/*
 * Copyright (c) 2008, 2018, 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 sun.nio.fs;

import java.nio.file.*;
import java.nio.file.attribute.*;
import java.nio.file.spi.FileTypeDetector;
import java.nio.channels.*;
import java.net.URI;
import java.util.concurrent.ExecutorService;
import java.io.IOException;
import java.io.FilePermission;
import java.util.*;
import java.security.AccessController;

import sun.nio.ch.ThreadPool;
import sun.security.util.SecurityConstants;
import static sun.nio.fs.UnixNativeDispatcher.*;
import static sun.nio.fs.UnixConstants.*;

Base implementation of FileSystemProvider
/**
 * Base implementation of FileSystemProvider
 */

public abstract class UnixFileSystemProvider
    extends AbstractFileSystemProvider
{
    private static final String USER_DIR = "user.dir";
    private final UnixFileSystem theFileSystem;

    public UnixFileSystemProvider() {
        String userDir = System.getProperty(USER_DIR);
        theFileSystem = newFileSystem(userDir);
    }

    UnixFileSystem theFileSystem() {
        return theFileSystem;
    }

    
Constructs a new file system using the given default directory.
/**
     * Constructs a new file system using the given default directory.
     */
    abstract UnixFileSystem newFileSystem(String dir);

    @Override
    public final String getScheme() {
        return "file";
    }

    private void checkUri(URI uri) {
        if (!uri.getScheme().equalsIgnoreCase(getScheme()))
            throw new IllegalArgumentException("URI does not match this provider");
        if (uri.getRawAuthority() != null)
            throw new IllegalArgumentException("Authority component present");
        String path = uri.getPath();
        if (path == null)
            throw new IllegalArgumentException("Path component is undefined");
        if (!path.equals("/"))
            throw new IllegalArgumentException("Path component should be '/'");
        if (uri.getRawQuery() != null)
            throw new IllegalArgumentException("Query component present");
        if (uri.getRawFragment() != null)
            throw new IllegalArgumentException("Fragment component present");
    }

    @Override
    public final FileSystem newFileSystem(URI uri, Map<String,?> env) {
        checkUri(uri);
        throw new FileSystemAlreadyExistsException();
    }

    @Override
    public final FileSystem getFileSystem(URI uri) {
        checkUri(uri);
        return theFileSystem;
    }

    @Override
    public Path getPath(URI uri) {
        return UnixUriUtils.fromUri(theFileSystem, uri);
    }

    UnixPath checkPath(Path obj) {
        if (obj == null)
            throw new NullPointerException();
        if (!(obj instanceof UnixPath))
            throw new ProviderMismatchException();
        return (UnixPath)obj;
    }

    @Override
    @SuppressWarnings("unchecked")
    public <V extends FileAttributeView> V getFileAttributeView(Path obj,
                                                                Class<V> type,
                                                                LinkOption... options)
    {
        UnixPath file = UnixPath.toUnixPath(obj);
        boolean followLinks = Util.followLinks(options);
        if (type == BasicFileAttributeView.class)
            return (V) UnixFileAttributeViews.createBasicView(file, followLinks);
        if (type == PosixFileAttributeView.class)
            return (V) UnixFileAttributeViews.createPosixView(file, followLinks);
        if (type == FileOwnerAttributeView.class)
            return (V) UnixFileAttributeViews.createOwnerView(file, followLinks);
        if (type == null)
            throw new NullPointerException();
        return (V) null;
    }

    @Override
    @SuppressWarnings("unchecked")
    public <A extends BasicFileAttributes> A readAttributes(Path file,
                                                               Class<A> type,
                                                               LinkOption... options)
        throws IOException
    {
        Class<? extends BasicFileAttributeView> view;
        if (type == BasicFileAttributes.class)
            view = BasicFileAttributeView.class;
        else if (type == PosixFileAttributes.class)
            view = PosixFileAttributeView.class;
        else if (type == null)
            throw new NullPointerException();
        else
            throw new UnsupportedOperationException();
        return (A) getFileAttributeView(file, view, options).readAttributes();
    }

