ThumbCache*.db parser

ThumbCache

using System;
using System.Collections.Generic;
using System.Data;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Drawing;
using System.IO;
using System.Threading.Tasks;

namespace ThumbCache
{
    public class ThumbCache
    {
        public List<Bitmap> Images { get; }

        public ThumbCache(string fileName)
        {
            var s = new FileStream(fileName,FileMode.Open,FileAccess.Read);
            var bs = new BinaryReader(s);

            Images = new List<Bitmap>();

            var rawBytes = bs.ReadBytes((int) bs.BaseStream.Length);

            bs.Close();
            s.Close();

            var index = 0;

            var sig = Encoding.ASCII.GetString(rawBytes, index, 4);

            if (sig.Equals("CMMM") == false)
            {
                throw new InvalidDataException("Header != CMMM");    
            }
            
            index += 4;

            var ver = BitConverter.ToUInt32(rawBytes, index);
            index += 4;

            var cacheType = BitConverter.ToUInt32(rawBytes, index);
            index += 4;

            var firstOffset = BitConverter.ToUInt32(rawBytes, index);
            index += 4;

            var firstAvailOffset = BitConverter.ToUInt32(rawBytes, index);
            index += 4;

            var numEntries = BitConverter.ToUInt32(rawBytes, index);
            index += 4;

            while (index < rawBytes.Length)
            {
                sig = Encoding.ASCII.GetString(rawBytes, index, 4);

                var lastStart = index;

                index += 4;

                var cacheSize = BitConverter.ToUInt32(rawBytes, index);
                index += 4;

                index += 8; //skip entry hash

                var identifierSize = BitConverter.ToInt32(rawBytes, index);
                index += 4;

                var paddingSize = BitConverter.ToInt32(rawBytes, index);
                index += 4;

                var dataSize = BitConverter.ToUInt32(rawBytes, index);
                index += 4;

                index += 4;//skip unknown

                index += 8;//skip data checksum
                index += 8;//skip header checksum

                index += 8;//move 8 for rest to work

                var identifier = Encoding.Unicode.GetString(rawBytes, index, identifierSize);
                index += identifierSize;

                index += paddingSize;

                var rawImageBytes = rawBytes.Skip(index).Take((int) dataSize).ToArray();

                if (rawImageBytes.Length > 0)
                {
                    Bitmap newBitmap = GetImageFromByteArray(rawImageBytes);

                    Images.Add(newBitmap);
                }

                index = lastStart + (int) cacheSize;
            }

        }

        //from http://stackoverflow.com/questions/3801275/how-to-convert-image-in-byte-array/16576471#16576471
        private static readonly ImageConverter _imageConverter = new ImageConverter();

        public static Bitmap GetImageFromByteArray(byte[] byteArray)
        {
            Bitmap bm = (Bitmap)_imageConverter.ConvertFrom(byteArray);

            if (bm != null && (bm.HorizontalResolution != (int)bm.HorizontalResolution ||
                               bm.VerticalResolution != (int)bm.VerticalResolution))
            {
                // Correct a strange glitch that has been observed in the test program when converting 
                //  from a PNG file image created by CopyImageToByteArray() - the dpi value "drifts" 
                //  slightly away from the nominal integer value
                bm.SetResolution((int)(bm.HorizontalResolution + 0.5f),
                                 (int)(bm.VerticalResolution + 0.5f));
            }

            return bm;
        }


    }
}