Aaru/Aaru.Images/HDCopy/Read.cs

// /***************************************************************************
// Aaru Data Preservation Suite
// ----------------------------------------------------------------------------
//
// Filename       : Read.cs
// Author(s)      : Natalia Portillo <claunia@claunia.com>
//
// Component      : Disk image plugins.
//
// --[ Description ] ----------------------------------------------------------
//
//     Reads HD-Copy 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 © 2017 Michael Drüing
// Copyright © 2011-2023 Natalia Portillo
// ****************************************************************************/

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

namespace Aaru.DiscImages;

public sealed partial class HdCopy
{
    /// <inheritdoc />
    public ErrorNumber Open(IFilter imageFilter)
    {
        Stream stream = imageFilter.GetDataForkStream();

        var fheader = new FileHeader();

        // the start offset of the track data
        long currentOffset = 0;

        if(!TryReadHeader(stream, ref fheader, ref currentOffset))
            return ErrorNumber.InvalidArgument;

        AaruConsole.DebugWriteLine(MODULE_NAME,
                                   Localization.Detected_HD_Copy_image_with_0_tracks_and_1_sectors_per_track,
                                   fheader.lastCylinder + 1, fheader.sectorsPerTrack);

        _imageInfo.Cylinders       = (uint)fheader.lastCylinder + 1;
        _imageInfo.SectorsPerTrack = fheader.sectorsPerTrack;
        _imageInfo.SectorSize      = 512; // only 512 bytes per sector supported
        _imageInfo.Heads           = 2;   // only 2-sided floppies are supported
        _imageInfo.Sectors         = 2                  * _imageInfo.Cylinders * _imageInfo.SectorsPerTrack;
        _imageInfo.ImageSize       = _imageInfo.Sectors * _imageInfo.SectorSize;

        _imageInfo.MetadataMediaType = MetadataMediaType.BlockMedia;

        _imageInfo.CreationTime         = imageFilter.CreationTime;
        _imageInfo.LastModificationTime = imageFilter.LastWriteTime;
        _imageInfo.MediaTitle           = Path.GetFileNameWithoutExtension(imageFilter.Filename);

        _imageInfo.MediaType = Geometry.GetMediaType(((ushort)_imageInfo.Cylinders, 2,
                                                      (ushort)_imageInfo.SectorsPerTrack, 512, MediaEncoding.MFM,
                                                      false));

        // build table of track offsets
        for(int i = 0; i < _imageInfo.Cylinders * 2; i++)
            if(fheader.trackMap[i] == 0)
                _trackOffset[i] = -1;
            else
            {
                // track is present, read the block header
                if(currentOffset + 3 >= stream.Length)
                    return ErrorNumber.InvalidArgument;

                byte[] blkHeader = new byte[2];
                stream.EnsureRead(blkHeader, 0, 2);
                short blkLength = BitConverter.ToInt16(blkHeader, 0);

                // assume block sizes are positive
                if(blkLength < 0)
                    return ErrorNumber.InvalidArgument;

                AaruConsole.DebugWriteLine(MODULE_NAME, Localization.Track_0_offset_1_size_equals_2, i, currentOffset,
                                           blkLength);

                _trackOffset[i] = currentOffset;

                currentOffset += 2 + blkLength;

                // skip the block data
                stream.Seek(blkLength, SeekOrigin.Current);
            }

        // ensure that the last track is present completely
        if(currentOffset > stream.Length)
            return ErrorNumber.InvalidArgument;

        // save some variables for later use
        _fileHeader      = fheader;
        _hdcpImageFilter = imageFilter;

        return ErrorNumber.NoError;
    }

    /// <inheritdoc />
    public ErrorNumber ReadSector(ulong sectorAddress, out byte[] buffer)
    {
        buffer = null;
        int trackNum     = (int)(sectorAddress / _imageInfo.SectorsPerTrack);
        int sectorOffset = (int)(sectorAddress % _imageInfo.SectorsPerTrack);

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

        if(trackNum > 2 * _imageInfo.Cylinders)
            return ErrorNumber.SectorNotFound;

        buffer = new byte[_imageInfo.SectorSize];

        if(_trackOffset[trackNum] == -1)
            Array.Clear(buffer, 0, (int)_imageInfo.SectorSize);
        else
        {
            // track is present in file, make sure it has been loaded
            if(!_trackCache.ContainsKey(trackNum))
            {
                ErrorNumber errno = ReadTrackIntoCache(_hdcpImageFilter.GetDataForkStream(), trackNum);

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

            Array.Copy(_trackCache[trackNum], sectorOffset * _imageInfo.SectorSize, buffer, 0, _imageInfo.SectorSize);
        }

        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;
    }
}