumer.accept(inode);
        }
        walk(inode.sibling, consumer);
    }

    
Extract the root name from a versioned entry name.
E.g. given inode 'META-INF/versions/9/foo/bar.class'
and prefix 'META-INF/versions/9/' returns 'foo/bar.class'.
/**
     * Extract the root name from a versioned entry name.
     * E.g. given inode 'META-INF/versions/9/foo/bar.class'
     * and prefix 'META-INF/versions/9/' returns 'foo/bar.class'.
     */
    private byte[] getRootName(IndexNode inode, IndexNode prefix) {
        byte[] fullName = inode.name;
        return Arrays.copyOfRange(fullName, prefix.name.length, fullName.length);
    }

    // Reads zip file central directory. Returns the file position of first
    // CEN header, otherwise returns -1 if an error occurred. If zip->msg != NULL
    // then the error was a zip format error and zip->msg has the error text.
    // Always pass in -1 for knownTotal; it's used for a recursive call.
    private byte[] initCEN() throws IOException {
        end = findEND();
        if (end.endpos == 0) {
            inodes = new LinkedHashMap<>(10);
            locpos = 0;
            buildNodeTree();
            return null;         // only END header present
        }
        if (end.cenlen > end.endpos)
            throw new ZipException("invalid END header (bad central directory size)");
        long cenpos = end.endpos - end.cenlen;     // position of CEN table

        // Get position of first local file (LOC) header, taking into
        // account that there may be a stub prefixed to the zip file.
        locpos = cenpos - end.cenoff;
        if (locpos < 0)
            throw new ZipException("invalid END header (bad central directory offset)");

        // read in the CEN and END
        byte[] cen = new byte[(int)(end.cenlen + ENDHDR)];
        if (readFullyAt(cen, 0, cen.length, cenpos) != end.cenlen + ENDHDR) {
            throw new ZipException("read CEN tables failed");
        }
        // Iterate through the entries in the central directory
        inodes = new LinkedHashMap<>(end.centot + 1);
        int pos = 0;
        int limit = cen.length - ENDHDR;
        while (pos < limit) {
            if (!cenSigAt(cen, pos))
                throw new ZipException("invalid CEN header (bad signature)");
            int method = CENHOW(cen, pos);
            int nlen   = CENNAM(cen, pos);
            int elen   = CENEXT(cen, pos);
            int clen   = CENCOM(cen, pos);
            int flag   = CENFLG(cen, pos);
            if ((flag & 1) != 0) {
                throw new ZipException("invalid CEN header (encrypted entry)");
            }
            if (method != METHOD_STORED && method != METHOD_DEFLATED) {
                throw new ZipException("invalid CEN header (unsupported compression method: " + method + ")");
            }
            if (pos + CENHDR + nlen > limit) {
                throw new ZipException("invalid CEN header (bad header size)");
            }
            IndexNode inode = new IndexNode(cen, pos, nlen);
            inodes.put(inode, inode);
            if (zc.isUTF8() || (flag & FLAG_USE_UTF8) != 0) {
                checkUTF8(inode.name);
            } else {
                checkEncoding(inode.name);
            }
            // skip ext and comment
            pos += (CENHDR + nlen + elen + clen);
        }
        if (pos + ENDHDR != cen.length) {
            throw new ZipException("invalid CEN header (bad header size)");
        }
        buildNodeTree();
        return cen;
    }

    private  final void checkUTF8(byte[] a) throws ZipException {
        try {
            int end = a.length;
            int pos = 0;
            while (pos < end) {
                // ASCII fast-path: When checking that a range of bytes is
                // valid UTF-8, we can avoid some allocation by skipping
                // past bytes in the 0-127 range
                if (a[pos] < 0) {
                    zc.toString(Arrays.copyOfRange(a, pos, a.length));
                    break;
                }
                pos++;
            }
        } catch(Exception e) {
            throw new ZipException("invalid CEN header (bad entry name)");
        }
    }

    private final void checkEncoding( byte[] a) throws ZipException {
        try {
            zc.toString(a);
        } catch(Exception e) {
            throw new ZipException("invalid CEN header (bad entry name)");
        }
    }


    private void ensureOpen() {
        if (!isOpen)
            throw new ClosedFileSystemException();
    }

    // Creates a new empty temporary file in the same directory as the
    // specified file.  A variant of Files.createTempFile.
    private Path createTempFileInSameDirectoryAs(Path path) throws IOException {
        Path parent = path.toAbsolutePath().getParent();
        Path dir = (parent == null) ? path.getFileSystem().getPath(".") : parent;
        Path tmpPath = Files.createTempFile(dir, "zipfstmp", null);
        tmppaths.add(tmpPath);
        return tmpPath;
    }

    ////////////////////update & sync //////////////////////////////////////

    private boolean hasUpdate = false;

    // shared key. consumer guarantees the "writeLock" before use it.
    private final IndexNode LOOKUPKEY = new IndexNode(null, -1);

    private void updateDelete(IndexNode inode) {
        beginWrite();
        try {
            removeFromTree(inode);
            inodes.remove(inode);
            hasUpdate = true;
        } finally {
             endWrite();
        }
    }

    private void update(Entry e) {
        beginWrite();
        try {
            IndexNode old = inodes.put(e, e);
            if (old != null) {
                removeFromTree(old);
            }
            if (e.type == Entry.NEW || e.type == Entry.FILECH || e.type == Entry.COPY) {
                IndexNode parent = inodes.get(LOOKUPKEY.as(getParent(e.name)));
                e.sibling = parent.child;
                parent.child = e;
            }
            hasUpdate = true;
        } finally {
            endWrite();
        }
    }

    // copy over the whole LOC entry (header if necessary, data and ext) from
    // old zip to the new one.
    private long copyLOCEntry(Entry e, boolean updateHeader,
                              OutputStream os,
                              long written, byte[] buf)
        throws IOException
    {
        long locoff = e.locoff;  // where to read
        e.locoff = written;      // update the e.locoff with new value

        // calculate the size need to write out
        long size = 0;
        //  if there is A ext
        if ((e.flag & FLAG_DATADESCR) != 0) {
            if (e.size >= ZIP64_MINVAL || e.csize >= ZIP64_MINVAL)
                size = 24;
            else
                size = 16;
        }
        // read loc, use the original loc.elen/nlen
        //
        // an extra byte after loc is read, which should be the first byte of the
        // 'name' field of the loc. if this byte is '/', which means the original
        // entry has an absolute path in original zip/jar file, the e.writeLOC()
        // is used to output the loc, in which the leading "/" will be removed
        if (readFullyAt(buf, 0, LOCHDR + 1 , locoff) != LOCHDR + 1)
            throw new ZipException("loc: reading failed");

