Aaru/Aaru.Images/Apridisk/Read.cs

// /***************************************************************************
// Aaru Data Preservation Suite
// ----------------------------------------------------------------------------
//
// Filename       : Read.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : Disk image plugins.
//
// --[ Description ] ----------------------------------------------------------
//
//     Reads Apridisk disk images.
//
// --[ 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 © 2011-2025 Natalia Portillo
// ****************************************************************************/

using System.IO;
using Aaru.CommonTypes;
using Aaru.CommonTypes.Enums;
using Aaru.CommonTypes.Interfaces;
using Aaru.Helpers;
using Aaru.Logging;

namespace Aaru.Images;

public sealed partial class Apridisk
{
#region IWritableImage Members

    /// <inheritdoc />
    public ErrorNumber Open(IFilter imageFilter)
    {
        Stream stream = imageFilter.GetDataForkStream();
        stream.Seek(0, SeekOrigin.Begin);

        // Skip signature
        stream.Seek(_signature.Length, SeekOrigin.Begin);

        int totalCylinders = -1;
        int totalHeads     = -1;
        int maxSector      = -1;
        int recordSize     = Marshal.SizeOf<Record>();

        // Count cylinders
        while(stream.Position < stream.Length)
        {
            byte[] recB = new byte[recordSize];
            stream.EnsureRead(recB, 0, recordSize);

            Record record = Marshal.SpanToStructureLittleEndian<Record>(recB);

            switch(record.type)
            {
                // Deleted record, just skip it
                case RecordType.Deleted:
                    AaruLogging.Debug(MODULE_NAME, Localization.Found_deleted_record_at_0, stream.Position);

                    stream.Seek(record.headerSize - recordSize + record.dataSize, SeekOrigin.Current);

                    break;
                case RecordType.Comment:
                    AaruLogging.Debug(MODULE_NAME, Localization.Found_comment_record_at_0, stream.Position);

                    stream.Seek(record.headerSize - recordSize, SeekOrigin.Current);
                    byte[] commentB = new byte[record.dataSize];
                    stream.EnsureRead(commentB, 0, commentB.Length);
                    _imageInfo.Comments = StringHandlers.CToString(commentB);
                    AaruLogging.Debug(MODULE_NAME, Localization.Comment_0, _imageInfo.Comments);

                    break;
                case RecordType.Creator:
                    AaruLogging.Debug(MODULE_NAME, Localization.Found_creator_record_at_0, stream.Position);

                    stream.Seek(record.headerSize - recordSize, SeekOrigin.Current);
                    byte[] creatorB = new byte[record.dataSize];
                    stream.EnsureRead(creatorB, 0, creatorB.Length);
                    _imageInfo.Creator = StringHandlers.CToString(creatorB);
                    AaruLogging.Debug(MODULE_NAME, Localization.Creator_0, _imageInfo.Creator);

                    break;
                case RecordType.Sector:
                    if(record.compression != CompressType.Compressed && record.compression != CompressType.Uncompresed)
                        return ErrorNumber.NotSupported;

                    AaruLogging.Debug(MODULE_NAME,
                                               record.compression == CompressType.Compressed
                                                   ? Localization
                                                      .Found_compressed_sector_record_at_0_for_cylinder_1_head_2_sector_3
                                                   : Localization
                                                      .Found_uncompressed_sector_record_at_0_for_cylinder_1_head_2_sector_3,
                                               stream.Position,
                                               record.cylinder,
                                               record.head,
                                               record.sector);

                    if(record.cylinder > totalCylinders) totalCylinders = record.cylinder;

                    if(record.head > totalHeads) totalHeads = record.head;

                    if(record.sector > maxSector) maxSector = record.sector;

                    stream.Seek(record.headerSize - recordSize + record.dataSize, SeekOrigin.Current);

                    break;
                default:
                    return ErrorNumber.NotSupported;
            }
        }

        totalCylinders++;
        totalHeads++;

        if(totalCylinders <= 0 || totalHeads <= 0) return ErrorNumber.NotSupported;

        _sectorsData = new byte[totalCylinders][][][];

        // Total sectors per track
        uint[][] spts = new uint[totalCylinders][];

        _imageInfo.Cylinders = (ushort)totalCylinders;
        _imageInfo.Heads     = (byte)totalHeads;

        AaruLogging.Debug(MODULE_NAME,
                                   Localization.Found_0_cylinders_and_1_heads_with_a_maximum_sector_number_of_2,
                                   totalCylinders,
                                   totalHeads,
                                   maxSector);

