Add test dmg

Add read-only support for Dmg archives

.config/dotnet-tools.json

@@ -0,0 +1,12 @@
+{
+  "version": 1,
+  "isRoot": true,
+  "tools": {
+    "dotnet-format": {
+      "version": "4.1.131201",
+      "commands": [
+        "dotnet-format"
+      ]
+    }
+  }
+}

.github/workflows/dotnetcore.yml

@@ -12,7 +12,7 @@ jobs:
     - uses: actions/checkout@v1
     - uses: actions/setup-dotnet@v1
       with:
-        dotnet-version: 3.1.302
+        dotnet-version: 5.0.101
     - run: dotnet run -p build/build.csproj
     - uses: actions/upload-artifact@v2
       with:

FORMATS.md

@@ -19,7 +19,6 @@
 | Tar.XZ                 | LZMA2                                             | Decompress          | TarArchive      | TarReader  | TarWriter (3) |
 | GZip (single file)     | DEFLATE                                           | Both                | GZipArchive     | GZipReader | GZipWriter    |
 | 7Zip (4)               | LZMA, LZMA2, BZip2, PPMd, BCJ, BCJ2, Deflate      | Decompress          | SevenZipArchive | N/A        | N/A           |
-| LZip (single file) (5) | LZip (LZMA)                                       | Both                | LZipArchive     | LZipReader | LZipWriter    |
 
 1. SOLID Rars are only supported in the RarReader API.
 2. Zip format supports pkware and WinzipAES encryption. However, encrypted LZMA is not supported. Zip64 reading/writing is supported but only with seekable streams as the Zip spec doesn't support Zip64 data in post data descriptors. Deflate64 is only supported for reading.

README.md

@@ -1,6 +1,6 @@
 # SharpCompress
 
-SharpCompress is a compression library in pure C# for .NET Standard 2.0, 2.1 and NET 4.6 that can unrar, un7zip, unzip, untar unbzip2, ungzip, unlzip with forward-only reading and file random access APIs. Write support for zip/tar/bzip2/gzip/lzip are implemented.
+SharpCompress is a compression library in pure C# for .NET Standard 2.0, 2.1, .NET Core 3.1 and .NET 5.0 that can unrar, un7zip, unzip, untar unbzip2, ungzip, unlzip with forward-only reading and file random access APIs. Write support for zip/tar/bzip2/gzip/lzip are implemented.
 
 The major feature is support for non-seekable streams so large files can be processed on the fly (i.e. download stream).
 

build/Program.cs

@@ -9,10 +9,11 @@ using static SimpleExec.Command;
 class Program
 {
     private const string Clean = "clean";
+    private const string Format = "format";
     private const string Build = "build";
     private const string Test = "test";
     private const string Publish = "publish";
-    
+
     static void Main(string[] args)
     {
         Target(Clean,
@@ -39,30 +40,36 @@ class Program
                 }
             });
 
-        Target(Build, ForEach("net46", "netstandard2.0", "netstandard2.1"), 
+        Target(Format, () =>
+        {
+            Run("dotnet", "tool restore");
+            Run("dotnet", "format --check");
+        });
+
+        Target(Build, DependsOn(Format),
                framework =>
                {
-                    if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows) && framework == "net46")
-                    {
-                        return;
-                    }
-                    Run("dotnet", "build src/SharpCompress/SharpCompress.csproj -c Release");
-                });
+                   if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows) && framework == "net46")
+                   {
+                       return;
+                   }
+                   Run("dotnet", "build src/SharpCompress/SharpCompress.csproj -c Release");
+               });
 
-        Target(Test, DependsOn(Build), ForEach("netcoreapp3.1"), 
-            framework =>
-            {
-                IEnumerable<string> GetFiles(string d)
-                {
-                    return Glob.Files(".", d);
-                }
+        Target(Test, DependsOn(Build), ForEach("net5.0"),
+               framework =>
+               {
+                   IEnumerable<string> GetFiles(string d)
+                   {
+                       return Glob.Files(".", d);
+                   }
+
+                   foreach (var file in GetFiles("**/*.Test.csproj"))
+                   {
+                       Run("dotnet", $"test {file} -c Release -f {framework}");
+                   }
+               });
 
-                foreach (var file in GetFiles("**/*.Test.csproj"))
-                {
-                    Run("dotnet", $"test {file} -c Release -f {framework}");
-                }
-            });
-        
         Target(Publish, DependsOn(Test),
                () =>
                {
@@ -70,7 +77,7 @@ class Program
                });
 
         Target("default", DependsOn(Publish), () => Console.WriteLine("Done!"));
-        
+
         RunTargetsAndExit(args);
     }
 }

build/build.csproj

@@ -2,13 +2,13 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <TargetFramework>net5.0</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Bullseye" Version="3.3.0" />
-    <PackageReference Include="Glob" Version="1.1.7" />
-    <PackageReference Include="SimpleExec" Version="6.2.0" />
+    <PackageReference Include="Bullseye" Version="3.6.0" />
+    <PackageReference Include="Glob" Version="1.1.8" />
+    <PackageReference Include="SimpleExec" Version="6.4.0" />
   </ItemGroup>
 
 </Project>

global.json

@@ -1,5 +1,5 @@
 {
   "sdk": {
-    "version": "3.1.302"
+    "version": "5.0.101"
   }
 }

src/SharpCompress/Algorithms/Alder32.cs

@@ -0,0 +1,285 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the GNU Affero General Public License, Version 3.
+
+using System;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+#if !NETSTANDARD2_0 && !NETSTANDARD2_1
+using System.Runtime.Intrinsics;
+using System.Runtime.Intrinsics.X86;
+#endif
+
+namespace SharpCompress.Algorithms
+{
+    /// <summary>
+    /// Calculates the 32 bit Adler checksum of a given buffer according to
+    /// RFC 1950. ZLIB Compressed Data Format Specification version 3.3)
+    /// </summary>
+    internal static class Adler32
+    {
+        /// <summary>
+        /// The default initial seed value of a Adler32 checksum calculation.
+        /// </summary>
+        public const uint SeedValue = 1U;
+
+#if !NETSTANDARD2_0 && !NETSTANDARD2_1
+        private const int MinBufferSize = 64;
+#endif
+
+        // Largest prime smaller than 65536
+        private const uint BASE = 65521;
+
+        // NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1
+        private const uint NMAX = 5552;
+
+        /// <summary>
+        /// Calculates the Adler32 checksum with the bytes taken from the span.
+        /// </summary>
+        /// <param name="buffer">The readonly span of bytes.</param>
+        /// <returns>The <see cref="uint"/>.</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static uint Calculate(ReadOnlySpan<byte> buffer)
+        {
+            return Calculate(SeedValue, buffer);
+        }
+
+        /// <summary>
+        /// Calculates the Adler32 checksum with the bytes taken from the span and seed.
+        /// </summary>
+        /// <param name="adler">The input Adler32 value.</param>
+        /// <param name="buffer">The readonly span of bytes.</param>
+        /// <returns>The <see cref="uint"/>.</returns>
+        public static uint Calculate(uint adler, ReadOnlySpan<byte> buffer)
+        {
+            if (buffer.IsEmpty)
+            {
+                return SeedValue;
+            }
+
+#if !NETSTANDARD2_0 && !NETSTANDARD2_1
+            if (Sse3.IsSupported && buffer.Length >= MinBufferSize)
+            {
+                return CalculateSse(adler, buffer);
+            }
+
+            return CalculateScalar(adler, buffer);
+#else
+            return CalculateScalar(adler, buffer);
+#endif
+        }
+
+        // Based on https://github.com/chromium/chromium/blob/master/third_party/zlib/adler32_simd.c
+#if !NETSTANDARD2_0 && !NETSTANDARD2_1
+        private static unsafe uint CalculateSse(uint adler, ReadOnlySpan<byte> buffer)
+        {
+            uint s1 = adler & 0xFFFF;
+            uint s2 = (adler >> 16) & 0xFFFF;
+
+            // Process the data in blocks.
+            const int BLOCK_SIZE = 1 << 5;
+
+            uint length = (uint)buffer.Length;
+            uint blocks = length / BLOCK_SIZE;
+            length -= blocks * BLOCK_SIZE;
+
+            int index = 0;
+            fixed (byte* bufferPtr = &buffer[0])
+            {
+                index += (int)blocks * BLOCK_SIZE;
+                var localBufferPtr = bufferPtr;
+
+                // _mm_setr_epi8 on x86
+                var tap1 = Vector128.Create(32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17);
+                var tap2 = Vector128.Create(16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1);
+                Vector128<byte> zero = Vector128<byte>.Zero;
+                var ones = Vector128.Create((short)1);
+
+                while (blocks > 0)
+                {
+                    uint n = NMAX / BLOCK_SIZE;  /* The NMAX constraint. */
+                    if (n > blocks)
+                    {
+                        n = blocks;
+                    }
+
+                    blocks -= n;
+
+                    // Process n blocks of data. At most NMAX data bytes can be
+                    // processed before s2 must be reduced modulo BASE.
+                    Vector128<int> v_ps = Vector128.CreateScalar(s1 * n).AsInt32();
+                    Vector128<int> v_s2 = Vector128.CreateScalar(s2).AsInt32();
+                    Vector128<int> v_s1 = Vector128<int>.Zero;
+
+                    do
+                    {
+                        // Load 32 input bytes.
+                        Vector128<byte> bytes1 = Sse3.LoadDquVector128(localBufferPtr);
+                        Vector128<byte> bytes2 = Sse3.LoadDquVector128(localBufferPtr + 16);
+
+                        // Add previous block byte sum to v_ps.
+                        v_ps = Sse2.Add(v_ps, v_s1);
+
+                        // Horizontally add the bytes for s1, multiply-adds the
+                        // bytes by [ 32, 31, 30, ... ] for s2.
+                        v_s1 = Sse2.Add(v_s1, Sse2.SumAbsoluteDifferences(bytes1, zero).AsInt32());
+                        Vector128<short> mad1 = Ssse3.MultiplyAddAdjacent(bytes1, tap1);
+                        v_s2 = Sse2.Add(v_s2, Sse2.MultiplyAddAdjacent(mad1, ones));
+
+                        v_s1 = Sse2.Add(v_s1, Sse2.SumAbsoluteDifferences(bytes2, zero).AsInt32());
+                        Vector128<short> mad2 = Ssse3.MultiplyAddAdjacent(bytes2, tap2);
+                        v_s2 = Sse2.Add(v_s2, Sse2.MultiplyAddAdjacent(mad2, ones));
+
+                        localBufferPtr += BLOCK_SIZE;
+                    }
+                    while (--n > 0);
+
+                    v_s2 = Sse2.Add(v_s2, Sse2.ShiftLeftLogical(v_ps, 5));
+
+                    // Sum epi32 ints v_s1(s2) and accumulate in s1(s2).
+                    const byte S2301 = 0b1011_0001;  // A B C D -> B A D C
+                    const byte S1032 = 0b0100_1110;  // A B C D -> C D A B
+
+                    v_s1 = Sse2.Add(v_s1, Sse2.Shuffle(v_s1, S2301));
+                    v_s1 = Sse2.Add(v_s1, Sse2.Shuffle(v_s1, S1032));
+
+                    s1 += (uint)v_s1.ToScalar();
+
+                    v_s2 = Sse2.Add(v_s2, Sse2.Shuffle(v_s2, S2301));
+                    v_s2 = Sse2.Add(v_s2, Sse2.Shuffle(v_s2, S1032));
+
+                    s2 = (uint)v_s2.ToScalar();
+
+                    // Reduce.
+                    s1 %= BASE;
+                    s2 %= BASE;
+                }
+            }
+
+            ref byte bufferRef = ref MemoryMarshal.GetReference(buffer);
+
+            if (length > 0)
+            {
+                if (length >= 16)
+                {
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    length -= 16;
+                }
+
+                while (length-- > 0)
+                {
+                    s2 += s1 += Unsafe.Add(ref bufferRef, index++);
+                }
+
+                if (s1 >= BASE)
+                {
+                    s1 -= BASE;
+                }
+
+                s2 %= BASE;
+            }
+
+            return s1 | (s2 << 16);
+        }
+#endif
+
+        private static uint CalculateScalar(uint adler, ReadOnlySpan<byte> buffer)
+        {
+            uint s1 = adler & 0xFFFF;
+            uint s2 = (adler >> 16) & 0xFFFF;
+            uint k;
+
+            ref byte bufferRef = ref MemoryMarshal.GetReference<byte>(buffer);
+            uint length = (uint)buffer.Length;
+            int index = 0;
+
+            while (length > 0)
+            {
+                k = length < NMAX ? length : NMAX;
+                length -= k;
+
+                while (k >= 16)
+                {
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    s1 += Unsafe.Add(ref bufferRef, index++);
+                    s2 += s1;
+                    k -= 16;
+                }
+
+                if (k != 0)
+                {
+                    do
+                    {
+                        s1 += Unsafe.Add(ref bufferRef, index++);
+                        s2 += s1;
+                    }
+                    while (--k != 0);
+                }
+
+                s1 %= BASE;
+                s2 %= BASE;
+            }
+
+            return (s2 << 16) | s1;
+        }
+    }
+}

src/SharpCompress/Archives/AbstractArchive.cs

@@ -81,29 +81,29 @@ namespace SharpCompress.Archives
         /// <summary>
         /// Returns an ReadOnlyCollection of all the RarArchiveEntries across the one or many parts of the RarArchive.
         /// </summary>
-        public virtual ICollection<TEntry> Entries { get { return lazyEntries; } }
+        public virtual ICollection<TEntry> Entries => lazyEntries;
 
         /// <summary>
         /// Returns an ReadOnlyCollection of all the RarArchiveVolumes across the one or many parts of the RarArchive.
         /// </summary>
-        public ICollection<TVolume> Volumes { get { return lazyVolumes; } }
+        public ICollection<TVolume> Volumes => lazyVolumes;
 
         /// <summary>
         /// The total size of the files compressed in the archive.
         /// </summary>
-        public virtual long TotalSize { get { return Entries.Aggregate(0L, (total, cf) => total + cf.CompressedSize); } }
+        public virtual long TotalSize => Entries.Aggregate(0L, (total, cf) => total + cf.CompressedSize);
 
         /// <summary>
         /// The total size of the files as uncompressed in the archive.
         /// </summary>
-        public virtual long TotalUncompressSize { get { return Entries.Aggregate(0L, (total, cf) => total + cf.Size); } }
+        public virtual long TotalUncompressSize => Entries.Aggregate(0L, (total, cf) => total + cf.Size);
 
         protected abstract IEnumerable<TVolume> LoadVolumes(IEnumerable<Stream> streams);
         protected abstract IEnumerable<TEntry> LoadEntries(IEnumerable<TVolume> volumes);
 
-        IEnumerable<IArchiveEntry> IArchive.Entries { get { return Entries.Cast<IArchiveEntry>(); } }
+        IEnumerable<IArchiveEntry> IArchive.Entries => Entries.Cast<IArchiveEntry>();
 
-        IEnumerable<IVolume> IArchive.Volumes { get { return lazyVolumes.Cast<IVolume>(); } }
+        IEnumerable<IVolume> IArchive.Volumes => lazyVolumes.Cast<IVolume>();
 
         public virtual void Dispose()
         {
@@ -132,9 +132,9 @@ namespace SharpCompress.Archives
         void IExtractionListener.FireFilePartExtractionBegin(string name, long size, long compressedSize)
         {
             FilePartExtractionBegin?.Invoke(this, new FilePartExtractionBeginEventArgs(
-                compressedSize : compressedSize,
-                size           : size,
-                name           : name
+                compressedSize: compressedSize,
+                size: size,
+                name: name
             ));
         }
 
@@ -160,7 +160,7 @@ namespace SharpCompress.Archives
         /// <summary>
         /// Archive is SOLID (this means the Archive saved bytes by reusing information which helps for archives containing many small files).
         /// </summary>
-        public virtual bool IsSolid { get { return false; } }
+        public virtual bool IsSolid => false;
 
         /// <summary>
         /// The archive can find all the parts of the archive needed to fully extract the archive.  This forces the parsing of the entire archive.

src/SharpCompress/Archives/AbstractWritableArchive.cs

@@ -12,11 +12,28 @@ namespace SharpCompress.Archives
         where TEntry : IArchiveEntry
         where TVolume : IVolume
     {
+        private class RebuildPauseDisposable : IDisposable
+        {
+            private readonly AbstractWritableArchive<TEntry, TVolume> archive;
+
+            public RebuildPauseDisposable(AbstractWritableArchive<TEntry, TVolume> archive)
+            {
+                this.archive = archive;
+                archive.pauseRebuilding = true;
+            }
+
+            public void Dispose()
+            {
+                archive.pauseRebuilding = false;
+                archive.RebuildModifiedCollection();
+            }
+        }
         private readonly List<TEntry> newEntries = new List<TEntry>();
         private readonly List<TEntry> removedEntries = new List<TEntry>();
 
         private readonly List<TEntry> modifiedEntries = new List<TEntry>();
         private bool hasModifications;
+        private bool pauseRebuilding;
 
         internal AbstractWritableArchive(ArchiveType type)
             : base(type)
@@ -45,8 +62,17 @@ namespace SharpCompress.Archives
             }
         }
 
+        public IDisposable PauseEntryRebuilding()
+        {
+            return new RebuildPauseDisposable(this);
+        }
+
         private void RebuildModifiedCollection()
         {
+            if (pauseRebuilding)
+            {
+                return;
+            }
             hasModifications = true;
             newEntries.RemoveAll(v => removedEntries.Contains(v));
             modifiedEntries.Clear();
@@ -83,8 +109,7 @@ namespace SharpCompress.Archives
         public TEntry AddEntry(string key, Stream source, bool closeStream,
                                long size = 0, DateTime? modified = null)
         {
-            if (key.StartsWith("/")
-                || key.StartsWith("\\"))
+            if (key.Length > 0 && key[0] is '/' or '\\')
             {
                 key = key.Substring(1);
             }
@@ -103,7 +128,7 @@ namespace SharpCompress.Archives
             foreach (var path in Entries.Select(x => x.Key))
             {
                 var p = path.Replace('/', '\\');
-                if (p.StartsWith("\\"))
+                if (p.Length > 0 && p[0] == '\\')
                 {
                     p = p.Substring(1);
                 }

src/SharpCompress/Archives/ArchiveFactory.cs

@@ -1,5 +1,6 @@
 using System;
 using System.IO;
+using SharpCompress.Archives.Dmg;
 using SharpCompress.Archives.GZip;
 using SharpCompress.Archives.Rar;
 using SharpCompress.Archives.SevenZip;
@@ -10,7 +11,7 @@ using SharpCompress.Readers;
 
 namespace SharpCompress.Archives
 {
-    public class ArchiveFactory
+    public static class ArchiveFactory
     {
         /// <summary>
         /// Opens an Archive for random access
@@ -25,7 +26,7 @@ namespace SharpCompress.Archives
             {
                 throw new ArgumentException("Stream should be readable and seekable");
             }
-            readerOptions = readerOptions ?? new ReaderOptions();
+            readerOptions ??= new ReaderOptions();
             if (ZipArchive.IsZipFile(stream, null))
             {
                 stream.Seek(0, SeekOrigin.Begin);
@@ -44,6 +45,12 @@ namespace SharpCompress.Archives
                 return GZipArchive.Open(stream, readerOptions);
             }
             stream.Seek(0, SeekOrigin.Begin);
+            if (DmgArchive.IsDmgFile(stream))
+            {
+                stream.Seek(0, SeekOrigin.Begin);
+                return DmgArchive.Open(stream, readerOptions);
+            }
+            stream.Seek(0, SeekOrigin.Begin);
             if (RarArchive.IsRarFile(stream, readerOptions))
             {
                 stream.Seek(0, SeekOrigin.Begin);
@@ -55,30 +62,18 @@ namespace SharpCompress.Archives
                 stream.Seek(0, SeekOrigin.Begin);
                 return TarArchive.Open(stream, readerOptions);
             }
-            throw new InvalidOperationException("Cannot determine compressed stream type. Supported Archive Formats: Zip, GZip, Tar, Rar, 7Zip, LZip");
+            throw new InvalidOperationException("Cannot determine compressed stream type. Supported Archive Formats: Zip, GZip, Tar, Rar, 7Zip, LZip, Dmg");
         }
 
         public static IWritableArchive Create(ArchiveType type)
         {
-            switch (type)
+            return type switch
             {
-                case ArchiveType.Zip:
-                {
-                    return ZipArchive.Create();
-                }
-                case ArchiveType.Tar:
-                {
-                    return TarArchive.Create();
-                }
-                case ArchiveType.GZip:
-                {
-                    return GZipArchive.Create();
-                }
-                default:
-                {
-                    throw new NotSupportedException("Cannot create Archives of type: " + type);
-                }
-            }
+                ArchiveType.Zip => ZipArchive.Create(),
+                ArchiveType.Tar => TarArchive.Create(),
+                ArchiveType.GZip => GZipArchive.Create(),
+                _ => throw new NotSupportedException("Cannot create Archives of type: " + type)
+            };
         }
 