        if (updateHeader || LOCNAM(buf) > 0 && buf[LOCHDR] == '/') {
            locoff += LOCHDR + LOCNAM(buf) + LOCEXT(buf);  // skip header
            size += e.csize;
            written = e.writeLOC(os) + size;
        } else {
            os.write(buf, 0, LOCHDR);    // write out the loc header
            locoff += LOCHDR;
            // use e.csize,  LOCSIZ(buf) is zero if FLAG_DATADESCR is on
            // size += LOCNAM(buf) + LOCEXT(buf) + LOCSIZ(buf);
            size += LOCNAM(buf) + LOCEXT(buf) + e.csize;
            written = LOCHDR + size;
        }
        int n;
        while (size > 0 &&
            (n = (int)readFullyAt(buf, 0, buf.length, locoff)) != -1)
        {
            if (size < n)
                n = (int)size;
            os.write(buf, 0, n);
            size -= n;
            locoff += n;
        }
        return written;
    }

    private long writeEntry(Entry e, OutputStream os)
        throws IOException {

        if (e.bytes == null && e.file == null)    // dir, 0-length data
            return 0;

        long written = 0;
        if (e.method != METHOD_STORED && e.csize > 0 && (e.crc != 0 || e.size == 0)) {
            // pre-compressed entry, write directly to output stream
            writeTo(e, os);
        } else {
            try (OutputStream os2 = (e.method == METHOD_STORED) ?
                    new EntryOutputStreamCRC32(e, os) : new EntryOutputStreamDef(e, os)) {
                writeTo(e, os2);
            }
        }
        written += e.csize;
        if ((e.flag & FLAG_DATADESCR) != 0) {
            written += e.writeEXT(os);
        }
        return written;
    }

    private void writeTo(Entry e, OutputStream os) throws IOException {
        if (e.bytes != null) {
            os.write(e.bytes, 0, e.bytes.length);
        } else if (e.file != null) {
            if (e.type == Entry.NEW || e.type == Entry.FILECH) {
                try (InputStream is = Files.newInputStream(e.file)) {
                    is.transferTo(os);
                }
            }
            Files.delete(e.file);
            tmppaths.remove(e.file);
        }
    }

    // sync the zip file system, if there is any update
    private void sync() throws IOException {
        if (!hasUpdate)
            return;
        PosixFileAttributes attrs = getPosixAttributes(zfpath);
        Path tmpFile = createTempFileInSameDirectoryAs(zfpath);
        try (OutputStream os = new BufferedOutputStream(Files.newOutputStream(tmpFile, WRITE))) {
            ArrayList<Entry> elist = new ArrayList<>(inodes.size());
            long written = 0;
            byte[] buf = null;
            Entry e;

            final IndexNode manifestInode = inodes.get(
                    IndexNode.keyOf(getBytes("/META-INF/MANIFEST.MF")));
            final Iterator<IndexNode> inodeIterator = inodes.values().iterator();
            boolean manifestProcessed = false;

            // write loc
            while (inodeIterator.hasNext()) {
                final IndexNode inode;

                // write the manifest inode (if any) first so that
                // java.util.jar.JarInputStream can find it
                if (manifestInode == null) {
                    inode = inodeIterator.next();
                } else {
                    if (manifestProcessed) {
                        // advance to next node, filtering out the manifest
                        // which was already written
                        inode = inodeIterator.next();
                        if (inode == manifestInode) {
                            continue;
                        }
                    } else {
                        inode = manifestInode;
                        manifestProcessed = true;
                    }
                }

                if (inode instanceof Entry) {    // an updated inode
                    e = (Entry)inode;
                    try {
                        if (e.type == Entry.COPY) {
                            // entry copy: the only thing changed is the "name"
                            // and "nlen" in LOC header, so we update/rewrite the
                            // LOC in new file and simply copy the rest (data and
                            // ext) without enflating/deflating from the old zip
                            // file LOC entry.
                            if (buf == null)
                                buf = new byte[8192];
                            written += copyLOCEntry(e, true, os, written, buf);
                        } else {                          // NEW, FILECH or CEN
                            e.locoff = written;
                            written += e.writeLOC(os);    // write loc header
                            written += writeEntry(e, os);
                        }
                        elist.add(e);
                    } catch (IOException x) {
                        x.printStackTrace();    // skip any in-accurate entry
                    }
                } else {                        // unchanged inode
                    if (inode.pos == -1) {
                        continue;               // pseudo directory node
                    }
                    if (inode.name.length == 1 && inode.name[0] == '/') {
                        continue;               // no root '/' directory even if it
                                                // exists in original zip/jar file.
                    }
                    e = supportPosix ? new PosixEntry(this, inode) : new Entry(this, inode);
                    try {
                        if (buf == null)
                            buf = new byte[8192];
                        written += copyLOCEntry(e, false, os, written, buf);
                        elist.add(e);
                    } catch (IOException x) {
                        x.printStackTrace();    // skip any wrong entry
                    }
                }
            }

            // now write back the cen and end table
            end.cenoff = written;
            for (Entry entry : elist) {
                written += entry.writeCEN(os);
            }
            end.centot = elist.size();
            end.cenlen = written - end.cenoff;
            end.write(os, written, forceEnd64);
        }
        ch.close();
        Files.delete(zfpath);

        // Set the POSIX permissions of the original Zip File if available
        // before moving the temp file
        if (attrs != null) {
            Files.setPosixFilePermissions(tmpFile, attrs.permissions());
        }
        Files.move(tmpFile, zfpath, REPLACE_EXISTING);
        hasUpdate = false;    // clear
    }

    
Returns a file's POSIX file attributes.
Params:
path – The path to the file
Throws:
IOException – If an error occurs obtaining the POSIX attributes for
                   the specified file
Returns:
The POSIX file attributes for the specified file or
        null if the POSIX attribute view is not available/**
     * Returns a file's POSIX file attributes.
     * @param path The path to the file
     * @return The POSIX file attributes for the specified file or
     *         null if the POSIX attribute view is not available
     * @throws IOException If an error occurs obtaining the POSIX attributes for
     *                    the specified file
     */
    private PosixFileAttributes getPosixAttributes(Path path) throws IOException {
        try {
            PosixFileAttributeView view =
                    Files.getFileAttributeView(path, PosixFileAttributeView.class);
            // Return if the attribute view is not supported
            if (view == null) {
                return null;
            }
            return view.readAttributes();
        } catch (UnsupportedOperationException e) {
            // PosixFileAttributes not available
            return null;
        }
    }

    private IndexNode getInode(byte[] path) {
        return inodes.get(IndexNode.keyOf(Objects.requireNonNull(entryLookup.apply(path), "path")));
    }

    
Return the IndexNode from the root tree. If it doesn't exist,
it gets created along with all parent directory IndexNodes.
/**
     * Return the IndexNode from the root tree. If it doesn't exist,
     * it gets created along with all parent directory IndexNodes.
     */
    private IndexNode getOrCreateInode(byte[] path, boolean isdir) {
        IndexNode node = getInode(path);
        // if node exists, return it
        if (node != null) {
            return node;
        }

