// /***************************************************************************
// The Disc Image Chef
// ----------------------------------------------------------------------------
//
// Filename       : BTRFS.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : B-tree file system plugin.
//
// --[ Description ] ----------------------------------------------------------
//
//     Identifies the B-tree file system and shows information.
//
// --[ License ] --------------------------------------------------------------
//
//     This library is free software; you can redistribute it and/or modify
//     it under the terms of the GNU Lesser General Public License as
//     published by the Free Software Foundation; either version 2.1 of the
//     License, or (at your option) any later version.
//
//     This library 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
//     Lesser General Public License for more details.
//
//     You should have received a copy of the GNU Lesser General Public
//     License along with this library; if not, see <http://www.gnu.org/licenses/>.
//
// ----------------------------------------------------------------------------
// Copyright © 2011-2017 Natalia Portillo
// ****************************************************************************/

using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System.Text;
using DiscImageChef.CommonTypes;
using DiscImageChef.Console;

namespace DiscImageChef.Filesystems
{
    public class BTRFS : Filesystem
    {
        /// <summary>
        /// BTRFS magic "_BHRfS_M"
        /// </summary>
        const ulong btrfsMagic = 0x4D5F53665248425F;

        public BTRFS()
        {
            Name = "B-tree file system";
            PluginUUID = new Guid("C904CF15-5222-446B-B7DB-02EAC5D781B3");
            CurrentEncoding = Encoding.GetEncoding("iso-8859-15");
        }

        public BTRFS(ImagePlugins.ImagePlugin imagePlugin, Partition partition, Encoding encoding)
        {
            Name = "B-tree file system";
            PluginUUID = new Guid("C904CF15-5222-446B-B7DB-02EAC5D781B3");
            if(encoding == null)
                CurrentEncoding = Encoding.GetEncoding("iso-8859-15");
            else
                CurrentEncoding = encoding;
        }

        [StructLayout(LayoutKind.Sequential, Pack = 1)]
        struct SuperBlock
        {
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 0x20)]
            public byte[] checksum;
            public Guid uuid;
            public ulong pba;
            public ulong flags;
            public ulong magic;
            public ulong generation;
            public ulong root_lba;
            public ulong chunk_lba;
            public ulong log_lba;
            public ulong log_root_transid;
            public ulong total_bytes;
            public ulong bytes_used;
            public ulong root_dir_objectid;
            public ulong num_devices;
            public uint sectorsize;
            public uint nodesize;
            public uint leafsize;
            public uint stripesize;
            public uint n;
            public ulong chunk_root_generation;
            public ulong compat_flags;
            public ulong compat_ro_flags;
            public ulong incompat_flags;
            public ushort csum_type;
            public byte root_level;
            public byte chunk_root_level;
            public byte log_root_level;
            public DevItem dev_item;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 0x100)]
            public string label;
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 0x100)]
            public byte[] reserved;
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 0x800)]
            public byte[] chunkpairs;
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 0x4D5)]
            public byte[] unused;
        }

        [StructLayout(LayoutKind.Sequential, Pack = 1)]
        struct DevItem
        {
            public ulong id;
            public ulong bytes;
            public ulong used;
            public uint optimal_align;
            public uint optimal_width;
            public uint minimal_size;
            public ulong type;
            public ulong generation;
            public ulong start_offset;
            public uint dev_group;
            public byte seek_speed;
            public byte bandwitdh;
            public Guid device_uuid;
            public Guid uuid;
        }

        public override bool Identify(ImagePlugins.ImagePlugin imagePlugin, Partition partition)
        {
            if(partition.Start >= partition.End)
                return false;

            ulong sbSectorOff = 0x10000 / imagePlugin.GetSectorSize();
            uint sbSectorSize = 0x1000 / imagePlugin.GetSectorSize();

            if((sbSectorOff + partition.Start) >= partition.End)
                return false;

            byte[] sector = imagePlugin.ReadSectors(sbSectorOff + partition.Start, sbSectorSize);
            SuperBlock btrfsSb;

            try
            {
                GCHandle handle = GCHandle.Alloc(sector, GCHandleType.Pinned);
                btrfsSb = (SuperBlock)Marshal.PtrToStructure(handle.AddrOfPinnedObject(), typeof(SuperBlock));
                handle.Free();
            }
            catch
            {
                return false;
            }