         /// <summary>
@@ -100,35 +95,40 @@ namespace SharpCompress.Archives
         public static IArchive Open(FileInfo fileInfo, ReaderOptions? options = null)
         {
             fileInfo.CheckNotNull(nameof(fileInfo));
-            options = options ?? new ReaderOptions { LeaveStreamOpen = false };
-            using (var stream = fileInfo.OpenRead())
+            options ??= new ReaderOptions { LeaveStreamOpen = false };
+
+            using var stream = fileInfo.OpenRead();
+            if (ZipArchive.IsZipFile(stream, null))
             {
-                if (ZipArchive.IsZipFile(stream, null))
-                {
-                    return ZipArchive.Open(fileInfo, options);
-                }
-                stream.Seek(0, SeekOrigin.Begin);
-                if (SevenZipArchive.IsSevenZipFile(stream))
-                {
-                    return SevenZipArchive.Open(fileInfo, options);
-                }
-                stream.Seek(0, SeekOrigin.Begin);
-                if (GZipArchive.IsGZipFile(stream))
-                {
-                    return GZipArchive.Open(fileInfo, options);
-                }
-                stream.Seek(0, SeekOrigin.Begin);
-                if (RarArchive.IsRarFile(stream, options))
-                {
-                   return RarArchive.Open(fileInfo, options);
-                }
-                stream.Seek(0, SeekOrigin.Begin);
-                if (TarArchive.IsTarFile(stream))
-                {
-                    return TarArchive.Open(fileInfo, options);
-                }
-                throw new InvalidOperationException("Cannot determine compressed stream type. Supported Archive Formats: Zip, GZip, Tar, Rar, 7Zip");
+                return ZipArchive.Open(fileInfo, options);
             }
+            stream.Seek(0, SeekOrigin.Begin);
+            if (SevenZipArchive.IsSevenZipFile(stream))
+            {
+                return SevenZipArchive.Open(fileInfo, options);
+            }
+            stream.Seek(0, SeekOrigin.Begin);
+            if (GZipArchive.IsGZipFile(stream))
+            {
+                return GZipArchive.Open(fileInfo, options);
+            }
+            stream.Seek(0, SeekOrigin.Begin);
+            if (DmgArchive.IsDmgFile(stream))
+            {
+                stream.Seek(0, SeekOrigin.Begin);
+                return DmgArchive.Open(fileInfo, options);
+            }
+            stream.Seek(0, SeekOrigin.Begin);
+            if (RarArchive.IsRarFile(stream, options))
+            {
+                return RarArchive.Open(fileInfo, options);
+            }
+            stream.Seek(0, SeekOrigin.Begin);
+            if (TarArchive.IsTarFile(stream))
+            {
+                return TarArchive.Open(fileInfo, options);
+            }
+            throw new InvalidOperationException("Cannot determine compressed stream type. Supported Archive Formats: Zip, GZip, Tar, Rar, 7Zip, Dmg");
         }
 
         /// <summary>
@@ -137,12 +137,10 @@ namespace SharpCompress.Archives
         public static void WriteToDirectory(string sourceArchive, string destinationDirectory,
                                             ExtractionOptions? options = null)
         {
-            using (IArchive archive = Open(sourceArchive))
+            using IArchive archive = Open(sourceArchive);
+            foreach (IArchiveEntry entry in archive.Entries)
             {
-                foreach (IArchiveEntry entry in archive.Entries)
-                {
-                    entry.WriteToDirectory(destinationDirectory, options);
-                }
+                entry.WriteToDirectory(destinationDirectory, options);
             }
         }
     }

src/SharpCompress/Archives/Dmg/DmgArchive.cs

@@ -0,0 +1,117 @@
+using SharpCompress.Common;
+using SharpCompress.Common.Dmg;
+using SharpCompress.Common.Dmg.Headers;
+using SharpCompress.Common.Dmg.HFS;
+using SharpCompress.Readers;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+
+namespace SharpCompress.Archives.Dmg
+{
+    public class DmgArchive : AbstractArchive<DmgArchiveEntry, DmgVolume>
+    {
+        private readonly string _fileName;
+
+        internal DmgArchive(FileInfo fileInfo, ReaderOptions readerOptions)
+            : base(ArchiveType.Dmg, fileInfo, readerOptions)
+        {
+            _fileName = fileInfo.FullName;
+        }
+
+        internal DmgArchive(Stream stream, ReaderOptions readerOptions)
+            : base(ArchiveType.Dmg, stream.AsEnumerable(), readerOptions)
+        {
+            _fileName = string.Empty;
+        }
+
+        protected override IReader CreateReaderForSolidExtraction()
+            => new DmgReader(ReaderOptions, this, _fileName);
+
+        protected override IEnumerable<DmgArchiveEntry> LoadEntries(IEnumerable<DmgVolume> volumes)
+            => volumes.Single().LoadEntries();
+
+        protected override IEnumerable<DmgVolume> LoadVolumes(FileInfo file)
+            => new DmgVolume(this, file.OpenRead(), file.FullName, ReaderOptions).AsEnumerable();
+
+        protected override IEnumerable<DmgVolume> LoadVolumes(IEnumerable<Stream> streams)
+            => new DmgVolume(this, streams.Single(), string.Empty, ReaderOptions).AsEnumerable();
+
+        public static bool IsDmgFile(FileInfo fileInfo)
+        {
+            if (!fileInfo.Exists) return false;
+
+            using var stream = fileInfo.OpenRead();
+            return IsDmgFile(stream);
+        }
+
+        public static bool IsDmgFile(Stream stream)
+        {
+            long headerPos = stream.Length - DmgHeader.HeaderSize;
+            if (headerPos < 0) return false;
+            stream.Position = headerPos;
+
+            return DmgHeader.TryRead(stream, out _);
+        }
+
+        /// <summary>
+        /// Constructor expects a filepath to an existing file.
+        /// </summary>
+        /// <param name="filePath"></param>
+        /// <param name="readerOptions"></param>
+        public static DmgArchive Open(string filePath, ReaderOptions? readerOptions = null)
+        {
+            filePath.CheckNotNullOrEmpty(nameof(filePath));
+            return Open(new FileInfo(filePath), readerOptions ?? new ReaderOptions());
+        }
+
+        /// <summary>
+        /// Constructor with a FileInfo object to an existing file.
+        /// </summary>
+        /// <param name="fileInfo"></param>
+        /// <param name="readerOptions"></param>
+        public static DmgArchive Open(FileInfo fileInfo, ReaderOptions? readerOptions = null)
+        {
+            fileInfo.CheckNotNull(nameof(fileInfo));
+            return new DmgArchive(fileInfo, readerOptions ?? new ReaderOptions());
+        }
+
+        /// <summary>
+        /// Takes a seekable Stream as a source
+        /// </summary>
+        /// <param name="stream"></param>
+        /// <param name="readerOptions"></param>
+        public static DmgArchive Open(Stream stream, ReaderOptions? readerOptions = null)
+        {
+            stream.CheckNotNull(nameof(stream));
+            return new DmgArchive(stream, readerOptions ?? new ReaderOptions());
+        }
+
+        private sealed class DmgReader : AbstractReader<DmgEntry, DmgVolume>
+        {
+            private readonly DmgArchive _archive;
+            private readonly string _fileName;
+            private readonly Stream? _partitionStream;
+
+            public override DmgVolume Volume { get; }
+
+            internal DmgReader(ReaderOptions readerOptions, DmgArchive archive, string fileName)
+                : base(readerOptions, ArchiveType.Dmg)
+            {
+                _archive = archive;
+                _fileName = fileName;
+                Volume = archive.Volumes.Single();
+
+                using var compressedStream = DmgUtil.LoadHFSPartitionStream(Volume.Stream, Volume.Header);
+                _partitionStream = compressedStream?.Decompress();
+            }
+
+            protected override IEnumerable<DmgEntry> GetEntries(Stream stream)
+            {
+                if (_partitionStream is null) return Array.Empty<DmgArchiveEntry>();
+                else return HFSUtil.LoadEntriesFromPartition(_partitionStream, _fileName, _archive);
+            }
+        }
+    }
+}

src/SharpCompress/Archives/Dmg/DmgArchiveEntry.cs

@@ -0,0 +1,32 @@
+using SharpCompress.Common.Dmg;
+using SharpCompress.Common.Dmg.HFS;
+using System;
+using System.IO;
+
+namespace SharpCompress.Archives.Dmg
+{
+    public sealed class DmgArchiveEntry : DmgEntry, IArchiveEntry
+    {
+        private readonly Stream? _stream;
+
+        public bool IsComplete { get; } = true;
+
+        public IArchive Archive { get; }
+
+        internal DmgArchiveEntry(Stream? stream, DmgArchive archive, HFSCatalogRecord record, string path, DmgFilePart part)
+            : base(record, path, stream?.Length ?? 0, part)
+        {
+            _stream = stream;
+            Archive = archive;
+        }
+
+        public Stream OpenEntryStream()
+        {
+            if (IsDirectory)
+                throw new NotSupportedException("Directories cannot be opened as stream");
+
+            _stream!.Position = 0;
+            return _stream;
+        }
+    }
+}

src/SharpCompress/Archives/GZip/GZipArchive.cs

@@ -77,10 +77,9 @@ namespace SharpCompress.Archives.GZip
             {
                 return false;
             }
-            using (Stream stream = fileInfo.OpenRead())
-            {
-                return IsGZipFile(stream);
-            }
+
+            using Stream stream = fileInfo.OpenRead();
+            return IsGZipFile(stream);
         }
 
         public void SaveTo(string filePath)
@@ -99,7 +98,7 @@ namespace SharpCompress.Archives.GZip
         public static bool IsGZipFile(Stream stream)
         {
             // read the header on the first read
-            byte[] header = new byte[10];
+            Span<byte> header = stackalloc byte[10];
 
             // workitem 8501: handle edge case (decompress empty stream)
             if (!stream.ReadFully(header))

src/SharpCompress/Archives/IArchiveEntryExtensions.cs

@@ -31,7 +31,7 @@ namespace SharpCompress.Archives
             }
             streamListener.FireEntryExtractionEnd(archiveEntry);
         }
-        
+
         /// <summary>
         /// Extract to specific directory, retaining filename
         /// </summary>
@@ -45,11 +45,11 @@ namespace SharpCompress.Archives
         /// <summary>
         /// Extract to specific file
         /// </summary>
-        public static void WriteToFile(this IArchiveEntry entry, 
+        public static void WriteToFile(this IArchiveEntry entry,
                                        string destinationFileName,
                                        ExtractionOptions? options = null)
         {
-            
+
             ExtractionMethods.WriteEntryToFile(entry, destinationFileName, options,
                                                (x, fm) =>
                                                {

src/SharpCompress/Archives/IWritableArchive.cs

@@ -11,5 +11,11 @@ namespace SharpCompress.Archives
         IArchiveEntry AddEntry(string key, Stream source, bool closeStream, long size = 0, DateTime? modified = null);
 
         void SaveTo(Stream stream, WriterOptions options);
+
+        /// <summary>
+        /// Use this to pause entry rebuilding when adding large collections of entries.  Dispose when complete.  A  using statement is recommended.
+        /// </summary>
+        /// <returns>IDisposeable to resume entry rebuilding</returns>
+        IDisposable PauseEntryRebuilding();
     }
 }

src/SharpCompress/Archives/IWritableArchiveExtensions.cs

@@ -35,11 +35,14 @@ namespace SharpCompress.Archives
             this IWritableArchive writableArchive,
             string filePath, string searchPattern = "*.*", SearchOption searchOption = SearchOption.AllDirectories)
         {
-            foreach (var path in Directory.EnumerateFiles(filePath, searchPattern, searchOption))
+            using (writableArchive.PauseEntryRebuilding())
             {
-                var fileInfo = new FileInfo(path);
-                writableArchive.AddEntry(path.Substring(filePath.Length), fileInfo.OpenRead(), true, fileInfo.Length,
-                                         fileInfo.LastWriteTime);
+                foreach (var path in Directory.EnumerateFiles(filePath, searchPattern, searchOption))
+                {
+                    var fileInfo = new FileInfo(path);
+                    writableArchive.AddEntry(path.Substring(filePath.Length), fileInfo.OpenRead(), true, fileInfo.Length,
+                                            fileInfo.LastWriteTime);
+                }
             }
         }
         public static IArchiveEntry AddEntry(this IWritableArchive writableArchive, string key, FileInfo fileInfo)

src/SharpCompress/Archives/Rar/RarArchive.cs

@@ -10,7 +10,8 @@ using SharpCompress.Readers.Rar;
 
 namespace SharpCompress.Archives.Rar
 {
-    public class RarArchive : AbstractArchive<RarArchiveEntry, RarVolume>
+    public class 
+        RarArchive : AbstractArchive<RarArchiveEntry, RarVolume>
     {
         internal Lazy<IRarUnpack> UnpackV2017 { get; } = new Lazy<IRarUnpack>(() => new SharpCompress.Compressors.Rar.UnpackV2017.Unpack());
         internal Lazy<IRarUnpack> UnpackV1 { get; } = new Lazy<IRarUnpack>(() => new SharpCompress.Compressors.Rar.UnpackV1.Unpack());
@@ -42,7 +43,7 @@ namespace SharpCompress.Archives.Rar
 
         protected override IEnumerable<RarArchiveEntry> LoadEntries(IEnumerable<RarVolume> volumes)
         {
-            return RarArchiveEntryFactory.GetEntries(this, volumes);
+            return RarArchiveEntryFactory.GetEntries(this, volumes, ReaderOptions);
         }
 
         protected override IEnumerable<RarVolume> LoadVolumes(IEnumerable<Stream> streams)
@@ -120,7 +121,7 @@ namespace SharpCompress.Archives.Rar
                 return IsRarFile(stream);
             }
         }
-        
+
         public static bool IsRarFile(Stream stream, ReaderOptions? options = null)
         {
             try

src/SharpCompress/Archives/Rar/RarArchiveEntry.cs

@@ -6,6 +6,7 @@ using SharpCompress.Common;
 using SharpCompress.Common.Rar;
 using SharpCompress.Common.Rar.Headers;
 using SharpCompress.Compressors.Rar;
+using SharpCompress.Readers;
 
 namespace SharpCompress.Archives.Rar
 {
@@ -13,11 +14,13 @@ namespace SharpCompress.Archives.Rar
     {
         private readonly ICollection<RarFilePart> parts;
         private readonly RarArchive archive;
+        private readonly ReaderOptions readerOptions;
 
-        internal RarArchiveEntry(RarArchive archive, IEnumerable<RarFilePart> parts)
+        internal RarArchiveEntry(RarArchive archive, IEnumerable<RarFilePart> parts, ReaderOptions readerOptions)
         {
             this.parts = parts.ToList();
             this.archive = archive;
+            this.readerOptions = readerOptions;
         }
 
         public override CompressionType CompressionType => CompressionType.Rar;
@@ -61,21 +64,22 @@ namespace SharpCompress.Archives.Rar
             {
                 return new RarStream(archive.UnpackV1.Value, FileHeader, new MultiVolumeReadOnlyStream(Parts.Cast<RarFilePart>(), archive));
             }
-            
+
             return new RarStream(archive.UnpackV2017.Value, FileHeader, new MultiVolumeReadOnlyStream(Parts.Cast<RarFilePart>(), archive));
         }
 
-        public bool IsComplete 
-        { 
-            get 
-            { 
-                return parts.Select(fp => fp.FileHeader).Any(fh => !fh.IsSplitAfter); 
-            } 
+        public bool IsComplete
+        {
+            get
+            {
+                var headers = parts.Select(x => x.FileHeader);
+                return !headers.First().IsSplitBefore && !headers.Last().IsSplitAfter;
+            }
         }
 
         private void CheckIncomplete()
         {
-            if (!IsComplete)
+            if (!readerOptions.DisableCheckIncomplete && !IsComplete)
             {
                 throw new IncompleteArchiveException("ArchiveEntry is incomplete and cannot perform this operation.");
             }

src/SharpCompress/Archives/Rar/RarArchiveEntryFactory.cs

@@ -1,5 +1,6 @@
 using System.Collections.Generic;
 using SharpCompress.Common.Rar;
+using SharpCompress.Readers;
 
 namespace SharpCompress.Archives.Rar
 {
@@ -36,11 +37,12 @@ namespace SharpCompress.Archives.Rar
         }
 
         internal static IEnumerable<RarArchiveEntry> GetEntries(RarArchive archive,
-                                                                IEnumerable<RarVolume> rarParts)
+                                                                IEnumerable<RarVolume> rarParts,
+                                                                ReaderOptions readerOptions)
         {
             foreach (var groupedParts in GetMatchedFileParts(rarParts))
             {
-                yield return new RarArchiveEntry(archive, groupedParts);
+                yield return new RarArchiveEntry(archive, groupedParts, readerOptions);
             }
         }
     }

src/SharpCompress/Archives/Rar/RarArchiveVolumeFactory.cs

@@ -23,7 +23,7 @@ namespace SharpCompress.Archives.Rar
                 yield return part;
             }
         }
-        
+
         internal static IEnumerable<RarVolume> GetParts(FileInfo fileInfo, ReaderOptions options)
         {
             FileInfoRarArchiveVolume part = new FileInfoRarArchiveVolume(fileInfo, options);
@@ -68,7 +68,7 @@ namespace SharpCompress.Archives.Rar
             // .rar, .r00, .r01, ...
             string extension = currentFileInfo.Extension;
 
