Aaru/DiscImageChef.Filesystems/SysV.cs

// /***************************************************************************
// The Disc Image Chef
// ----------------------------------------------------------------------------
//
// Filename       : SysV.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : UNIX System V filesystem plugin.
//
// --[ Description ] ----------------------------------------------------------
//
//     Identifies the UNIX System V filesystem 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 © 2011-2018 Natalia Portillo
// ****************************************************************************/

using System;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using System.Text;
using DiscImageChef.CommonTypes;
using DiscImageChef.CommonTypes.Interfaces;
using Schemas;

namespace DiscImageChef.Filesystems
{
    // Information from the Linux kernel
    [SuppressMessage("ReSharper", "InconsistentNaming")]
    public class SysVfs : IFilesystem
    {
        const uint XENIX_MAGIC = 0x002B5544;
        const uint XENIX_CIGAM = 0x44552B00;
        const uint SYSV_MAGIC  = 0xFD187E20;
        const uint SYSV_CIGAM  = 0x207E18FD;
        // Rest have no magic.
        // Per a Linux kernel, Coherent fs has following:
        const string COH_FNAME = "noname";
        const string COH_FPACK = "nopack";
        const string COH_XXXXX = "xxxxx";
        const string COH_XXXXS = "xxxxx ";
        const string COH_XXXXN = "xxxxx\n";
        // SCO AFS
        const ushort SCO_NFREE = 0xFFFF;
        // UNIX 7th Edition has nothing to detect it, so check for a valid filesystem is a must :(
        const ushort V7_NICINOD = 100;
        const ushort V7_NICFREE = 100;
        const uint   V7_MAXSIZE = 0x00FFFFFF;

        public FileSystemType XmlFsType { get; private set; }
        public Encoding       Encoding  { get; private set; }
        public string         Name      => "UNIX System V filesystem";
        public Guid           Id        => new Guid("9B8D016A-8561-400E-A12A-A198283C211D");

        public bool Identify(IMediaImage imagePlugin, Partition partition)
        {
            if(2 + partition.Start >= partition.End) return false;

            byte sb_size_in_sectors;

            if(imagePlugin.Info.SectorSize <= 0x400
            ) // Check if underlying device sector size is smaller than SuperBlock size
                sb_size_in_sectors  = (byte)(0x400 / imagePlugin.Info.SectorSize);
            else sb_size_in_sectors = 1; // If not a single sector can store it

            if(partition.End <= partition.Start + 4 * (ulong)sb_size_in_sectors + sb_size_in_sectors
            ) // Device must be bigger than SB location + SB size + offset
                return false;

            // Sectors in a cylinder
            int spc = (int)(imagePlugin.Info.Heads * imagePlugin.Info.SectorsPerTrack);

            // Superblock can start on 0x000, 0x200, 0x600 and 0x800, not aligned, so we assume 16 (128 bytes/sector) sectors as a safe value
            int[] locations =
            {
                0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
                // Superblock can also skip one cylinder (for boot)
                spc
            };

            foreach(byte[] sb_sector in locations
                                       .TakeWhile(i => (ulong)i + partition.Start + sb_size_in_sectors <
                                                       imagePlugin.Info.Sectors)
                                       .Select(i => imagePlugin.ReadSectors((ulong)i + partition.Start,
                                                                            sb_size_in_sectors)))
            {
                uint magic = BitConverter.ToUInt32(sb_sector, 0x3F8);

                if(magic == XENIX_MAGIC || magic == XENIX_CIGAM || magic == SYSV_MAGIC || magic == SYSV_CIGAM)
                    return true;

                magic = BitConverter.ToUInt32(sb_sector, 0x1F8); // System V magic location

                if(magic == SYSV_MAGIC || magic == SYSV_CIGAM) return true;

                magic = BitConverter.ToUInt32(sb_sector, 0x1F0); // XENIX 3 magic location

                if(magic == XENIX_MAGIC || magic == XENIX_CIGAM) return true;

                byte[] coherent_string = new byte[6];
                Array.Copy(sb_sector, 0x1E4, coherent_string, 0, 6); // Coherent UNIX s_fname location
                string s_fname = StringHandlers.CToString(coherent_string);
                Array.Copy(sb_sector, 0x1EA, coherent_string, 0, 6); // Coherent UNIX s_fpack location
                string s_fpack = StringHandlers.CToString(coherent_string);

                if(s_fname == COH_FNAME && s_fpack == COH_FPACK || s_fname == COH_XXXXX && s_fpack == COH_XXXXX ||
                   s_fname == COH_XXXXS && s_fpack == COH_XXXXN) return true;

                // Now try to identify 7th edition
                uint   s_fsize  = BitConverter.ToUInt32(sb_sector, 0x002);
                ushort s_nfree  = BitConverter.ToUInt16(sb_sector, 0x006);
                ushort s_ninode = BitConverter.ToUInt16(sb_sector, 0x0D0);

                if(s_fsize  <= 0 || s_fsize >= 0xFFFFFFFF || s_nfree <= 0 || s_nfree >= 0xFFFF || s_ninode <= 0 ||
                   s_ninode >= 0xFFFF) continue;

                if((s_fsize & 0xFF) == 0x00 && (s_nfree & 0xFF) == 0x00 && (s_ninode & 0xFF) == 0x00)
                {
                    // Byteswap
                    s_fsize = ((s_fsize & 0xFF)       << 24) + ((s_fsize & 0xFF00) << 8) + ((s_fsize & 0xFF0000) >> 8) +
                              ((s_fsize & 0xFF000000) >> 24);
                    s_nfree  = (ushort)(s_nfree  >> 8);
                    s_ninode = (ushort)(s_ninode >> 8);
                }

                if((s_fsize  & 0xFF000000) != 0x00 || (s_nfree & 0xFF00) != 0x00 ||
                   (s_ninode & 0xFF00)     != 0x00) continue;

                if(s_fsize >= V7_MAXSIZE || s_nfree >= V7_NICFREE || s_ninode >= V7_NICINOD) continue;

                if(s_fsize * 1024 == (partition.End - partition.Start) * imagePlugin.Info.SectorSize ||
                   s_fsize * 512  == (partition.End - partition.Start) * imagePlugin.Info.SectorSize) return true;
            }

            return false;
        }

        public void GetInformation(IMediaImage imagePlugin, Partition partition, out string information,
                                   Encoding    encoding)
        {
            Encoding    = encoding ?? Encoding.GetEncoding("iso-8859-15");
            information = "";