        // otherwise create new pseudo node and parent directory hierarchy
        node = new IndexNode(path, isdir);
        beginWrite();
        try {
            makeParentDirs(node, Objects.requireNonNull(inodes.get(IndexNode.keyOf(ROOTPATH)), "no root node found"));
            return node;
        } finally {
            endWrite();
        }
    }

    private Entry getEntry(byte[] path) throws IOException {
        IndexNode inode = getInode(path);
        if (inode instanceof Entry)
            return (Entry)inode;
        if (inode == null || inode.pos == -1)
            return null;
        return supportPosix ? new PosixEntry(this, inode): new Entry(this, inode);
    }

    public void deleteFile(byte[] path, boolean failIfNotExists)
        throws IOException
    {
        checkWritable();
        IndexNode inode = getInode(path);
        if (inode == null) {
            if (path != null && path.length == 0)
                throw new ZipException("root directory </> can't not be delete");
            if (failIfNotExists)
                throw new NoSuchFileException(getString(path));
        } else {
            if (inode.isDir() && inode.child != null)
                throw new DirectoryNotEmptyException(getString(path));
            updateDelete(inode);
        }
    }

    // Returns an out stream for either
    // (1) writing the contents of a new entry, if the entry exists, or
    // (2) updating/replacing the contents of the specified existing entry.
    private OutputStream getOutputStream(Entry e) throws IOException {
        if (e.mtime == -1)
            e.mtime = System.currentTimeMillis();
        if (e.method == -1)
            e.method = defaultCompressionMethod;
        // store size, compressed size, and crc-32 in datadescr
        e.flag = FLAG_DATADESCR;
        if (zc.isUTF8())
            e.flag |= FLAG_USE_UTF8;
        OutputStream os;
        if (useTempFile) {
            e.file = getTempPathForEntry(null);
            os = Files.newOutputStream(e.file, WRITE);
        } else {
            os = new ByteArrayOutputStream((e.size > 0)? (int)e.size : 8192);
        }
        if (e.method == METHOD_DEFLATED) {
            return new DeflatingEntryOutputStream(e, os);
        } else {
            return new EntryOutputStream(e, os);
        }
    }

    private class EntryOutputStream extends FilterOutputStream {
        private final Entry e;
        private long written;
        private boolean isClosed;

        EntryOutputStream(Entry e, OutputStream os) {
            super(os);
            this.e =  Objects.requireNonNull(e, "Zip entry is null");
            // this.written = 0;
        }

        @Override
        public synchronized void write(int b) throws IOException {
            out.write(b);
            written += 1;
        }

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

        @Override
        public synchronized void close() throws IOException {
            if (isClosed) {
                return;
            }
            isClosed = true;
            e.size = written;
            if (out instanceof ByteArrayOutputStream)
                e.bytes = ((ByteArrayOutputStream)out).toByteArray();
            super.close();
            update(e);
        }
    }

    // Output stream returned when writing "deflated" entries into memory,
    // to enable eager (possibly parallel) deflation and reduce memory required.
    private class DeflatingEntryOutputStream extends DeflaterOutputStream {
        private final CRC32 crc;
        private final Entry e;
        private boolean isClosed;

        DeflatingEntryOutputStream(Entry e, OutputStream os) {
            super(os, getDeflater());
            this.e = Objects.requireNonNull(e, "Zip entry is null");
            this.crc = new CRC32();
        }

        @Override
        public synchronized void write(byte[] b, int off, int len)
                throws IOException {
            super.write(b, off, len);
            crc.update(b, off, len);
        }

        @Override
        public synchronized void close() throws IOException {
            if (isClosed)
                return;
            isClosed = true;
            finish();
            e.size  = def.getBytesRead();
            e.csize = def.getBytesWritten();
            e.crc = crc.getValue();
            if (out instanceof ByteArrayOutputStream)
                e.bytes = ((ByteArrayOutputStream)out).toByteArray();
            super.close();
            update(e);
            releaseDeflater(def);
        }
    }

    // Wrapper output stream class to write out a "stored" entry.
    // (1) this class does not close the underlying out stream when
    //     being closed.
    // (2) no need to be "synchronized", only used by sync()
    private class EntryOutputStreamCRC32 extends FilterOutputStream {
        private final CRC32 crc;
        private final Entry e;
        private long written;
        private boolean isClosed;

        EntryOutputStreamCRC32(Entry e, OutputStream os) {
            super(os);
            this.e =  Objects.requireNonNull(e, "Zip entry is null");
            this.crc = new CRC32();
        }

        @Override
        public void write(int b) throws IOException {
            out.write(b);
            crc.update(b);
            written += 1;
        }

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

        @Override
        public void close() {
            if (isClosed)
                return;
            isClosed = true;
            e.size = e.csize = written;
            e.crc = crc.getValue();
        }
    }

    // Wrapper output stream class to write out a "deflated" entry.
    // (1) this class does not close the underlying out stream when
    //     being closed.
    // (2) no need to be "synchronized", only used by sync()
    private class EntryOutputStreamDef extends DeflaterOutputStream {
        private final CRC32 crc;
        private final Entry e;
        private boolean isClosed;

        EntryOutputStreamDef(Entry e, OutputStream os) {
            super(os, getDeflater());
            this.e = Objects.requireNonNull(e, "Zip entry is null");
            this.crc = new CRC32();
        }

        @Override
        public void write(byte[] b, int off, int len) throws IOException {
            super.write(b, off, len);
            crc.update(b, off, len);
        }

        @Override
        public void close() throws IOException {
            if (isClosed)
                return;
            isClosed = true;
            finish();
            e.size = def.getBytesRead();
            e.csize = def.getBytesWritten();
            e.crc = crc.getValue();
            releaseDeflater(def);
        }
    }

    private InputStream getInputStream(Entry e)
        throws IOException
    {
        InputStream eis;
        if (e.type == Entry.NEW) {
            if (e.bytes != null)
                eis = new ByteArrayInputStream(e.bytes);
            else if (e.file != null)
                eis = Files.newInputStream(e.file);
            else
                throw new ZipException("update entry data is missing");
        } else if (e.type == Entry.FILECH) {
            // FILECH result is un-compressed.
            eis = Files.newInputStream(e.file);
            // TBD: wrap to hook close()
            // streams.add(eis);
            return eis;
        } else {  // untouched CEN or COPY
            eis = new EntryInputStream(e, ch);
        }
        if (e.method == METHOD_DEFLATED) {
            // MORE: Compute good size for inflater stream:
            long bufSize = e.size + 2; // Inflater likes a bit of slack
            if (bufSize > 65536)
                bufSize = 8192;
            final long size = e.size;
            eis = new InflaterInputStream(eis, getInflater(), (int)bufSize) {
                private boolean isClosed = false;
                public void close() throws IOException {
                    if (!isClosed) {
                        releaseInflater(inf);
                        this.in.close();
                        isClosed = true;
                        streams.remove(this);
                    }
                }
                // Override fill() method to provide an extra "dummy" byte
                // at the end of the input stream. This is required when
                // using the "nowrap" Inflater option. (it appears the new
                // zlib in 7 does not need it, but keep it for now)
                protected void fill() throws IOException {
                    if (eof) {
                        throw new EOFException(
                            "Unexpected end of ZLIB input stream");
                    }
                    len = this.in.read(buf, 0, buf.length);
                    if (len == -1) {
                        buf[0] = 0;
                        len = 1;
                        eof = true;
                    }
                    inf.setInput(buf, 0, len);
                }
                private boolean eof;

                public int available() {
                    if (isClosed)
                        return 0;
                    long avail = size - inf.getBytesWritten();
                    return avail > (long) Integer.MAX_VALUE ?
                        Integer.MAX_VALUE : (int) avail;
                }
            };
        } else if (e.method == METHOD_STORED) {
            // TBD: wrap/ it does not seem necessary
        } else {
            throw new ZipException("invalid compression method");
        }
        streams.add(eis);
        return eis;
    }