-            StringBuilder buffer = new StringBuilder(currentFileInfo.FullName.Length);
+            var buffer = new StringBuilder(currentFileInfo.FullName.Length);
             buffer.Append(currentFileInfo.FullName.Substring(0,
                                                              currentFileInfo.FullName.Length - extension.Length));
             if (string.Compare(extension, ".rar", StringComparison.OrdinalIgnoreCase) == 0)
@@ -77,8 +77,7 @@ namespace SharpCompress.Archives.Rar
             }
             else
             {
-                int num = 0;
-                if (int.TryParse(extension.Substring(2, 2), out num))
+                if (int.TryParse(extension.Substring(2, 2), out int num))
                 {
                     num++;
                     buffer.Append(".r");
@@ -111,12 +110,11 @@ namespace SharpCompress.Archives.Rar
             }
             StringBuilder buffer = new StringBuilder(currentFileInfo.FullName.Length);
             buffer.Append(currentFileInfo.FullName, 0, startIndex);
-            int num = 0;
             string numString = currentFileInfo.FullName.Substring(startIndex + 5,
                                                                   currentFileInfo.FullName.IndexOf('.', startIndex + 5) -
                                                                   startIndex - 5);
             buffer.Append(".part");
-            if (int.TryParse(numString, out num))
+            if (int.TryParse(numString, out int num))
             {
                 num++;
                 for (int i = 0; i < numString.Length - num.ToString().Length; i++)

src/SharpCompress/Archives/SevenZip/SevenZipArchive.cs

@@ -131,7 +131,7 @@ namespace SharpCompress.Archives.SevenZip
             }
         }
 
-        private static ReadOnlySpan<byte> SIGNATURE => new byte[] {(byte)'7', (byte)'z', 0xBC, 0xAF, 0x27, 0x1C};
+        private static ReadOnlySpan<byte> SIGNATURE => new byte[] { (byte)'7', (byte)'z', 0xBC, 0xAF, 0x27, 0x1C };
 
         private static bool SignatureMatch(Stream stream)
         {

src/SharpCompress/Archives/Tar/TarArchive.cs

@@ -79,7 +79,7 @@ namespace SharpCompress.Archives.Tar
             }
             return false;
         }
-        
+
         /// <summary>
         /// Constructor with a FileInfo object to an existing file.
         /// </summary>

src/SharpCompress/Archives/Zip/ZipArchive.cs

@@ -24,7 +24,7 @@ namespace SharpCompress.Archives.Zip
         /// if the compression method is set to deflate
         /// </summary>
         public CompressionLevel DeflateCompressionLevel { get; set; }
-        
+
         /// <summary>
         /// Constructor expects a filepath to an existing file.
         /// </summary>
@@ -57,7 +57,7 @@ namespace SharpCompress.Archives.Zip
             stream.CheckNotNull(nameof(stream));
             return new ZipArchive(stream, readerOptions ?? new ReaderOptions());
         }
-        
+
         public static bool IsZipFile(string filePath, string? password = null)
         {
             return IsZipFile(new FileInfo(filePath), password);
@@ -80,8 +80,7 @@ namespace SharpCompress.Archives.Zip
             StreamingZipHeaderFactory headerFactory = new StreamingZipHeaderFactory(password, new ArchiveEncoding());
             try
             {
-                ZipHeader header =
-                    headerFactory.ReadStreamHeader(stream).FirstOrDefault(x => x.ZipHeaderType != ZipHeaderType.Split);
+                ZipHeader? header = headerFactory.ReadStreamHeader(stream).FirstOrDefault(x => x.ZipHeaderType != ZipHeaderType.Split);
                 if (header is null)
                 {
                     return false;
@@ -97,7 +96,7 @@ namespace SharpCompress.Archives.Zip
                 return false;
             }
         }
-        
+
         /// <summary>
         /// Constructor with a FileInfo object to an existing file.
         /// </summary>

src/SharpCompress/Common/ArchiveEncoding.cs

@@ -36,7 +36,7 @@ namespace SharpCompress.Common
             Password = password;
         }
 
-#if NETSTANDARD1_3 || NETSTANDARD2_0 || NETSTANDARD2_1
+#if !NET461
         static ArchiveEncoding()
         {
             Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);

src/SharpCompress/Common/ArchiveException.cs

@@ -8,5 +8,10 @@ namespace SharpCompress.Common
             : base(message)
         {
         }
+
+        public ArchiveException(string message, Exception inner)
+            : base(message, inner)
+        {
+        }
     }
 }

src/SharpCompress/Common/ArchiveType.cs

@@ -6,6 +6,7 @@
         Zip,
         Tar,
         SevenZip,
-        GZip
+        GZip,
+        Dmg
     }
 }

src/SharpCompress/Common/Dmg/DmgBlockDataStream.cs

@@ -0,0 +1,323 @@
+using SharpCompress.Common.Dmg.Headers;
+using SharpCompress.Compressors;
+using SharpCompress.Compressors.ADC;
+using SharpCompress.Compressors.BZip2;
+using SharpCompress.Compressors.Deflate;
+using SharpCompress.IO;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace SharpCompress.Common.Dmg
+{
+    internal sealed class DmgBlockDataStream : Stream
+    {
+        private readonly Stream _baseStream;
+        private readonly DmgHeader _header;
+        private readonly BlkxTable _table;
+        private long _position;
+        private bool _isEnded;
+        private int _chunkIndex;
+        private Stream? _chunkStream;
+        private long _chunkPos;
+        
+        public override bool CanRead => true;
+        public override bool CanWrite => false;
+        public override bool CanSeek => true;
+        public override long Length { get; }
+
+        public override long Position
+        {
+            get => _position;
+            set
+            {
+                if ((value < 0) || (value > Length)) throw new ArgumentOutOfRangeException(nameof(value));
+
+                if (value == Length)
+                {
+                    // End of the stream
+
+                    _position = Length;
+                    _isEnded = true;
+                    _chunkIndex = -1;
+                    _chunkStream = null;
+                }
+                else if (value != _position)
+                {
+                    _position = value;
+
+                    // We can only seek over entire chunks at a time because some chunks may be compressed.
+                    // So we first find the chunk that we are now in, then we read to the exact position inside that chunk.
+
+                    for (int i = 0; i < _table.Chunks.Count; i++)
+                    {
+                        var chunk = _table.Chunks[i];
+                        if (IsChunkValid(chunk) && (chunk.UncompressedOffset <= (ulong)_position)
+                            && ((chunk.UncompressedOffset + chunk.UncompressedLength) > (ulong)_position))
+                        {
+                            if (i == _chunkIndex)
+                            {
+                                // We are still in the same chunk, so if the new position is
+                                // behind the previous one we can just read to the new position.
+
+                                long offset = (long)chunk.UncompressedOffset + _chunkPos;
+                                if (offset <= _position)
+                                {
+                                    long skip = _position - offset;
+                                    _chunkStream!.Skip(skip);
+                                    _chunkPos += skip;
+                                    break;
+                                }
+                            }
+
+                            _chunkIndex = i;
+                            _chunkStream = GetChunkStream();
+                            _chunkPos = 0;
+
+                            // If the chunk happens to not be compressed this read will still result in a fast seek
+                            if ((ulong)_position != chunk.UncompressedOffset)
+                            {
+                                long skip = _position - (long)chunk.UncompressedOffset;
+                                _chunkStream.Skip(skip);
+                                _chunkPos = skip;
+                            }
+
+                            break;
+                        }
+                    }
+                }
+            }
+        }
+
+        public DmgBlockDataStream(Stream baseStream, DmgHeader header, BlkxTable table)
+        {
+            if (!baseStream.CanRead) throw new ArgumentException("Requires a readable stream", nameof(baseStream));
+            if (!baseStream.CanSeek) throw new ArgumentException("Requires a seekable stream", nameof(baseStream));
+
+            _baseStream = baseStream;
+            _header = header;
+            _table = table;
+
+            Length = 0;
+            foreach (var chunk in table.Chunks)
+            {
+                if (IsChunkValid(chunk))
+                    Length += (long)chunk.UncompressedLength;
+            }
+
+            _position = 0;
+            _chunkIndex = -1;
+            _chunkIndex = GetNextChunk();
+            _isEnded = _chunkIndex < 0;
+            if (!_isEnded) _chunkStream = GetChunkStream();
+            _chunkPos = 0;
+        }
+
+        private static bool IsChunkValid(BlkxChunk chunk)
+        {
+            return chunk.Type switch
+            {
+                BlkxChunkType.Zero => true,
+                BlkxChunkType.Uncompressed => true,
+                BlkxChunkType.Ignore => true,
+                BlkxChunkType.AdcCompressed => true,
+                BlkxChunkType.ZlibCompressed => true,
+                BlkxChunkType.Bz2Compressed => true,
+                _ => false
+            };
+        }
+
+        private int GetNextChunk()
+        {
+            int index = _chunkIndex;
+            bool isValid = false;
+            while (!isValid)
+            {
+                index++;
+                if (index >= _table.Chunks.Count) return -1;
+
+                var chunk = _table.Chunks[index];
+                if (chunk.Type == BlkxChunkType.Last) return -1;
+
+                isValid = IsChunkValid(chunk);
+            }
+            return index;
+        }
+
+        private Stream GetChunkStream()
+        {
+            if (_chunkIndex < 0)
+                throw new InvalidOperationException("Invalid chunk index");
+
+            var chunk = _table.Chunks[_chunkIndex];
+
+            // For our purposes, ignore behaves the same as zero
+            if ((chunk.Type == BlkxChunkType.Zero) || (chunk.Type == BlkxChunkType.Ignore))
+                return new ConstantStream(0, (long)chunk.UncompressedLength);
+
+            // We first create a sub-stream on the region of the base stream where the
+            // (possibly compressed) data is physically located at.
+            var subStream = new SeekableSubStream(_baseStream,
+                (long)(_header.DataForkOffset + _table.DataOffset + chunk.CompressedOffset),
+                (long)chunk.CompressedLength);
+
+            // Then we nest that sub-stream into the apropriate compressed stream.
+            return chunk.Type switch
+            {
+                BlkxChunkType.Uncompressed => subStream,
+                BlkxChunkType.AdcCompressed => new ADCStream(subStream, CompressionMode.Decompress),
+                BlkxChunkType.ZlibCompressed => new ZlibStream(subStream, CompressionMode.Decompress),
+                BlkxChunkType.Bz2Compressed => new BZip2Stream(subStream, CompressionMode.Decompress, false),
+                _ => throw new InvalidOperationException("Invalid chunk type")
+            };
+        }
+
+        // Decompresses the entire stream in memory for faster extraction.
+        // This is about two orders of magnitude faster than decompressing
+        // on-the-fly while extracting, but also eats RAM for breakfest.
+        public Stream Decompress()
+        {
+            // We have to load all the chunks into separate memory streams first
+            // because otherwise the decompression threads would block each other
+            // and actually be slower than just a single decompression thread.
+
+            var rawStreams = new Stream?[_table.Chunks.Count];
+            for (int i = 0; i < rawStreams.Length; i++)
+            {
+                var chunk = _table.Chunks[i];
+                if (IsChunkValid(chunk))
+                {
+                    if ((chunk.Type == BlkxChunkType.Zero) || (chunk.Type == BlkxChunkType.Ignore))
+                    {
+                        rawStreams[i] = new ConstantStream(0, (long)chunk.UncompressedLength);
+                    }
+                    else
+                    {
+                        var subStream = new SeekableSubStream(_baseStream,
+                        (long)(_header.DataForkOffset + _table.DataOffset + chunk.CompressedOffset),
+                        (long)chunk.CompressedLength);
+
+                        var memStream = new MemoryStream();
+                        subStream.CopyTo(memStream);
+                        memStream.Position = 0;
+                        rawStreams[i] = memStream;
+                    }
+                }
+                else
+                {
+                    rawStreams[i] = null;
+                }
+            }
+
+            // Now we can decompress the chunks multithreaded
+
+            var streams = new Stream?[_table.Chunks.Count];
+            Parallel.For(0, streams.Length, i =>
+            {
+                var rawStream = rawStreams[i];
+                if (rawStream is not null)
+                {
+                    var chunk = _table.Chunks[i];
+                    if ((chunk.Type == BlkxChunkType.Zero)
+                     || (chunk.Type == BlkxChunkType.Ignore)
+                     || (chunk.Type == BlkxChunkType.Uncompressed))
+                    {
+                        streams[i] = rawStream;
+                    }
+                    else
+                    {
+                        Stream compStream = chunk.Type switch
+                        {
+                            BlkxChunkType.AdcCompressed => new ADCStream(rawStream, CompressionMode.Decompress),
+                            BlkxChunkType.ZlibCompressed => new ZlibStream(rawStream, CompressionMode.Decompress),
+                            BlkxChunkType.Bz2Compressed => new BZip2Stream(rawStream, CompressionMode.Decompress, false),
+                            _ => throw new InvalidOperationException("Invalid chunk type")
+                        };
+
+                        var memStream = new MemoryStream();
+                        compStream.CopyTo(memStream);
+                        compStream.Dispose();
+
+                        memStream.Position = 0;
+                        streams[i] = memStream;
+                    }
+
+                    rawStream.Dispose();
+                    rawStreams[i] = null;
+                }
+                else
+                {
+                    streams[i] = null;
+                }
+            });
+
+            return new CompositeStream((IEnumerable<Stream>)streams.Where(s => s is not null));
+        }
+
+        public override int Read(byte[] buffer, int offset, int count)
+        {
+            if (_isEnded) return 0;
+
+            int readCount = _chunkStream!.Read(buffer, offset, count);
+            _chunkPos += readCount;
+
+            while (readCount < count)
+            {
+                // Current chunk has ended, so we have to continue reading from the next chunk.
+
+                _chunkIndex = GetNextChunk();
+                if (_chunkIndex < 0)
+                {
+                    // We have reached the last chunk
+
+                    _isEnded = true;
+                    _chunkPos = 0;
+                    _position += readCount;
+                    return readCount;
+                }
+
+                _chunkStream = GetChunkStream();
+                int rc = _chunkStream.Read(buffer, offset + readCount, count - readCount);
+                _chunkPos = rc;
+                readCount += rc;
+            }
+
+            _position += readCount;
+            return readCount;
+        }
+
+        public override void Flush()
+        { }
+
+        public override long Seek(long offset, SeekOrigin origin)
+        {
+            switch (origin)
+            {
+                case SeekOrigin.Begin:
+                    Position = offset;
+                    break;
+
+                case SeekOrigin.Current:
+                    Position += offset;
+                    break;
+
+                case SeekOrigin.End:
+                    Position = Length - offset;
+                    break;
+            }
+
+            return Position;
+        }
+
+        public override void SetLength(long value)
+            => throw new NotSupportedException();
+
+        public override void Write(byte[] buffer, int offset, int count)
+            => throw new NotSupportedException();
+
+        protected override void Dispose(bool disposing)
+        { }
+    }
+}

src/SharpCompress/Common/Dmg/DmgEntry.cs

@@ -0,0 +1,52 @@
+using SharpCompress.Common.Dmg.HFS;
+using System;
+using System.Collections.Generic;
+
+namespace SharpCompress.Common.Dmg
+{
+    public abstract class DmgEntry : Entry
+    {
+        public override string Key { get; }
+        public override bool IsDirectory { get; }
+        public override long Size { get; }
+        public override long CompressedSize { get; }
+        public override CompressionType CompressionType { get; }
+        public override DateTime? LastModifiedTime { get; }
+        public override DateTime? CreatedTime { get; }
+        public override DateTime? LastAccessedTime { get; }
+        public override DateTime? ArchivedTime { get; }
+        
+        public override long Crc { get; } = 0; // Not stored
+        public override string? LinkTarget { get; } = null;
+        public override bool IsEncrypted { get; } = false;
+        public override bool IsSplitAfter { get; } = false;
+
+        internal override IEnumerable<FilePart> Parts { get; }
+
+        internal DmgEntry(HFSCatalogRecord record, string path, long size, DmgFilePart part)
+        {
+            Key = path;
+            IsDirectory = record.Type == HFSCatalogRecordType.Folder;
+            Size = CompressedSize = size;              // There is no way to get the actual compressed size or the compression type of
+            CompressionType = CompressionType.Unknown; // a file in a DMG archive since the files are nested inside the HFS partition.
+            Parts = part.AsEnumerable();
+
+            if (IsDirectory)
+            {
+                var folder = (HFSCatalogFolder)record;
+                LastModifiedTime = (folder.AttributeModDate > folder.ContentModDate) ? folder.AttributeModDate : folder.ContentModDate;
+                CreatedTime = folder.CreateDate;
+                LastAccessedTime = folder.AccessDate;
+                ArchivedTime = folder.BackupDate;
+            }
+            else
+            {
+                var file = (HFSCatalogFile)record;
+                LastModifiedTime = (file.AttributeModDate > file.ContentModDate) ? file.AttributeModDate : file.ContentModDate;
+                CreatedTime = file.CreateDate;
+                LastAccessedTime = file.AccessDate;
+                ArchivedTime = file.BackupDate;
+            }
+        }
+    }
+}

src/SharpCompress/Common/Dmg/DmgFilePart.cs

@@ -0,0 +1,21 @@
+using System.IO;
+
+namespace SharpCompress.Common.Dmg
+{
+    internal sealed class DmgFilePart : FilePart
+    {
+        private readonly Stream _stream;
+
+        internal override string FilePartName { get; }
+
+        public DmgFilePart(Stream stream, string fileName)
+            : base(new ArchiveEncoding())
+        {
+            _stream = stream;
+            FilePartName = fileName;
+        }
+
+        internal override Stream GetCompressedStream() => _stream;
+        internal override Stream? GetRawStream() => null;
+    }
+}

