Geometry as readonly struct

Library/DiscUtils.Core/DiskImageBuilder.cs

@@ -38,7 +38,7 @@ public abstract class DiskImageBuilder
     /// <summary>
     /// Gets or sets the geometry of this disk, as reported by the BIOS, will be implied from the content stream if not set.
     /// </summary>
-    public Geometry BiosGeometry { get; set; }
+    public Geometry? BiosGeometry { get; set; }
 
     /// <summary>
     /// Gets or sets the content for this disk, implying the size of the disk.
@@ -53,7 +53,7 @@ public abstract class DiskImageBuilder
     /// <summary>
     /// Gets or sets the geometry of this disk, will be implied from the content stream if not set.
     /// </summary>
-    public Geometry Geometry { get; set; }
+    public Geometry? Geometry { get; set; }
 
     /// <summary>
     /// Gets a value indicating whether this file format preserves BIOS geometry information.

Library/DiscUtils.Core/Geometry.cs

@@ -30,7 +30,7 @@ namespace DiscUtils;
 /// Struct that represent disk geometries.
 /// </summary>
 /// <remarks>Instances of this struct are immutable.</remarks>
-public sealed class Geometry : IEquatable<Geometry>
+public readonly struct Geometry : IEquatable<Geometry>
 {
     /// <summary>
     /// Initializes a new instance of the Geometry class.  The default 512 bytes per sector is assumed.
@@ -199,19 +199,19 @@ public static Geometry LbaAssistedBiosGeometry(long capacity, int bytesPerSector
     /// <param name="capacity">The capacity of the disk.</param>
     /// <returns>The new geometry.</returns>
     /// <remarks>This method returns the LBA-Assisted geometry if the given geometry isn't BIOS-safe.</remarks>
-    public static Geometry MakeBiosSafe(Geometry geometry, long capacity)
+    public static Geometry MakeBiosSafe(Geometry? geometry, long capacity)
     {
         if (geometry == null)
         {
             return LbaAssistedBiosGeometry(capacity, Sizes.Sector);
         }
 
-        if (geometry.IsBiosSafe)
+        if (geometry.Value.IsBiosSafe)
         {
-            return geometry;
+            return geometry.Value;
         }
 
-        return LbaAssistedBiosGeometry(capacity, geometry.BytesPerSector);
+        return LbaAssistedBiosGeometry(capacity, geometry.Value.BytesPerSector);
     }
 
     /// <summary>
@@ -424,16 +424,10 @@ public Geometry TranslateToBios(long capacity, GeometryTranslation translation)
     /// <param name="other">The object to test against.</param>
     /// <returns><c>true</c> if the <paramref name="other"/> is equivalent, else <c>false</c>.</returns>
     public bool Equals(Geometry other)
-    {
-        return other is not null &&
-            Cylinders == other.Cylinders && HeadsPerCylinder == other.HeadsPerCylinder &&
-            SectorsPerTrack == other.SectorsPerTrack && BytesPerSector == other.BytesPerSector;
-    }
+        => Cylinders == other.Cylinders && HeadsPerCylinder == other.HeadsPerCylinder &&
+        SectorsPerTrack == other.SectorsPerTrack && BytesPerSector == other.BytesPerSector;
 
-    public static bool Equals(Geometry a, Geometry b)
-    {
-        return ReferenceEquals(a, b) || (a is not null && a.Equals(b));
-    }
+    public static bool Equals(Geometry a, Geometry b) => a.Equals(b);
 
     /// <summary>
     /// Determines if this object is equivalent to another.

Library/DiscUtils.Core/LogicalVolumeInfo.cs

@@ -83,7 +83,7 @@ public override string Identity
     /// <summary>
     /// Gets the disk geometry of the underlying storage medium, if any (may be Geometry.Null).
     /// </summary>
-    public override Geometry PhysicalGeometry => _physicalVol == null ? Geometry.Null : _physicalVol.PhysicalGeometry;
+    public override Geometry? PhysicalGeometry => _physicalVol == null ? Geometry.Null : _physicalVol.PhysicalGeometry;
 
     /// <summary>
     /// Gets the offset of this volume in the underlying storage medium, if any (may be Zero).