    // Inner class implementing the input stream used to read
    // a (possibly compressed) zip file entry.
    private class EntryInputStream extends InputStream {
        private final SeekableByteChannel zfch; // local ref to zipfs's "ch". zipfs.ch might
                                                // point to a new channel after sync()
        private long pos;                       // current position within entry data
        private long rem;                       // number of remaining bytes within entry

        EntryInputStream(Entry e, SeekableByteChannel zfch)
            throws IOException
        {
            this.zfch = zfch;
            rem = e.csize;
            pos = e.locoff;
            if (pos == -1) {
                Entry e2 = getEntry(e.name);
                if (e2 == null) {
                    throw new ZipException("invalid loc for entry <" + getString(e.name) + ">");
                }
                pos = e2.locoff;
            }
            pos = -pos;  // lazy initialize the real data offset
        }

        public int read(byte[] b, int off, int len) throws IOException {
            ensureOpen();
            initDataPos();
            if (rem == 0) {
                return -1;
            }
            if (len <= 0) {
                return 0;
            }
            if (len > rem) {
                len = (int) rem;
            }
            // readFullyAt()
            long n;
            ByteBuffer bb = ByteBuffer.wrap(b);
            bb.position(off);
            bb.limit(off + len);
            synchronized(zfch) {
                n = zfch.position(pos).read(bb);
            }
            if (n > 0) {
                pos += n;
                rem -= n;
            }
            if (rem == 0) {
                close();
            }
            return (int)n;
        }

        public int read() throws IOException {
            byte[] b = new byte[1];
            if (read(b, 0, 1) == 1) {
                return b[0] & 0xff;
            } else {
                return -1;
            }
        }

        public long skip(long n) {
            ensureOpen();
            if (n > rem)
                n = rem;
            pos += n;
            rem -= n;
            if (rem == 0) {
                close();
            }
            return n;
        }

        public int available() {
            return rem > Integer.MAX_VALUE ? Integer.MAX_VALUE : (int) rem;
        }

        public void close() {
            rem = 0;
            streams.remove(this);
        }

        private void initDataPos() throws IOException {
            if (pos <= 0) {
                pos = -pos + locpos;
                byte[] buf = new byte[LOCHDR];
                if (readFullyAt(buf, 0, buf.length, pos) != LOCHDR) {
                    throw new ZipException("invalid loc " + pos + " for entry reading");
                }
                pos += LOCHDR + LOCNAM(buf) + LOCEXT(buf);
            }
        }
    }

    // Maxmum number of de/inflater we cache
    private final int MAX_FLATER = 20;
    // List of available Inflater objects for decompression
    private final List<Inflater> inflaters = new ArrayList<>();

    // Gets an inflater from the list of available inflaters or allocates
    // a new one.
    private Inflater getInflater() {
        synchronized (inflaters) {
            int size = inflaters.size();
            if (size > 0) {
                return inflaters.remove(size - 1);
            } else {
                return new Inflater(true);
            }
        }
    }

    // Releases the specified inflater to the list of available inflaters.
    private void releaseInflater(Inflater inf) {
        synchronized (inflaters) {
            if (inflaters.size() < MAX_FLATER) {
                inf.reset();
                inflaters.add(inf);
            } else {
                inf.end();
            }
        }
    }

    // List of available Deflater objects for compression
    private final List<Deflater> deflaters = new ArrayList<>();

    // Gets a deflater from the list of available deflaters or allocates
    // a new one.
    private Deflater getDeflater() {
        synchronized (deflaters) {
            int size = deflaters.size();
            if (size > 0) {
                return deflaters.remove(size - 1);
            } else {
                return new Deflater(Deflater.DEFAULT_COMPRESSION, true);
            }
        }
    }

    // Releases the specified inflater to the list of available inflaters.
    private void releaseDeflater(Deflater def) {
        synchronized (deflaters) {
            if (deflaters.size() < MAX_FLATER) {
               def.reset();
               deflaters.add(def);
            } else {
               def.end();
            }
        }
    }

    // End of central directory record
    static class END {
        // The fields that are commented out below are not used by anyone and write() uses "0"
        // int  disknum;
        // int  sdisknum;
        // int  endsub;
        int  centot;        // 4 bytes
        long cenlen;        // 4 bytes
        long cenoff;        // 4 bytes
        // int  comlen;     // comment length
        // byte[] comment;

        // members of Zip64 end of central directory locator
        // int diskNum;
        long endpos;
        // int disktot;

        void write(OutputStream os, long offset, boolean forceEnd64) throws IOException {
            boolean hasZip64 = forceEnd64; // false;
            long xlen = cenlen;
            long xoff = cenoff;
            if (xlen >= ZIP64_MINVAL) {
                xlen = ZIP64_MINVAL;
                hasZip64 = true;
            }
            if (xoff >= ZIP64_MINVAL) {
                xoff = ZIP64_MINVAL;
                hasZip64 = true;
            }
            int count = centot;
            if (count >= ZIP64_MINVAL32) {
                count = ZIP64_MINVAL32;
                hasZip64 = true;
            }
            if (hasZip64) {
                //zip64 end of central directory record
                writeInt(os, ZIP64_ENDSIG);       // zip64 END record signature
                writeLong(os, ZIP64_ENDHDR - 12); // size of zip64 end
                writeShort(os, 45);               // version made by
                writeShort(os, 45);               // version needed to extract
                writeInt(os, 0);                  // number of this disk
                writeInt(os, 0);                  // central directory start disk
                writeLong(os, centot);            // number of directory entries on disk
                writeLong(os, centot);            // number of directory entries
                writeLong(os, cenlen);            // length of central directory
                writeLong(os, cenoff);            // offset of central directory

                //zip64 end of central directory locator
                writeInt(os, ZIP64_LOCSIG);       // zip64 END locator signature
                writeInt(os, 0);                  // zip64 END start disk
                writeLong(os, offset);            // offset of zip64 END
                writeInt(os, 1);                  // total number of disks (?)
            }
            writeInt(os, ENDSIG);                 // END record signature
            writeShort(os, 0);                    // number of this disk
            writeShort(os, 0);                    // central directory start disk
            writeShort(os, count);                // number of directory entries on disk
            writeShort(os, count);                // total number of directory entries
            writeInt(os, xlen);                   // length of central directory
            writeInt(os, xoff);                   // offset of central directory
            writeShort(os, 0);                    // zip file comment, not used
        }
    }