src/SharpCompress/Common/Dmg/DmgUtil.cs

@@ -0,0 +1,183 @@
+using SharpCompress.Common.Dmg.Headers;
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.IO;
+using System.Text;
+using System.Xml.Linq;
+
+namespace SharpCompress.Common.Dmg
+{
+    internal static class DmgUtil
+    {
+        private const string MalformedXmlMessage = "Malformed XML block";
+
+        private static T[] ParseArray<T>(in XElement parent, in Func<XElement, T> parseElement)
+        {
+            var list = new List<T>();
+
+            foreach (var node in parent.Elements())
+                list.Add(parseElement(node));
+
+            return list.ToArray();
+        }
+
+        private static Dictionary<string, T> ParseDict<T>(in XElement parent, in Func<XElement, T> parseValue)
+        {
+            var dict = new Dictionary<string, T>();
+
+            string? key = null;
+            foreach (var node in parent.Elements())
+            {
+                if (string.Equals(node.Name.LocalName, "key", StringComparison.Ordinal))
+                {
+                    key = node.Value;
+                }
+                else if (key is not null)
+                {
+                    var value = parseValue(node);
+                    dict.Add(key, value);
+                    key = null;
+                }
+            }
+
+            return dict;
+        }
+
+        private static Dictionary<string, Dictionary<string, Dictionary<string, string>[]>> ParsePList(in XDocument doc)
+        {
+            var dictNode = doc.Root?.Element("dict");
+            if (dictNode is null) throw new InvalidFormatException(MalformedXmlMessage);
+
+            static Dictionary<string, string> ParseObject(XElement parent)
+                => ParseDict(parent, node => node.Value);
+
+            static Dictionary<string, string>[] ParseObjectArray(XElement parent)
+                => ParseArray(parent, ParseObject);
+
+            static Dictionary<string, Dictionary<string, string>[]> ParseSubDict(XElement parent)
+                => ParseDict(parent, ParseObjectArray);
+
+            return ParseDict(dictNode, ParseSubDict);
+        }
+
+        private static BlkxData CreateDataFromDict(in Dictionary<string, string> dict)
+        {
+            static bool TryParseHex(string? s, out uint value)
+            {
+                value = 0;
+                if (string.IsNullOrEmpty(s)) return false;
+
+                if (s!.StartsWith("0x", StringComparison.OrdinalIgnoreCase))
+                    s = s.Substring(2);
+
+                return uint.TryParse(s, NumberStyles.HexNumber, CultureInfo.InvariantCulture, out value);
+            }
+
+            if (!dict.TryGetValue("ID", out string? idStr) || !int.TryParse(idStr, out int id))
+                throw new InvalidFormatException(MalformedXmlMessage);
+            if (!dict.TryGetValue("Name", out string? name))
+                throw new InvalidFormatException(MalformedXmlMessage);
+            if (!dict.TryGetValue("Attributes", out string? attribStr) || !TryParseHex(attribStr, out uint attribs))
+                throw new InvalidFormatException(MalformedXmlMessage);
+            if (!dict.TryGetValue("Data", out string? base64Data) || string.IsNullOrEmpty(base64Data))
+                throw new InvalidFormatException(MalformedXmlMessage);
+
+            try
+            {
+                var data = Convert.FromBase64String(base64Data);
+                if (!BlkxTable.TryRead(data, out var table))
+                    throw new InvalidFormatException("Invalid BLKX table");
+
+                return new BlkxData(id, name, attribs, table!);
+            }
+            catch (FormatException ex)
+            {
+                throw new InvalidFormatException(MalformedXmlMessage, ex);
+            }
+        }
+
+        public static DmgBlockDataStream? LoadHFSPartitionStream(Stream baseStream, DmgHeader header)
+        {
+            if ((header.XMLOffset + header.XMLLength) >= (ulong)baseStream.Length)
+                throw new IncompleteArchiveException("XML block incomplete");
+            if ((header.DataForkOffset + header.DataForkLength) >= (ulong)baseStream.Length)
+                throw new IncompleteArchiveException("Data block incomplete");
+
+            baseStream.Position = (long)header.XMLOffset;
+            var xmlBuffer = new byte[header.XMLLength];
+            baseStream.Read(xmlBuffer, 0, (int)header.XMLLength);
+            var xml = Encoding.ASCII.GetString(xmlBuffer);
+
+            var doc = XDocument.Parse(xml);
+            var pList = ParsePList(doc);
+            if (!pList.TryGetValue("resource-fork", out var resDict) || !resDict.TryGetValue("blkx", out var blkxDicts))
+                throw new InvalidFormatException(MalformedXmlMessage);
+
+            var objs = new BlkxData[blkxDicts.Length];
+            for (int i = 0; i < objs.Length; i++)
+                objs[i] = CreateDataFromDict(blkxDicts[i]);
+
+            // Index 0 is the protective MBR partition
+            // Index 1 is the GPT header
+            // Index 2 is the GPT partition table
+
+            try
+            {
+                var headerData = objs[1];
+                using var headerStream = new DmgBlockDataStream(baseStream, header, headerData.Table);
+                if (!GptHeader.TryRead(headerStream, out var gptHeader))
+                    throw new InvalidFormatException("Invalid GPT header");
+
+                var tableData = objs[2];
+                using var tableStream = new DmgBlockDataStream(baseStream, header, tableData.Table);
+                var gptTable = new GptPartitionEntry[gptHeader!.EntriesCount];
+                for (int i = 0; i < gptHeader.EntriesCount; i++)
+                    gptTable[i] = GptPartitionEntry.Read(tableStream);
+
+                foreach (var entry in gptTable)
+                {
+                    if (entry.TypeGuid == PartitionFormat.AppleHFS)
+                    {
+                        BlkxData? partitionData = null;
+                        for (int i = 3; i < objs.Length; i++)
+                        {
+                            if (objs[i].Name.StartsWith(entry.Name, StringComparison.Ordinal))
+                            {
+                                partitionData = objs[i];
+                                break;
+                            }
+                        }
+
+                        if (partitionData is null)
+                            throw new InvalidFormatException($"Missing partition {entry.Name}");
+
+                        return new DmgBlockDataStream(baseStream, header, partitionData.Table);
+                    }
+                }
+
+                return null;
+            }
+            catch (EndOfStreamException ex)
+            {
+                throw new IncompleteArchiveException("Partition incomplete", ex);
+            }
+        }
+
+        private sealed class BlkxData
+        {
+            public int Id { get; }
+            public string Name { get; }
+            public uint Attributes { get; }
+            public BlkxTable Table { get; }
+
+            public BlkxData(int id, string name, uint attributes, BlkxTable table)
+            {
+                Id = id;
+                Name = name;
+                Attributes = attributes;
+                Table = table;
+            }
+        }
+    }
+}

src/SharpCompress/Common/Dmg/DmgVolume.cs

@@ -0,0 +1,38 @@
+using SharpCompress.Archives.Dmg;
+using SharpCompress.Common.Dmg.Headers;
+using SharpCompress.Common.Dmg.HFS;
+using System;
+using System.Collections.Generic;
+using System.IO;
+
+namespace SharpCompress.Common.Dmg
+{
+    public class DmgVolume : Volume
+    {
+        private readonly DmgArchive _archive;
+        private readonly string _fileName;
+
+        internal DmgHeader Header { get; }
+
+        public DmgVolume(DmgArchive archive, Stream stream, string fileName, Readers.ReaderOptions readerOptions)
+            : base(stream, readerOptions)
+        {
+            _archive = archive;
+            _fileName = fileName;
+
+            long pos = stream.Length - DmgHeader.HeaderSize;
+            if (pos < 0) throw new InvalidFormatException("Invalid DMG volume");
+            stream.Position = pos;
+
+            if (DmgHeader.TryRead(stream, out var header)) Header = header!;
+            else throw new InvalidFormatException("Invalid DMG volume");
+        }
+
+        internal IEnumerable<DmgArchiveEntry> LoadEntries()
+        {
+            var partitionStream = DmgUtil.LoadHFSPartitionStream(Stream, Header);
+            if (partitionStream is null) return Array.Empty<DmgArchiveEntry>();
+            else return HFSUtil.LoadEntriesFromPartition(partitionStream, _fileName, _archive);
+        }
+    }
+}

src/SharpCompress/Common/Dmg/HFS/HFSCatalogRecord.cs

@@ -0,0 +1,336 @@
+using System;
+
+namespace SharpCompress.Common.Dmg.HFS
+{
+    internal sealed class HFSCatalogKey : HFSStructBase, IEquatable<HFSCatalogKey>, IComparable<HFSCatalogKey>, IComparable
+    {
+        private readonly StringComparer _comparer;
+
+        public uint ParentId { get; }
+
+        public string Name { get; }
+
+        private static StringComparer GetComparer(HFSKeyCompareType compareType, bool isHFSX)
+        {
+            if (isHFSX)
+            {
+                return compareType switch
+                {
+                    HFSKeyCompareType.CaseFolding => StringComparer.InvariantCultureIgnoreCase,
+                    HFSKeyCompareType.BinaryCompare => StringComparer.Ordinal,
+                    _ => StringComparer.InvariantCultureIgnoreCase
+                };
+            }
+            else
+            {
+                return StringComparer.InvariantCultureIgnoreCase;
+            }
+        }
+
+        public HFSCatalogKey(uint parentId, string name, HFSKeyCompareType compareType, bool isHFSX)
+        {
+            ParentId = parentId;
+            Name = name;
+            _comparer = GetComparer(compareType, isHFSX);
+        }
+
+        public HFSCatalogKey(byte[] key, HFSKeyCompareType compareType, bool isHFSX)
+        {
+            ReadOnlySpan<byte> data = key.AsSpan();
+            ParentId = ReadUInt32(ref data);
+            Name = ReadString(ref data, true);
+            _comparer = GetComparer(compareType, isHFSX);
+        }
+
+        public bool Equals(HFSCatalogKey? other)
+        {
+            if (other is null) return false;
+            else return (ParentId == other.ParentId) && _comparer.Equals(Name, other.Name);
+        }
+
+        public override bool Equals(object? obj)
+        {
+            if (obj is HFSCatalogKey other) return Equals(other);
+            else return false;
+        }
+
+        public int CompareTo(HFSCatalogKey? other)
+        {
+            if (other is null) return 1;
+
+            int result = ParentId.CompareTo(other.ParentId);
+            if (result == 0) result = _comparer.Compare(Name, other.Name);
+            return result;
+        }
+
+        public int CompareTo(object? obj)
+        {
+            if (obj is null) return 1;
+            else if (obj is HFSCatalogKey other) return CompareTo(other);
+            else throw new ArgumentException("Object is not of type CatalogKey", nameof(obj));
+        }
+
+        public override int GetHashCode()
+            => ParentId.GetHashCode() ^ _comparer.GetHashCode(Name);
+
+        public static bool operator ==(HFSCatalogKey? left, HFSCatalogKey? right)
+        {
+            if (left is null) return right is null;
+            else return left.Equals(right);
+        }
+
+        public static bool operator !=(HFSCatalogKey? left, HFSCatalogKey? right)
+        {
+            if (left is null) return right is not null;
+            else return !left.Equals(right);
+        }
+
+        public static bool operator <(HFSCatalogKey? left, HFSCatalogKey? right)
+        {
+            if (left is null) return right is not null;
+            else return left.CompareTo(right) < 0;
+        }
+
+        public static bool operator >(HFSCatalogKey? left, HFSCatalogKey? right)
+        {
+            if (left is null) return false;
+            else return left.CompareTo(right) > 0;
+        }
+
+        public static bool operator <=(HFSCatalogKey? left, HFSCatalogKey? right)
+        {
+            if (left is null) return true;
+            else return left.CompareTo(right) <= 0;
+        }
+
+        public static bool operator >=(HFSCatalogKey? left, HFSCatalogKey? right)
+        {
+            if (left is null) return right is null;
+            else return left.CompareTo(right) >= 0;
+        }
+    }
+
+    internal enum HFSCatalogRecordType : ushort
+    {
+        Folder = 0x0001,
+        File = 0x0002,
+        FolderThread = 0x0003,
+        FileThread = 0x0004
+    }
+
+    internal abstract class HFSCatalogRecord : HFSStructBase
+    {
+        public HFSCatalogRecordType Type { get; }
+
+        protected HFSCatalogRecord(HFSCatalogRecordType type)
+            => Type = type;
+
+        public static bool TryRead(ref ReadOnlySpan<byte> data, HFSKeyCompareType compareType, bool isHFSX, out HFSCatalogRecord? record)
+        {
+            record = null;
+
+            ushort rawType = ReadUInt16(ref data);
+            if (!Enum.IsDefined(typeof(HFSCatalogRecordType), rawType)) return false;
+
+            var type = (HFSCatalogRecordType)rawType;
+            switch (type)
+            {
+                case HFSCatalogRecordType.Folder:
+                    record = HFSCatalogFolder.Read(ref data);
+                    return true;
+
+                case HFSCatalogRecordType.File:
+                    record = HFSCatalogFile.Read(ref data);
+                    return true;
+
+                case HFSCatalogRecordType.FolderThread:
+                    record = HFSCatalogThread.Read(ref data, false, compareType, isHFSX);
+                    return true;
+
+                case HFSCatalogRecordType.FileThread:
+                    record = HFSCatalogThread.Read(ref data, true, compareType, isHFSX);
+                    return true;
+            }
+
+            return false;
+        }
+    }
+
+    internal sealed class HFSCatalogFolder : HFSCatalogRecord
+    {
+        public uint Valence { get; }
+        public uint FolderId { get; }
+        public DateTime CreateDate { get; }
+        public DateTime ContentModDate { get; }
+        public DateTime AttributeModDate { get; }
+        public DateTime AccessDate { get; }
+        public DateTime BackupDate { get; }
+        public HFSPermissions Permissions { get; }
+        public HFSFolderInfo Info { get; }
+        public uint TextEncoding { get; }
+
+        private HFSCatalogFolder(
+            uint valence,
+            uint folderId,
+            DateTime createDate,
+            DateTime contentModDate,
+            DateTime attributeModDate,
+            DateTime accessDate,
+            DateTime backupDate,
+            HFSPermissions permissions,
+            HFSFolderInfo info,
+            uint textEncoding)
+            : base(HFSCatalogRecordType.Folder)
+        {
+            Valence = valence;
+            FolderId = folderId;
+            CreateDate = createDate;
+            ContentModDate = contentModDate;
+            AttributeModDate = attributeModDate;
+            AccessDate = accessDate;
+            BackupDate = backupDate;
+            Permissions = permissions;
+            Info = info;
+            TextEncoding = textEncoding;
+        }
+
+        public static HFSCatalogFolder Read(ref ReadOnlySpan<byte> data)
+        {
+            _ = ReadUInt16(ref data); // reserved
+            uint valence = ReadUInt32(ref data);
+            uint folderId = ReadUInt32(ref data);
+            var createDate = ReadDate(ref data);
+            var contentModDate = ReadDate(ref data);
+            var attributeModDate = ReadDate(ref data);
+            var accessDate = ReadDate(ref data);
+            var backupDate = ReadDate(ref data);
+            var permissions = HFSPermissions.Read(ref data);
+            var info = HFSFolderInfo.Read(ref data);
+            uint textEncoding = ReadUInt32(ref data);
+            _ = ReadUInt32(ref data); // reserved
+
+            return new HFSCatalogFolder(
+                valence,
+                folderId,
+                createDate,
+                contentModDate,
+                attributeModDate,
+                accessDate,
+                backupDate,
+                permissions,
+                info,
+                textEncoding);
+        }
+    }
+
+    internal enum HFSFileFlags : ushort
+    {
+        LockedBit = 0x0000,
+        LockedMask = 0x0001,
+        ThreadExistsBit = 0x0001,
+        ThreadExistsMask = 0x0002
+    }
+
+    internal sealed class HFSCatalogFile : HFSCatalogRecord
+    {
+        public HFSFileFlags Flags { get; }
+        public uint FileId { get; }
+        public DateTime CreateDate { get; }
+        public DateTime ContentModDate { get; }
+        public DateTime AttributeModDate { get; }
+        public DateTime AccessDate { get; }
+        public DateTime BackupDate { get; }
+        public HFSPermissions Permissions { get; }
+        public HFSFileInfo Info { get; }
+        public uint TextEncoding { get; }
+
+        public HFSForkData DataFork { get; }
+        public HFSForkData ResourceFork { get; }
+
+        private HFSCatalogFile(
+            HFSFileFlags flags,
+            uint fileId,
+            DateTime createDate,
+            DateTime contentModDate,
+            DateTime attributeModDate,
+            DateTime accessDate,
+            DateTime backupDate,
+            HFSPermissions permissions,
+            HFSFileInfo info,
+            uint textEncoding,
+            HFSForkData dataFork,
+            HFSForkData resourceFork)
+            :base(HFSCatalogRecordType.File)
+        {
+            Flags = flags;
+            FileId = fileId;
+            CreateDate = createDate;
+            ContentModDate = contentModDate;
+            AttributeModDate = attributeModDate;
+            AccessDate = accessDate;
+            BackupDate = backupDate;
+            Permissions = permissions;
+            Info = info;
+            TextEncoding = textEncoding;
+            DataFork = dataFork;
+            ResourceFork = resourceFork;
+        }
+
+        public static HFSCatalogFile Read(ref ReadOnlySpan<byte> data)
+        {
+            var flags = (HFSFileFlags)ReadUInt16(ref data);
+            _ = ReadUInt32(ref data); // reserved
+            uint fileId = ReadUInt32(ref data);
+            var createDate = ReadDate(ref data);
+            var contentModDate = ReadDate(ref data);
+            var attributeModDate = ReadDate(ref data);
+            var accessDate = ReadDate(ref data);
+            var backupDate = ReadDate(ref data);
+            var permissions = HFSPermissions.Read(ref data);
+            var info = HFSFileInfo.Read(ref data);
+            uint textEncoding = ReadUInt32(ref data);
+            _ = ReadUInt32(ref data); // reserved
+
+            var dataFork = HFSForkData.Read(ref data);
+            var resourceFork = HFSForkData.Read(ref data);
+
+            return new HFSCatalogFile(
+                flags,
+                fileId,
+                createDate,
+                contentModDate,
+                attributeModDate,
+                accessDate,
+                backupDate,
+                permissions,
+                info,
+                textEncoding,
+                dataFork,
+                resourceFork);
+        }
+    }
+
+    internal sealed class HFSCatalogThread : HFSCatalogRecord
+    {
+        public uint ParentId { get; }
+        public string NodeName { get; }
+        public HFSCatalogKey CatalogKey { get; }
+
+        private HFSCatalogThread(uint parentId, string nodeName, bool isFile, HFSKeyCompareType compareType, bool isHFSX)
+            : base(isFile ? HFSCatalogRecordType.FileThread : HFSCatalogRecordType.FolderThread)
+        {
+            ParentId = parentId;
+            NodeName = nodeName;
+            CatalogKey = new HFSCatalogKey(ParentId, NodeName, compareType, isHFSX);
+        }
+
+        public static HFSCatalogThread Read(ref ReadOnlySpan<byte> data, bool isFile, HFSKeyCompareType compareType, bool isHFSX)
+        {
+            _ = ReadInt16(ref data); // reserved
+            uint parentId = ReadUInt32(ref data);
+            string nodeName = ReadString(ref data, true);
+
+            return new HFSCatalogThread(parentId, nodeName, isFile, compareType, isHFSX);
+        }
+    }
+}

src/SharpCompress/Common/Dmg/HFS/HFSExtentDescriptor.cs

@@ -0,0 +1,31 @@
+using System;
+using System.IO;
+
+namespace SharpCompress.Common.Dmg.HFS
+{
+    internal sealed class HFSExtentDescriptor : HFSStructBase
+    {
+        public uint StartBlock { get; }
+        public uint BlockCount { get; }
+
+        private HFSExtentDescriptor(uint startBlock, uint blockCount)
+        {
+            StartBlock = startBlock;
+            BlockCount = blockCount;
+        }
+
+        public static HFSExtentDescriptor Read(Stream stream)
+        {
+            return new HFSExtentDescriptor(
+                ReadUInt32(stream),
+                ReadUInt32(stream));
+        }
+
+        public static HFSExtentDescriptor Read(ref ReadOnlySpan<byte> data)
+        {
+            return new HFSExtentDescriptor(
+                ReadUInt32(ref data),
+                ReadUInt32(ref data));
+        }
+    }
+}