    @Override
    protected DynamicFileAttributeView getFileAttributeView(Path obj,
                                                            String name,
                                                            LinkOption... options)
    {
        UnixPath file = UnixPath.toUnixPath(obj);
        boolean followLinks = Util.followLinks(options);
        if (name.equals("basic"))
            return UnixFileAttributeViews.createBasicView(file, followLinks);
        if (name.equals("posix"))
            return UnixFileAttributeViews.createPosixView(file, followLinks);
        if (name.equals("unix"))
            return UnixFileAttributeViews.createUnixView(file, followLinks);
        if (name.equals("owner"))
            return UnixFileAttributeViews.createOwnerView(file, followLinks);
        return null;
    }

    @Override
    public FileChannel newFileChannel(Path obj,
                                      Set<? extends OpenOption> options,
                                      FileAttribute<?>... attrs)
        throws IOException
    {
        UnixPath file = checkPath(obj);
        int mode = UnixFileModeAttribute
            .toUnixMode(UnixFileModeAttribute.ALL_READWRITE, attrs);
        try {
            return UnixChannelFactory.newFileChannel(file, options, mode);
        } catch (UnixException x) {
            x.rethrowAsIOException(file);
            return null;
        }
    }

    @Override
    public AsynchronousFileChannel newAsynchronousFileChannel(Path obj,
                                                              Set<? extends OpenOption> options,
                                                              ExecutorService executor,
                                                              FileAttribute<?>... attrs) throws IOException
    {
        UnixPath file = checkPath(obj);
        int mode = UnixFileModeAttribute
            .toUnixMode(UnixFileModeAttribute.ALL_READWRITE, attrs);
        ThreadPool pool = (executor == null) ? null : ThreadPool.wrap(executor, 0);
        try {
            return UnixChannelFactory
                .newAsynchronousFileChannel(file, options, mode, pool);
        } catch (UnixException x) {
            x.rethrowAsIOException(file);
            return null;
        }
    }


    @Override
    public SeekableByteChannel newByteChannel(Path obj,
                                              Set<? extends OpenOption> options,
                                              FileAttribute<?>... attrs)
         throws IOException
    {
        UnixPath file = UnixPath.toUnixPath(obj);
        int mode = UnixFileModeAttribute
            .toUnixMode(UnixFileModeAttribute.ALL_READWRITE, attrs);
        try {
            return UnixChannelFactory.newFileChannel(file, options, mode);
        } catch (UnixException x) {
            x.rethrowAsIOException(file);
            return null;  // keep compiler happy
        }
    }

    @Override
    boolean implDelete(Path obj, boolean failIfNotExists) throws IOException {
        UnixPath file = UnixPath.toUnixPath(obj);
        file.checkDelete();

        // need file attributes to know if file is directory
        UnixFileAttributes attrs = null;
        try {
            attrs = UnixFileAttributes.get(file, false);
            if (attrs.isDirectory()) {
                rmdir(file);
            } else {
                unlink(file);
            }
            return true;
        } catch (UnixException x) {
            // no-op if file does not exist
            if (!failIfNotExists && x.errno() == ENOENT)
                return false;

            // DirectoryNotEmptyException if not empty
            if (attrs != null && attrs.isDirectory() &&
                (x.errno() == EEXIST || x.errno() == ENOTEMPTY))
                throw new DirectoryNotEmptyException(file.getPathForExceptionMessage());

            x.rethrowAsIOException(file);
            return false;
        }
    }

    @Override
    public void copy(Path source, Path target, CopyOption... options)
        throws IOException
    {
        UnixCopyFile.copy(UnixPath.toUnixPath(source),
                          UnixPath.toUnixPath(target),
                          options);
    }

    @Override
    public void move(Path source, Path target, CopyOption... options)
        throws IOException
    {
        UnixCopyFile.move(UnixPath.toUnixPath(source),
                          UnixPath.toUnixPath(target),
                          options);
    }

    @Override
    public void checkAccess(Path obj, AccessMode... modes) throws IOException {
        UnixPath file = UnixPath.toUnixPath(obj);
        boolean e = false;
        boolean r = false;
        boolean w = false;
        boolean x = false;

        if (modes.length == 0) {
            e = true;
        } else {
            for (AccessMode mode: modes) {
                switch (mode) {
                    case READ : r = true; break;
                    case WRITE : w = true; break;
                    case EXECUTE : x = true; break;
                    default: throw new AssertionError("Should not get here");
                }
            }
        }

        int mode = 0;
        if (e || r) {
            file.checkRead();
            mode |= (r) ? R_OK : F_OK;
        }
        if (w) {
            file.checkWrite();
            mode |= W_OK;
        }
        if (x) {
            SecurityManager sm = System.getSecurityManager();
            if (sm != null) {
                // not cached
                sm.checkExec(file.getPathForPermissionCheck());
            }
            mode |= X_OK;
        }
        try {
            access(file, mode);
        } catch (UnixException exc) {
            exc.rethrowAsIOException(file);
        }
    }