    // Internal node that links a "name" to its pos in cen table.
    // The node itself can be used as a "key" to lookup itself in
    // the HashMap inodes.
    static class IndexNode {
        byte[]  name;
        int     hashcode;    // node is hashable/hashed by its name
        boolean isdir;
        int     pos = -1;    // position in cen table, -1 means the
                             // entry does not exist in zip file
        IndexNode child;     // first child
        IndexNode sibling;   // next sibling

        IndexNode() {}

        IndexNode(byte[] name, boolean isdir) {
            name(name);
            this.isdir = isdir;
            this.pos = -1;
        }

        IndexNode(byte[] name, int pos) {
            name(name);
            this.pos = pos;
        }

        // constructor for initCEN() (1) remove trailing '/' (2) pad leading '/'
        IndexNode(byte[] cen, int pos, int nlen) {
            int noff = pos + CENHDR;
            if (cen[noff + nlen - 1] == '/') {
                isdir = true;
                nlen--;
            }
            if (nlen > 0 && cen[noff] == '/') {
                name = Arrays.copyOfRange(cen, noff, noff + nlen);
            } else {
                name = new byte[nlen + 1];
                System.arraycopy(cen, noff, name, 1, nlen);
                name[0] = '/';
            }
            name(normalize(name));
            this.pos = pos;
        }

        // Normalize the IndexNode.name field.
        private byte[] normalize(byte[] path) {
            int len = path.length;
            if (len == 0)
                return path;
            byte prevC = 0;
            for (int pathPos = 0; pathPos < len; pathPos++) {
                byte c = path[pathPos];
                if (c == '/' && prevC == '/')
                    return normalize(path, pathPos - 1);
                prevC = c;
            }
            if (len > 1 && prevC == '/') {
                return Arrays.copyOf(path, len - 1);
            }
            return path;
        }

        private byte[] normalize(byte[] path, int off) {
            // As we know we have at least one / to trim, we can reduce
            // the size of the resulting array
            byte[] to = new byte[path.length - 1];
            int pathPos = 0;
            while (pathPos < off) {
                to[pathPos] = path[pathPos];
                pathPos++;
            }
            int toPos = pathPos;
            byte prevC = 0;
            while (pathPos < path.length) {
                byte c = path[pathPos++];
                if (c == '/' && prevC == '/')
                    continue;
                to[toPos++] = c;
                prevC = c;
            }
            if (toPos > 1 && to[toPos - 1] == '/')
                toPos--;
            return (toPos == to.length) ? to : Arrays.copyOf(to, toPos);
        }

        private static final ThreadLocal<IndexNode> cachedKey = new ThreadLocal<>();

        static final IndexNode keyOf(byte[] name) { // get a lookup key;
            IndexNode key = cachedKey.get();
            if (key == null) {
                key = new IndexNode(name, -1);
                cachedKey.set(key);
            }
            return key.as(name);
        }

        final void name(byte[] name) {
            this.name = name;
            this.hashcode = Arrays.hashCode(name);
        }

        final IndexNode as(byte[] name) {           // reuse the node, mostly
            name(name);                             // as a lookup "key"
            return this;
        }

        boolean isDir() {
            return isdir;
        }

        @Override
        public boolean equals(Object other) {
            if (!(other instanceof IndexNode)) {
                return false;
            }
            if (other instanceof ParentLookup) {
                return ((ParentLookup)other).equals(this);
            }
            return Arrays.equals(name, ((IndexNode)other).name);
        }

        @Override
        public int hashCode() {
            return hashcode;
        }

        @Override
        public String toString() {
            return new String(name) + (isdir ? " (dir)" : " ") + ", index: " + pos;
        }
    }

    static class Entry extends IndexNode implements ZipFileAttributes {
        static final int CEN    = 1;  // entry read from cen
        static final int NEW    = 2;  // updated contents in bytes or file
        static final int FILECH = 3;  // fch update in "file"
        static final int COPY   = 4;  // copy of a CEN entry

        byte[] bytes;                 // updated content bytes
        Path   file;                  // use tmp file to store bytes;
        int    type = CEN;            // default is the entry read from cen

        // entry attributes
        int    version;
        int    flag;
        int    posixPerms = -1; // posix permissions
        int    method = -1;    // compression method
        long   mtime  = -1;    // last modification time (in DOS time)
        long   atime  = -1;    // last access time
        long   ctime  = -1;    // create time
        long   crc    = -1;    // crc-32 of entry data
        long   csize  = -1;    // compressed size of entry data
        long   size   = -1;    // uncompressed size of entry data
        byte[] extra;

        // CEN
        // The fields that are commented out below are not used by anyone and write() uses "0"
        // int    versionMade;
        // int    disk;
        // int    attrs;
        // long   attrsEx;
        long   locoff;
        byte[] comment;

        Entry(byte[] name, boolean isdir, int method) {
            name(name);
            this.isdir = isdir;
            this.mtime  = this.ctime = this.atime = System.currentTimeMillis();
            this.crc    = 0;
            this.size   = 0;
            this.csize  = 0;
            this.method = method;
        }

        @SuppressWarnings("unchecked")
        Entry(byte[] name, int type, boolean isdir, int method, FileAttribute<?>... attrs) {
            this(name, isdir, method);
            this.type = type;
            for (FileAttribute<?> attr : attrs) {
                String attrName = attr.name();
                if (attrName.equals("posix:permissions")) {
                    posixPerms = ZipUtils.permsToFlags((Set<PosixFilePermission>)attr.value());
                }
            }
        }

        Entry(byte[] name, Path file, int type, FileAttribute<?>... attrs) {
            this(name, type, false, METHOD_STORED, attrs);
            this.file = file;
        }

        Entry(Entry e, int type, int compressionMethod) {
            this(e, type);
            this.method = compressionMethod;
        }

        Entry(Entry e, int type) {
            name(e.name);
            this.isdir     = e.isdir;
            this.version   = e.version;
            this.ctime     = e.ctime;
            this.atime     = e.atime;
            this.mtime     = e.mtime;
            this.crc       = e.crc;
            this.size      = e.size;
            this.csize     = e.csize;
            this.method    = e.method;
            this.extra     = e.extra;
            /*
            this.versionMade = e.versionMade;
            this.disk      = e.disk;
            this.attrs     = e.attrs;
            this.attrsEx   = e.attrsEx;
            */
            this.locoff    = e.locoff;
            this.comment   = e.comment;
            this.posixPerms = e.posixPerms;
            this.type      = type;
        }

        Entry(ZipFileSystem zipfs, IndexNode inode) throws IOException {
            readCEN(zipfs, inode);
        }

        // Calculates a suitable base for the version number to
        // be used for fields version made by/version needed to extract.
        // The lower bytes of these 2 byte fields hold the version number
        // (value/10 = major; value%10 = minor)
        // For different features certain minimum versions apply:
        // stored = 10 (1.0), deflated = 20 (2.0), zip64 = 45 (4.5)
        private int version(boolean zip64) throws ZipException {
            if (zip64) {
                return 45;
            }
            if (method == METHOD_DEFLATED)
                return 20;
            else if (method == METHOD_STORED)
                return 10;
            throw new ZipException("unsupported compression method");
        }

