Aaru/Aaru.Filesystems/AppleMFS/Super.cs

// /***************************************************************************
// Aaru Data Preservation Suite
// ----------------------------------------------------------------------------
//
// Filename       : Super.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : Apple Macintosh File System plugin.
//
// --[ 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 © 2011-2024 Natalia Portillo
// ****************************************************************************/

using System;
using System.Collections.Generic;
using System.Text;
using Aaru.CommonTypes.AaruMetadata;
using Aaru.CommonTypes.Enums;
using Aaru.CommonTypes.Interfaces;
using Aaru.CommonTypes.Structs;
using Aaru.Helpers;
using Partition = Aaru.CommonTypes.Partition;

namespace Aaru.Filesystems;

// Information from Inside Macintosh Volume II
public sealed partial class AppleMFS
{
    const int BYTES_BEFORE_BLOCK_MAP = 64;

#region IReadOnlyFilesystem Members

    /// <inheritdoc />
    public ErrorNumber Mount(IMediaImage                imagePlugin, Partition partition, Encoding encoding,
                             Dictionary<string, string> options,     string    @namespace)
    {
        _device         = imagePlugin;
        _partitionStart = partition.Start;
        _encoding       = encoding ?? Encoding.GetEncoding("macintosh");

        options ??= GetDefaultOptions();

        if(options.TryGetValue("debug", out string debugString)) bool.TryParse(debugString, out _debug);

        _volMdb = new MasterDirectoryBlock();

        ErrorNumber errno = _device.ReadSector(2 + _partitionStart, out _mdbBlocks);

        if(errno != ErrorNumber.NoError) return errno;

        errno = _device.ReadSector(0 + _partitionStart, out _bootBlocks);

        if(errno != ErrorNumber.NoError) return errno;

        _volMdb.drSigWord = BigEndianBitConverter.ToUInt16(_mdbBlocks, 0x000);

        if(_volMdb.drSigWord != MFS_MAGIC) return ErrorNumber.InvalidArgument;

        _volMdb.drCrDate   = BigEndianBitConverter.ToUInt32(_mdbBlocks, 0x002);
        _volMdb.drLsBkUp   = BigEndianBitConverter.ToUInt32(_mdbBlocks, 0x006);
        _volMdb.drAtrb     = (AppleCommon.VolumeAttributes)BigEndianBitConverter.ToUInt16(_mdbBlocks, 0x00A);
        _volMdb.drNmFls    = BigEndianBitConverter.ToUInt16(_mdbBlocks, 0x00C);
        _volMdb.drDirSt    = BigEndianBitConverter.ToUInt16(_mdbBlocks, 0x00E);
        _volMdb.drBlLen    = BigEndianBitConverter.ToUInt16(_mdbBlocks, 0x010);
        _volMdb.drNmAlBlks = BigEndianBitConverter.ToUInt16(_mdbBlocks, 0x012);
        _volMdb.drAlBlkSiz = BigEndianBitConverter.ToUInt32(_mdbBlocks, 0x014);
        _volMdb.drClpSiz   = BigEndianBitConverter.ToUInt32(_mdbBlocks, 0x018);
        _volMdb.drAlBlSt   = BigEndianBitConverter.ToUInt16(_mdbBlocks, 0x01C);
        _volMdb.drNxtFNum  = BigEndianBitConverter.ToUInt32(_mdbBlocks, 0x01E);
        _volMdb.drFreeBks  = BigEndianBitConverter.ToUInt16(_mdbBlocks, 0x022);
        _volMdb.drVNSiz    = _mdbBlocks[0x024];
        var variableSize = new byte[_volMdb.drVNSiz + 1];
        Array.Copy(_mdbBlocks, 0x024, variableSize, 0, _volMdb.drVNSiz + 1);
        _volMdb.drVN = StringHandlers.PascalToString(variableSize, _encoding);

        errno = _device.ReadSectors(_volMdb.drDirSt + _partitionStart, _volMdb.drBlLen, out _directoryBlocks);

        if(errno != ErrorNumber.NoError) return errno;

        int bytesInBlockMap = _volMdb.drNmAlBlks * 12 / 8 + _volMdb.drNmAlBlks * 12 % 8;
        int bytesInWholeMdb = bytesInBlockMap             + BYTES_BEFORE_BLOCK_MAP;

        int sectorsInWholeMdb = bytesInWholeMdb / (int)_device.Info.SectorSize +
                                bytesInWholeMdb % (int)_device.Info.SectorSize;

        errno = _device.ReadSectors(_partitionStart + 2, (uint)sectorsInWholeMdb, out byte[] wholeMdb);

        if(errno != ErrorNumber.NoError) return errno;