            StringBuilder sb = new StringBuilder();
            BigEndianBitConverter.IsLittleEndian =
                true; // Start in little endian until we know what are we handling here
            int    start    = 0;
            bool   xenix    = false;
            bool   sysv     = false;
            bool   sys7th   = false;
            bool   coherent = false;
            bool   xenix3   = false;
            byte[] sb_sector;
            byte   sb_size_in_sectors;
            int    offset = 0;

            if(imagePlugin.Info.SectorSize <= 0x400
            ) // Check if underlying device sector size is smaller than SuperBlock size
                sb_size_in_sectors  = (byte)(0x400 / imagePlugin.Info.SectorSize);
            else sb_size_in_sectors = 1; // If not a single sector can store it
            // Sectors in a cylinder
            int spc = (int)(imagePlugin.Info.Heads * imagePlugin.Info.SectorsPerTrack);

            // Superblock can start on 0x000, 0x200, 0x600 and 0x800, not aligned, so we assume 16 (128 bytes/sector) sectors as a safe value
            int[] locations =
            {
                0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
                // Superblock can also skip one cylinder (for boot)
                spc
            };

            foreach(int i in locations)
            {
                sb_sector = imagePlugin.ReadSectors((ulong)i + partition.Start, sb_size_in_sectors);
                uint magic = BigEndianBitConverter.ToUInt32(sb_sector, 0x3F8);

                if(magic == XENIX_MAGIC || magic == SYSV_MAGIC)
                {
                    BigEndianBitConverter.IsLittleEndian = true; // Little endian
                    if(magic == SYSV_MAGIC)
                    {
                        sysv   = true;
                        offset = 0x200;
                    }
                    else xenix = true;

                    start = i;
                    break;
                }

                if(magic == XENIX_CIGAM || magic == SYSV_CIGAM)
                {
                    BigEndianBitConverter.IsLittleEndian = false; // Big endian
                    if(magic == SYSV_CIGAM)
                    {
                        sysv   = true;
                        offset = 0x200;
                    }
                    else xenix = true;

                    start = i;
                    break;
                }

                magic = BigEndianBitConverter.ToUInt32(sb_sector, 0x1F0); // XENIX 3 magic location

                if(magic == XENIX_MAGIC)
                {
                    BigEndianBitConverter.IsLittleEndian = true; // Little endian
                    xenix3                               = true;
                    start                                = i;
                    break;
                }

                if(magic == XENIX_CIGAM)
                {
                    BigEndianBitConverter.IsLittleEndian = false; // Big endian
                    xenix3                               = true;
                    start                                = i;
                    break;
                }

                magic = BigEndianBitConverter.ToUInt32(sb_sector, 0x1F8); // XENIX magic location

                if(magic == SYSV_MAGIC)
                {
                    BigEndianBitConverter.IsLittleEndian = true; // Little endian
                    sysv                                 = true;
                    start                                = i;
                    break;
                }

                if(magic == SYSV_CIGAM)
                {
                    BigEndianBitConverter.IsLittleEndian = false; // Big endian
                    sysv                                 = true;
                    start                                = i;
                    break;
                }

                byte[] coherent_string = new byte[6];
                Array.Copy(sb_sector, 0x1E4, coherent_string, 0, 6); // Coherent UNIX s_fname location
                string s_fname = StringHandlers.CToString(coherent_string, Encoding);
                Array.Copy(sb_sector, 0x1EA, coherent_string, 0, 6); // Coherent UNIX s_fpack location
                string s_fpack = StringHandlers.CToString(coherent_string, Encoding);

                if(s_fname == COH_FNAME && s_fpack == COH_FPACK || s_fname == COH_XXXXX && s_fpack == COH_XXXXX ||
                   s_fname == COH_XXXXS && s_fpack == COH_XXXXN)
                {
                    BigEndianBitConverter.IsLittleEndian = true; // Coherent is in PDP endianness, use helper for that
                    coherent                             = true;
                    start                                = i;
                    break;
                }

                // Now try to identify 7th edition
                uint   s_fsize  = BitConverter.ToUInt32(sb_sector, 0x002);
                ushort s_nfree  = BitConverter.ToUInt16(sb_sector, 0x006);
                ushort s_ninode = BitConverter.ToUInt16(sb_sector, 0x0D0);

                if(s_fsize  <= 0 || s_fsize >= 0xFFFFFFFF || s_nfree <= 0 || s_nfree >= 0xFFFF || s_ninode <= 0 ||
                   s_ninode >= 0xFFFF) continue;

                if((s_fsize & 0xFF) == 0x00 && (s_nfree & 0xFF) == 0x00 && (s_ninode & 0xFF) == 0x00)
                {
                    // Byteswap
                    s_fsize = ((s_fsize & 0xFF)       << 24) + ((s_fsize & 0xFF00) << 8) + ((s_fsize & 0xFF0000) >> 8) +
                              ((s_fsize & 0xFF000000) >> 24);
                    s_nfree  = (ushort)(s_nfree  >> 8);
                    s_ninode = (ushort)(s_ninode >> 8);
                }

                if((s_fsize  & 0xFF000000) != 0x00 || (s_nfree & 0xFF00) != 0x00 ||
                   (s_ninode & 0xFF00)     != 0x00) continue;

                if(s_fsize >= V7_MAXSIZE || s_nfree >= V7_NICFREE || s_ninode >= V7_NICINOD) continue;

                if(s_fsize * 1024 != (partition.End - partition.Start) * imagePlugin.Info.SectorSize &&
                   s_fsize * 512  != (partition.End - partition.Start) * imagePlugin.Info.SectorSize) continue;

                sys7th                               = true;
                BigEndianBitConverter.IsLittleEndian = true;
                start                                = i;
                break;
            }

            if(!sys7th && !sysv && !coherent && !xenix && !xenix3) return;

