Aaru/DiscImageChef.DiscImages/WCDiskImage/Identify.cs

// /***************************************************************************
// The Disc Image Chef
// ----------------------------------------------------------------------------
//
// Filename       : Identify.cs
// Author(s)      : Michael Drüing <michael@drueing.de>
//
// Component      : Disk image plugins.
//
// --[ Description ] ----------------------------------------------------------
//
//     Identifies d2f/WC DISK IMAGE 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 © 2018 Michael Drüing
// Copyright © 2011-2018 Natalia Portillo
// ****************************************************************************/

using System;
using System.IO;
using System.Text;
using System.Runtime.InteropServices;
using DiscImageChef.CommonTypes.Interfaces;

namespace DiscImageChef.DiscImages
{
    public partial class WCDiskImage
    {
        public bool Identify(IFilter imageFilter)
        {
            Stream stream = imageFilter.GetDataForkStream();
            stream.Seek(0, SeekOrigin.Begin);

            if (stream.Length < 32) return false;

            byte[] header = new byte[32];
            stream.Read(header, 0, 32);

            IntPtr hdrPtr = Marshal.AllocHGlobal(32);
            Marshal.Copy(header, 0, hdrPtr, 32);
            WCDiskImageFileHeader fheader = (WCDiskImageFileHeader)Marshal.PtrToStructure(hdrPtr, typeof(WCDiskImageFileHeader));
            Marshal.FreeHGlobal(hdrPtr);

            /* check the signature */
            if (Encoding.ASCII.GetString(fheader.signature).TrimEnd('\x00') != WCDiskImage.fileSignature)
                return false;

            /* Some sanity checks on the values we just read. */
            if (fheader.version > 1) return false;

            if (fheader.heads < 1 || fheader.heads > 2) return false;

            if (fheader.sectorsPerTrack < 8 || fheader.sectorsPerTrack > 18) return false;

            if (fheader.cylinders < 1 || fheader.cylinders > 80) return false;

            if (fheader.extraTracks[0] > 1 || fheader.extraTracks[1] > 1 || fheader.extraTracks[2] > 1 || fheader.extraTracks[3] > 1)
                return false;

            if (((byte)fheader.extraFlags & ~0x03) != 0) return false;

            // TODO: validate all sectors
            // For now, having a valid header will suffice.
            return true;
        }
    }
}