Library/DiscUtils.Core/Partitions/GuidPartitionTable.cs

@@ -48,7 +48,8 @@ public sealed class GuidPartitionTable : PartitionTable
     /// <param name="disk">The disk containing the partition table.</param>
     public GuidPartitionTable(VirtualDisk disk)
     {
-        Init(disk.Content, disk.Geometry);
+        Init(disk.Content, disk.Geometry
+            ?? throw new InvalidOperationException("Unknown disk geometry"));
     }
 
     /// <summary>
@@ -88,7 +89,8 @@ public GuidPartitionTable(Stream disk, Geometry diskGeometry)
     /// <returns>An object to access the newly created partition table.</returns>
     public static GuidPartitionTable Initialize(VirtualDisk disk)
     {
-        return Initialize(disk.Content, disk.Geometry);
+        return Initialize(disk.Content, disk.Geometry
+            ?? throw new InvalidOperationException("Unknown disk geometry"));
     }
 
     /// <summary>

Library/DiscUtils.Core/PhysicalVolumeInfo.cs

@@ -148,7 +148,7 @@ public Guid PartitionIdentity
     /// <summary>
     /// Gets the disk geometry of the underlying storage medium, if any (may be null).
     /// </summary>
-    public override Geometry PhysicalGeometry => _disk.Geometry;
+    public override Geometry? PhysicalGeometry => _disk.Geometry;
 
     /// <summary>
     /// Gets the offset of this volume in the underlying storage medium, if any (may be Zero).

Library/DiscUtils.Core/Raw/Disk.cs

@@ -43,15 +43,15 @@ public sealed class Disk : VirtualDisk
     /// <param name="stream">The stream to read.</param>
     /// <param name="ownsStream">Indicates if the new instance should control the lifetime of the stream.</param>
     public Disk(Stream stream, Ownership ownsStream)
-        : this(stream, ownsStream, default) {}
+        : this(stream, ownsStream, null) {}
 
     /// <summary>
     /// Initializes a new instance of the Disk class.
     /// </summary>
     /// <param name="stream">The stream to read.</param>
     /// <param name="ownsStream">Indicates if the new instance should control the lifetime of the stream.</param>
     /// <param name="geometry">The emulated geometry of the disk.</param>
-    public Disk(Stream stream, Ownership ownsStream, Geometry geometry)
+    public Disk(Stream stream, Ownership ownsStream, Geometry? geometry)
     {
         _file = new DiskImageFile(stream, ownsStream, geometry);
     }
@@ -80,7 +80,7 @@ public Disk(string path, FileAccess access)
     {
         var share = access == FileAccess.Read ? FileShare.Read : FileShare.None;
         var locator = new LocalFileLocator(string.Empty, useAsync: false);
-        _file = new DiskImageFile(locator.Open(path, FileMode.Open, access, share), Ownership.Dispose, default);
+        _file = new DiskImageFile(locator.Open(path, FileMode.Open, access, share), Ownership.Dispose, null);
     }
 
     /// <summary>
@@ -93,7 +93,7 @@ public Disk(string path, FileAccess access, bool useAsync)
     {
         var share = access == FileAccess.Read ? FileShare.Read : FileShare.None;
         var locator = new LocalFileLocator(string.Empty, useAsync);
-        _file = new DiskImageFile(locator.Open(path, FileMode.Open, access, share), Ownership.Dispose, default);
+        _file = new DiskImageFile(locator.Open(path, FileMode.Open, access, share), Ownership.Dispose, null);
     }
 
     /// <summary>
@@ -138,7 +138,7 @@ private Disk(DiskImageFile file)
     /// <summary>
     /// Gets the geometry of the disk.
     /// </summary>
-    public override Geometry Geometry => _file.Geometry;
+    public override Geometry? Geometry => _file.Geometry;
 
     /// <summary>
     /// Gets the layers that make up the disk.
@@ -155,7 +155,7 @@ public override IEnumerable<VirtualDiskLayer> Layers
     /// <returns>An object that accesses the stream as a disk.</returns>
     public static Disk Initialize(Stream stream, Ownership ownsStream, long capacity)
     {
-        return Initialize(stream, ownsStream, capacity, default);
+        return Initialize(stream, ownsStream, capacity, null);
     }
 
     /// <summary>
@@ -166,7 +166,7 @@ public static Disk Initialize(Stream stream, Ownership ownsStream, long capacity
     /// <param name="capacity">The desired capacity of the new disk.</param>
     /// <param name="geometry">The desired geometry of the new disk, or <c>null</c> for default.</param>
     /// <returns>An object that accesses the stream as a disk.</returns>
-    public static Disk Initialize(Stream stream, Ownership ownsStream, long capacity, Geometry geometry)
+    public static Disk Initialize(Stream stream, Ownership ownsStream, long capacity, Geometry? geometry)
     {
         return new Disk(DiskImageFile.Initialize(stream, ownsStream, capacity, geometry));
     }