src/SharpCompress/Common/Dmg/HFS/HFSExtentRecord.cs

@@ -0,0 +1,115 @@
+using System;
+using System.Collections.Generic;
+
+namespace SharpCompress.Common.Dmg.HFS
+{
+    internal sealed class HFSExtentKey : HFSStructBase, IEquatable<HFSExtentKey>, IComparable<HFSExtentKey>, IComparable
+    {
+        public byte ForkType { get; }
+        public uint FileId { get; }
+        public uint StartBlock { get; }
+
+        public HFSExtentKey(byte forkType, uint fileId, uint startBlock)
+        {
+            ForkType = forkType;
+            FileId = fileId;
+            StartBlock = startBlock;
+        }
+
+        public HFSExtentKey(byte[] key)
+        {
+            ReadOnlySpan<byte> data = key.AsSpan();
+            ForkType = ReadUInt8(ref data);
+            _ = ReadUInt8(ref data); // padding
+            FileId = ReadUInt32(ref data);
+            StartBlock = ReadUInt32(ref data);
+        }
+
+        public bool Equals(HFSExtentKey? other)
+        {
+            if (other is null) return false;
+            else return (ForkType == other.ForkType) && (FileId == other.FileId) && (StartBlock == other.StartBlock);
+        }
+
+        public override bool Equals(object? obj)
+        {
+            if (obj is HFSExtentKey other) return Equals(other);
+            else return false;
+        }
+
+        public int CompareTo(HFSExtentKey? other)
+        {
+            if (other is null) return 1;
+
+            int result = FileId.CompareTo(other.FileId);
+            if (result == 0) result = ForkType.CompareTo(other.ForkType);
+            if (result == 0) result = StartBlock.CompareTo(other.StartBlock);
+            return result;
+        }
+
+        public int CompareTo(object? obj)
+        {
+            if (obj is null) return 1;
+            else if (obj is HFSExtentKey other) return CompareTo(other);
+            else throw new ArgumentException("Object is not of type ExtentKey", nameof(obj));
+        }
+
+        public override int GetHashCode()
+            => ForkType.GetHashCode() ^ FileId.GetHashCode() ^ StartBlock.GetHashCode();
+
+        public static bool operator ==(HFSExtentKey? left, HFSExtentKey? right)
+        {
+            if (left is null) return right is null;
+            else return left.Equals(right);
+        }
+
+        public static bool operator !=(HFSExtentKey? left, HFSExtentKey? right)
+        {
+            if (left is null) return right is not null;
+            else return !left.Equals(right);
+        }
+
+        public static bool operator <(HFSExtentKey? left, HFSExtentKey? right)
+        {
+            if (left is null) return right is not null;
+            else return left.CompareTo(right) < 0;
+        }
+
+        public static bool operator >(HFSExtentKey? left, HFSExtentKey? right)
+        {
+            if (left is null) return false;
+            else return left.CompareTo(right) > 0;
+        }
+
+        public static bool operator <=(HFSExtentKey? left, HFSExtentKey? right)
+        {
+            if (left is null) return true;
+            else return left.CompareTo(right) <= 0;
+        }
+
+        public static bool operator >=(HFSExtentKey? left, HFSExtentKey? right)
+        {
+            if (left is null) return right is null;
+            else return left.CompareTo(right) >= 0;
+        }
+    }
+
+    internal sealed class HFSExtentRecord : HFSStructBase
+    {
+        private const int ExtentCount = 8;
+
+        public IReadOnlyList<HFSExtentDescriptor> Extents { get; }
+
+        private HFSExtentRecord(IReadOnlyList<HFSExtentDescriptor> extents)
+            => Extents = extents;
+
+        public static HFSExtentRecord Read(ref ReadOnlySpan<byte> data)
+        {
+            var extents = new HFSExtentDescriptor[ExtentCount];
+            for (int i = 0; i < ExtentCount; i++)
+                extents[i] = HFSExtentDescriptor.Read(ref data);
+
+            return new HFSExtentRecord(extents);
+        }
+    }
+}

src/SharpCompress/Common/Dmg/HFS/HFSFinderInfo.cs

@@ -0,0 +1,145 @@
+using System;
+
+namespace SharpCompress.Common.Dmg.HFS
+{
+    internal struct HFSPoint
+    {
+        public short V;
+        public short H;
+    }
+
+    internal struct HFSRect
+    {
+        public short Top;
+        public short Left;
+        public short Bottom;
+        public short Right;
+    }
+
+    [Flags]
+    internal enum HFSFinderFlags : ushort
+    {
+        None = 0x0000,
+
+        IsOnDesk = 0x0001,      /* Files and folders (System 6) */
+        Color = 0x000E,         /* Files and folders */
+        IsShared = 0x0040,      /* Files only (Applications only) If */
+                                /* clear, the application needs */
+                                /* to write to its resource fork, */
+                                /* and therefore cannot be shared */
+                                /* on a server */
+        HasNoINITs = 0x0080,    /* Files only (Extensions/Control */
+                                /* Panels only) */
+                                /* This file contains no INIT resource */
+        HasBeenInited = 0x0100, /* Files only.  Clear if the file */
+                                /* contains desktop database resources */
+                                /* ('BNDL', 'FREF', 'open', 'kind'...) */
+                                /* that have not been added yet.  Set */
+                                /* only by the Finder. */
+                                /* Reserved for folders */
+        HasCustomIcon = 0x0400, /* Files and folders */
+        IsStationery = 0x0800,  /* Files only */
+        NameLocked = 0x1000,    /* Files and folders */
+        HasBundle = 0x2000,     /* Files only */
+        IsInvisible = 0x4000,   /* Files and folders */
+        IsAlias = 0x8000        /* Files only */
+    }
+
+    [Flags]
+    internal enum HFSExtendedFinderFlags : ushort
+    {
+        None = 0x0000,
+
+        ExtendedFlagsAreInvalid = 0x8000, /* The other extended flags */
+                                          /* should be ignored */
+        HasCustomBadge = 0x0100,          /* The file or folder has a */
+                                          /* badge resource */
+        HasRoutingInfo = 0x0004           /* The file contains routing */
+                                          /* info resource */
+    }
+
+    internal sealed class HFSFileInfo : HFSStructBase
+    {
+        public string FileType { get; }             /* The type of the file */
+        public string FileCreator { get; }          /* The file's creator */
+        public HFSFinderFlags FinderFlags { get; }
+        public HFSPoint Location { get; }           /* File's location in the folder. */
+        public HFSExtendedFinderFlags ExtendedFinderFlags { get; }
+        public int PutAwayFolderId { get; }
+
+        private HFSFileInfo(
+            string fileType,
+            string fileCreator,
+            HFSFinderFlags finderFlags,
+            HFSPoint location,
+            HFSExtendedFinderFlags extendedFinderFlags,
+            int putAwayFolderId)
+        {
+            FileType = fileType;
+            FileCreator = fileCreator;
+            FinderFlags = finderFlags;
+            Location = location;
+            ExtendedFinderFlags = extendedFinderFlags;
+            PutAwayFolderId = putAwayFolderId;
+        }
+
+        public static HFSFileInfo Read(ref ReadOnlySpan<byte> data)
+        {
+            string fileType = ReadOSType(ref data);
+            string fileCreator = ReadOSType(ref data);
+            var finderFlags = (HFSFinderFlags)ReadUInt16(ref data);
+            var location = ReadPoint(ref data);
+            _ = ReadUInt16(ref data); // reserved
+            data = data.Slice(4 * sizeof(short)); // reserved
+            var extendedFinderFlags = (HFSExtendedFinderFlags)ReadUInt16(ref data);
+            _ = ReadInt16(ref data); // reserved
+            int putAwayFolderId = ReadInt32(ref data);
+
+            return new HFSFileInfo(fileType, fileCreator, finderFlags, location, extendedFinderFlags, putAwayFolderId);
+        }
+    }
+
+    internal sealed class HFSFolderInfo : HFSStructBase
+    {
+        public HFSRect WindowBounds { get; }    /* The position and dimension of the */
+                                                /* folder's window */
+        public HFSFinderFlags FinderFlags { get; }
+        public HFSPoint Location { get; }       /* Folder's location in the parent */
+                                                /* folder. If set to {0, 0}, the Finder */
+                                                /* will place the item automatically */
+        public HFSPoint ScrollPosition { get; } /* Scroll position (for icon views) */
+        public HFSExtendedFinderFlags ExtendedFinderFlags { get; }
+        public int PutAwayFolderId { get; }
+
+        private HFSFolderInfo(
+            HFSRect windowBounds,
+            HFSFinderFlags finderFlags,
+            HFSPoint location,
+            HFSPoint scrollPosition,
+            HFSExtendedFinderFlags extendedFinderFlags,
+            int putAwayFolderId)
+        {
+            WindowBounds = windowBounds;
+            FinderFlags = finderFlags;
+            Location = location;
+            ScrollPosition = scrollPosition;
+            ExtendedFinderFlags = extendedFinderFlags;
+            PutAwayFolderId = putAwayFolderId;
+        }
+
+        public static HFSFolderInfo Read(ref ReadOnlySpan<byte> data)
+        {
+            var windowBounds = ReadRect(ref data);
+            var finderFlags = (HFSFinderFlags)ReadUInt16(ref data);
+            var location = ReadPoint(ref data);
+            _ = ReadUInt16(ref data); // reserved
+            var scrollPosition = ReadPoint(ref data);
+            _ = ReadInt32(ref data); // reserved
+            var extendedFinderFlags = (HFSExtendedFinderFlags)ReadUInt16(ref data);
+            _ = ReadInt16(ref data); // reserved
+            int putAwayFolderId = ReadInt32(ref data);
+
+            return new HFSFolderInfo(windowBounds, finderFlags, location, scrollPosition, extendedFinderFlags, putAwayFolderId);
+        }
+    }
+}

src/SharpCompress/Common/Dmg/HFS/HFSForkData.cs

@@ -0,0 +1,50 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+
+namespace SharpCompress.Common.Dmg.HFS
+{
+    internal sealed class HFSForkData : HFSStructBase
+    {
+        private const int ExtentCount = 8;
+
+        public ulong LogicalSize { get; }
+        public uint ClumpSize { get; }
+        public uint TotalBlocks { get; }
+        public IReadOnlyList<HFSExtentDescriptor> Extents { get; }
+
+        private HFSForkData(ulong logicalSize, uint clumpSize, uint totalBlocks, IReadOnlyList<HFSExtentDescriptor> extents)
+        {
+            LogicalSize = logicalSize;
+            ClumpSize = clumpSize;
+            TotalBlocks = totalBlocks;
+            Extents = extents;
+        }
+
+        public static HFSForkData Read(Stream stream)
+        {
+            ulong logicalSize = ReadUInt64(stream);
+            uint clumpSize = ReadUInt32(stream);
+            uint totalBlocks = ReadUInt32(stream);
+
+            var extents = new HFSExtentDescriptor[ExtentCount];
+            for (int i = 0; i < ExtentCount; i++)
+                extents[i] = HFSExtentDescriptor.Read(stream);
+
+            return new HFSForkData(logicalSize, clumpSize, totalBlocks, extents);
+        }
+
+        public static HFSForkData Read(ref ReadOnlySpan<byte> data)
+        {
+            ulong logicalSize = ReadUInt64(ref data);
+            uint clumpSize = ReadUInt32(ref data);
+            uint totalBlocks = ReadUInt32(ref data);
+
+            var extents = new HFSExtentDescriptor[ExtentCount];
+            for (int i = 0; i < ExtentCount; i++)
+                extents[i] = HFSExtentDescriptor.Read(ref data);
+
+            return new HFSForkData(logicalSize, clumpSize, totalBlocks, extents);
+        }
+    }
+}

src/SharpCompress/Common/Dmg/HFS/HFSForkStream.cs

@@ -0,0 +1,196 @@
+using SharpCompress.IO;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+
+namespace SharpCompress.Common.Dmg.HFS
+{
+    internal sealed class HFSForkStream : Stream
+    {
+        private readonly Stream _baseStream;
+        private readonly HFSVolumeHeader _volumeHeader;
+        private readonly IReadOnlyList<HFSExtentDescriptor> _extents;
+        private long _position;
+        private bool _isEnded;
+        private int _extentIndex;
+        private Stream? _extentStream;
+
+        public override bool CanRead => true;
+        public override bool CanWrite => false;
+        public override bool CanSeek => true;
+        public override long Length { get; }
+
+        public override long Position
+        {
+            get => _position;
+            set
+            {
+                if ((value < 0) || (value > Length)) throw new ArgumentOutOfRangeException(nameof(value));
+
+                if (value == Length)
+                {
+                    // End of the stream
+
+                    _position = Length;
+                    _isEnded = true;
+                    _extentIndex = -1;
+                    _extentStream = null;
+                }
+                else if (value != _position)
+                {
+                    _position = value;
+
+                    // We first have to determine in which extent we are now, then we seek to the exact position in that extent.
+
+                    long offsetInExtent = _position;
+                    for (int i = 0; i < _extents.Count; i++)
+                    {
+                        var extent = _extents[i];
+                        long extentSize = extent.BlockCount * _volumeHeader.BlockSize;
+                        if (extentSize < offsetInExtent)
+                        {
+                            if (i == _extentIndex)
+                            {
+                                // We are in the same extent so just seek to the correct position
+                                _extentStream!.Position = offsetInExtent;
+                            }
+                            else
+                            {
+                                _extentIndex = i;
+                                _extentStream = GetExtentStream();
+                                _extentStream.Position = offsetInExtent;
+                            }
+
+                            break;
+                        }
+                        else
+                        {
+                            offsetInExtent -= extentSize;
+                        }
+                    }
+                }
+            }
+        }
+
+        public HFSForkStream(Stream baseStream, HFSVolumeHeader volumeHeader, HFSForkData forkData)
+        {
+            _baseStream = baseStream;
+            _volumeHeader = volumeHeader;
+            _extents = forkData.Extents;
+            Length = (long)forkData.LogicalSize;
+
+            _position = 0;
+            _extentIndex = -1;
+            _extentIndex = GetNextExtent();
+            _isEnded = _extentIndex < 0;
+            if (!_isEnded) _extentStream = GetExtentStream();
+        }
+
+        public HFSForkStream(
+            Stream baseStream, HFSVolumeHeader volumeHeader, HFSForkData forkData, uint fileId,
+            IReadOnlyDictionary<HFSExtentKey, HFSExtentRecord> extents)
+        {
+            _baseStream = baseStream;
+            _volumeHeader = volumeHeader;
+            Length = (long)forkData.LogicalSize;
+
+            uint blocks = (uint)forkData.Extents.Sum(e => e.BlockCount);
+            var totalExtents = new List<HFSExtentDescriptor>(forkData.Extents);
+            _extents = totalExtents;
+
+            var nextKey = new HFSExtentKey(0, fileId, blocks);
+            while (extents.TryGetValue(nextKey, out var record))
+            {
+                blocks += (uint)record.Extents.Sum(e => e.BlockCount);
+                totalExtents.AddRange(record.Extents);
+
+                nextKey = new HFSExtentKey(0, fileId, blocks);
+            }
+
+            _position = 0;
+            _extentIndex = -1;
+            _extentIndex = GetNextExtent();
+            _isEnded = _extentIndex < 0;
+            if (!_isEnded) _extentStream = GetExtentStream();
+        }
+
+        private int GetNextExtent()
+        {
+            int index = _extentIndex + 1;
+            if (index >= _extents.Count) return -1;
+
+            var extent = _extents[index];
+            if ((extent.StartBlock == 0) && (extent.BlockCount == 0)) return -1;
+            return index;
+        }
+
+        private Stream GetExtentStream()
+        {
+            if (_extentIndex < 0)
+                throw new InvalidOperationException("Invalid extent index");
+
+            var extent = _extents[_extentIndex];
+            return new HFSExtentStream(_baseStream, _volumeHeader, extent);
+        }
+
+        public override void Flush()
+        { }
+
+        public override int Read(byte[] buffer, int offset, int count)
+        {
+            if (_isEnded) return 0;
+
+            count = (int)Math.Min(count, Length - Position);
+            int readCount = _extentStream!.Read(buffer, offset, count);
+            while (readCount < count)
+            {
+                _extentIndex = GetNextExtent();
+                if (_extentIndex < 0)
+                {
+                    _isEnded = true;
+                    return readCount;
+                }
+
+                _extentStream = GetExtentStream();
+                readCount += _extentStream.Read(buffer, offset + readCount, count - readCount);
+            }
+
+            _position += readCount;
+            return readCount;
+        }
+
+        public override long Seek(long offset, SeekOrigin origin)
+        {
+            switch (origin)
+            {
+                case SeekOrigin.Begin:
+                    Position = offset;
+                    break;
+
+                case SeekOrigin.Current:
+                    Position += offset;
+                    break;
+
+                case SeekOrigin.End:
+                    Position = Length - offset;
+                    break;
+            }
+
+            return Position;
+        }
+
+        public override void SetLength(long value)
+            => throw new NotSupportedException();
+
+        public override void Write(byte[] buffer, int offset, int count)
+            => throw new NotSupportedException();
+
+        private sealed class HFSExtentStream : SeekableSubStream
+        {
+            public HFSExtentStream(Stream stream, HFSVolumeHeader volumeHeader, HFSExtentDescriptor extent)
+                : base(stream, (long)extent.StartBlock * volumeHeader.BlockSize, (long)extent.BlockCount * volumeHeader.BlockSize)
+            { }
+        }
+    }
+}

src/SharpCompress/Common/Dmg/HFS/HFSKeyedRecord.cs

@@ -0,0 +1,91 @@
+using System;
+
+namespace SharpCompress.Common.Dmg.HFS
+{
+    internal abstract class HFSKeyedRecord : HFSStructBase
+    {
+        private readonly HFSKeyCompareType _compareType;
+        private readonly bool _isHFSX;
+        private HFSCatalogKey? _catalogKey;
+        private HFSExtentKey? _extentKey;
+
+        public byte[] Key { get; }
+
+        public HFSCatalogKey GetCatalogKey() => _catalogKey ??= new HFSCatalogKey(Key, _compareType, _isHFSX);
+
+        public HFSExtentKey GetExtentKey() => _extentKey ??= new HFSExtentKey(Key);
+
+        protected HFSKeyedRecord(byte[] key, HFSKeyCompareType compareType, bool isHFSX)
+        {
+            Key = key;
+            _compareType = compareType;
+            _isHFSX = isHFSX;
+        }
+    }
+
+    internal sealed class HFSPointerRecord : HFSKeyedRecord
+    {
+        public uint NodeNumber { get; }
+
+        private HFSPointerRecord(byte[] key, uint nodeNumber, HFSKeyCompareType compareType, bool isHFSX)
+            : base(key, compareType, isHFSX)
+        {
+            NodeNumber = nodeNumber;
+        }
+
+        public static HFSPointerRecord Read(ref ReadOnlySpan<byte> data, HFSTreeHeaderRecord headerRecord, bool isHFSX)
+        {
+            bool isBigKey = headerRecord.Attributes.HasFlag(HFSTreeAttributes.BigKeys);
+            ushort keyLength = isBigKey ? ReadUInt16(ref data) : ReadUInt8(ref data);
+            if (!headerRecord.Attributes.HasFlag(HFSTreeAttributes.VariableIndexKeys)) keyLength = headerRecord.MaxKeyLength;
+            int keySize = (isBigKey ? 2 : 1) + keyLength;
+
+            var key = new byte[keyLength];
+            data.Slice(0, keyLength).CopyTo(key);
+            data = data.Slice(keyLength);
+
+            // data is always aligned to 2 bytes
+            if (keySize % 2 == 1) data = data.Slice(1);
+
+            uint nodeNumber = ReadUInt32(ref data);
+
+            return new HFSPointerRecord(key, nodeNumber, headerRecord.KeyCompareType, isHFSX);
+        }
+    }
+
+    internal sealed class HFSDataRecord : HFSKeyedRecord
+    {
+        public byte[] Data { get; }
+
+        private HFSDataRecord(byte[] key, byte[] data, HFSKeyCompareType compareType, bool isHFSX)
+            : base(key, compareType, isHFSX)
+        {
+            Data = data;
+        }
+
+        public static HFSDataRecord Read(ref ReadOnlySpan<byte> data, int size, HFSTreeHeaderRecord headerRecord, bool isHFSX)
+        {
+            bool isBigKey = headerRecord.Attributes.HasFlag(HFSTreeAttributes.BigKeys);
+            ushort keyLength = isBigKey ? ReadUInt16(ref data) : ReadUInt8(ref data);
+            int keySize = (isBigKey ? 2 : 1) + keyLength;
+            size -= keySize;
+
+            var key = new byte[keyLength];
+            data.Slice(0, keyLength).CopyTo(key);
+            data = data.Slice(keyLength);
+
+            // data is always aligned to 2 bytes
+            if (keySize % 2 == 1)
+            {
+                data = data.Slice(1);
+                size--;
+            }
+
+            var structData = new byte[size];
+            data.Slice(0, size).CopyTo(structData);
+            data = data.Slice(size);
+
+            return new HFSDataRecord(key, structData, headerRecord.KeyCompareType, isHFSX);
+        }
+    }
+}