        
Adds information about compatibility of file attribute information
to a version value.
/**
         * Adds information about compatibility of file attribute information
         * to a version value.
         */
        private int versionMadeBy(int version) {
            return (posixPerms < 0) ? version :
                VERSION_MADE_BY_BASE_UNIX | (version & 0xff);
        }

        ///////////////////// CEN //////////////////////
        private void readCEN(ZipFileSystem zipfs, IndexNode inode) throws IOException {
            byte[] cen = zipfs.cen;
            int pos = inode.pos;
            if (!cenSigAt(cen, pos))
                throw new ZipException("invalid CEN header (bad signature)");
            version     = CENVER(cen, pos);
            flag        = CENFLG(cen, pos);
            method      = CENHOW(cen, pos);
            mtime       = dosToJavaTime(CENTIM(cen, pos));
            crc         = CENCRC(cen, pos);
            csize       = CENSIZ(cen, pos);
            size        = CENLEN(cen, pos);
            int nlen    = CENNAM(cen, pos);
            int elen    = CENEXT(cen, pos);
            int clen    = CENCOM(cen, pos);
            /*
            versionMade = CENVEM(cen, pos);
            disk        = CENDSK(cen, pos);
            attrs       = CENATT(cen, pos);
            attrsEx     = CENATX(cen, pos);
            */
            if (CENVEM_FA(cen, pos) == FILE_ATTRIBUTES_UNIX) {
                posixPerms = CENATX_PERMS(cen, pos) & 0xFFF; // 12 bits for setuid, setgid, sticky + perms
            }
            locoff      = CENOFF(cen, pos);
            pos += CENHDR;
            this.name = inode.name;
            this.isdir = inode.isdir;
            this.hashcode = inode.hashcode;

            pos += nlen;
            if (elen > 0) {
                extra = Arrays.copyOfRange(cen, pos, pos + elen);
                pos += elen;
                readExtra(zipfs);
            }
            if (clen > 0) {
                comment = Arrays.copyOfRange(cen, pos, pos + clen);
            }
        }

        private int writeCEN(OutputStream os) throws IOException {
            long csize0  = csize;
            long size0   = size;
            long locoff0 = locoff;
            int elen64   = 0;                // extra for ZIP64
            int elenNTFS = 0;                // extra for NTFS (a/c/mtime)
            int elenEXTT = 0;                // extra for Extended Timestamp
            boolean foundExtraTime = false;  // if time stamp NTFS, EXTT present

            byte[] zname = isdir ? toDirectoryPath(name) : name;

            // confirm size/length
            int nlen = (zname != null) ? zname.length - 1 : 0;  // name has [0] as "slash"
            int elen = (extra != null) ? extra.length : 0;
            int eoff = 0;
            int clen = (comment != null) ? comment.length : 0;
            if (csize >= ZIP64_MINVAL) {
                csize0 = ZIP64_MINVAL;
                elen64 += 8;                 // csize(8)
            }
            if (size >= ZIP64_MINVAL) {
                size0 = ZIP64_MINVAL;        // size(8)
                elen64 += 8;
            }
            if (locoff >= ZIP64_MINVAL) {
                locoff0 = ZIP64_MINVAL;
                elen64 += 8;                 // offset(8)
            }
            if (elen64 != 0) {
                elen64 += 4;                 // header and data sz 4 bytes
            }
            boolean zip64 = (elen64 != 0);
            int version0 = version(zip64);
            while (eoff + 4 < elen) {
                int tag = SH(extra, eoff);
                int sz = SH(extra, eoff + 2);
                if (tag == EXTID_EXTT || tag == EXTID_NTFS) {
                    foundExtraTime = true;
                }
                eoff += (4 + sz);
            }
            if (!foundExtraTime) {
                if (isWindows) {             // use NTFS
                    elenNTFS = 36;           // total 36 bytes
                } else {                     // Extended Timestamp otherwise
                    elenEXTT = 9;            // only mtime in cen
                }
            }
            writeInt(os, CENSIG);            // CEN header signature
            writeShort(os, versionMadeBy(version0)); // version made by
            writeShort(os, version0);        // version needed to extract
            writeShort(os, flag);            // general purpose bit flag
            writeShort(os, method);          // compression method
                                             // last modification time
            writeInt(os, (int)javaToDosTime(mtime));
            writeInt(os, crc);               // crc-32
            writeInt(os, csize0);            // compressed size
            writeInt(os, size0);             // uncompressed size
            writeShort(os, nlen);
            writeShort(os, elen + elen64 + elenNTFS + elenEXTT);

            if (comment != null) {
                writeShort(os, Math.min(clen, 0xffff));
            } else {
                writeShort(os, 0);
            }
            writeShort(os, 0);              // starting disk number
            writeShort(os, 0);              // internal file attributes (unused)
            writeInt(os, posixPerms > 0 ? posixPerms << 16 : 0); // external file
                                            // attributes, used for storing posix
                                            // permissions
            writeInt(os, locoff0);          // relative offset of local header
            writeBytes(os, zname, 1, nlen);
            if (zip64) {
                writeShort(os, EXTID_ZIP64);// Zip64 extra
                writeShort(os, elen64 - 4); // size of "this" extra block
                if (size0 == ZIP64_MINVAL)
                    writeLong(os, size);
                if (csize0 == ZIP64_MINVAL)
                    writeLong(os, csize);
                if (locoff0 == ZIP64_MINVAL)
                    writeLong(os, locoff);
            }
            if (elenNTFS != 0) {
                writeShort(os, EXTID_NTFS);
                writeShort(os, elenNTFS - 4);
                writeInt(os, 0);            // reserved
                writeShort(os, 0x0001);     // NTFS attr tag
                writeShort(os, 24);
                writeLong(os, javaToWinTime(mtime));
                writeLong(os, javaToWinTime(atime));
                writeLong(os, javaToWinTime(ctime));
            }
            if (elenEXTT != 0) {
                writeShort(os, EXTID_EXTT);
                writeShort(os, elenEXTT - 4);
                if (ctime == -1)
                    os.write(0x3);          // mtime and atime
                else
                    os.write(0x7);          // mtime, atime and ctime
                writeInt(os, javaToUnixTime(mtime));
            }
            if (extra != null)              // whatever not recognized
                writeBytes(os, extra);
            if (comment != null)            //TBD: 0, Math.min(commentBytes.length, 0xffff));
                writeBytes(os, comment);
            return CENHDR + nlen + elen + clen + elen64 + elenNTFS + elenEXTT;
        }