        // Create heads
        for(int i = 0; i < totalCylinders; i++)
        {
            _sectorsData[i] = new byte[totalHeads][][];
            spts[i]         = new uint[totalHeads];

            for(int j = 0; j < totalHeads; j++) _sectorsData[i][j] = new byte[maxSector + 1][];
        }

        _imageInfo.SectorSize = uint.MaxValue;

        ulong headerSizes = 0;

        // Read sectors
        stream.Seek(_signature.Length, SeekOrigin.Begin);

        while(stream.Position < stream.Length)
        {
            byte[] recB = new byte[recordSize];
            stream.EnsureRead(recB, 0, recordSize);

            Record record = Marshal.SpanToStructureLittleEndian<Record>(recB);

            switch(record.type)
            {
                // Not sector record, just skip it
                case RecordType.Deleted:
                case RecordType.Comment:
                case RecordType.Creator:
                    stream.Seek(record.headerSize - recordSize + record.dataSize, SeekOrigin.Current);
                    headerSizes += record.headerSize + record.dataSize;

                    break;
                case RecordType.Sector:
                    stream.Seek(record.headerSize - recordSize, SeekOrigin.Current);

                    byte[] data = new byte[record.dataSize];
                    stream.EnsureRead(data, 0, data.Length);

                    spts[record.cylinder][record.head]++;
                    uint realLength = record.dataSize;

                    if(record.compression == CompressType.Compressed)
                        realLength = Decompress(data, out _sectorsData[record.cylinder][record.head][record.sector]);
                    else
                        _sectorsData[record.cylinder][record.head][record.sector] = data;

                    if(realLength < _imageInfo.SectorSize) _imageInfo.SectorSize = realLength;

                    headerSizes += record.headerSize + record.dataSize;

                    break;
            }
        }

        AaruLogging.Debug(MODULE_NAME,
                                   Localization.Found_a_minimum_of_0_bytes_per_sector,
                                   _imageInfo.SectorSize);

        // Count sectors per track
        uint spt = uint.MaxValue;

        for(ushort cyl = 0; cyl < _imageInfo.Cylinders; cyl++)
        {
            for(ushort head = 0; head < _imageInfo.Heads; head++)
            {
                if(spts[cyl][head] < spt) spt = spts[cyl][head];
            }
        }

        _imageInfo.SectorsPerTrack = spt;

        AaruLogging.Debug(MODULE_NAME,
                                   Localization.Found_a_minimum_of_0_sectors_per_track,
                                   _imageInfo.SectorsPerTrack);

        _imageInfo.MediaType = Geometry.GetMediaType(((ushort)_imageInfo.Cylinders, (byte)_imageInfo.Heads,
                                                      (ushort)_imageInfo.SectorsPerTrack, 512, MediaEncoding.MFM,
                                                      false));

        _imageInfo.ImageSize            = (ulong)stream.Length - headerSizes;
        _imageInfo.CreationTime         = imageFilter.CreationTime;
        _imageInfo.LastModificationTime = imageFilter.LastWriteTime;
        _imageInfo.MediaTitle           = Path.GetFileNameWithoutExtension(imageFilter.Filename);
        _imageInfo.Sectors              = _imageInfo.Cylinders * _imageInfo.Heads * _imageInfo.SectorsPerTrack;
        _imageInfo.MetadataMediaType    = MetadataMediaType.BlockMedia;

        return ErrorNumber.NoError;
    }

    /// <inheritdoc />
    public ErrorNumber ReadSector(ulong sectorAddress, out byte[] buffer)
    {
        buffer                                    = null;
        (ushort cylinder, byte head, byte sector) = LbaToChs(sectorAddress);

        if(cylinder >= _sectorsData.Length) return ErrorNumber.SectorNotFound;

        if(head >= _sectorsData[cylinder].Length) return ErrorNumber.SectorNotFound;

        if(sector > _sectorsData[cylinder][head].Length) return ErrorNumber.SectorNotFound;

        buffer = _sectorsData[cylinder][head][sector];

        return ErrorNumber.NoError;
    }

    /// <inheritdoc />
    public ErrorNumber ReadSectors(ulong sectorAddress, uint length, out byte[] buffer)
    {
        buffer = null;

        if(sectorAddress > _imageInfo.Sectors - 1) return ErrorNumber.OutOfRange;

        if(sectorAddress + length > _imageInfo.Sectors) return ErrorNumber.OutOfRange;

        var ms = new MemoryStream();

        for(uint i = 0; i < length; i++)
        {
            ErrorNumber errno = ReadSector(sectorAddress + i, out byte[] sector);

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

            ms.Write(sector, 0, sector.Length);
        }

        buffer = ms.ToArray();

        return ErrorNumber.NoError;
    }

#endregion
}