            XmlFsType = new FileSystemType();

            if(xenix || xenix3)
            {
                byte[]          xenix_strings = new byte[6];
                XenixSuperBlock xnx_sb        = new XenixSuperBlock();
                sb_sector = imagePlugin.ReadSectors((ulong)start + partition.Start, sb_size_in_sectors);

                if(xenix3)
                {
                    xnx_sb.s_isize   = BigEndianBitConverter.ToUInt16(sb_sector, 0x000);
                    xnx_sb.s_fsize   = BigEndianBitConverter.ToUInt32(sb_sector, 0x002);
                    xnx_sb.s_nfree   = BigEndianBitConverter.ToUInt16(sb_sector, 0x006);
                    xnx_sb.s_ninode  = BigEndianBitConverter.ToUInt16(sb_sector, 0x0D0);
                    xnx_sb.s_flock   = sb_sector[0x19A];
                    xnx_sb.s_ilock   = sb_sector[0x19B];
                    xnx_sb.s_fmod    = sb_sector[0x19C];
                    xnx_sb.s_ronly   = sb_sector[0x19D];
                    xnx_sb.s_time    = BigEndianBitConverter.ToInt32(sb_sector, 0x19E);
                    xnx_sb.s_tfree   = BigEndianBitConverter.ToUInt32(sb_sector, 0x1A2);
                    xnx_sb.s_tinode  = BigEndianBitConverter.ToUInt16(sb_sector, 0x1A6);
                    xnx_sb.s_cylblks = BigEndianBitConverter.ToUInt16(sb_sector, 0x1A8);
                    xnx_sb.s_gapblks = BigEndianBitConverter.ToUInt16(sb_sector, 0x1AA);
                    xnx_sb.s_dinfo0  = BigEndianBitConverter.ToUInt16(sb_sector, 0x1AC);
                    xnx_sb.s_dinfo1  = BigEndianBitConverter.ToUInt16(sb_sector, 0x1AE);
                    Array.Copy(sb_sector, 0x1B0, xenix_strings, 0, 6);
                    xnx_sb.s_fname = StringHandlers.CToString(xenix_strings, Encoding);
                    Array.Copy(sb_sector, 0x1B6, xenix_strings, 0, 6);
                    xnx_sb.s_fpack = StringHandlers.CToString(xenix_strings, Encoding);
                    xnx_sb.s_clean = sb_sector[0x1BC];
                    xnx_sb.s_magic = BigEndianBitConverter.ToUInt32(sb_sector, 0x1F0);
                    xnx_sb.s_type  = BigEndianBitConverter.ToUInt32(sb_sector, 0x1F4);
                }
                else
                {
                    xnx_sb.s_isize   = BigEndianBitConverter.ToUInt16(sb_sector, 0x000);
                    xnx_sb.s_fsize   = BigEndianBitConverter.ToUInt32(sb_sector, 0x002);
                    xnx_sb.s_nfree   = BigEndianBitConverter.ToUInt16(sb_sector, 0x006);
                    xnx_sb.s_ninode  = BigEndianBitConverter.ToUInt16(sb_sector, 0x198);
                    xnx_sb.s_flock   = sb_sector[0x262];
                    xnx_sb.s_ilock   = sb_sector[0x263];
                    xnx_sb.s_fmod    = sb_sector[0x264];
                    xnx_sb.s_ronly   = sb_sector[0x265];
                    xnx_sb.s_time    = BigEndianBitConverter.ToInt32(sb_sector, 0x266);
                    xnx_sb.s_tfree   = BigEndianBitConverter.ToUInt32(sb_sector, 0x26A);
                    xnx_sb.s_tinode  = BigEndianBitConverter.ToUInt16(sb_sector, 0x26E);
                    xnx_sb.s_cylblks = BigEndianBitConverter.ToUInt16(sb_sector, 0x270);
                    xnx_sb.s_gapblks = BigEndianBitConverter.ToUInt16(sb_sector, 0x272);
                    xnx_sb.s_dinfo0  = BigEndianBitConverter.ToUInt16(sb_sector, 0x274);
                    xnx_sb.s_dinfo1  = BigEndianBitConverter.ToUInt16(sb_sector, 0x276);
                    Array.Copy(sb_sector, 0x278, xenix_strings, 0, 6);
                    xnx_sb.s_fname = StringHandlers.CToString(xenix_strings, Encoding);
                    Array.Copy(sb_sector, 0x27E, xenix_strings, 0, 6);
                    xnx_sb.s_fpack = StringHandlers.CToString(xenix_strings, Encoding);
                    xnx_sb.s_clean = sb_sector[0x284];
                    xnx_sb.s_magic = BigEndianBitConverter.ToUInt32(sb_sector, 0x3F8);
                    xnx_sb.s_type  = BigEndianBitConverter.ToUInt32(sb_sector, 0x3FC);
                }

                uint bs = 512;
                sb.AppendLine("XENIX filesystem");
                XmlFsType.Type = "XENIX fs";
                switch(xnx_sb.s_type)
                {
                    case 1:
                        sb.AppendLine("512 bytes per block");
                        XmlFsType.ClusterSize = 512;
                        break;
                    case 2:
                        sb.AppendLine("1024 bytes per block");
                        bs                    = 1024;
                        XmlFsType.ClusterSize = 1024;
                        break;
                    case 3:
                        sb.AppendLine("2048 bytes per block");
                        bs                    = 2048;
                        XmlFsType.ClusterSize = 2048;
                        break;
                    default:
                        sb.AppendFormat("Unknown s_type value: 0x{0:X8}", xnx_sb.s_type).AppendLine();
                        break;
                }

                if(imagePlugin.Info.SectorSize == 2336 || imagePlugin.Info.SectorSize == 2352 ||
                   imagePlugin.Info.SectorSize == 2448)
                {
                    if(bs != 2048)
                        sb
                           .AppendFormat("WARNING: Filesystem indicates {0} bytes/block while device indicates {1} bytes/sector",
                                         bs, 2048).AppendLine();
                }
                else
                {
                    if(bs != imagePlugin.Info.SectorSize)
                        sb
                           .AppendFormat("WARNING: Filesystem indicates {0} bytes/block while device indicates {1} bytes/sector",
                                         bs, imagePlugin.Info.SectorSize).AppendLine();
                }

