/*

 * 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 sun.nio.fs;

import java.nio.file.*;

import java.nio.file.attribute.*;

import java.nio.channels.SeekableByteChannel;

import java.util.*;

import java.util.concurrent.TimeUnit;

import java.io.IOException;

import static sun.nio.fs.UnixNativeDispatcher.*;

import static sun.nio.fs.UnixConstants.*;

/**

 * Unix implementation of SecureDirectoryStream.

 */

class UnixSecureDirectoryStream

    implements SecureDirectoryStream<Path>

{

    private final UnixDirectoryStream ds;

    private final int dfd;

    UnixSecureDirectoryStream(UnixPath dir,

                              long dp,

                              int dfd,

                              DirectoryStream.Filter<? super Path> filter)

    {

        this.ds = new UnixDirectoryStream(dir, dp, filter);

        this.dfd = dfd;

    }

    @Override

    public void close()

        throws IOException

    {

        ds.writeLock().lock();

        try {

            if (ds.closeImpl()) {

                UnixNativeDispatcher.close(dfd);

            }

        } finally {

            ds.writeLock().unlock();

        }

    }

    @Override

    public Iterator<Path> iterator() {

        return ds.iterator(this);

    }

    private UnixPath getName(Path obj) {

        if (obj == null)

            throw new NullPointerException();

        if (!(obj instanceof UnixPath))

            throw new ProviderMismatchException();

        return (UnixPath)obj;

    }

    private boolean followLinks(LinkOption... options) {

        boolean followLinks = true;

        for (LinkOption option: options) {

            if (option == LinkOption.NOFOLLOW_LINKS) {

                followLinks = false;

                continue;

            }

            if (option == null)

                throw new NullPointerException();

            throw new AssertionError("Should not get here");

        }

        return followLinks;

    }

    /**

     * Opens sub-directory in this directory

     */

    @Override

    public SecureDirectoryStream<Path> newDirectoryStream(Path obj,

                                                          LinkOption... options)

        throws IOException

    {

        UnixPath file = getName(obj);

        UnixPath child = ds.directory().resolve(file);

        boolean followLinks = followLinks(options);

        // permission check using name resolved against original path of directory

        SecurityManager sm = System.getSecurityManager();

        if (sm != null) {

            child.checkRead();

        }

        ds.readLock().lock();

        try {

            if (!ds.isOpen())

                throw new ClosedDirectoryStreamException();

            // open directory and create new secure directory stream

            int newdfd1 = -1;

            int newdfd2 = -1;

            long ptr = 0L;

            try {

                int flags = O_RDONLY;

                if (!followLinks)

                    flags |= O_NOFOLLOW;

                newdfd1 = openat(dfd, file.asByteArray(), flags , 0);

                newdfd2 = dup(newdfd1);

                ptr = fdopendir(newdfd1);

            } catch (UnixException x) {

                if (newdfd1 != -1)

                    UnixNativeDispatcher.close(newdfd1);

                if (newdfd2 != -1)

                    UnixNativeDispatcher.close(newdfd2);

                if (x.errno() == UnixConstants.ENOTDIR)

                    throw new NotDirectoryException(file.toString());

                x.rethrowAsIOException(file);

            }

            return new UnixSecureDirectoryStream(child, ptr, newdfd2, null);

        } finally {

            ds.readLock().unlock();

        }

    }

    /**

     * Opens file in this directory

     */

    @Override

    public SeekableByteChannel newByteChannel(Path obj,

                                              Set<? extends OpenOption> options,

                                              FileAttribute<?>... attrs)

        throws IOException

    {

        UnixPath file = getName(obj);

        int mode = UnixFileModeAttribute

            .toUnixMode(UnixFileModeAttribute.ALL_READWRITE, attrs);

        // path for permission check

        String pathToCheck = ds.directory().resolve(file).getPathForPermissionCheck();

        ds.readLock().lock();

        try {

            if (!ds.isOpen())

                throw new ClosedDirectoryStreamException();

            try {

                return UnixChannelFactory.newFileChannel(dfd, file, pathToCheck, options, mode);

            } catch (UnixException x) {

                x.rethrowAsIOException(file);

                return null; // keep compiler happy

            }

        } finally {

            ds.readLock().unlock();

        }

    }

    /**

     * Deletes file/directory in this directory. Works in a race-free manner

     * when invoked with flags.

     */

    private void implDelete(Path obj, boolean haveFlags, int flags)

        throws IOException

    {

        UnixPath file = getName(obj);

        // permission check using name resolved against original path of directory

        SecurityManager sm = System.getSecurityManager();

        if (sm != null) {

            ds.directory().resolve(file).checkDelete();

        }

        ds.readLock().lock();

        try {

            if (!ds.isOpen())

                throw new ClosedDirectoryStreamException();

            if (!haveFlags) {

                // need file attribute to know if file is directory. This creates

                // a race in that the file may be replaced by a directory or a

                // directory replaced by a file between the time we query the

                // file type and unlink it.

