Added a new disk scheme

osbuilder/Program.cs

@@ -440,6 +440,8 @@ static DiskLayouts.IDiskScheme CreateDiskScheme(IDisk disk, ProjectConfiguration
                 scheme = new DiskLayouts.MBR();
             else if (config.Scheme.ToLower() == "gpt")
                 scheme = new DiskLayouts.GPT();
+            else if (config.Scheme.ToLower() == "singleton")
+                scheme = new DiskLayouts.Singleton();
             else {
                 throw new Exception($"{nameof(Program)} | {nameof(CreateDiskScheme)} | ERROR: Invalid schema specified in the model");
             }

osbuilder/disklayouts/Singleton.cs

@@ -0,0 +1,83 @@
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System;
+
+namespace OSBuilder.DiskLayouts {
+    public class Singleton : IDiskScheme {
+    private IDisk _disk = null;
+    private List<FileSystems.IFileSystem> _fileSystems = new List<FileSystems.IFileSystem>();
+
+    private ulong _sectorsAllocated = 0;
+
+    public bool Open(IDisk disk)
+    {
+        // Store disk
+        _disk = disk;
+
+        // ensure disk is open for read/write
+        if (!_disk.IsOpen())
+            return false;
+
+        return true;
+    }
+
+    public void Dispose()
+    {
+        if (_disk == null)
+            return;
+
+        // dispose of filesystems
+        foreach (var fs in _fileSystems)
+        {
+            fs.Dispose();
+        }
+
+        // cleanup
+        _fileSystems.Clear();
+        _disk = null;
+    }
+
+
+    public bool Create(IDisk disk) 
+    {
+        _disk = disk;
+
+        // ensure disk is open for read/write
+        if (!_disk.IsOpen())
+            return false;
+
+        return true;
+    }
+
+    public bool AddPartition(FileSystems.IFileSystem fileSystem, ulong sectorCount, string vbrImage, string reservedSectorsImage)
+    {
+        ulong partitionSize = GetFreeSectorCount();
+        if (_disk == null || fileSystem == null)
+            return false;
+
+        if (_fileSystems.Count != 0)
+        {
+            return false;
+        }
+        _sectorsAllocated += partitionSize;
+        // Initialize the file-system
+        fileSystem.Initialize(_disk, 0, partitionSize, vbrImage, reservedSectorsImage);
+
+        // Add sectors allocated
+        _fileSystems.Add(fileSystem);
+        return fileSystem.Format();
+    }
+    public ulong GetFreeSectorCount()
+    {
+        if (_disk == null)
+            return 0;
+        return _disk.SectorCount - _sectorsAllocated;
+    }
+    public IEnumerable<FileSystems.IFileSystem> GetFileSystems()
+    {
+        return _fileSystems;
+    }
+
+    }
+}