Library/DiscUtils.Core/Raw/DiskImageFile.cs

@@ -48,7 +48,7 @@ public DiskImageFile(Stream stream)
     /// <param name="stream">The stream to interpret.</param>
     /// <param name="ownsStream">Indicates if the new instance should control the lifetime of the stream.</param>
     /// <param name="geometry">The emulated geometry of the disk.</param>
-    public DiskImageFile(Stream stream, Ownership ownsStream, Geometry geometry = default)
+    public DiskImageFile(Stream stream, Ownership ownsStream, Geometry? geometry = null)
     {
         Content = stream as SparseStream;
         _ownsContent = ownsStream;
@@ -59,7 +59,7 @@ public DiskImageFile(Stream stream, Ownership ownsStream, Geometry geometry = de
             _ownsContent = Ownership.Dispose;
         }
 
-        Geometry = geometry != default ? geometry : DetectGeometry(Content);
+        Geometry = geometry ?? DetectGeometry(Content);
     }
 
     public override long Capacity => Content.Length;
@@ -96,7 +96,7 @@ public DiskImageFile(Stream stream, Ownership ownsStream, Geometry geometry = de
     /// <param name="capacity">The desired capacity of the new disk.</param>
     /// <param name="geometry">The geometry of the new disk.</param>
     /// <returns>An object that accesses the stream as a raw disk image.</returns>
-    public static DiskImageFile Initialize(Stream stream, Ownership ownsStream, long capacity, Geometry geometry = default)
+    public static DiskImageFile Initialize(Stream stream, Ownership ownsStream, long capacity, Geometry? geometry = null)
     {
         stream.SetLength(MathUtilities.RoundUp(capacity, Sizes.Sector));
 

Library/DiscUtils.Core/VirtualDisk.cs

@@ -73,7 +73,7 @@ public abstract class VirtualDisk :
     /// <summary>
     /// Gets the geometry of the disk.
     /// </summary>
-    public abstract Geometry Geometry { get; }
+    public abstract Geometry? Geometry { get; }
 
     /// <summary>
     /// Gets the geometry of the disk as it is anticipated a hypervisor BIOS will represent it.
@@ -242,7 +242,7 @@ public static VirtualDiskTypeInfo GetDiskType(string type, string variant)
     /// <param name="geometry">The geometry of the new disk (or null).</param>
     /// <param name="parameters">Untyped parameters controlling the creation process (TBD).</param>
     /// <returns>The newly created disk.</returns>
-    public static VirtualDisk CreateDisk(DiscFileSystem fileSystem, string type, string variant, string path, long capacity, Geometry geometry, Dictionary<string, string> parameters)
+    public static VirtualDisk CreateDisk(DiscFileSystem fileSystem, string type, string variant, string path, long capacity, Geometry? geometry, Dictionary<string, string> parameters)
     {
         var factory = VirtualDiskManager.TypeMap[type];
 
@@ -274,7 +274,7 @@ public static VirtualDisk CreateDisk(DiscFileSystem fileSystem, string type, str
     /// <param name="geometry">The geometry of the new disk (or null).</param>
     /// <param name="parameters">Untyped parameters controlling the creation process (TBD).</param>
     /// <returns>The newly created disk.</returns>
-    public static VirtualDisk CreateDisk(string type, string variant, string path, long capacity, Geometry geometry, Dictionary<string, string> parameters)
+    public static VirtualDisk CreateDisk(string type, string variant, string path, long capacity, Geometry? geometry, Dictionary<string, string> parameters)
     {
         return CreateDisk(type, variant, path, capacity, geometry, null, null, parameters);
     }
@@ -290,7 +290,7 @@ public static VirtualDisk CreateDisk(string type, string variant, string path, l
     /// <param name="parameters">Untyped parameters controlling the creation process (TBD).</param>
     /// <param name="useAsync">Underlying files will be opened optimized for async use.</param>
     /// <returns>The newly created disk.</returns>
-    public static VirtualDisk CreateDisk(string type, string variant, string path, long capacity, Geometry geometry, Dictionary<string, string> parameters, bool useAsync)
+    public static VirtualDisk CreateDisk(string type, string variant, string path, long capacity, Geometry? geometry, Dictionary<string, string> parameters, bool useAsync)
     {
         return CreateDisk(type, variant, path, capacity, geometry, null, null, parameters, useAsync);
     }
@@ -307,7 +307,7 @@ public static VirtualDisk CreateDisk(string type, string variant, string path, l
     /// <param name="password">The password to use when accessing the <c>path</c> (or null).</param>
     /// <param name="parameters">Untyped parameters controlling the creation process (TBD).</param>
     /// <returns>The newly created disk.</returns>
-    public static VirtualDisk CreateDisk(string type, string variant, string path, long capacity, Geometry geometry, string user, string password, Dictionary<string, string> parameters)
+    public static VirtualDisk CreateDisk(string type, string variant, string path, long capacity, Geometry? geometry, string user, string password, Dictionary<string, string> parameters)
         => CreateDisk(type, variant, path, capacity, geometry, user, password, parameters, useAsync: false);
 