        ///////////////////// LOC //////////////////////

        private int writeLOC(OutputStream os) throws IOException {
            byte[] zname = isdir ? toDirectoryPath(name) : name;
            int nlen = (zname != null) ? zname.length - 1 : 0; // [0] is slash
            int elen = (extra != null) ? extra.length : 0;
            boolean foundExtraTime = false;     // if extra timestamp present
            int eoff = 0;
            int elen64 = 0;
            boolean zip64 = false;
            int elenEXTT = 0;
            int elenNTFS = 0;
            writeInt(os, LOCSIG);               // LOC header signature
            if ((flag & FLAG_DATADESCR) != 0) {
                writeShort(os, version(false)); // version needed to extract
                writeShort(os, flag);           // general purpose bit flag
                writeShort(os, method);         // compression method
                // last modification time
                writeInt(os, (int)javaToDosTime(mtime));
                // store size, uncompressed size, and crc-32 in data descriptor
                // immediately following compressed entry data
                writeInt(os, 0);
                writeInt(os, 0);
                writeInt(os, 0);
            } else {
                if (csize >= ZIP64_MINVAL || size >= ZIP64_MINVAL) {
                    elen64 = 20;    //headid(2) + size(2) + size(8) + csize(8)
                    zip64 = true;
                }
                writeShort(os, version(zip64)); // version needed to extract
                writeShort(os, flag);           // general purpose bit flag
                writeShort(os, method);         // compression method
                                                // last modification time
                writeInt(os, (int)javaToDosTime(mtime));
                writeInt(os, crc);              // crc-32
                if (zip64) {
                    writeInt(os, ZIP64_MINVAL);
                    writeInt(os, ZIP64_MINVAL);
                } else {
                    writeInt(os, csize);        // compressed size
                    writeInt(os, size);         // uncompressed size
                }
            }
            while (eoff + 4 < elen) {
                int tag = SH(extra, eoff);
                int sz = SH(extra, eoff + 2);
                if (tag == EXTID_EXTT || tag == EXTID_NTFS) {
                    foundExtraTime = true;
                }
                eoff += (4 + sz);
            }
            if (!foundExtraTime) {
                if (isWindows) {
                    elenNTFS = 36;              // NTFS, total 36 bytes
                } else {                        // on unix use "ext time"
                    elenEXTT = 9;
                    if (atime != -1)
                        elenEXTT += 4;
                    if (ctime != -1)
                        elenEXTT += 4;
                }
            }
            writeShort(os, nlen);
            writeShort(os, elen + elen64 + elenNTFS + elenEXTT);
            writeBytes(os, zname, 1, nlen);
            if (zip64) {
                writeShort(os, EXTID_ZIP64);
                writeShort(os, 16);
                writeLong(os, size);
                writeLong(os, csize);
            }
            if (elenNTFS != 0) {
                writeShort(os, EXTID_NTFS);
                writeShort(os, elenNTFS - 4);
                writeInt(os, 0);            // reserved
                writeShort(os, 0x0001);     // NTFS attr tag
                writeShort(os, 24);
                writeLong(os, javaToWinTime(mtime));
                writeLong(os, javaToWinTime(atime));
                writeLong(os, javaToWinTime(ctime));
            }
            if (elenEXTT != 0) {
                writeShort(os, EXTID_EXTT);
                writeShort(os, elenEXTT - 4);// size for the folowing data block
                int fbyte = 0x1;
                if (atime != -1)           // mtime and atime
                    fbyte |= 0x2;
                if (ctime != -1)           // mtime, atime and ctime
                    fbyte |= 0x4;
                os.write(fbyte);           // flags byte
                writeInt(os, javaToUnixTime(mtime));
                if (atime != -1)
                    writeInt(os, javaToUnixTime(atime));
                if (ctime != -1)
                    writeInt(os, javaToUnixTime(ctime));
            }
            if (extra != null) {
                writeBytes(os, extra);
            }
            return LOCHDR + nlen + elen + elen64 + elenNTFS + elenEXTT;
        }

        // Data Descriptor
        private int writeEXT(OutputStream os) throws IOException {
            writeInt(os, EXTSIG);           // EXT header signature
            writeInt(os, crc);              // crc-32
            if (csize >= ZIP64_MINVAL || size >= ZIP64_MINVAL) {
                writeLong(os, csize);
                writeLong(os, size);
                return 24;
            } else {
                writeInt(os, csize);        // compressed size
                writeInt(os, size);         // uncompressed size
                return 16;
            }
        }

        // read NTFS, UNIX and ZIP64 data from cen.extra
        private void readExtra(ZipFileSystem zipfs) throws IOException {
            // Note that Section 4.5, Extensible data fields, of the PKWARE ZIP File
            // Format Specification does not mandate a specific order for the
            // data in the extra field, therefore Zip FS cannot assume the data
            // is written in the same order by Zip libraries as Zip FS.
            if (extra == null)
                return;
            int elen = extra.length;
            int off = 0;
            int newOff = 0;
            boolean hasZip64LocOffset = false;
            while (off + 4 < elen) {
                // extra spec: HeaderID+DataSize+Data
                int pos = off;
                int tag = SH(extra, pos);
                int sz = SH(extra, pos + 2);
                pos += 4;
                if (pos + sz > elen)         // invalid data
                    break;
                switch (tag) {
                case EXTID_ZIP64 :
                    if (size == ZIP64_MINVAL) {
                        if (pos + 8 > elen)  // invalid zip64 extra
                            break;           // fields, just skip
                        size = LL(extra, pos);
                        pos += 8;
                    }
                    if (csize == ZIP64_MINVAL) {
                        if (pos + 8 > elen)
                            break;
                        csize = LL(extra, pos);
                        pos += 8;
                    }
                    if (locoff == ZIP64_MINVAL) {
                        if (pos + 8 > elen)
                            break;
                        locoff = LL(extra, pos);
                    }
                    break;
                case EXTID_NTFS:
                    if (sz < 32)
                        break;
                    pos += 4;    // reserved 4 bytes
                    if (SH(extra, pos) !=  0x0001)
                        break;
                    if (SH(extra, pos + 2) != 24)
                        break;
                    // override the loc field, datatime here is
                    // more "accurate"
                    mtime  = winToJavaTime(LL(extra, pos + 4));
                    atime  = winToJavaTime(LL(extra, pos + 12));
                    ctime  = winToJavaTime(LL(extra, pos + 20));
                    break;
                case EXTID_EXTT:
                    // spec says the Extended timestamp in cen only has mtime
                    // need to read the loc to get the extra a/ctime, if flag
                    // "zipinfo-time" is not specified to false;
                    // there is performance cost (move up to loc and read) to
                    // access the loc table foreach entry;
                    if (zipfs.noExtt) {
                        if (sz == 5)
                            mtime = unixToJavaTime(LG(extra, pos + 1));
                         break;
                    }
                    // If the LOC offset is 0xFFFFFFFF, then we need to read the
                    // LOC offset from the EXTID_ZIP64 extra data. Therefore
                    // wait until all of the CEN extra data fields have been processed
                    // prior to reading the LOC extra data field in order to obtain
                    // the Info-ZIP Extended Timestamp.
                    if (locoff != ZIP64_MINVAL) {
                        readLocEXTT(zipfs);
                    } else {
                        hasZip64LocOffset = true;
                    }
                    break;
                default:    // unknown tag
                    System.arraycopy(extra, off, extra, newOff, sz + 4);
                    newOff += (sz + 4);
                }
                off += (sz + 4);
            }

            // We need to read the LOC extra data and the LOC offset was obtained
            // from the EXTID_ZIP64 field.
            if (hasZip64LocOffset) {
                readLocEXTT(zipfs);
            }

            if (newOff != 0 && newOff != extra.length)
                extra = Arrays.copyOf(extra, newOff);
            else
                extra = null;
        }