                sb.AppendFormat("{0} zones on volume ({1} bytes)", xnx_sb.s_fsize, xnx_sb.s_fsize * bs).AppendLine();
                sb.AppendFormat("{0} free zones on volume ({1} bytes)", xnx_sb.s_tfree, xnx_sb.s_tfree * bs)
                  .AppendLine();
                sb.AppendFormat("{0} free blocks on list ({1} bytes)", xnx_sb.s_nfree, xnx_sb.s_nfree * bs)
                  .AppendLine();
                sb.AppendFormat("{0} blocks per cylinder ({1} bytes)", xnx_sb.s_cylblks, xnx_sb.s_cylblks * bs)
                  .AppendLine();
                sb.AppendFormat("{0} blocks per gap ({1} bytes)", xnx_sb.s_gapblks, xnx_sb.s_gapblks * bs).AppendLine();
                sb.AppendFormat("First data zone: {0}", xnx_sb.s_isize).AppendLine();
                sb.AppendFormat("{0} free inodes on volume", xnx_sb.s_tinode).AppendLine();
                sb.AppendFormat("{0} free inodes on list", xnx_sb.s_ninode).AppendLine();
                if(xnx_sb.s_flock > 0) sb.AppendLine("Free block list is locked");
                if(xnx_sb.s_ilock > 0) sb.AppendLine("inode cache is locked");
                if(xnx_sb.s_fmod  > 0) sb.AppendLine("Superblock is being modified");
                if(xnx_sb.s_ronly > 0) sb.AppendLine("Volume is mounted read-only");
                sb.AppendFormat("Superblock last updated on {0}", DateHandlers.UnixToDateTime(xnx_sb.s_time))
                  .AppendLine();
                if(xnx_sb.s_time != 0)
                {
                    XmlFsType.ModificationDate          = DateHandlers.UnixToDateTime(xnx_sb.s_time);
                    XmlFsType.ModificationDateSpecified = true;
                }

                sb.AppendFormat("Volume name: {0}", xnx_sb.s_fname).AppendLine();
                XmlFsType.VolumeName = xnx_sb.s_fname;
                sb.AppendFormat("Pack name: {0}", xnx_sb.s_fpack).AppendLine();
                if(xnx_sb.s_clean == 0x46) sb.AppendLine("Volume is clean");
                else
                {
                    sb.AppendLine("Volume is dirty");
                    XmlFsType.Dirty = true;
                }
            }

            if(sysv)
            {
                sb_sector = imagePlugin.ReadSectors((ulong)start + partition.Start, sb_size_in_sectors);
                byte[] sysv_strings = new byte[6];

                SystemVRelease4SuperBlock sysv_sb = new SystemVRelease4SuperBlock
                {
                    s_type = BigEndianBitConverter.ToUInt32(sb_sector, 0x1FC + offset)
                };
                uint bs = 512;
                switch(sysv_sb.s_type)
                {
                    case 1:
                        XmlFsType.ClusterSize = 512;
                        break;
                    case 2:
                        bs                    = 1024;
                        XmlFsType.ClusterSize = 1024;
                        break;
                    case 3:
                        bs                    = 2048;
                        XmlFsType.ClusterSize = 2048;
                        break;
                    default:
                        sb.AppendFormat("Unknown s_type value: 0x{0:X8}", sysv_sb.s_type).AppendLine();
                        break;
                }

                sysv_sb.s_fsize = BigEndianBitConverter.ToUInt32(sb_sector, 0x002 + offset);

                bool sysvr4 = sysv_sb.s_fsize * bs <= 0 || sysv_sb.s_fsize * bs != partition.Size;

                if(sysvr4)
                {
                    sysv_sb.s_isize   = BigEndianBitConverter.ToUInt16(sb_sector, 0x000 + offset);
                    sysv_sb.s_state   = BigEndianBitConverter.ToUInt32(sb_sector, 0x1F4 + offset);
                    sysv_sb.s_magic   = BigEndianBitConverter.ToUInt32(sb_sector, 0x1F8 + offset);
                    sysv_sb.s_fsize   = BigEndianBitConverter.ToUInt32(sb_sector, 0x004 + offset);
                    sysv_sb.s_nfree   = BigEndianBitConverter.ToUInt16(sb_sector, 0x008 + offset);
                    sysv_sb.s_ninode  = BigEndianBitConverter.ToUInt16(sb_sector, 0x0D4 + offset);
                    sysv_sb.s_flock   = sb_sector[0x1A0                                 + offset];
                    sysv_sb.s_ilock   = sb_sector[0x1A1                                 + offset];
                    sysv_sb.s_fmod    = sb_sector[0x1A2                                 + offset];
                    sysv_sb.s_ronly   = sb_sector[0x1A3                                 + offset];
                    sysv_sb.s_time    = BigEndianBitConverter.ToUInt32(sb_sector, 0x1A4 + offset);
                    sysv_sb.s_cylblks = BigEndianBitConverter.ToUInt16(sb_sector, 0x1A8 + offset);
                    sysv_sb.s_gapblks = BigEndianBitConverter.ToUInt16(sb_sector, 0x1AA + offset);
                    sysv_sb.s_dinfo0  = BigEndianBitConverter.ToUInt16(sb_sector, 0x1AC + offset);
                    sysv_sb.s_dinfo1  = BigEndianBitConverter.ToUInt16(sb_sector, 0x1AE + offset);
                    sysv_sb.s_tfree   = BigEndianBitConverter.ToUInt32(sb_sector, 0x1B0 + offset);
                    sysv_sb.s_tinode  = BigEndianBitConverter.ToUInt16(sb_sector, 0x1B4 + offset);
                    Array.Copy(sb_sector, 0x1B6 + offset, sysv_strings, 0, 6);
                    sysv_sb.s_fname = StringHandlers.CToString(sysv_strings, Encoding);
                    Array.Copy(sb_sector, 0x1BC + offset, sysv_strings, 0, 6);
                    sysv_sb.s_fpack = StringHandlers.CToString(sysv_strings, Encoding);
                    sb.AppendLine("System V Release 4 filesystem");
                    XmlFsType.Type = "SVR4 fs";
                }
                else
                {
                    sysv_sb.s_isize   = BigEndianBitConverter.ToUInt16(sb_sector, 0x000 + offset);
                    sysv_sb.s_state   = BigEndianBitConverter.ToUInt32(sb_sector, 0x1F4 + offset);
                    sysv_sb.s_magic   = BigEndianBitConverter.ToUInt32(sb_sector, 0x1F8 + offset);
                    sysv_sb.s_fsize   = BigEndianBitConverter.ToUInt32(sb_sector, 0x002 + offset);
                    sysv_sb.s_nfree   = BigEndianBitConverter.ToUInt16(sb_sector, 0x006 + offset);
                    sysv_sb.s_ninode  = BigEndianBitConverter.ToUInt16(sb_sector, 0x0D0 + offset);
                    sysv_sb.s_flock   = sb_sector[0x19A                                 + offset];
                    sysv_sb.s_ilock   = sb_sector[0x19B                                 + offset];
                    sysv_sb.s_fmod    = sb_sector[0x19C                                 + offset];
                    sysv_sb.s_ronly   = sb_sector[0x19D                                 + offset];
                    sysv_sb.s_time    = BigEndianBitConverter.ToUInt32(sb_sector, 0x19E + offset);
                    sysv_sb.s_cylblks = BigEndianBitConverter.ToUInt16(sb_sector, 0x1A2 + offset);
                    sysv_sb.s_gapblks = BigEndianBitConverter.ToUInt16(sb_sector, 0x1A4 + offset);
                    sysv_sb.s_dinfo0  = BigEndianBitConverter.ToUInt16(sb_sector, 0x1A6 + offset);
                    sysv_sb.s_dinfo1  = BigEndianBitConverter.ToUInt16(sb_sector, 0x1A8 + offset);
                    sysv_sb.s_tfree   = BigEndianBitConverter.ToUInt32(sb_sector, 0x1AA + offset);
                    sysv_sb.s_tinode  = BigEndianBitConverter.ToUInt16(sb_sector, 0x1AE + offset);
                    Array.Copy(sb_sector, 0x1B0 + offset, sysv_strings, 0, 6);
                    sysv_sb.s_fname = StringHandlers.CToString(sysv_strings, Encoding);
                    Array.Copy(sb_sector, 0x1B6 + offset, sysv_strings, 0, 6);
                    sysv_sb.s_fpack = StringHandlers.CToString(sysv_strings, Encoding);
                    sb.AppendLine("System V Release 2 filesystem");
                    XmlFsType.Type = "SVR2 fs";
                }