     /// <summary>
@@ -323,7 +323,7 @@ public static VirtualDisk CreateDisk(string type, string variant, string path, l
     /// <param name="parameters">Untyped parameters controlling the creation process (TBD).</param>
     /// <param name="useAsync">Underlying files will be opened optimized for async use.</param>
     /// <returns>The newly created disk.</returns>
-    public static VirtualDisk CreateDisk(string type, string variant, string path, long capacity, Geometry geometry, string user, string password, Dictionary<string, string> parameters, bool useAsync)
+    public static VirtualDisk CreateDisk(string type, string variant, string path, long capacity, Geometry? geometry, string user, string password, Dictionary<string, string> parameters, bool useAsync)
     {
         var diskParams = new VirtualDiskParameters
         {

Library/DiscUtils.Core/VirtualDiskParameters.cs

@@ -60,5 +60,5 @@ public sealed class VirtualDiskParameters
     /// <summary>
     /// Gets or sets the physical (aka IDE) geometry of the disk.
     /// </summary>
-    public Geometry Geometry { get; set; }
+    public Geometry? Geometry { get; set; }
 }

Library/DiscUtils.Core/VolumeInfo.cs

@@ -55,7 +55,7 @@ internal VolumeInfo() {}
     /// <summary>
     /// Gets the disk geometry of the underlying storage medium, if any (may be null).
     /// </summary>
-    public abstract Geometry PhysicalGeometry { get; }
+    public abstract Geometry? PhysicalGeometry { get; }
 
     /// <summary>
     /// Gets the disk geometry of the underlying storage medium (as used in BIOS calls), may be null.

Library/DiscUtils.Dmg/Disk.cs

@@ -90,7 +90,7 @@ public override SparseStream Content
     /// <summary>
     /// Gets the geometry of the disk.
     /// </summary>
-    public override Geometry Geometry => _file.Geometry;
+    public override Geometry? Geometry => _file.Geometry;
 
     /// <summary>
     /// Gets the layers that make up the disk.

Library/DiscUtils.Iscsi/Disk.cs

@@ -108,13 +108,13 @@ public override SparseStream Content
         CanBeHardDisk = true,
         DeterministicGeometry = false,
         PreservesBiosGeometry = false,
-        CalcGeometry = Geometry.FromCapacity
+        CalcGeometry = DiscUtils.Geometry.FromCapacity
     };
 
     /// <summary>
     /// The Geometry of the disk.
     /// </summary>
-    public override Geometry Geometry
+    public override Geometry? Geometry
     {
         get
         {

Library/DiscUtils.OpticalDiscSharing/Disc.cs

@@ -82,7 +82,7 @@ internal Disc(Uri uri, string userName, string password)
     /// <summary>
     /// Gets the geometry of the disk.
     /// </summary>
-    public override Geometry Geometry => _file.Geometry;
+    public override Geometry? Geometry => _file.Geometry;
 
     /// <summary>
     /// Gets the layers that make up the disc.

Library/DiscUtils.OpticalDisk/Disc.cs

@@ -138,7 +138,7 @@ public Disc(string path, FileAccess access, bool useAsync)
     /// <summary>
     /// Gets the geometry of the disk.
     /// </summary>
-    public override Geometry Geometry => _file.Geometry;
+    public override Geometry? Geometry => _file.Geometry;
 
     /// <summary>
     /// Gets the layers that make up the disc.

Library/DiscUtils.OpticalDisk/FileSystemFactory.cs

@@ -23,6 +23,7 @@
 using System.Collections.Generic;
 using System.IO;
 using DiscUtils.Iso9660;
+using DiscUtils.Streams;
 using DiscUtils.Udf;
 using DiscUtils.Vfs;
 
@@ -48,7 +49,7 @@ private UdfReader OpenUdf(Stream stream, VolumeInfo volumeInfo, FileSystemParame
     {
         if (volumeInfo != null)
         {
-            return new UdfReader(stream, volumeInfo.PhysicalGeometry.BytesPerSector);
+            return new UdfReader(stream, volumeInfo.PhysicalGeometry?.BytesPerSector ?? Sizes.Sector);
         }
 
         return new UdfReader(stream);