/*

 * 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.io.IOException;

/**

 * Linux implementation of FileStore

 */

class LinuxFileStore

    extends UnixFileStore

{

    // used when checking if extended attributes are enabled or not

    private volatile boolean xattrChecked;

    private volatile boolean xattrEnabled;

    LinuxFileStore(UnixPath file) throws IOException {

        super(file);

    }

    LinuxFileStore(UnixFileSystem fs, UnixMountEntry entry) throws IOException {

        super(fs, entry);

    }

    /**

     * Finds, and returns, the mount entry for the file system where the file

     * resides.

     */

    @Override

    UnixMountEntry findMountEntry() throws IOException {

        LinuxFileSystem fs = (LinuxFileSystem)file().getFileSystem();

        // step 1: get realpath

        UnixPath path = null;

        try {

            byte[] rp = UnixNativeDispatcher.realpath(file());

            path = new UnixPath(fs, rp);

        } catch (UnixException x) {

            x.rethrowAsIOException(file());

        }

        // step 2: find mount point

        List<UnixMountEntry> procMountsEntries =

            fs.getMountEntries("/proc/mounts");

        UnixPath parent = path.getParent();

        while (parent != null) {

            UnixFileAttributes attrs = null;

            try {

                attrs = UnixFileAttributes.get(parent, true);

            } catch (UnixException x) {

                x.rethrowAsIOException(parent);

            }

            if (attrs.dev() != dev()) {

                // step 3: lookup mounted file systems (use /proc/mounts to

                // ensure we find the file system even when not in /etc/mtab)

                byte[] dir = path.asByteArray();

                for (UnixMountEntry entry : procMountsEntries) {

                    if (Arrays.equals(dir, entry.dir()))

                        return entry;

                }

            }

            path = parent;

            parent = parent.getParent();

        }

        // step 3: lookup mounted file systems (use /proc/mounts to

        // ensure we find the file system even when not in /etc/mtab)

        byte[] dir = path.asByteArray();

        for (UnixMountEntry entry : procMountsEntries) {

            if (Arrays.equals(dir, entry.dir()))

                return entry;

        }

        throw new IOException("Mount point not found");

    }

    // returns true if extended attributes enabled on file system where given

    // file resides, returns false if disabled or unable to determine.

    private boolean isExtendedAttributesEnabled(UnixPath path) {

        int fd = -1;

        try {

            fd = path.openForAttributeAccess(false);

            // fgetxattr returns size if called with size==0

            byte[] name = Util.toBytes("user.java");

            LinuxNativeDispatcher.fgetxattr(fd, name, 0L, 0);

            return true;

        } catch (UnixException e) {

            // attribute does not exist

            if (e.errno() == UnixConstants.ENODATA)

                return true;

        } finally {

            UnixNativeDispatcher.close(fd);

        }

        return false;

    }

    @Override

    public boolean supportsFileAttributeView(Class<? extends FileAttributeView> type) {

        // support DosFileAttributeView and UserDefinedAttributeView if extended

        // attributes enabled

        if (type == DosFileAttributeView.class ||

            type == UserDefinedFileAttributeView.class)

        {

            // lookup fstypes.properties

            FeatureStatus status = checkIfFeaturePresent("user_xattr");

            if (status == FeatureStatus.PRESENT)

                return true;

            if (status == FeatureStatus.NOT_PRESENT)

                return false;

            // if file system is mounted with user_xattr option then assume

            // extended attributes are enabled

            if ((entry().hasOption("user_xattr")))

                return true;

            }

            // not ext3/4 so probe mount point

            if (!xattrChecked) {

                UnixPath dir = new UnixPath(file().getFileSystem(), entry().dir());

                xattrEnabled = isExtendedAttributesEnabled(dir);

                xattrChecked = true;

            }

            return xattrEnabled;

        }

        // POSIX attributes not supported on FAT

        if (type == PosixFileAttributeView.class && entry().fstype().equals("vfat"))

            return false;

        return super.supportsFileAttributeView(type);

    }

    @Override

    public boolean supportsFileAttributeView(String name) {

        if (name.equals("dos"))

            return supportsFileAttributeView(DosFileAttributeView.class);

        if (name.equals("user"))

            return supportsFileAttributeView(UserDefinedFileAttributeView.class);

        return super.supportsFileAttributeView(name);

    }

}