            DicConsole.DebugWriteLine("BTRFS Plugin", "sbSectorOff = {0}", sbSectorOff);
            DicConsole.DebugWriteLine("BTRFS Plugin", "sbSectorSize = {0}", sbSectorSize);
            DicConsole.DebugWriteLine("BTRFS Plugin", "partition.PartitionStartSector = {0}", partition.Start);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.magic = 0x{0:X16}", btrfsSb.magic);

            return btrfsSb.magic == btrfsMagic;
        }

        public override void GetInformation(ImagePlugins.ImagePlugin imagePlugin, Partition partition, out string information)
        {
            StringBuilder sbInformation = new StringBuilder();
            xmlFSType = new Schemas.FileSystemType();
            information = "";

            ulong sbSectorOff = 0x10000 / imagePlugin.GetSectorSize();
            uint sbSectorSize = 0x1000 / imagePlugin.GetSectorSize();

            byte[] sector = imagePlugin.ReadSectors(sbSectorOff + partition.Start, sbSectorSize);
            SuperBlock btrfsSb;

            GCHandle handle = GCHandle.Alloc(sector, GCHandleType.Pinned);
            btrfsSb = (SuperBlock)Marshal.PtrToStructure(handle.AddrOfPinnedObject(), typeof(SuperBlock));
            handle.Free();

            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.checksum = {0}", btrfsSb.checksum);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.uuid = {0}", btrfsSb.uuid);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.pba = {0}", btrfsSb.pba);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.flags = {0}", btrfsSb.flags);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.magic = {0}", btrfsSb.magic);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.generation = {0}", btrfsSb.generation);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.root_lba = {0}", btrfsSb.root_lba);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.chunk_lba = {0}", btrfsSb.chunk_lba);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.log_lba = {0}", btrfsSb.log_lba);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.log_root_transid = {0}", btrfsSb.log_root_transid);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.total_bytes = {0}", btrfsSb.total_bytes);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.bytes_used = {0}", btrfsSb.bytes_used);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.root_dir_objectid = {0}", btrfsSb.root_dir_objectid);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.num_devices = {0}", btrfsSb.num_devices);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.sectorsize = {0}", btrfsSb.sectorsize);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.nodesize = {0}", btrfsSb.nodesize);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.leafsize = {0}", btrfsSb.leafsize);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.stripesize = {0}", btrfsSb.stripesize);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.n = {0}", btrfsSb.n);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.chunk_root_generation = {0}", btrfsSb.chunk_root_generation);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.compat_flags = 0x{0:X16}", btrfsSb.compat_flags);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.compat_ro_flags = 0x{0:X16}", btrfsSb.compat_ro_flags);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.incompat_flags = 0x{0:X16}", btrfsSb.incompat_flags);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.csum_type = {0}", btrfsSb.csum_type);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.root_level = {0}", btrfsSb.root_level);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.chunk_root_level = {0}", btrfsSb.chunk_root_level);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.log_root_level = {0}", btrfsSb.log_root_level);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.dev_item.id = 0x{0:X16}", btrfsSb.dev_item.id);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.dev_item.bytes = {0}", btrfsSb.dev_item.bytes);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.dev_item.used = {0}", btrfsSb.dev_item.used);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.dev_item.optimal_align = {0}", btrfsSb.dev_item.optimal_align);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.dev_item.optimal_width = {0}", btrfsSb.dev_item.optimal_width);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.dev_item.minimal_size = {0}", btrfsSb.dev_item.minimal_size);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.dev_item.type = {0}", btrfsSb.dev_item.type);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.dev_item.generation = {0}", btrfsSb.dev_item.generation);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.dev_item.start_offset = {0}", btrfsSb.dev_item.start_offset);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.dev_item.dev_group = {0}", btrfsSb.dev_item.dev_group);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.dev_item.seek_speed = {0}", btrfsSb.dev_item.seek_speed);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.dev_item.bandwitdh = {0}", btrfsSb.dev_item.bandwitdh);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.dev_item.device_uuid = {0}", btrfsSb.dev_item.device_uuid);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.dev_item.uuid = {0}", btrfsSb.dev_item.uuid);
            DicConsole.DebugWriteLine("BTRFS Plugin", "btrfsSb.label = {0}", btrfsSb.label);