    @Override
    public boolean isSameFile(Path obj1, Path obj2) throws IOException {
        UnixPath file1 = UnixPath.toUnixPath(obj1);
        if (file1.equals(obj2))
            return true;
        if (obj2 == null)
            throw new NullPointerException();
        if (!(obj2 instanceof UnixPath))
            return false;
        UnixPath file2 = (UnixPath)obj2;

        // check security manager access to both files
        file1.checkRead();
        file2.checkRead();

        UnixFileAttributes attrs1;
        UnixFileAttributes attrs2;
        try {
             attrs1 = UnixFileAttributes.get(file1, true);
        } catch (UnixException x) {
            x.rethrowAsIOException(file1);
            return false;    // keep compiler happy
        }
        try {
            attrs2 = UnixFileAttributes.get(file2, true);
        } catch (UnixException x) {
            x.rethrowAsIOException(file2);
            return false;    // keep compiler happy
        }
        return attrs1.isSameFile(attrs2);
    }

    @Override
    public boolean isHidden(Path obj) {
        UnixPath file = UnixPath.toUnixPath(obj);
        file.checkRead();
        UnixPath name = file.getFileName();
        if (name == null)
            return false;
        return (name.asByteArray()[0] == '.');
    }

    
Returns a FileStore to represent the file system where the given file
reside.
/**
     * Returns a FileStore to represent the file system where the given file
     * reside.
     */
    abstract FileStore getFileStore(UnixPath path) throws IOException;

    @Override
    public FileStore getFileStore(Path obj) throws IOException {
        UnixPath file = UnixPath.toUnixPath(obj);
        SecurityManager sm = System.getSecurityManager();
        if (sm != null) {
            sm.checkPermission(new RuntimePermission("getFileStoreAttributes"));
            file.checkRead();
        }
        return getFileStore(file);
    }

    @Override
    public void createDirectory(Path obj, FileAttribute<?>... attrs)
        throws IOException
    {
        UnixPath dir = UnixPath.toUnixPath(obj);
        dir.checkWrite();

        int mode = UnixFileModeAttribute.toUnixMode(UnixFileModeAttribute.ALL_PERMISSIONS, attrs);
        try {
            mkdir(dir, mode);
        } catch (UnixException x) {
            if (x.errno() == EISDIR)
                throw new FileAlreadyExistsException(dir.toString());
            x.rethrowAsIOException(dir);
        }
    }


    @Override
    public DirectoryStream<Path> newDirectoryStream(Path obj, DirectoryStream.Filter<? super Path> filter)
        throws IOException
    {
        UnixPath dir = UnixPath.toUnixPath(obj);
        dir.checkRead();
        if (filter == null)
            throw new NullPointerException();

        // can't return SecureDirectoryStream on kernels that don't support openat
        // or O_NOFOLLOW
        if (!openatSupported() || O_NOFOLLOW == 0) {
            try {
                long ptr = opendir(dir);
                return new UnixDirectoryStream(dir, ptr, filter);
            } catch (UnixException x) {
                if (x.errno() == ENOTDIR)
                    throw new NotDirectoryException(dir.getPathForExceptionMessage());
                x.rethrowAsIOException(dir);
            }
        }

        // open directory and dup file descriptor for use by
        // opendir/readdir/closedir
        int dfd1 = -1;
        int dfd2 = -1;
        long dp = 0L;
        try {
            dfd1 = open(dir, O_RDONLY, 0);
            dfd2 = dup(dfd1);
            dp = fdopendir(dfd1);
        } catch (UnixException x) {
            if (dfd1 != -1)
                UnixNativeDispatcher.close(dfd1);
            if (dfd2 != -1)
                UnixNativeDispatcher.close(dfd2);
            if (x.errno() == UnixConstants.ENOTDIR)
                throw new NotDirectoryException(dir.getPathForExceptionMessage());
            x.rethrowAsIOException(dir);
        }
        return new UnixSecureDirectoryStream(dir, dp, dfd2, filter);
    }