                UnixFileAttributes attrs = null;

                try {

                    attrs = UnixFileAttributes.get(dfd, file, false);

                } catch (UnixException x) {

                    x.rethrowAsIOException(file);

                }

                flags = (attrs.isDirectory()) ? AT_REMOVEDIR : 0;

            }

            try {

                unlinkat(dfd, file.asByteArray(), flags);

            } catch (UnixException x) {

                if ((flags & AT_REMOVEDIR) != 0) {

                    if (x.errno() == EEXIST || x.errno() == ENOTEMPTY) {

                        throw new DirectoryNotEmptyException(null);

                    }

                }

                x.rethrowAsIOException(file);

            }

        } finally {

            ds.readLock().unlock();

        }

    }

    @Override

    public void deleteFile(Path file) throws IOException {

        implDelete(file, true, 0);

    }

    @Override

    public void deleteDirectory(Path dir) throws IOException {

        implDelete(dir, true, AT_REMOVEDIR);

    }

    /**

     * Rename/move file in this directory to another (open) directory

     */

    @Override

    public void move(Path fromObj, SecureDirectoryStream<Path> dir, Path toObj)

        throws IOException

    {

        UnixPath from = getName(fromObj);

        UnixPath to = getName(toObj);

        if (dir == null)

            throw new NullPointerException();

        if (!(dir instanceof UnixSecureDirectoryStream))

            throw new ProviderMismatchException();

        UnixSecureDirectoryStream that = (UnixSecureDirectoryStream)dir;

        // permission check

        SecurityManager sm = System.getSecurityManager();

        if (sm != null) {

            this.ds.directory().resolve(from).checkWrite();

            that.ds.directory().resolve(to).checkWrite();

        }

        // lock ordering doesn't matter

        this.ds.readLock().lock();

        try {

            that.ds.readLock().lock();

            try {

                if (!this.ds.isOpen() || !that.ds.isOpen())

                    throw new ClosedDirectoryStreamException();

                try {

                    renameat(this.dfd, from.asByteArray(), that.dfd, to.asByteArray());

                } catch (UnixException x) {

                    if (x.errno() == EXDEV) {

                        throw new AtomicMoveNotSupportedException(

                            from.toString(), to.toString(), x.errorString());

                    }

                    x.rethrowAsIOException(from, to);

                }

            } finally {

                that.ds.readLock().unlock();

            }

        } finally {

            this.ds.readLock().unlock();

        }

    }

    @SuppressWarnings("unchecked")

    private <V extends FileAttributeView> V getFileAttributeViewImpl(UnixPath file,

                                                                     Class<V> type,

                                                                     boolean followLinks)

    {

        if (type == null)

            throw new NullPointerException();

        Class<?> c = type;

        if (c == BasicFileAttributeView.class) {

            return (V) new BasicFileAttributeViewImpl(file, followLinks);

        }

        if (c == PosixFileAttributeView.class || c == FileOwnerAttributeView.class) {

            return (V) new PosixFileAttributeViewImpl(file, followLinks);

        }

        // TBD - should also support AclFileAttributeView

        return (V) null;

    }

    /**

     * Returns file attribute view bound to this directory

     */

    @Override

    public <V extends FileAttributeView> V getFileAttributeView(Class<V> type) {

        return getFileAttributeViewImpl(null, type, false);

    }

    /**

     * Returns file attribute view bound to dfd/filename.

     */

    @Override

    public <V extends FileAttributeView> V getFileAttributeView(Path obj,

                                                                Class<V> type,

                                                                LinkOption... options)

    {

        UnixPath file = getName(obj);

        boolean followLinks = followLinks(options);

        return getFileAttributeViewImpl(file, type, followLinks);

    }

    /**

     * A BasicFileAttributeView implementation that using a dfd/name pair.