                sb.AppendFormat("{0} bytes per block", bs).AppendLine();

                XmlFsType.Clusters = sysv_sb.s_fsize;
                sb.AppendFormat("{0} zones on volume ({1} bytes)", sysv_sb.s_fsize, sysv_sb.s_fsize * bs).AppendLine();
                sb.AppendFormat("{0} free zones on volume ({1} bytes)", sysv_sb.s_tfree, sysv_sb.s_tfree * bs)
                  .AppendLine();
                sb.AppendFormat("{0} free blocks on list ({1} bytes)", sysv_sb.s_nfree, sysv_sb.s_nfree * bs)
                  .AppendLine();
                sb.AppendFormat("{0} blocks per cylinder ({1} bytes)", sysv_sb.s_cylblks, sysv_sb.s_cylblks * bs)
                  .AppendLine();
                sb.AppendFormat("{0} blocks per gap ({1} bytes)", sysv_sb.s_gapblks, sysv_sb.s_gapblks * bs)
                  .AppendLine();
                sb.AppendFormat("First data zone: {0}", sysv_sb.s_isize).AppendLine();
                sb.AppendFormat("{0} free inodes on volume", sysv_sb.s_tinode).AppendLine();
                sb.AppendFormat("{0} free inodes on list", sysv_sb.s_ninode).AppendLine();
                if(sysv_sb.s_flock > 0) sb.AppendLine("Free block list is locked");
                if(sysv_sb.s_ilock > 0) sb.AppendLine("inode cache is locked");
                if(sysv_sb.s_fmod  > 0) sb.AppendLine("Superblock is being modified");
                if(sysv_sb.s_ronly > 0) sb.AppendLine("Volume is mounted read-only");
                sb.AppendFormat("Superblock last updated on {0}", DateHandlers.UnixUnsignedToDateTime(sysv_sb.s_time))
                  .AppendLine();
                if(sysv_sb.s_time != 0)
                {
                    XmlFsType.ModificationDate          = DateHandlers.UnixUnsignedToDateTime(sysv_sb.s_time);
                    XmlFsType.ModificationDateSpecified = true;
                }

                sb.AppendFormat("Volume name: {0}", sysv_sb.s_fname).AppendLine();
                XmlFsType.VolumeName = sysv_sb.s_fname;
                sb.AppendFormat("Pack name: {0}", sysv_sb.s_fpack).AppendLine();
                if(sysv_sb.s_state == 0x7C269D38 - sysv_sb.s_time) sb.AppendLine("Volume is clean");
                else
                {
                    sb.AppendLine("Volume is dirty");
                    XmlFsType.Dirty = true;
                }
            }

            if(coherent)
            {
                sb_sector = imagePlugin.ReadSectors((ulong)start + partition.Start, sb_size_in_sectors);
                CoherentSuperBlock coh_sb      = new CoherentSuperBlock();
                byte[]             coh_strings = new byte[6];

                coh_sb.s_isize  = BitConverter.ToUInt16(sb_sector, 0x000);
                coh_sb.s_fsize  = Swapping.PDPFromLittleEndian(BitConverter.ToUInt32(sb_sector, 0x002));
                coh_sb.s_nfree  = BitConverter.ToUInt16(sb_sector, 0x006);
                coh_sb.s_ninode = BitConverter.ToUInt16(sb_sector, 0x108);
                coh_sb.s_flock  = sb_sector[0x1D2];
                coh_sb.s_ilock  = sb_sector[0x1D3];
                coh_sb.s_fmod   = sb_sector[0x1D4];
                coh_sb.s_ronly  = sb_sector[0x1D5];
                coh_sb.s_time   = Swapping.PDPFromLittleEndian(BitConverter.ToUInt32(sb_sector, 0x1D6));
                coh_sb.s_tfree  = Swapping.PDPFromLittleEndian(BitConverter.ToUInt32(sb_sector, 0x1DA));
                coh_sb.s_tinode = BitConverter.ToUInt16(sb_sector, 0x1DE);
                coh_sb.s_int_m  = BitConverter.ToUInt16(sb_sector, 0x1E0);
                coh_sb.s_int_n  = BitConverter.ToUInt16(sb_sector, 0x1E2);
                Array.Copy(sb_sector, 0x1E4, coh_strings, 0, 6);
                coh_sb.s_fname = StringHandlers.CToString(coh_strings, Encoding);
                Array.Copy(sb_sector, 0x1EA, coh_strings, 0, 6);
                coh_sb.s_fpack = StringHandlers.CToString(coh_strings, Encoding);