    @Override
    public void createSymbolicLink(Path obj1, Path obj2, FileAttribute<?>... attrs)
        throws IOException
    {
        UnixPath link = UnixPath.toUnixPath(obj1);
        UnixPath target = UnixPath.toUnixPath(obj2);

        // no attributes supported when creating links
        if (attrs.length > 0) {
            UnixFileModeAttribute.toUnixMode(0, attrs);  // may throw NPE or UOE
            throw new UnsupportedOperationException("Initial file attributes" +
                "not supported when creating symbolic link");
        }

        // permission check
        SecurityManager sm = System.getSecurityManager();
        if (sm != null) {
            sm.checkPermission(new LinkPermission("symbolic"));
            link.checkWrite();
        }

        // create link
        try {
            symlink(target.asByteArray(), link);
        } catch (UnixException x) {
            x.rethrowAsIOException(link);
        }
    }

    @Override
    public void createLink(Path obj1, Path obj2) throws IOException {
        UnixPath link = UnixPath.toUnixPath(obj1);
        UnixPath existing = UnixPath.toUnixPath(obj2);

        // permission check
        SecurityManager sm = System.getSecurityManager();
        if (sm != null) {
            sm.checkPermission(new LinkPermission("hard"));
            link.checkWrite();
            existing.checkWrite();
        }
        try {
            link(existing, link);
        } catch (UnixException x) {
            x.rethrowAsIOException(link, existing);
        }
    }

    @Override
    public Path readSymbolicLink(Path obj1) throws IOException {
        UnixPath link = UnixPath.toUnixPath(obj1);
        // permission check
        SecurityManager sm = System.getSecurityManager();
        if (sm != null) {
            FilePermission perm = new FilePermission(link.getPathForPermissionCheck(),
                SecurityConstants.FILE_READLINK_ACTION);
            sm.checkPermission(perm);
        }
        try {
            byte[] target = readlink(link);
            return new UnixPath(link.getFileSystem(), target);
        } catch (UnixException x) {
           if (x.errno() == UnixConstants.EINVAL)
                throw new NotLinkException(link.getPathForExceptionMessage());
            x.rethrowAsIOException(link);
            return null;    // keep compiler happy
        }
    }

    @Override
    public final boolean isDirectory(Path obj) {
        UnixPath file = UnixPath.toUnixPath(obj);
        file.checkRead();
        int mode = UnixNativeDispatcher.stat(file);
        return ((mode & UnixConstants.S_IFMT) == UnixConstants.S_IFDIR);
    }

    @Override
    public final boolean isRegularFile(Path obj) {
        UnixPath file = UnixPath.toUnixPath(obj);
        file.checkRead();
        int mode = UnixNativeDispatcher.stat(file);
        return ((mode & UnixConstants.S_IFMT) == UnixConstants.S_IFREG);
    }

    @Override
    public final boolean exists(Path obj) {
        UnixPath file = UnixPath.toUnixPath(obj);
        file.checkRead();
        return UnixNativeDispatcher.exists(file);
    }

    
Returns a FileTypeDetector for this platform. /**
     * Returns a {@code FileTypeDetector} for this platform.
     */
    FileTypeDetector getFileTypeDetector() {
        return new AbstractFileTypeDetector() {
            @Override
            public String implProbeContentType(Path file) {
                return null;
            }
        };
    }

    
Returns a FileTypeDetector that chains the given array of file type detectors. When the implProbeContentType method is invoked then each of the detectors is invoked in turn, the result from the first to detect the file type is returned. /**
     * Returns a {@code FileTypeDetector} that chains the given array of file
     * type detectors. When the {@code implProbeContentType} method is invoked
     * then each of the detectors is invoked in turn, the result from the
     * first to detect the file type is returned.
     */
    final FileTypeDetector chain(final AbstractFileTypeDetector... detectors) {
        return new AbstractFileTypeDetector() {
            @Override
            protected String implProbeContentType(Path file) throws IOException {
                for (AbstractFileTypeDetector detector : detectors) {
                    String result = detector.implProbeContentType(file);
                    if (result != null && !result.isEmpty()) {
                        return result;
                    }
                }
                return null;
            }
        };
    }
}