src/SharpCompress/Common/Dmg/HFS/HFSPermissions.cs

@@ -0,0 +1,35 @@
+using System;
+
+namespace SharpCompress.Common.Dmg.HFS
+{
+    internal sealed class HFSPermissions : HFSStructBase
+    {
+        public uint OwnerID { get; }
+        public uint GroupID { get; }
+        public byte AdminFlags { get; }
+        public byte OwnerFlags { get; }
+        public ushort FileMode { get; }
+        public uint Special { get; }
+
+        private HFSPermissions(uint ownerID, uint groupID, byte adminFlags, byte ownerFlags, ushort fileMode, uint special)
+        {
+            OwnerID = ownerID;
+            GroupID = groupID;
+            AdminFlags = adminFlags;
+            OwnerFlags = ownerFlags;
+            FileMode = fileMode;
+            Special = special;
+        }
+
+        public static HFSPermissions Read(ref ReadOnlySpan<byte> data)
+        {
+            return new HFSPermissions(
+                ReadUInt32(ref data),
+                ReadUInt32(ref data),
+                ReadUInt8(ref data),
+                ReadUInt8(ref data),
+                ReadUInt16(ref data),
+                ReadUInt32(ref data));
+        }
+    }
+}

src/SharpCompress/Common/Dmg/HFS/HFSStructBase.cs

@@ -0,0 +1,187 @@
+using System;
+using System.Buffers.Binary;
+using System.IO;
+using System.Text;
+
+namespace SharpCompress.Common.Dmg.HFS
+{
+    internal abstract class HFSStructBase
+    {
+        private const int StringSize = 510;
+        private const int OSTypeSize = 4;
+        private static readonly DateTime Epoch = new DateTime(1904, 1, 1, 0, 0, 0, DateTimeKind.Utc);
+        private static readonly byte[] _buffer = new byte[StringSize];
+
+        protected static byte ReadUInt8(Stream stream)
+        {
+            if (stream.Read(_buffer, 0, sizeof(byte)) != sizeof(byte))
+                throw new EndOfStreamException();
+
+            return _buffer[0];
+        }
+
+        protected static ushort ReadUInt16(Stream stream)
+        {
+            if (stream.Read(_buffer, 0, sizeof(ushort)) != sizeof(ushort))
+                throw new EndOfStreamException();
+
+            return BinaryPrimitives.ReadUInt16BigEndian(_buffer);
+        }
+
+        protected static short ReadInt16(Stream stream)
+        {
+            if (stream.Read(_buffer, 0, sizeof(short)) != sizeof(short))
+                throw new EndOfStreamException();
+
+            return BinaryPrimitives.ReadInt16BigEndian(_buffer);
+        }
+
+        protected static uint ReadUInt32(Stream stream)
+        {
+            if (stream.Read(_buffer, 0, sizeof(uint)) != sizeof(uint))
+                throw new EndOfStreamException();
+
+            return BinaryPrimitives.ReadUInt32BigEndian(_buffer);
+        }
+
+        protected static int ReadInt32(Stream stream)
+        {
+            if (stream.Read(_buffer, 0, sizeof(int)) != sizeof(int))
+                throw new EndOfStreamException();
+
+            return BinaryPrimitives.ReadInt32BigEndian(_buffer);
+        }
+
+        protected static ulong ReadUInt64(Stream stream)
+        {
+            if (stream.Read(_buffer, 0, sizeof(ulong)) != sizeof(ulong))
+                throw new EndOfStreamException();
+
+            return BinaryPrimitives.ReadUInt64BigEndian(_buffer);
+        }
+
+        protected static long ReadInt64(Stream stream)
+        {
+            if (stream.Read(_buffer, 0, sizeof(long)) != sizeof(long))
+                throw new EndOfStreamException();
+
+            return BinaryPrimitives.ReadInt64BigEndian(_buffer);
+        }
+
+        protected static string ReadString(Stream stream)
+        {
+            ushort length = ReadUInt16(stream);
+            if (stream.Read(_buffer, 0, StringSize) != StringSize)
+                throw new EndOfStreamException();
+            return Encoding.Unicode.GetString(_buffer, 0, Math.Min(length * 2, StringSize));
+        }
+
+        protected static DateTime ReadDate(Stream stream)
+        {
+            uint seconds = ReadUInt32(stream);
+            var span = TimeSpan.FromSeconds(seconds);
+            return Epoch + span;
+        }
+
+        protected static byte ReadUInt8(ref ReadOnlySpan<byte> data)
+        {
+            byte val = data[0];
+            data = data.Slice(sizeof(byte));
+            return val;
+        }
+
+        protected static ushort ReadUInt16(ref ReadOnlySpan<byte> data)
+        {
+            ushort val = BinaryPrimitives.ReadUInt16BigEndian(data);
+            data = data.Slice(sizeof(ushort));
+            return val;
+        }
+
+        protected static short ReadInt16(ref ReadOnlySpan<byte> data)
+        {
+            short val = BinaryPrimitives.ReadInt16BigEndian(data);
+            data = data.Slice(sizeof(short));
+            return val;
+        }
+
+        protected static uint ReadUInt32(ref ReadOnlySpan<byte> data)
+        {
+            uint val = BinaryPrimitives.ReadUInt32BigEndian(data);
+            data = data.Slice(sizeof(uint));
+            return val;
+        }
+
+        protected static int ReadInt32(ref ReadOnlySpan<byte> data)
+        {
+            int val = BinaryPrimitives.ReadInt32BigEndian(data);
+            data = data.Slice(sizeof(int));
+            return val;
+        }
+
+        protected static ulong ReadUInt64(ref ReadOnlySpan<byte> data)
+        {
+            ulong val = BinaryPrimitives.ReadUInt64BigEndian(data);
+            data = data.Slice(sizeof(ulong));
+            return val;
+        }
+
+        protected static long ReadInt64(ref ReadOnlySpan<byte> data)
+        {
+            long val = BinaryPrimitives.ReadInt64BigEndian(data);
+            data = data.Slice(sizeof(long));
+            return val;
+        }
+
+        protected static string ReadString(ref ReadOnlySpan<byte> data, bool truncate)
+        {
+            int length = ReadUInt16(ref data);
+            if (truncate)
+            {
+                length = Math.Min(length * 2, StringSize);
+                data.Slice(0, length).CopyTo(_buffer);
+                data = data.Slice(length);
+                return Encoding.BigEndianUnicode.GetString(_buffer, 0, length);
+            }
+            else
+            {
+                data.Slice(0, StringSize).CopyTo(_buffer);
+                data = data.Slice(StringSize);
+                return Encoding.BigEndianUnicode.GetString(_buffer, 0, Math.Min(length * 2, StringSize));
+            }
+        }
+
+        protected static DateTime ReadDate(ref ReadOnlySpan<byte> data)
+        {
+            uint seconds = ReadUInt32(ref data);
+            var span = TimeSpan.FromSeconds(seconds);
+            return Epoch + span;
+        }
+
+        protected static string ReadOSType(ref ReadOnlySpan<byte> data)
+        {
+            data.Slice(0, OSTypeSize).CopyTo(_buffer);
+            data = data.Slice(OSTypeSize);
+            return Encoding.ASCII.GetString(_buffer, 0, OSTypeSize).NullTerminate();
+        }
+
+        protected static HFSPoint ReadPoint(ref ReadOnlySpan<byte> data)
+        {
+            return new HFSPoint()
+            {
+                V = ReadInt16(ref data),
+                H = ReadInt16(ref data)
+            };
+        }
+
+        protected static HFSRect ReadRect(ref ReadOnlySpan<byte> data)
+        {
+            return new HFSRect()
+            {
+                Top = ReadInt16(ref data),
+                Left = ReadInt16(ref data),
+                Bottom = ReadInt16(ref data),
+                Right = ReadInt16(ref data)
+            };
+        }
+    }
+}

src/SharpCompress/Common/Dmg/HFS/HFSTreeHeaderRecord.cs

@@ -0,0 +1,108 @@
+using System;
+using System.IO;
+
+namespace SharpCompress.Common.Dmg.HFS
+{
+    internal enum HFSTreeType : byte
+    {
+        HFS = 0,         // control file
+        User = 128,      // user btree type starts from 128
+        Reserved = 255
+    }
+
+    internal enum HFSKeyCompareType : byte
+    {
+        CaseFolding = 0xCF,	  // case-insensitive
+        BinaryCompare = 0xBC  // case-sensitive
+    }
+
+    [Flags]
+    internal enum HFSTreeAttributes : uint
+    {
+        None = 0x00000000,
+        BadClose = 0x00000001,
+        BigKeys = 0x00000002,
+        VariableIndexKeys = 0x00000004
+    }
+
+    internal sealed class HFSTreeHeaderRecord : HFSStructBase
+    {
+        public ushort TreeDepth;
+        public uint RootNode;
+        public uint LeafRecords;
+        public uint FirstLeafNode;
+        public uint LastLeafNode;
+        public ushort NodeSize;
+        public ushort MaxKeyLength;
+        public uint TotalNodes;
+        public uint FreeNodes;
+        public uint ClumpSize;
+        public HFSTreeType TreeType;
+        public HFSKeyCompareType KeyCompareType;
+        public HFSTreeAttributes Attributes;
+
+        private HFSTreeHeaderRecord(
+            ushort treeDepth,
+            uint rootNode,
+            uint leafRecords,
+            uint firstLeafNode,
+            uint lastLeafNode,
+            ushort nodeSize,
+            ushort maxKeyLength,
+            uint totalNodes,
+            uint freeNodes,
+            uint clumpSize,
+            HFSTreeType treeType,
+            HFSKeyCompareType keyCompareType,
+            HFSTreeAttributes attributes)
+        {
+            TreeDepth = treeDepth;
+            RootNode = rootNode;
+            LeafRecords = leafRecords;
+            FirstLeafNode = firstLeafNode;
+            LastLeafNode = lastLeafNode;
+            NodeSize = nodeSize;
+            MaxKeyLength = maxKeyLength;
+            TotalNodes = totalNodes;
+            FreeNodes = freeNodes;
+            ClumpSize = clumpSize;
+            TreeType = treeType;
+            KeyCompareType = keyCompareType;
+            Attributes = attributes;
+        }
+
+        public static HFSTreeHeaderRecord Read(Stream stream)
+        {
+            ushort treeDepth = ReadUInt16(stream);
+            uint rootNode = ReadUInt32(stream);
+            uint leafRecords = ReadUInt32(stream);
+            uint firstLeafNode = ReadUInt32(stream);
+            uint lastLeafNode = ReadUInt32(stream);
+            ushort nodeSize = ReadUInt16(stream);
+            ushort maxKeyLength = ReadUInt16(stream);
+            uint totalNodes = ReadUInt32(stream);
+            uint freeNodes = ReadUInt32(stream);
+            _ = ReadUInt16(stream); // reserved
+            uint clumpSize = ReadUInt32(stream);
+            var treeType = (HFSTreeType)ReadUInt8(stream);
+            var keyCompareType = (HFSKeyCompareType)ReadUInt8(stream);
+            var attributes = (HFSTreeAttributes)ReadUInt32(stream);
+            for (int i = 0; i < 16; i++) _ = ReadUInt32(stream); // reserved
+
+            return new HFSTreeHeaderRecord(
+                treeDepth,
+                rootNode,
+                leafRecords,
+                firstLeafNode,
+                lastLeafNode,
+                nodeSize,
+                maxKeyLength,
+                totalNodes,
+                freeNodes,
+                clumpSize,
+                treeType,
+                keyCompareType,
+                attributes);
+        }
+    }
+}

src/SharpCompress/Common/Dmg/HFS/HFSTreeNode.cs

@@ -0,0 +1,167 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+
+namespace SharpCompress.Common.Dmg.HFS
+{
+    internal abstract class HFSTreeNode : HFSStructBase
+    {
+        private static byte[]? _buffer = null;
+
+        public HFSTreeNodeDescriptor Descriptor { get; }
+
+        protected HFSTreeNode(HFSTreeNodeDescriptor descriptor)
+            => Descriptor = descriptor;
+
+        public static bool TryRead(Stream stream, HFSTreeHeaderRecord headerRecord, bool isHFSX, out HFSTreeNode? node)
+        {
+            node = null;
+
+            if (!HFSTreeNodeDescriptor.TryRead(stream, out var descriptor)) return false;
+
+            int size = (int)headerRecord.NodeSize - HFSTreeNodeDescriptor.Size;
+            if ((_buffer is null) || (_buffer.Length < size))
+                _buffer = new byte[size * 2];
+
+            if (stream.Read(_buffer, 0, size) != size)
+                throw new EndOfStreamException();
+            ReadOnlySpan<byte> data = _buffer.AsSpan(0, size);
+
+            switch (descriptor!.Kind)
+            {
+                case HFSTreeNodeKind.Leaf:
+                    node = HFSLeafTreeNode.Read(descriptor, data, headerRecord, isHFSX);
+                    return true;
+
+                case HFSTreeNodeKind.Index:
+                    node = HFSIndexTreeNode.Read(descriptor, data, headerRecord, isHFSX);
+                    return true;
+
+                case HFSTreeNodeKind.Map:
+                    node = HFSMapTreeNode.Read(descriptor, data);
+                    return true;
+            }
+
+            return false;
+        }
+    }
+
+    internal sealed class HFSHeaderTreeNode : HFSTreeNode
+    {
+        private const int UserDataSize = 128;
+
+        public HFSTreeHeaderRecord HeaderRecord { get; }
+
+        public IReadOnlyList<byte> UserData { get; }
+
+        public IReadOnlyList<byte> Map { get; }
+
+        private HFSHeaderTreeNode(
+            HFSTreeNodeDescriptor descriptor,
+            HFSTreeHeaderRecord headerRecord,
+            IReadOnlyList<byte> userData,
+            IReadOnlyList<byte> map)
+            : base(descriptor)
+        {
+            HeaderRecord = headerRecord;
+            UserData = userData;
+            Map = map;
+        }
+
+        public static HFSHeaderTreeNode Read(HFSTreeNodeDescriptor descriptor, Stream stream)
+        {
+            if (descriptor.Kind != HFSTreeNodeKind.Header)
+                throw new ArgumentException("Descriptor does not define a header node");
+
+            var headerRecord = HFSTreeHeaderRecord.Read(stream);
+            var userData = new byte[UserDataSize];
+            if (stream.Read(userData, 0, UserDataSize) != UserDataSize)
+                throw new EndOfStreamException();
+
+            int mapSize = (int)(headerRecord.NodeSize - 256);
+            var map = new byte[mapSize];
+            if (stream.Read(map, 0, mapSize) != mapSize)
+                throw new EndOfStreamException();
+
+            // offset values (not required for header node)
+            _ = ReadUInt16(stream);
+            _ = ReadUInt16(stream);
+            _ = ReadUInt16(stream);
+            _ = ReadUInt16(stream);
+
+            return new HFSHeaderTreeNode(descriptor, headerRecord, userData, map);
+        }
+    }
+
+    internal sealed class HFSMapTreeNode : HFSTreeNode
+    {
+        public IReadOnlyList<byte> Map { get; }
+
+        private HFSMapTreeNode(HFSTreeNodeDescriptor descriptor, IReadOnlyList<byte> map)
+            : base(descriptor)
+        {
+            Map = map;
+        }
+
+        public static HFSMapTreeNode Read(HFSTreeNodeDescriptor descriptor, ReadOnlySpan<byte> data)
+        {
+            int mapSize = data.Length - 6;
+            var map = new byte[mapSize];
+            data.Slice(0, mapSize).CopyTo(map);
+
+            return new HFSMapTreeNode(descriptor, map);
+        }
+    }
+
+    internal sealed class HFSIndexTreeNode : HFSTreeNode
+    {
+        public IReadOnlyList<HFSPointerRecord> Records { get; }
+
+        private HFSIndexTreeNode(HFSTreeNodeDescriptor descriptor, IReadOnlyList<HFSPointerRecord> records)
+            : base(descriptor)
+        {
+            Records = records;
+        }
+
+        public static HFSIndexTreeNode Read(HFSTreeNodeDescriptor descriptor, ReadOnlySpan<byte> data, HFSTreeHeaderRecord headerRecord, bool isHFSX)
+        {
+            int recordCount = descriptor.NumRecords;
+            var records = new HFSPointerRecord[recordCount];
+            for (int i = 0; i < recordCount; i++)
+                records[i] = HFSPointerRecord.Read(ref data, headerRecord, isHFSX);
+            return new HFSIndexTreeNode(descriptor, records);
+        }
+    }
+
+    internal sealed class HFSLeafTreeNode : HFSTreeNode
+    {
+        public IReadOnlyList<HFSDataRecord> Records { get; }
+
+        private HFSLeafTreeNode(HFSTreeNodeDescriptor descriptor, IReadOnlyList<HFSDataRecord> records)
+            : base(descriptor)
+        {
+            Records = records;
+        }
+
+        public static HFSLeafTreeNode Read(HFSTreeNodeDescriptor descriptor, ReadOnlySpan<byte> data, HFSTreeHeaderRecord headerRecord, bool isHFSX)
+        {
+            int recordCount = descriptor.NumRecords;
+            var recordOffsets = new int[recordCount + 1];
+            for (int i = 0; i < recordOffsets.Length; i++)
+            {
+                var offsetData = data.Slice(data.Length - (2 * i) - 2);
+                ushort offset = ReadUInt16(ref offsetData);
+                recordOffsets[i] = offset;
+            }
+
+            var records = new HFSDataRecord[recordCount];
+            for (int i = 0; i < recordCount; i++)
+            {
+                int size = recordOffsets[i + 1] - recordOffsets[i];
+                records[i] = HFSDataRecord.Read(ref data, size, headerRecord, isHFSX);
+            }
+
+            return new HFSLeafTreeNode(descriptor, records);
+        }
+    }
+}

src/SharpCompress/Common/Dmg/HFS/HFSTreeNodeDescriptor.cs

@@ -0,0 +1,55 @@
+using System;
+using System.IO;
+
+namespace SharpCompress.Common.Dmg.HFS
+{
+    internal enum HFSTreeNodeKind : sbyte
+    {
+        Leaf = -1,
+        Index = 0,
+        Header = 1,
+        Map = 2
+    }
+
+    internal sealed class HFSTreeNodeDescriptor : HFSStructBase
+    {
+        public const int Size = 14;
+
+        public uint FLink { get; }
+        public uint BLink { get; }
+        public HFSTreeNodeKind Kind { get; }
+        public byte Height { get; }
+        public ushort NumRecords { get; }
+
+        private HFSTreeNodeDescriptor(uint fLink, uint bLink, HFSTreeNodeKind kind, byte height, ushort numRecords)
+        {
+            FLink = fLink;
+            BLink = bLink;
+            Kind = kind;
+            Height = height;
+            NumRecords = numRecords;
+        }
+
+        public static bool TryRead(Stream stream, out HFSTreeNodeDescriptor? descriptor)
+        {
+            descriptor = null;
+
+            uint fLink = ReadUInt32(stream);
+            uint bLink = ReadUInt32(stream);
+
+            sbyte rawKind = (sbyte)ReadUInt8(stream);
+            if (!Enum.IsDefined(typeof(HFSTreeNodeKind), rawKind)) return false;
+            var kind = (HFSTreeNodeKind)rawKind;
+
+            byte height = ReadUInt8(stream);
+            if (((kind == HFSTreeNodeKind.Header) || (kind == HFSTreeNodeKind.Map)) && (height != 0)) return false;
+            if ((kind == HFSTreeNodeKind.Leaf) && (height != 1)) return false;
+
+            ushort numRecords = ReadUInt16(stream);
+            _ = ReadUInt16(stream); // reserved
+
+            descriptor = new HFSTreeNodeDescriptor(fLink, bLink, kind, height, numRecords);
+            return true;
+        }
+    }
+}