                XmlFsType.Type        = "Coherent fs";
                XmlFsType.ClusterSize = 512;
                XmlFsType.Clusters    = coh_sb.s_fsize;

                sb.AppendLine("Coherent UNIX filesystem");
                if(imagePlugin.Info.SectorSize != 512)
                    sb
                       .AppendFormat("WARNING: Filesystem indicates {0} bytes/block while device indicates {1} bytes/sector",
                                     512, 2048).AppendLine();
                sb.AppendFormat("{0} zones on volume ({1} bytes)", coh_sb.s_fsize, coh_sb.s_fsize * 512).AppendLine();
                sb.AppendFormat("{0} free zones on volume ({1} bytes)", coh_sb.s_tfree, coh_sb.s_tfree * 512)
                  .AppendLine();
                sb.AppendFormat("{0} free blocks on list ({1} bytes)", coh_sb.s_nfree, coh_sb.s_nfree * 512)
                  .AppendLine();
                sb.AppendFormat("First data zone: {0}", coh_sb.s_isize).AppendLine();
                sb.AppendFormat("{0} free inodes on volume", coh_sb.s_tinode).AppendLine();
                sb.AppendFormat("{0} free inodes on list", coh_sb.s_ninode).AppendLine();
                if(coh_sb.s_flock > 0) sb.AppendLine("Free block list is locked");
                if(coh_sb.s_ilock > 0) sb.AppendLine("inode cache is locked");
                if(coh_sb.s_fmod  > 0) sb.AppendLine("Superblock is being modified");
                if(coh_sb.s_ronly > 0) sb.AppendLine("Volume is mounted read-only");
                sb.AppendFormat("Superblock last updated on {0}", DateHandlers.UnixUnsignedToDateTime(coh_sb.s_time))
                  .AppendLine();
                if(coh_sb.s_time != 0)
                {
                    XmlFsType.ModificationDate          = DateHandlers.UnixUnsignedToDateTime(coh_sb.s_time);
                    XmlFsType.ModificationDateSpecified = true;
                }

                sb.AppendFormat("Volume name: {0}", coh_sb.s_fname).AppendLine();
                XmlFsType.VolumeName = coh_sb.s_fname;
                sb.AppendFormat("Pack name: {0}", coh_sb.s_fpack).AppendLine();
            }

            if(sys7th)
            {
                sb_sector = imagePlugin.ReadSectors((ulong)start + partition.Start, sb_size_in_sectors);
                UNIX7thEditionSuperBlock v7_sb        = new UNIX7thEditionSuperBlock();
                byte[]                   sys7_strings = new byte[6];

                v7_sb.s_isize  = BigEndianBitConverter.ToUInt16(sb_sector, 0x000);
                v7_sb.s_fsize  = BigEndianBitConverter.ToUInt32(sb_sector, 0x002);
                v7_sb.s_nfree  = BigEndianBitConverter.ToUInt16(sb_sector, 0x006);
                v7_sb.s_ninode = BigEndianBitConverter.ToUInt16(sb_sector, 0x0D0);
                v7_sb.s_flock  = sb_sector[0x19A];
                v7_sb.s_ilock  = sb_sector[0x19B];
                v7_sb.s_fmod   = sb_sector[0x19C];
                v7_sb.s_ronly  = sb_sector[0x19D];
                v7_sb.s_time   = BigEndianBitConverter.ToUInt32(sb_sector, 0x19E);
                v7_sb.s_tfree  = BigEndianBitConverter.ToUInt32(sb_sector, 0x1A2);
                v7_sb.s_tinode = BigEndianBitConverter.ToUInt16(sb_sector, 0x1A6);
                v7_sb.s_int_m  = BigEndianBitConverter.ToUInt16(sb_sector, 0x1A8);
                v7_sb.s_int_n  = BigEndianBitConverter.ToUInt16(sb_sector, 0x1AA);
                Array.Copy(sb_sector, 0x1AC, sys7_strings, 0, 6);
                v7_sb.s_fname = StringHandlers.CToString(sys7_strings, Encoding);
                Array.Copy(sb_sector, 0x1B2, sys7_strings, 0, 6);
                v7_sb.s_fpack = StringHandlers.CToString(sys7_strings, Encoding);

                XmlFsType.Type        = "UNIX 7th Edition fs";
                XmlFsType.ClusterSize = 512;
                XmlFsType.Clusters    = v7_sb.s_fsize;
                sb.AppendLine("UNIX 7th Edition filesystem");
                if(imagePlugin.Info.SectorSize != 512)
                    sb
                       .AppendFormat("WARNING: Filesystem indicates {0} bytes/block while device indicates {1} bytes/sector",
                                     512, 2048).AppendLine();
                sb.AppendFormat("{0} zones on volume ({1} bytes)", v7_sb.s_fsize, v7_sb.s_fsize * 512).AppendLine();
                sb.AppendFormat("{0} free zones on volume ({1} bytes)", v7_sb.s_tfree, v7_sb.s_tfree * 512)
                  .AppendLine();
                sb.AppendFormat("{0} free blocks on list ({1} bytes)", v7_sb.s_nfree, v7_sb.s_nfree * 512).AppendLine();
                sb.AppendFormat("First data zone: {0}", v7_sb.s_isize).AppendLine();
                sb.AppendFormat("{0} free inodes on volume", v7_sb.s_tinode).AppendLine();
                sb.AppendFormat("{0} free inodes on list", v7_sb.s_ninode).AppendLine();
                if(v7_sb.s_flock > 0) sb.AppendLine("Free block list is locked");
                if(v7_sb.s_ilock > 0) sb.AppendLine("inode cache is locked");
                if(v7_sb.s_fmod  > 0) sb.AppendLine("Superblock is being modified");
                if(v7_sb.s_ronly > 0) sb.AppendLine("Volume is mounted read-only");
                sb.AppendFormat("Superblock last updated on {0}", DateHandlers.UnixUnsignedToDateTime(v7_sb.s_time))
                  .AppendLine();
                if(v7_sb.s_time != 0)
                {
                    XmlFsType.ModificationDate          = DateHandlers.UnixUnsignedToDateTime(v7_sb.s_time);
                    XmlFsType.ModificationDateSpecified = true;
                }