            sbInformation.AppendLine("B-tree filesystem");
            sbInformation.AppendFormat("UUID: {0}", btrfsSb.uuid).AppendLine();
            sbInformation.AppendFormat("This superblock resides on physical block {0}", btrfsSb.pba).AppendLine();
            sbInformation.AppendFormat("Root tree starts at LBA {0}", btrfsSb.root_lba).AppendLine();
            sbInformation.AppendFormat("Chunk tree starts at LBA {0}", btrfsSb.chunk_lba).AppendLine();
            sbInformation.AppendFormat("Log tree starts at LBA {0}", btrfsSb.log_lba).AppendLine();
            sbInformation.AppendFormat("Volume has {0} bytes spanned in {1} devices", btrfsSb.total_bytes, btrfsSb.num_devices).AppendLine();
            sbInformation.AppendFormat("Volume has {0} bytes used", btrfsSb.bytes_used).AppendLine();
            sbInformation.AppendFormat("{0} bytes/sector", btrfsSb.sectorsize).AppendLine();
            sbInformation.AppendFormat("{0} bytes/node", btrfsSb.nodesize).AppendLine();
            sbInformation.AppendFormat("{0} bytes/leaf", btrfsSb.leafsize).AppendLine();
            sbInformation.AppendFormat("{0} bytes/stripe", btrfsSb.stripesize).AppendLine();
            sbInformation.AppendFormat("Flags: 0x{0:X}", btrfsSb.flags).AppendLine();
            sbInformation.AppendFormat("Compatible flags: 0x{0:X}", btrfsSb.compat_flags).AppendLine();
            sbInformation.AppendFormat("Read-only compatible flags: 0x{0:X}", btrfsSb.compat_ro_flags).AppendLine();
            sbInformation.AppendFormat("Incompatible flags: 0x{0:X}", btrfsSb.incompat_flags).AppendLine();
            sbInformation.AppendFormat("Device's UUID: {0}", btrfsSb.dev_item.uuid).AppendLine();
            sbInformation.AppendFormat("Volume label: {0}", btrfsSb.label).AppendLine();

            information = sbInformation.ToString();

            xmlFSType = new Schemas.FileSystemType();
            xmlFSType.Clusters = (long)(btrfsSb.total_bytes / btrfsSb.sectorsize);
            xmlFSType.ClusterSize = (int)btrfsSb.sectorsize;
            xmlFSType.FreeClusters = xmlFSType.Clusters - (long)(btrfsSb.bytes_used / btrfsSb.sectorsize);
            xmlFSType.FreeClustersSpecified = true;
            xmlFSType.VolumeName = btrfsSb.label;
            xmlFSType.VolumeSerial = string.Format("{0}", btrfsSb.uuid);
            xmlFSType.VolumeSetIdentifier = string.Format("{0}", btrfsSb.dev_item.device_uuid);
            xmlFSType.Type = Name;
        }

        public override Errno Mount()
        {
            return Errno.NotImplemented;
        }

        public override Errno Mount(bool debug)
        {
            return Errno.NotImplemented;
        }

        public override Errno Unmount()
        {
            return Errno.NotImplemented;
        }

        public override Errno MapBlock(string path, long fileBlock, ref long deviceBlock)
        {
            return Errno.NotImplemented;
        }

        public override Errno GetAttributes(string path, ref FileAttributes attributes)
        {
            return Errno.NotImplemented;
        }

        public override Errno ListXAttr(string path, ref List<string> xattrs)
        {
            return Errno.NotImplemented;
        }

        public override Errno GetXattr(string path, string xattr, ref byte[] buf)
        {
            return Errno.NotImplemented;
        }

        public override Errno Read(string path, long offset, long size, ref byte[] buf)
        {
            return Errno.NotImplemented;
        }

        public override Errno ReadDir(string path, ref List<string> contents)
        {
            return Errno.NotImplemented;
        }

        public override Errno StatFs(ref FileSystemInfo stat)
        {
            return Errno.NotImplemented;
        }

        public override Errno Stat(string path, ref FileEntryInfo stat)
        {
            return Errno.NotImplemented;
        }

        public override Errno ReadLink(string path, ref string dest)
        {
            return Errno.NotImplemented;
        }
    }
}