src/SharpCompress/Common/Dmg/HFS/HFSUtil.cs

@@ -0,0 +1,206 @@
+using SharpCompress.Archives.Dmg;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Text;
+
+namespace SharpCompress.Common.Dmg.HFS
+{
+    internal static class HFSUtil
+    {
+        private const string CorruptHFSMessage = "Corrupt HFS volume";
+
+        private static (HFSHeaderTreeNode, IReadOnlyList<HFSTreeNode>) ReadTree(Stream stream, bool isHFSX)
+        {
+            if (!HFSTreeNodeDescriptor.TryRead(stream, out var headerDesc))
+                throw new InvalidFormatException(CorruptHFSMessage);
+            var header = HFSHeaderTreeNode.Read(headerDesc!, stream);
+
+            var nodes = new HFSTreeNode[header.HeaderRecord.TotalNodes];
+            nodes[0] = header;
+
+            for (int i = 1; i < nodes.Length; i++)
+            {
+                if (!HFSTreeNode.TryRead(stream, header.HeaderRecord, isHFSX, out var node))
+                    throw new InvalidFormatException(CorruptHFSMessage);
+
+                nodes[i] = node!;
+            }
+
+            return (header, nodes);
+        }
+
+        private static void EnumerateExtentsTree(
+            IReadOnlyList<HFSTreeNode> extentsTree,
+            IDictionary<HFSExtentKey, HFSExtentRecord> records,
+            int parentIndex)
+        {
+            var parent = extentsTree[parentIndex];
+            if (parent is HFSLeafTreeNode leafNode)
+            {
+                foreach (var record in leafNode.Records)
+                {
+                    ReadOnlySpan<byte> data = record.Data.AsSpan();
+                    var recordData = HFSExtentRecord.Read(ref data);
+                    var key = record.GetExtentKey();
+                    records.Add(key, recordData);
+                }
+            }
+            else if (parent is HFSIndexTreeNode indexNode)
+            {
+                foreach (var record in indexNode.Records)
+                    EnumerateExtentsTree(extentsTree, records, (int)record.NodeNumber);
+            }
+            else
+            {
+                throw new InvalidFormatException(CorruptHFSMessage);
+            }
+        }
+
+        private static IReadOnlyDictionary<HFSExtentKey, HFSExtentRecord> LoadExtents(IReadOnlyList<HFSTreeNode> extentsTree, int rootIndex)
+        {
+            var records = new Dictionary<HFSExtentKey, HFSExtentRecord>();
+            if (rootIndex == 0) return records;
+
+            EnumerateExtentsTree(extentsTree, records, rootIndex);
+            return records;
+        }
+
+        private static void EnumerateCatalogTree(
+            HFSHeaderTreeNode catalogHeader,
+            IReadOnlyList<HFSTreeNode> catalogTree,
+            IDictionary<HFSCatalogKey, HFSCatalogRecord> records,
+            IDictionary<uint, HFSCatalogThread> threads,
+            int parentIndex,
+            bool isHFSX)
+        {
+            var parent = catalogTree[parentIndex];
+            if (parent is HFSLeafTreeNode leafNode)
+            {
+                foreach (var record in leafNode.Records)
+                {
+                    ReadOnlySpan<byte> data = record.Data.AsSpan();
+                    if (HFSCatalogRecord.TryRead(ref data, catalogHeader.HeaderRecord.KeyCompareType, isHFSX, out var recordData))
+                    {
+                        var key = record.GetCatalogKey();
+                        if ((recordData!.Type == HFSCatalogRecordType.FileThread) || (recordData!.Type == HFSCatalogRecordType.FolderThread))
+                        {
+                            threads.Add(key.ParentId, (HFSCatalogThread)recordData);
+                        }
+                        else
+                        {
+                            records.Add(key, recordData);
+                        }
+                    }
+                    else
+                    {
+                        throw new InvalidFormatException(CorruptHFSMessage);
+                    }
+                }
+            }
+            else if (parent is HFSIndexTreeNode indexNode)
+            {
+                foreach (var record in indexNode.Records)
+                    EnumerateCatalogTree(catalogHeader, catalogTree, records, threads, (int)record.NodeNumber, isHFSX);
+            }
+            else
+            {
+                throw new InvalidFormatException(CorruptHFSMessage);
+            }
+        }
+
+        private static (HFSCatalogKey, HFSCatalogRecord) GetRecord(uint id, IDictionary<HFSCatalogKey, HFSCatalogRecord> records, IDictionary<uint, HFSCatalogThread> threads)
+        {
+            if (threads.TryGetValue(id, out var thread))
+            {
+                if (records.TryGetValue(thread.CatalogKey, out var record))
+                    return (thread.CatalogKey, record!);
+            }
+
+            throw new InvalidFormatException(CorruptHFSMessage);
+        }
+
+        private static string SanitizePath(string path)
+        {
+            var sb = new StringBuilder(path.Length);
+            foreach (char c in path)
+            {
+                if (!char.IsControl(c))
+                    sb.Append(c);
+            }
+            return sb.ToString();
+        }
+
+        private static string GetPath(HFSCatalogKey key, IDictionary<HFSCatalogKey, HFSCatalogRecord> records, IDictionary<uint, HFSCatalogThread> threads)
+        {
+            if (key.ParentId == 1)
+            {
+                return key.Name;
+            }
+            else
+            {
+                var (parentKey, _) = GetRecord(key.ParentId, records, threads);
+                var path = Path.Combine(GetPath(parentKey, records, threads), key.Name);
+                return SanitizePath(path);
+            }
+        }
+
+        private static IEnumerable<DmgArchiveEntry> LoadEntriesFromCatalogTree(
+            Stream partitionStream,
+            DmgFilePart filePart,
+            HFSVolumeHeader volumeHeader,
+            HFSHeaderTreeNode catalogHeader,
+            IReadOnlyList<HFSTreeNode> catalogTree,
+            IReadOnlyDictionary<HFSExtentKey, HFSExtentRecord> extents,
+            DmgArchive archive,
+            int rootIndex)
+        {
+            if (rootIndex == 0) return Array.Empty<DmgArchiveEntry>();
+
+            var records = new Dictionary<HFSCatalogKey, HFSCatalogRecord>();
+            var threads = new Dictionary<uint, HFSCatalogThread>();
+            EnumerateCatalogTree(catalogHeader, catalogTree, records, threads, rootIndex, volumeHeader.IsHFSX);
+
+            var entries = new List<DmgArchiveEntry>();
+            foreach (var kvp in records)
+            {
+                var key = kvp.Key;
+                var record = kvp.Value;
+
+                string path = GetPath(key, records, threads);
+                var stream = (record is HFSCatalogFile file) ? new HFSForkStream(partitionStream, volumeHeader, file.DataFork, file.FileId, extents) : null;
+                var entry = new DmgArchiveEntry(stream, archive, record, path, filePart);
+                entries.Add(entry);
+            }
+
+            return entries;
+        }
+
+        public static IEnumerable<DmgArchiveEntry> LoadEntriesFromPartition(Stream partitionStream, string fileName, DmgArchive archive)
+        {
+            if (!HFSVolumeHeader.TryRead(partitionStream, out var volumeHeader))
+                throw new InvalidFormatException(CorruptHFSMessage);
+            var filePart = new DmgFilePart(partitionStream, fileName);
+
+            var extentsFile = volumeHeader!.ExtentsFile;
+            var extentsStream = new HFSForkStream(partitionStream, volumeHeader, extentsFile);
+            var (extentsHeader, extentsTree) = ReadTree(extentsStream, volumeHeader.IsHFSX);
+
+            var extents = LoadExtents(extentsTree, (int)extentsHeader.HeaderRecord.RootNode);
+
+            var catalogFile = volumeHeader!.CatalogFile;
+            var catalogStream = new HFSForkStream(partitionStream, volumeHeader, catalogFile);
+            var (catalogHeader, catalogTree) = ReadTree(catalogStream, volumeHeader.IsHFSX);
+
+            return LoadEntriesFromCatalogTree(
+                partitionStream,
+                filePart,
+                volumeHeader,
+                catalogHeader,
+                catalogTree,
+                extents,
+                archive,
+                (int)catalogHeader.HeaderRecord.RootNode);
+        }
+    }
+}

src/SharpCompress/Common/Dmg/HFS/HFSVolumeHeader.cs

@@ -0,0 +1,179 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+
+namespace SharpCompress.Common.Dmg.HFS
+{
+    internal sealed class HFSVolumeHeader : HFSStructBase
+    {
+        private const ushort SignaturePlus = 0x482B;
+        private const ushort SignatureX = 0x4858;
+        private const int FinderInfoCount = 8;
+
+        public bool IsHFSX { get; }
+        public ushort Version { get; }
+        public uint Attributes { get; }
+        public uint LastMountedVersion { get; }
+        public uint JournalInfoBlock { get; }
+
+        public DateTime CreateDate { get; }
+        public DateTime ModifyDate { get; }
+        public DateTime BackupDate { get; }
+        public DateTime CheckedDate { get; }
+
+        public uint FileCount { get; }
+        public uint FolderCount { get; }
+
+        public uint BlockSize { get; }
+        public uint TotalBlocks { get; }
+        public uint FreeBlocks { get; }
+
+        public uint NextAllocation { get; }
+        public uint RsrcClumpSize { get; }
+        public uint DataClumpSize { get; }
+        public uint NextCatalogID { get; }
+
+        public uint WriteCount { get; }
+        public ulong EncodingsBitmap { get; }
+
+        public IReadOnlyList<uint> FinderInfo { get; }
+
+        public HFSForkData AllocationFile { get; }
+        public HFSForkData ExtentsFile { get; }
+        public HFSForkData CatalogFile { get; }
+        public HFSForkData AttributesFile { get; }
+        public HFSForkData StartupFile { get; }
+
+        public HFSVolumeHeader(
+            bool isHFSX,
+            ushort version,
+            uint attributes,
+            uint lastMountedVersion,
+            uint journalInfoBlock,
+            DateTime createDate,
+            DateTime modifyDate,
+            DateTime backupDate,
+            DateTime checkedDate,
+            uint fileCount,
+            uint folderCount,
+            uint blockSize,
+            uint totalBlocks,
+            uint freeBlocks,
+            uint nextAllocation,
+            uint rsrcClumpSize,
+            uint dataClumpSize,
+            uint nextCatalogID,
+            uint writeCount,
+            ulong encodingsBitmap,
+            IReadOnlyList<uint> finderInfo,
+            HFSForkData allocationFile,
+            HFSForkData extentsFile,
+            HFSForkData catalogFile,
+            HFSForkData attributesFile,
+            HFSForkData startupFile)
+        {
+            IsHFSX = isHFSX;
+            Version = version;
+            Attributes = attributes;
+            LastMountedVersion = lastMountedVersion;
+            JournalInfoBlock = journalInfoBlock;
+            CreateDate = createDate;
+            ModifyDate = modifyDate;
+            BackupDate = backupDate;
+            CheckedDate = checkedDate;
+            FileCount = fileCount;
+            FolderCount = folderCount;
+            BlockSize = blockSize;
+            TotalBlocks = totalBlocks;
+            FreeBlocks = freeBlocks;
+            NextAllocation = nextAllocation;
+            RsrcClumpSize = rsrcClumpSize;
+            DataClumpSize = dataClumpSize;
+            NextCatalogID = nextCatalogID;
+            WriteCount = writeCount;
+            EncodingsBitmap = encodingsBitmap;
+            FinderInfo = finderInfo;
+            AllocationFile = allocationFile;
+            ExtentsFile = extentsFile;
+            CatalogFile = catalogFile;
+            AttributesFile = attributesFile;
+            StartupFile = startupFile;
+        }
+
+        private static IReadOnlyList<uint> ReadFinderInfo(Stream stream)
+        {
+            var finderInfo = new uint[FinderInfoCount];
+            for (int i = 0; i < FinderInfoCount; i++)
+                finderInfo[i] = ReadUInt32(stream);
+            return finderInfo;
+        }
+
+        public static bool TryRead(Stream stream, out HFSVolumeHeader? header)
+        {
+            header = null;
+            stream.Skip(1024); // reserved bytes
+
+            bool isHFSX;
+            ushort sig = ReadUInt16(stream);
+            if (sig == SignaturePlus) isHFSX = false;
+            else if (sig == SignatureX) isHFSX = true;
+            else return false;
+
+            ushort version = ReadUInt16(stream);
+            uint attributes = ReadUInt32(stream);
+            uint lastMountedVersion = ReadUInt32(stream);
+            uint journalInfoBlock = ReadUInt32(stream);
+            DateTime createDate = ReadDate(stream);
+            DateTime modifyDate = ReadDate(stream);
+            DateTime backupDate = ReadDate(stream);
+            DateTime checkedDate = ReadDate(stream);
+            uint fileCount = ReadUInt32(stream);
+            uint folderCount = ReadUInt32(stream);
+            uint blockSize = ReadUInt32(stream);
+            uint totalBlocks = ReadUInt32(stream);
+            uint freeBlocks = ReadUInt32(stream);
+            uint nextAllocation = ReadUInt32(stream);
+            uint rsrcClumpSize = ReadUInt32(stream);
+            uint dataClumpSize = ReadUInt32(stream);
+            uint nextCatalogID = ReadUInt32(stream);
+            uint writeCount = ReadUInt32(stream);
+            ulong encodingsBitmap = ReadUInt64(stream);
+            IReadOnlyList<uint> finderInfo = ReadFinderInfo(stream);
+            HFSForkData allocationFile = HFSForkData.Read(stream);
+            HFSForkData extentsFile = HFSForkData.Read(stream);
+            HFSForkData catalogFile = HFSForkData.Read(stream);
+            HFSForkData attributesFile = HFSForkData.Read(stream);
+            HFSForkData startupFile = HFSForkData.Read(stream);
+
+            header = new HFSVolumeHeader(
+                isHFSX,
+                version,
+                attributes,
+                lastMountedVersion,
+                journalInfoBlock,
+                createDate,
+                modifyDate,
+                backupDate,
+                checkedDate,
+                fileCount,
+                folderCount,
+                blockSize,
+                totalBlocks,
+                freeBlocks,
+                nextAllocation,
+                rsrcClumpSize,
+                dataClumpSize,
+                nextCatalogID,
+                writeCount,
+                encodingsBitmap,
+                finderInfo,
+                allocationFile,
+                extentsFile,
+                catalogFile,
+                attributesFile,
+                startupFile);
+
+            return true;
+        }
+    }
+}

src/SharpCompress/Common/Dmg/Headers/BlkxChunk.cs

@@ -0,0 +1,49 @@
+using System;
+
+namespace SharpCompress.Common.Dmg.Headers
+{
+    internal enum BlkxChunkType : uint
+    {
+        Zero = 0x00000000u,
+        Uncompressed = 0x00000001u,
+        Ignore = 0x00000002u,
+        AdcCompressed = 0x80000004u,
+        ZlibCompressed = 0x80000005u,
+        Bz2Compressed = 0x80000006u,
+        Comment = 0x7FFFFFFEu,
+        Last = 0xFFFFFFFFu,
+    }
+
+    internal sealed class BlkxChunk : DmgStructBase
+    {
+        private const int SectorSize = 512;
+
+        public BlkxChunkType Type { get; }      // Compression type used or chunk type
+        public uint Comment { get; }            // "+beg" or "+end", if EntryType is comment (0x7FFFFFFE). Else reserved.
+        public ulong UncompressedOffset { get; }      // Start sector of this chunk
+        public ulong UncompressedLength { get; }       // Number of sectors in this chunk
+        public ulong CompressedOffset { get; }  // Start of chunk in data fork
+        public ulong CompressedLength { get; }  // Count of bytes of chunk, in data fork
+
+        private BlkxChunk(BlkxChunkType type, uint comment, ulong sectorNumber, ulong sectorCount, ulong compressedOffset, ulong compressedLength)
+        {
+            Type = type;
+            Comment = comment;
+            UncompressedOffset = sectorNumber * SectorSize;
+            UncompressedLength = sectorCount * SectorSize;
+            CompressedOffset = compressedOffset;
+            CompressedLength = compressedLength;
+        }
+
+        public static bool TryRead(ref ReadOnlySpan<byte> data, out BlkxChunk? chunk)
+        {
+            chunk = null;
+
+            var type = (BlkxChunkType)ReadUInt32(ref data);
+            if (!Enum.IsDefined(typeof(BlkxChunkType), type)) return false;
+
+            chunk = new BlkxChunk(type, ReadUInt32(ref data), ReadUInt64(ref data), ReadUInt64(ref data), ReadUInt64(ref data), ReadUInt64(ref data));
+            return true;
+        }
+    }
+}

src/SharpCompress/Common/Dmg/Headers/BlkxTable.cs

@@ -0,0 +1,75 @@
+using System;
+using System.Collections.Generic;
+
+namespace SharpCompress.Common.Dmg.Headers
+{
+    internal sealed class BlkxTable : DmgStructBase
+    {
+        private const uint Signature = 0x6d697368u;
+
+        public uint Version { get; }             // Current version is 1
+        public ulong SectorNumber { get; }       // Starting disk sector in this blkx descriptor
+        public ulong SectorCount { get; }        // Number of disk sectors in this blkx descriptor
+
+        public ulong DataOffset { get; }
+        public uint BuffersNeeded { get; }
+        public uint BlockDescriptors { get; }    // Number of descriptors
+
+        public UdifChecksum Checksum { get; }
+
+        public IReadOnlyList<BlkxChunk> Chunks { get; }
+
+        private BlkxTable(
+            uint version,
+            ulong sectorNumber,
+            ulong sectorCount,
+            ulong dataOffset,
+            uint buffersNeeded,
+            uint blockDescriptors,
+            UdifChecksum checksum,
+            IReadOnlyList<BlkxChunk> chunks)
+        {
+            Version = version;
+            SectorNumber = sectorNumber;
+            SectorCount = sectorCount;
+            DataOffset = dataOffset;
+            BuffersNeeded = buffersNeeded;
+            BlockDescriptors = blockDescriptors;
+            Checksum = checksum;
+            Chunks = chunks;
+        }
+
+        public static bool TryRead(in byte[] buffer, out BlkxTable? header)
+        {
+            header = null;
+
+            ReadOnlySpan<byte> data = buffer.AsSpan();
+
+            uint sig = ReadUInt32(ref data);
+            if (sig != Signature) return false;
+
+            uint version = ReadUInt32(ref data);
+            ulong sectorNumber = ReadUInt64(ref data);
+            ulong sectorCount = ReadUInt64(ref data);
+
+            ulong dataOffset = ReadUInt64(ref data);
+            uint buffersNeeded = ReadUInt32(ref data);
+            uint blockDescriptors = ReadUInt32(ref data);
+
+            data = data.Slice(6 * sizeof(uint)); // reserved
+
+            var checksum = UdifChecksum.Read(ref data);
+
+            uint chunkCount = ReadUInt32(ref data);
+            var chunks = new BlkxChunk[chunkCount];
+            for (int i = 0; i < chunkCount; i++)
+            {
+                if (!BlkxChunk.TryRead(ref data, out var chunk)) return false;
+                chunks[i] = chunk!;
+            }
+
+            header = new BlkxTable(version, sectorNumber, sectorCount, dataOffset, buffersNeeded, blockDescriptors, checksum, chunks);
+            return true;
+        }
+    }
+}