        
Read the LOC extra field to obtain the Info-ZIP Extended Timestamp fields
Params:
zipfs – The Zip FS to use
Throws:
IOException – If an error occurs/**
         * Read the LOC extra field to obtain the Info-ZIP Extended Timestamp fields
         * @param zipfs The Zip FS to use
         * @throws IOException If an error occurs
         */
        private void readLocEXTT(ZipFileSystem zipfs) throws IOException {
            byte[] buf = new byte[LOCHDR];
            if (zipfs.readFullyAt(buf, 0, buf.length , locoff)
                != buf.length)
                throw new ZipException("loc: reading failed");
            if (!locSigAt(buf, 0))
                throw new ZipException("R"
                                   + Long.toString(getSig(buf, 0), 16));
            int locElen = LOCEXT(buf);
            if (locElen < 9)    // EXTT is at least 9 bytes
                return;
            int locNlen = LOCNAM(buf);
            buf = new byte[locElen];
            if (zipfs.readFullyAt(buf, 0, buf.length , locoff + LOCHDR + locNlen)
                != buf.length)
                throw new ZipException("loc extra: reading failed");
            int locPos = 0;
            while (locPos + 4 < buf.length) {
                int locTag = SH(buf, locPos);
                int locSZ  = SH(buf, locPos + 2);
                locPos += 4;
                if (locTag  != EXTID_EXTT) {
                    locPos += locSZ;
                     continue;
                }
                int end = locPos + locSZ - 4;
                int flag = CH(buf, locPos++);
                if ((flag & 0x1) != 0 && locPos <= end) {
                    mtime = unixToJavaTime(LG(buf, locPos));
                    locPos += 4;
                }
                if ((flag & 0x2) != 0 && locPos <= end) {
                    atime = unixToJavaTime(LG(buf, locPos));
                    locPos += 4;
                }
                if ((flag & 0x4) != 0 && locPos <= end) {
                    ctime = unixToJavaTime(LG(buf, locPos));
                }
                break;
            }
        }

        @Override
        public String toString() {
            StringBuilder sb = new StringBuilder(1024);
            Formatter fm = new Formatter(sb);
            fm.format("    name            : %s%n", new String(name));
            fm.format("    creationTime    : %tc%n", creationTime().toMillis());
            fm.format("    lastAccessTime  : %tc%n", lastAccessTime().toMillis());
            fm.format("    lastModifiedTime: %tc%n", lastModifiedTime().toMillis());
            fm.format("    isRegularFile   : %b%n", isRegularFile());
            fm.format("    isDirectory     : %b%n", isDirectory());
            fm.format("    isSymbolicLink  : %b%n", isSymbolicLink());
            fm.format("    isOther         : %b%n", isOther());
            fm.format("    fileKey         : %s%n", fileKey());
            fm.format("    size            : %d%n", size());
            fm.format("    compressedSize  : %d%n", compressedSize());
            fm.format("    crc             : %x%n", crc());
            fm.format("    method          : %d%n", method());
            Set<PosixFilePermission> permissions = storedPermissions().orElse(null);
            if (permissions != null) {
                fm.format("    permissions     : %s%n", permissions);
            }
            fm.close();
            return sb.toString();
        }

        ///////// basic file attributes ///////////
        @Override
        public FileTime creationTime() {
            return FileTime.fromMillis(ctime == -1 ? mtime : ctime);
        }

        @Override
        public boolean isDirectory() {
            return isDir();
        }

        @Override
        public boolean isOther() {
            return false;
        }

        @Override
        public boolean isRegularFile() {
            return !isDir();
        }

        @Override
        public FileTime lastAccessTime() {
            return FileTime.fromMillis(atime == -1 ? mtime : atime);
        }

        @Override
        public FileTime lastModifiedTime() {
            return FileTime.fromMillis(mtime);
        }

        @Override
        public long size() {
            return size;
        }

        @Override
        public boolean isSymbolicLink() {
            return false;
        }

        @Override
        public Object fileKey() {
            return null;
        }

        ///////// zip file attributes ///////////

        @Override
        public long compressedSize() {
            return csize;
        }

        @Override
        public long crc() {
            return crc;
        }

        @Override
        public int method() {
            return method;
        }

        @Override
        public byte[] extra() {
            if (extra != null)
                return Arrays.copyOf(extra, extra.length);
            return null;
        }

        @Override
        public byte[] comment() {
            if (comment != null)
                return Arrays.copyOf(comment, comment.length);
            return null;
        }

        @Override
        public Optional<Set<PosixFilePermission>> storedPermissions() {
            Set<PosixFilePermission> perms = null;
            if (posixPerms != -1) {
                perms = new HashSet<>(PosixFilePermission.values().length);
                for (PosixFilePermission perm : PosixFilePermission.values()) {
                    if ((posixPerms & ZipUtils.permToFlag(perm)) != 0) {
                        perms.add(perm);
                    }
                }
            }
            return Optional.ofNullable(perms);
        }
    }

    final class PosixEntry extends Entry implements PosixFileAttributes {
        private UserPrincipal owner = defaultOwner;
        private GroupPrincipal group = defaultGroup;

        PosixEntry(byte[] name, boolean isdir, int method) {
            super(name, isdir, method);
        }

        PosixEntry(byte[] name, int type, boolean isdir, int method, FileAttribute<?>... attrs) {
            super(name, type, isdir, method, attrs);
        }

        PosixEntry(byte[] name, Path file, int type, FileAttribute<?>... attrs) {
            super(name, file, type, attrs);
        }

        PosixEntry(PosixEntry e, int type, int compressionMethod) {
            super(e, type);
            this.method = compressionMethod;
        }

        PosixEntry(PosixEntry e, int type) {
            super(e, type);
            this.owner = e.owner;
            this.group = e.group;
        }

        PosixEntry(ZipFileSystem zipfs, IndexNode inode) throws IOException {
            super(zipfs, inode);
        }

        @Override
        public UserPrincipal owner() {
            return owner;
        }

        @Override
        public GroupPrincipal group() {
            return group;
        }

        @Override
        public Set<PosixFilePermission> permissions() {
            return storedPermissions().orElse(Set.copyOf(defaultPermissions));
        }
    }

    // purely for parent lookup, so we don't have to copy the parent
    // name every time
    static class ParentLookup extends IndexNode {
        int len;
        ParentLookup() {}

        final ParentLookup as(byte[] name, int len) { // as a lookup "key"
            name(name, len);
            return this;
        }

        void name(byte[] name, int len) {
            this.name = name;
            this.len = len;
            // calculate the hashcode the same way as Arrays.hashCode() does
            int result = 1;
            for (int i = 0; i < len; i++)
                result = 31 * result + name[i];
            this.hashcode = result;
        }

        @Override
        public boolean equals(Object other) {
            if (!(other instanceof IndexNode)) {
                return false;
            }
            byte[] oname = ((IndexNode)other).name;
            return Arrays.equals(name, 0, len,
                                 oname, 0, oname.length);
        }
    }
}