                sb.AppendFormat("Volume name: {0}", v7_sb.s_fname).AppendLine();
                XmlFsType.VolumeName = v7_sb.s_fname;
                sb.AppendFormat("Pack name: {0}", v7_sb.s_fpack).AppendLine();
            }

            information = sb.ToString();

            BigEndianBitConverter.IsLittleEndian = false; // Return to default (bigendian)
        }

        // Old XENIX use different offsets
        struct XenixSuperBlock
        {
            /// <summary>0x000, index of first data zone</summary>
            public ushort s_isize;
            /// <summary>0x002, total number of zones of this volume</summary>
            public uint s_fsize;
            // the start of the free block list:
            /// <summary>0x006, blocks in s_free, &lt;=100</summary>
            public ushort s_nfree;
            /// <summary>0x008, 100 entries, 50 entries for Xenix 3, first free block list chunk</summary>
            public uint[] s_free;
            // the cache of free inodes:
            /// <summary>0x198 (0xD0), number of inodes in s_inode, &lt;= 100</summary>
            public ushort s_ninode;
            /// <summary>0x19A (0xD2), 100 entries, some free inodes</summary>
            public ushort[] s_inode;
            /// <summary>0x262 (0x19A), free block list manipulation lock</summary>
            public byte s_flock;
            /// <summary>0x263 (0x19B), inode cache manipulation lock</summary>
            public byte s_ilock;
            /// <summary>0x264 (0x19C), superblock modification flag</summary>
            public byte s_fmod;
            /// <summary>0x265 (0x19D), read-only mounted flag</summary>
            public byte s_ronly;
            /// <summary>0x266 (0x19E), time of last superblock update</summary>
            public int s_time;
            /// <summary>0x26A (0x1A2), total number of free zones</summary>
            public uint s_tfree;
            /// <summary>0x26E (0x1A6), total number of free inodes</summary>
            public ushort s_tinode;
            /// <summary>0x270 (0x1A8), blocks per cylinder</summary>
            public ushort s_cylblks;
            /// <summary>0x272 (0x1AA), blocks per gap</summary>
            public ushort s_gapblks;
            /// <summary>0x274 (0x1AC), device information ??</summary>
            public ushort s_dinfo0;
            /// <summary>0x276 (0x1AE), device information ??</summary>
            public ushort s_dinfo1;
            /// <summary>0x278 (0x1B0), 6 bytes, volume name</summary>
            public string s_fname;
            /// <summary>0x27E (0x1B6), 6 bytes, pack name</summary>
            public string s_fpack;
            /// <summary>0x284 (0x1BC), 0x46 if volume is clean</summary>
            public byte s_clean;
            /// <summary>0x285 (0x1BD), 371 bytes, 51 bytes for Xenix 3</summary>
            public byte[] s_fill;
            /// <summary>0x3F8 (0x1F0), magic</summary>
            public uint s_magic;
            /// <summary>0x3FC (0x1F4), filesystem type (1 = 512 bytes/blk, 2 = 1024 bytes/blk, 3 = 2048 bytes/blk)</summary>
            public uint s_type;
        }

        struct SystemVRelease4SuperBlock
        {
            /// <summary>0x000, index of first data zone</summary>
            public ushort s_isize;
            /// <summary>0x002, padding</summary>
            public ushort s_pad0;
            /// <summary>0x004, total number of zones of this volume</summary>
            public uint s_fsize;
            // the start of the free block list:
            /// <summary>0x008, blocks in s_free, &lt;=100</summary>
            public ushort s_nfree;
            /// <summary>0x00A, padding</summary>
            public ushort s_pad1;
            /// <summary>0x00C, 50 entries, first free block list chunk</summary>
            public uint[] s_free;
            // the cache of free inodes:
            /// <summary>0x0D4, number of inodes in s_inode, &lt;= 100</summary>
            public ushort s_ninode;
            /// <summary>0x0D6, padding</summary>
            public ushort s_pad2;
            /// <summary>0x0D8, 100 entries, some free inodes</summary>
            public ushort[] s_inode;
            /// <summary>0x1A0, free block list manipulation lock</summary>
            public byte s_flock;
            /// <summary>0x1A1, inode cache manipulation lock</summary>
            public byte s_ilock;
            /// <summary>0x1A2, superblock modification flag</summary>
            public byte s_fmod;
            /// <summary>0x1A3, read-only mounted flag</summary>
            public byte s_ronly;
            /// <summary>0x1A4, time of last superblock update</summary>
            public uint s_time;
            /// <summary>0x1A8, blocks per cylinder</summary>
            public ushort s_cylblks;
            /// <summary>0x1AA, blocks per gap</summary>
            public ushort s_gapblks;
            /// <summary>0x1AC, device information ??</summary>
            public ushort s_dinfo0;
            /// <summary>0x1AE, device information ??</summary>
            public ushort s_dinfo1;
            /// <summary>0x1B0, total number of free zones</summary>
            public uint s_tfree;
            /// <summary>0x1B4, total number of free inodes</summary>
            public ushort s_tinode;
            /// <summary>0x1B6, padding</summary>
            public ushort s_pad3;
            /// <summary>0x1B8, 6 bytes, volume name</summary>
            public string s_fname;
            /// <summary>0x1BE, 6 bytes, pack name</summary>
            public string s_fpack;
            /// <summary>0x1C4, 48 bytes</summary>
            public byte[] s_fill;
            /// <summary>0x1F4, if s_state == (0x7C269D38 - s_time) then filesystem is clean</summary>
            public uint s_state;
            /// <summary>0x1F8, magic</summary>
            public uint s_magic;
            /// <summary>0x1FC, filesystem type (1 = 512 bytes/blk, 2 = 1024 bytes/blk)</summary>
            public uint s_type;
        }