     */

    private class BasicFileAttributeViewImpl

        implements BasicFileAttributeView

    {

        final UnixPath file;

        final boolean followLinks;

        BasicFileAttributeViewImpl(UnixPath file, boolean followLinks)

        {

            this.file = file;

            this.followLinks = followLinks;

        }

        int open() throws IOException {

            int oflags = O_RDONLY;

            if (!followLinks)

                oflags |= O_NOFOLLOW;

            try {

                return openat(dfd, file.asByteArray(), oflags, 0);

            } catch (UnixException x) {

                x.rethrowAsIOException(file);

                return -1; // keep compiler happy

            }

        }

        private void checkWriteAccess() {

            SecurityManager sm = System.getSecurityManager();

            if (sm != null) {

                if (file == null) {

                    ds.directory().checkWrite();

                } else {

                    ds.directory().resolve(file).checkWrite();

                }

            }

        }

        @Override

        public String name() {

            return "basic";

        }

        @Override

        public BasicFileAttributes readAttributes() throws IOException {

            ds.readLock().lock();

            try {

                if (!ds.isOpen())

                    throw new ClosedDirectoryStreamException();

                SecurityManager sm = System.getSecurityManager();

                if (sm != null) {

                    if (file == null) {

                        ds.directory().checkRead();

                    } else {

                        ds.directory().resolve(file).checkRead();

                    }

                }

                try {

                     UnixFileAttributes attrs = (file == null) ?

                         UnixFileAttributes.get(dfd) :

                         UnixFileAttributes.get(dfd, file, followLinks);

                     // SECURITY: must return as BasicFileAttribute

                     return attrs.asBasicFileAttributes();

                } catch (UnixException x) {

                    x.rethrowAsIOException(file);

                    return null;    // keep compiler happy

                }

            } finally {

                ds.readLock().unlock();

            }

        }

        @Override

        public void setTimes(FileTime lastModifiedTime,

                             FileTime lastAccessTime,

                             FileTime createTime) // ignore

            throws IOException

        {

            checkWriteAccess();

            ds.readLock().lock();

            try {

                if (!ds.isOpen())

                    throw new ClosedDirectoryStreamException();

                int fd = (file == null) ? dfd : open();

                try {

                    // if not changing both attributes then need existing attributes

                    if (lastModifiedTime == null || lastAccessTime == null) {

                        try {

                            UnixFileAttributes attrs = UnixFileAttributes.get(fd);

                            if (lastModifiedTime == null)

                                lastModifiedTime = attrs.lastModifiedTime();

                            if (lastAccessTime == null)

                                lastAccessTime = attrs.lastAccessTime();

                        } catch (UnixException x) {

                            x.rethrowAsIOException(file);

                        }

                    }

                    // update times

                    try {

                        futimes(fd,

                                lastAccessTime.to(TimeUnit.MICROSECONDS),

                                lastModifiedTime.to(TimeUnit.MICROSECONDS));

                    } catch (UnixException x) {

                        x.rethrowAsIOException(file);

                    }

                } finally {

                    if (file != null)

                        UnixNativeDispatcher.close(fd);

                }

            } finally {

                ds.readLock().unlock();

            }

        }

    }

    /**

     * A PosixFileAttributeView implementation that using a dfd/name pair.

     */

    private class PosixFileAttributeViewImpl

        extends BasicFileAttributeViewImpl implements PosixFileAttributeView

    {

        PosixFileAttributeViewImpl(UnixPath file, boolean followLinks) {

            super(file, followLinks);

        }

        private void checkWriteAndUserAccess() {

            SecurityManager sm = System.getSecurityManager();

            if (sm != null) {

                super.checkWriteAccess();

                sm.checkPermission(new RuntimePermission("accessUserInformation"));

            }

        }

        @Override

        public String name() {

            return "posix";

        }

        @Override

        public PosixFileAttributes readAttributes() throws IOException {

            SecurityManager sm = System.getSecurityManager();

            if (sm != null) {

                if (file == null)

                    ds.directory().checkRead();

                else

                    ds.directory().resolve(file).checkRead();

                sm.checkPermission(new RuntimePermission("accessUserInformation"));

            }

            ds.readLock().lock();

            try {

                if (!ds.isOpen())

                    throw new ClosedDirectoryStreamException();

                try {

                     UnixFileAttributes attrs = (file == null) ?

                         UnixFileAttributes.get(dfd) :

                         UnixFileAttributes.get(dfd, file, followLinks);

                     return attrs;

                } catch (UnixException x) {

                    x.rethrowAsIOException(file);

                    return null;    // keep compiler happy

                }

            } finally {

                ds.readLock().unlock();

            }

        }

        @Override

        public void setPermissions(Set<PosixFilePermission> perms)

            throws IOException

        {

            // permission check

            checkWriteAndUserAccess();

            ds.readLock().lock();

            try {

                if (!ds.isOpen())

                    throw new ClosedDirectoryStreamException();

                int fd = (file == null) ? dfd : open();

                try {

                    fchmod(fd, UnixFileModeAttribute.toUnixMode(perms));

                } catch (UnixException x) {

                    x.rethrowAsIOException(file);

                } finally {

                    if (file != null && fd >= 0)

                        UnixNativeDispatcher.close(fd);

                }

            } finally {

                ds.readLock().unlock();

            }

        }

        private void setOwners(int uid, int gid) throws IOException {

            // permission check

            checkWriteAndUserAccess();