        _blockMapBytes = new byte[bytesInBlockMap];
        Array.Copy(wholeMdb, BYTES_BEFORE_BLOCK_MAP, _blockMapBytes, 0, _blockMapBytes.Length);

        var offset = 0;
        _blockMap = new uint[_volMdb.drNmAlBlks + 2 + 1];

        for(var i = 2; i < _volMdb.drNmAlBlks + 2; i += 8)
        {
            uint tmp1 = 0;
            uint tmp2 = 0;
            uint tmp3 = 0;

            if(offset + 4 <= _blockMapBytes.Length) tmp1 = BigEndianBitConverter.ToUInt32(_blockMapBytes, offset);

            if(offset + 4 + 4 <= _blockMapBytes.Length)
                tmp2 = BigEndianBitConverter.ToUInt32(_blockMapBytes, offset + 4);

            if(offset + 8 + 4 <= _blockMapBytes.Length)
                tmp3 = BigEndianBitConverter.ToUInt32(_blockMapBytes, offset + 8);

            if(i < _blockMap.Length) _blockMap[i] = (tmp1 & 0xFFF00000) >> 20;

            if(i + 2 < _blockMap.Length) _blockMap[i + 1] = (tmp1 & 0xFFF00) >> 8;

            if(i + 3 < _blockMap.Length) _blockMap[i + 2] = ((tmp1 & 0xFF) << 4) + ((tmp2 & 0xF0000000) >> 28);

            if(i + 4 < _blockMap.Length) _blockMap[i + 3] = (tmp2 & 0xFFF0000) >> 16;

            if(i + 5 < _blockMap.Length) _blockMap[i + 4] = (tmp2 & 0xFFF0) >> 4;

            if(i + 6 < _blockMap.Length) _blockMap[i + 5] = ((tmp2 & 0xF) << 8) + ((tmp3 & 0xFF000000) >> 24);

            if(i + 7 < _blockMap.Length) _blockMap[i + 6] = (tmp3 & 0xFFF000) >> 12;

            if(i + 8 < _blockMap.Length) _blockMap[i + 7] = tmp3 & 0xFFF;

            offset += 12;
        }

        if(_device.Info.ReadableSectorTags.Contains(SectorTagType.AppleSectorTag))
        {
            _device.ReadSectorTag(2 + _partitionStart, SectorTagType.AppleSectorTag, out _mdbTags);
            _device.ReadSectorTag(0 + _partitionStart, SectorTagType.AppleSectorTag, out _bootTags);

            _device.ReadSectorsTag(_volMdb.drDirSt + _partitionStart,
                                   _volMdb.drBlLen,
                                   SectorTagType.AppleSectorTag,
                                   out _directoryTags);

            _device.ReadSectorsTag(_partitionStart + 2,
                                   (uint)sectorsInWholeMdb,
                                   SectorTagType.AppleSectorTag,
                                   out _bitmapTags);
        }

        _sectorsPerBlock = (int)(_volMdb.drAlBlkSiz / _device.Info.SectorSize);

        if(!FillDirectory()) return ErrorNumber.InvalidArgument;

        _mounted = true;

        var bbSig = BigEndianBitConverter.ToUInt16(_bootBlocks, 0x000);

        if(bbSig != AppleCommon.BB_MAGIC) _bootBlocks = null;

        Metadata = new FileSystem();

        if(_volMdb.drLsBkUp > 0) Metadata.BackupDate = DateHandlers.MacToDateTime(_volMdb.drLsBkUp);

        Metadata.Bootable    = bbSig == AppleCommon.BB_MAGIC;
        Metadata.Clusters    = _volMdb.drNmAlBlks;
        Metadata.ClusterSize = _volMdb.drAlBlkSiz;

        if(_volMdb.drCrDate > 0) Metadata.CreationDate = DateHandlers.MacToDateTime(_volMdb.drCrDate);

        Metadata.Files        = _volMdb.drNmFls;
        Metadata.FreeClusters = _volMdb.drFreeBks;
        Metadata.Type         = FS_TYPE;
        Metadata.VolumeName   = _volMdb.drVN;

        return ErrorNumber.NoError;
    }

    /// <inheritdoc />
    public ErrorNumber Unmount()
    {
        _mounted      = false;
        _idToFilename = null;
        _idToEntry    = null;
        _filenameToId = null;
        _bootBlocks   = null;

        return ErrorNumber.NoError;
    }

    /// <inheritdoc />
    public ErrorNumber StatFs(out FileSystemInfo stat)
    {
        stat = new FileSystemInfo
        {
            Blocks         = _volMdb.drNmAlBlks,
            FilenameLength = 255,
            Files          = _volMdb.drNmFls,
            FreeBlocks     = _volMdb.drFreeBks,
            PluginId       = Id,
            Type           = FS_TYPE
        };

        stat.FreeFiles = uint.MaxValue - stat.Files;

        return ErrorNumber.NoError;
    }

#endregion
}