        struct SystemVRelease2SuperBlock
        {
            /// <summary>0x000, index of first data zone</summary>
            public ushort s_isize;
            /// <summary>0x002, total number of zones of this volume</summary>
            public uint s_fsize;
            // the start of the free block list:
            /// <summary>0x006, blocks in s_free, &lt;=100</summary>
            public ushort s_nfree;
            /// <summary>0x008, 50 entries, first free block list chunk</summary>
            public uint[] s_free;
            // the cache of free inodes:
            /// <summary>0x0D0, number of inodes in s_inode, &lt;= 100</summary>
            public ushort s_ninode;
            /// <summary>0x0D2, 100 entries, some free inodes</summary>
            public ushort[] s_inode;
            /// <summary>0x19A, free block list manipulation lock</summary>
            public byte s_flock;
            /// <summary>0x19B, inode cache manipulation lock</summary>
            public byte s_ilock;
            /// <summary>0x19C, superblock modification flag</summary>
            public byte s_fmod;
            /// <summary>0x19D, read-only mounted flag</summary>
            public byte s_ronly;
            /// <summary>0x19E, time of last superblock update</summary>
            public uint s_time;
            /// <summary>0x1A2, blocks per cylinder</summary>
            public ushort s_cylblks;
            /// <summary>0x1A4, blocks per gap</summary>
            public ushort s_gapblks;
            /// <summary>0x1A6, device information ??</summary>
            public ushort s_dinfo0;
            /// <summary>0x1A8, device information ??</summary>
            public ushort s_dinfo1;
            /// <summary>0x1AA, total number of free zones</summary>
            public uint s_tfree;
            /// <summary>0x1AE, total number of free inodes</summary>
            public ushort s_tinode;
            /// <summary>0x1B0, 6 bytes, volume name</summary>
            public string s_fname;
            /// <summary>0x1B6, 6 bytes, pack name</summary>
            public string s_fpack;
            /// <summary>0x1BC, 56 bytes</summary>
            public byte[] s_fill;
            /// <summary>0x1F4, if s_state == (0x7C269D38 - s_time) then filesystem is clean</summary>
            public uint s_state;
            /// <summary>0x1F8, magic</summary>
            public uint s_magic;
            /// <summary>0x1FC, filesystem type (1 = 512 bytes/blk, 2 = 1024 bytes/blk)</summary>
            public uint s_type;
        }

        struct UNIX7thEditionSuperBlock
        {
            /// <summary>0x000, index of first data zone</summary>
            public ushort s_isize;
            /// <summary>0x002, total number of zones of this volume</summary>
            public uint s_fsize;
            // the start of the free block list:
            /// <summary>0x006, blocks in s_free, &lt;=100</summary>
            public ushort s_nfree;
            /// <summary>0x008, 50 entries, first free block list chunk</summary>
            public uint[] s_free;
            // the cache of free inodes:
            /// <summary>0x0D0, number of inodes in s_inode, &lt;= 100</summary>
            public ushort s_ninode;
            /// <summary>0x0D2, 100 entries, some free inodes</summary>
            public ushort[] s_inode;
            /// <summary>0x19A, free block list manipulation lock</summary>
            public byte s_flock;
            /// <summary>0x19B, inode cache manipulation lock</summary>
            public byte s_ilock;
            /// <summary>0x19C, superblock modification flag</summary>
            public byte s_fmod;
            /// <summary>0x19D, read-only mounted flag</summary>
            public byte s_ronly;
            /// <summary>0x19E, time of last superblock update</summary>
            public uint s_time;
            /// <summary>0x1A2, total number of free zones</summary>
            public uint s_tfree;
            /// <summary>0x1A6, total number of free inodes</summary>
            public ushort s_tinode;
            /// <summary>0x1A8, interleave factor</summary>
            public ushort s_int_m;
            /// <summary>0x1AA, interleave factor</summary>
            public ushort s_int_n;
            /// <summary>0x1AC, 6 bytes, volume name</summary>
            public string s_fname;
            /// <summary>0x1B2, 6 bytes, pack name</summary>
            public string s_fpack;
        }

        struct CoherentSuperBlock
        {
            /// <summary>0x000, index of first data zone</summary>
            public ushort s_isize;
            /// <summary>0x002, total number of zones of this volume</summary>
            public uint s_fsize;
            // the start of the free block list:
            /// <summary>0x006, blocks in s_free, &lt;=100</summary>
            public ushort s_nfree;
            /// <summary>0x008, 64 entries, first free block list chunk</summary>
            public uint[] s_free;
            // the cache of free inodes:
            /// <summary>0x108, number of inodes in s_inode, &lt;= 100</summary>
            public ushort s_ninode;
            /// <summary>0x10A, 100 entries, some free inodes</summary>
            public ushort[] s_inode;
            /// <summary>0x1D2, free block list manipulation lock</summary>
            public byte s_flock;
            /// <summary>0x1D3, inode cache manipulation lock</summary>
            public byte s_ilock;
            /// <summary>0x1D4, superblock modification flag</summary>
            public byte s_fmod;
            /// <summary>0x1D5, read-only mounted flag</summary>
            public byte s_ronly;
            /// <summary>0x1D6, time of last superblock update</summary>
            public uint s_time;
            /// <summary>0x1DE, total number of free zones</summary>
            public uint s_tfree;
            /// <summary>0x1E2, total number of free inodes</summary>
            public ushort s_tinode;
            /// <summary>0x1E4, interleave factor</summary>
            public ushort s_int_m;
            /// <summary>0x1E6, interleave factor</summary>
            public ushort s_int_n;
            /// <summary>0x1E8, 6 bytes, volume name</summary>
            public string s_fname;
            /// <summary>0x1EE, 6 bytes, pack name</summary>
            public string s_fpack;
            /// <summary>0x1F4, zero-filled</summary>
            public uint s_unique;
        }
    }
}