src/SharpCompress/Common/Dmg/Headers/DmgHeader.cs

@@ -0,0 +1,138 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+
+namespace SharpCompress.Common.Dmg.Headers
+{
+    internal sealed class DmgHeader : DmgStructBase
+    {
+        public const int HeaderSize = 512;
+        private const uint Signature = 0x6B6F6C79u;
+        private const int UuidSize = 16; // 128 bit
+
+        public uint Version { get; }                     // Current version is 4
+        public uint Flags { get; }                       // Flags
+        public ulong RunningDataForkOffset { get; }      //
+        public ulong DataForkOffset { get; }             // Data fork offset (usually 0, beginning of file)
+        public ulong DataForkLength { get; }             // Size of data fork (usually up to the XMLOffset, below)
+        public ulong RsrcForkOffset { get; }             // Resource fork offset, if any
+        public ulong RsrcForkLength { get; }             // Resource fork length, if any
+        public uint SegmentNumber { get; }               // Usually 1, may be 0
+        public uint SegmentCount { get; }                // Usually 1, may be 0
+        public IReadOnlyList<byte> SegmentID { get; }    // 128-bit GUID identifier of segment (if SegmentNumber !=0)
+
+        public UdifChecksum DataChecksum { get; }
+
+        public ulong XMLOffset { get; }                  // Offset of property list in DMG, from beginning
+        public ulong XMLLength { get; }                  // Length of property list
+
+        public UdifChecksum Checksum { get; }
+        
+        public uint ImageVariant { get; }                // Commonly 1
+        public ulong SectorCount { get; }                // Size of DMG when expanded, in sectors
+
+        private DmgHeader(
+            uint version,
+            uint flags,
+            ulong runningDataForkOffset,
+            ulong dataForkOffset,
+            ulong dataForkLength,
+            ulong rsrcForkOffset,
+            ulong rsrcForkLength,
+            uint segmentNumber,
+            uint segmentCount,
+            IReadOnlyList<byte> segmentID,
+            UdifChecksum dataChecksum,
+            ulong xMLOffset,
+            ulong xMLLength,
+            UdifChecksum checksum,
+            uint imageVariant,
+            ulong sectorCount)
+        {
+            Version = version;
+            Flags = flags;
+            RunningDataForkOffset = runningDataForkOffset;
+            DataForkOffset = dataForkOffset;
+            DataForkLength = dataForkLength;
+            RsrcForkOffset = rsrcForkOffset;
+            RsrcForkLength = rsrcForkLength;
+            SegmentNumber = segmentNumber;
+            SegmentCount = segmentCount;
+            SegmentID = segmentID;
+            DataChecksum = dataChecksum;
+            XMLOffset = xMLOffset;
+            XMLLength = xMLLength;
+            Checksum = checksum;
+            ImageVariant = imageVariant;
+            SectorCount = sectorCount;
+        }
+
+        private static void ReadUuid(ref ReadOnlySpan<byte> data, byte[] buffer)
+        {
+            data.Slice(0, UuidSize).CopyTo(buffer);
+            data = data.Slice(UuidSize);
+        }
+
+        internal static bool TryRead(Stream input, out DmgHeader? header)
+        {
+            header = null;
+
+            var buffer = new byte[HeaderSize];
+            int count = input.Read(buffer, 0, HeaderSize);
+            if (count != HeaderSize) return false;
+            ReadOnlySpan<byte> data = buffer.AsSpan();
+
+            uint sig = ReadUInt32(ref data);
+            if (sig != Signature) return false;
+
+            uint version = ReadUInt32(ref data);
+
+            uint size = ReadUInt32(ref data);
+            if (size != (uint)HeaderSize) return false;
+
+            uint flags = ReadUInt32(ref data);
+            ulong runningDataForkOffset = ReadUInt64(ref data);
+            ulong dataForkOffset = ReadUInt64(ref data);
+            ulong dataForkLength = ReadUInt64(ref data);
+            ulong rsrcForkOffset = ReadUInt64(ref data);
+            ulong rsrcForkLength = ReadUInt64(ref data);
+            uint segmentNumber = ReadUInt32(ref data);
+            uint segmentCount = ReadUInt32(ref data);
+
+            var segmentID = new byte[UuidSize];
+            ReadUuid(ref data, segmentID);
+
+            var dataChecksum = UdifChecksum.Read(ref data);
+
+            ulong xmlOffset = ReadUInt64(ref data);
+            ulong xmlLength = ReadUInt64(ref data);
+
+            data = data.Slice(120); // Reserved bytes
+
+            var checksum = UdifChecksum.Read(ref data);
+
+            uint imageVariant = ReadUInt32(ref data);
+            ulong sectorCount = ReadUInt64(ref data);
+
+            header = new DmgHeader(
+                version,
+                flags,
+                runningDataForkOffset,
+                dataForkOffset,
+                dataForkLength,
+                rsrcForkOffset,
+                rsrcForkLength,
+                segmentNumber,
+                segmentCount,
+                segmentID,
+                dataChecksum,
+                xmlOffset,
+                xmlLength,
+                checksum,
+                imageVariant,
+                sectorCount);
+
+            return true;
+        }
+    }
+}

src/SharpCompress/Common/Dmg/Headers/DmgStructBase.cs

@@ -0,0 +1,22 @@
+using System;
+using System.Buffers.Binary;
+
+namespace SharpCompress.Common.Dmg.Headers
+{
+    internal abstract class DmgStructBase
+    {
+        protected static uint ReadUInt32(ref ReadOnlySpan<byte> data)
+        {
+            uint val = BinaryPrimitives.ReadUInt32BigEndian(data);
+            data = data.Slice(sizeof(uint));
+            return val;
+        }
+
+        protected static ulong ReadUInt64(ref ReadOnlySpan<byte> data)
+        {
+            ulong val = BinaryPrimitives.ReadUInt64BigEndian(data);
+            data = data.Slice(sizeof(ulong));
+            return val;
+        }
+    }
+}

src/SharpCompress/Common/Dmg/Headers/GptHeader.cs

@@ -0,0 +1,90 @@
+using System;
+using System.Buffers.Binary;
+using System.IO;
+
+namespace SharpCompress.Common.Dmg.Headers
+{
+    internal sealed class GptHeader : GptStructBase
+    {
+        private const int HeaderSize = 92;
+        private static readonly ulong Signature = BinaryPrimitives.ReadUInt64LittleEndian(new byte[] { 69, 70, 73, 32, 80, 65, 82, 84 });
+
+        public uint Revision { get; }
+        public uint Crc32Header { get; }
+        public ulong CurrentLba { get; }
+        public ulong BackupLba { get; }
+        public ulong FirstUsableLba { get; }
+        public ulong LastUsableLba { get; }
+        public Guid DiskGuid { get; }
+        public ulong EntriesStart { get; }
+        public uint EntriesCount { get; }
+        public uint EntriesSize { get; }
+        public uint Crc32Array { get; }
+
+        private GptHeader(
+            uint revision,
+            uint crc32Header,
+            ulong currentLba,
+            ulong backupLba,
+            ulong firstUsableLba,
+            ulong lastUsableLba,
+            Guid diskGuid,
+            ulong entriesStart,
+            uint entriesCount,
+            uint entriesSize,
+            uint crc32Array)
+        {
+            Revision = revision;
+            Crc32Header = crc32Header;
+            CurrentLba = currentLba;
+            BackupLba = backupLba;
+            FirstUsableLba = firstUsableLba;
+            LastUsableLba = lastUsableLba;
+            DiskGuid = diskGuid;
+            EntriesStart = entriesStart;
+            EntriesCount = entriesCount;
+            EntriesSize = entriesSize;
+            Crc32Array = crc32Array;
+        }
+
+        public static bool TryRead(Stream stream, out GptHeader? header)
+        {
+            header = null;
+
+            ulong sig = ReadUInt64(stream);
+            if (sig != Signature) return false;
+
+            uint revision = ReadUInt32(stream);
+
+            uint headerSize = ReadUInt32(stream);
+            if (headerSize != HeaderSize) return false;
+
+            uint crc32Header = ReadUInt32(stream);
+            _ = ReadUInt32(stream); // reserved
+            ulong currentLba = ReadUInt64(stream);
+            ulong backupLba = ReadUInt64(stream);
+            ulong firstUsableLba = ReadUInt64(stream);
+            ulong lastUsableLba = ReadUInt64(stream);
+            Guid diskGuid = ReadGuid(stream);
+            ulong entriesStart = ReadUInt64(stream);
+            uint entriesCount = ReadUInt32(stream);
+            uint entriesSize = ReadUInt32(stream);
+            uint crc32Array = ReadUInt32(stream);
+
+            header = new GptHeader(
+                revision,
+                crc32Header,
+                currentLba,
+                backupLba,
+                firstUsableLba,
+                lastUsableLba,
+                diskGuid,
+                entriesStart,
+                entriesCount,
+                entriesSize,
+                crc32Array);
+
+            return true;
+        }
+    }
+}

src/SharpCompress/Common/Dmg/Headers/GptPartitionEntry.cs

@@ -0,0 +1,36 @@
+using System;
+using System.IO;
+
+namespace SharpCompress.Common.Dmg.Headers
+{
+    internal sealed class GptPartitionEntry : GptStructBase
+    {
+        public Guid TypeGuid { get; }
+        public Guid Guid { get; }
+        public ulong FirstLba { get; }
+        public ulong LastLba { get; }
+        public ulong Attributes { get; }
+        public string Name { get; }
+
+        private GptPartitionEntry(Guid typeGuid, Guid guid, ulong firstLba, ulong lastLba, ulong attributes, string name)
+        {
+            TypeGuid = typeGuid;
+            Guid = guid;
+            FirstLba = firstLba;
+            LastLba = lastLba;
+            Attributes = attributes;
+            Name = name;
+        }
+
+        public static GptPartitionEntry Read(Stream stream)
+        {
+            return new GptPartitionEntry(
+                ReadGuid(stream),
+                ReadGuid(stream),
+                ReadUInt64(stream),
+                ReadUInt64(stream),
+                ReadUInt64(stream),
+                ReadString(stream, 72));
+        }
+    }
+}

src/SharpCompress/Common/Dmg/Headers/GptStructBase.cs

@@ -0,0 +1,56 @@
+using System;
+using System.Buffers.Binary;
+using System.IO;
+using System.Text;
+
+namespace SharpCompress.Common.Dmg.Headers
+{
+    internal abstract class GptStructBase
+    {
+        private static readonly byte[] _buffer = new byte[8];
+
+        protected static ushort ReadUInt16(Stream stream)
+        {
+            if (stream.Read(_buffer, 0, sizeof(ushort)) != sizeof(ushort))
+                throw new EndOfStreamException();
+
+            return BinaryPrimitives.ReadUInt16LittleEndian(_buffer);
+        }
+
+        protected static uint ReadUInt32(Stream stream)
+        {
+            if (stream.Read(_buffer, 0, sizeof(uint)) != sizeof(uint))
+                throw new EndOfStreamException();
+
+            return BinaryPrimitives.ReadUInt32LittleEndian(_buffer);
+        }
+
+        protected static ulong ReadUInt64(Stream stream)
+        {
+            if (stream.Read(_buffer, 0, sizeof(ulong)) != sizeof(ulong))
+                throw new EndOfStreamException();
+
+            return BinaryPrimitives.ReadUInt64LittleEndian(_buffer);
+        }
+
+        protected static Guid ReadGuid(Stream stream)
+        {
+            int a = (int)ReadUInt32(stream);
+            short b = (short)ReadUInt16(stream);
+            short c = (short)ReadUInt16(stream);
+
+            if (stream.Read(_buffer, 0, 8) != 8)
+                throw new EndOfStreamException();
+
+            return new Guid(a, b, c, _buffer);
+        }
+
+        protected static string ReadString(Stream stream, int byteSize)
+        {
+            var buffer = new byte[byteSize];
+            if (stream.Read(buffer, 0, byteSize) != byteSize)
+                throw new EndOfStreamException();
+            return Encoding.Unicode.GetString(buffer).NullTerminate();
+        }
+    }
+}

src/SharpCompress/Common/Dmg/Headers/UdifChecksum.cs

@@ -0,0 +1,33 @@
+using System;
+using System.Collections.Generic;
+
+namespace SharpCompress.Common.Dmg.Headers
+{
+    internal sealed class UdifChecksum : DmgStructBase
+    {
+        private const int MaxSize = 32; // * 4 to get byte size
+
+        public uint Type { get; }
+        public uint Size { get; } // in bits
+        public IReadOnlyList<uint> Bits { get; }
+
+        private UdifChecksum(uint type, uint size, IReadOnlyList<uint> bits)
+        {
+            Type = type;
+            Size = size;
+            Bits = bits;
+        }
+
+        public static UdifChecksum Read(ref ReadOnlySpan<byte> data)
+        {
+            uint type = ReadUInt32(ref data);
+            uint size = ReadUInt32(ref data);
+
+            var bits = new uint[MaxSize];
+            for (int i = 0; i < MaxSize; i++)
+                bits[i] = ReadUInt32(ref data);
+
+            return new UdifChecksum(type, size, bits);
+        }
+    }
+}

src/SharpCompress/Common/Dmg/PartitionFormat.cs

@@ -0,0 +1,14 @@
+using System;
+
+namespace SharpCompress.Common.Dmg
+{
+    internal static class PartitionFormat
+    {
+        public static readonly Guid AppleHFS         = new Guid("48465300-0000-11AA-AA11-00306543ECAC");
+        public static readonly Guid AppleUFS         = new Guid("55465300-0000-11AA-AA11-00306543ECAC");
+        public static readonly Guid AppleBoot        = new Guid("426F6F74-0000-11AA-AA11-00306543ECAC");
+        public static readonly Guid AppleRaid        = new Guid("52414944-0000-11AA-AA11-00306543ECAC");
+        public static readonly Guid AppleRaidOffline = new Guid("52414944-5F4F-11AA-AA11-00306543ECAC");
+        public static readonly Guid AppleLabel       = new Guid("4C616265-6C00-11AA-AA11-00306543ECAC");
+    }
+}

src/SharpCompress/Common/EntryStream.cs

@@ -47,7 +47,8 @@ namespace SharpCompress.Common
 
         public override bool CanWrite => false;
 
-        public override void Flush() {
+        public override void Flush()
+        {
         }
 
         public override long Length => _stream.Length;

src/SharpCompress/Common/ExtractionMethods.cs

@@ -8,9 +8,9 @@ namespace SharpCompress.Common
         /// <summary>
         /// Extract to specific directory, retaining filename
         /// </summary>
-        public static void WriteEntryToDirectory(IEntry entry, 
+        public static void WriteEntryToDirectory(IEntry entry,
                                                  string destinationDirectory,
-                                                 ExtractionOptions? options, 
+                                                 ExtractionOptions? options,
                                                  Action<string, ExtractionOptions?> write)
         {
             string destinationFileName;
@@ -18,20 +18,18 @@ namespace SharpCompress.Common
             string fullDestinationDirectoryPath = Path.GetFullPath(destinationDirectory);
 
             options ??= new ExtractionOptions()
-                        {
-                            Overwrite = true
-                        };
+            {
+                Overwrite = true
+            };
 
             if (options.ExtractFullPath)
             {
-                string folder = Path.GetDirectoryName(entry.Key);
-                string destdir = Path.GetFullPath(
-                                                  Path.Combine(fullDestinationDirectoryPath, folder)
-                                                 );
+                string folder = Path.GetDirectoryName(entry.Key)!;
+                string destdir = Path.GetFullPath(Path.Combine(fullDestinationDirectoryPath, folder));
 
                 if (!Directory.Exists(destdir))
                 {
-                    if (!destdir.StartsWith(fullDestinationDirectoryPath))
+                    if (!destdir.StartsWith(fullDestinationDirectoryPath, StringComparison.Ordinal))
                     {
                         throw new ExtractionException("Entry is trying to create a directory outside of the destination directory.");
                     }
@@ -41,7 +39,7 @@ namespace SharpCompress.Common
                 destinationFileName = Path.Combine(destdir, file);
             }
             else
-            {        
+            {
                 destinationFileName = Path.Combine(fullDestinationDirectoryPath, file);
 
             }
@@ -50,7 +48,7 @@ namespace SharpCompress.Common
             {
                 destinationFileName = Path.GetFullPath(destinationFileName);
 
-                if (!destinationFileName.StartsWith(fullDestinationDirectoryPath))
+                if (!destinationFileName.StartsWith(fullDestinationDirectoryPath, StringComparison.Ordinal))
                 {
                     throw new ExtractionException("Entry is trying to write a file outside of the destination directory.");
                 }
@@ -61,7 +59,7 @@ namespace SharpCompress.Common
                 Directory.CreateDirectory(destinationFileName);
             }
         }
-        
+
         public static void WriteEntryToFile(IEntry entry, string destinationFileName,
                                             ExtractionOptions? options,
                                             Action<string, FileMode> openAndWrite)
@@ -78,9 +76,9 @@ namespace SharpCompress.Common
             {
                 FileMode fm = FileMode.Create;
                 options ??= new ExtractionOptions()
-                                {
-                                    Overwrite = true
-                                };
+                {
+                    Overwrite = true
+                };
 
                 if (!options.Overwrite)
                 {

src/SharpCompress/Common/ExtractionOptions.cs

@@ -7,7 +7,7 @@ namespace SharpCompress.Common
         /// <summary>
         /// overwrite target if it exists
         /// </summary>
-        public bool Overwrite  {get; set; }
+        public bool Overwrite { get; set; }
 
         /// <summary>
         /// extract with internal directory structure

src/SharpCompress/Common/GZip/GZipEntry.cs

@@ -15,7 +15,7 @@ namespace SharpCompress.Common.GZip
 
         public override CompressionType CompressionType => CompressionType.GZip;
 
-        public override long Crc => 0;
+        public override long Crc => _filePart.Crc ?? 0;
 
         public override string Key => _filePart.FilePartName;
 
@@ -23,7 +23,7 @@ namespace SharpCompress.Common.GZip
 
         public override long CompressedSize => 0;
 
-        public override long Size => 0;
+        public override long Size => _filePart.UncompressedSize ?? 0;
 
         public override DateTime? LastModifiedTime => _filePart.DateModified;
 

src/SharpCompress/Common/GZip/GZipFilePart.cs

@@ -8,7 +8,7 @@ using SharpCompress.Compressors.Deflate;
 
 namespace SharpCompress.Common.GZip
 {
-    internal class GZipFilePart : FilePart
+    internal sealed class GZipFilePart : FilePart
     {
         private string? _name;
         private readonly Stream _stream;
@@ -16,14 +16,23 @@ namespace SharpCompress.Common.GZip
         internal GZipFilePart(Stream stream, ArchiveEncoding archiveEncoding)
             : base(archiveEncoding)
         {
-            ReadAndValidateGzipHeader(stream);
-            EntryStartPosition = stream.Position;
             _stream = stream;
+            ReadAndValidateGzipHeader();
+            if (stream.CanSeek)
+            {
+                long position = stream.Position;
+                stream.Position = stream.Length - 8;
+                ReadTrailer();
+                stream.Position = position;
+            }
+            EntryStartPosition = stream.Position;
         }
 
         internal long EntryStartPosition { get; }
 
         internal DateTime? DateModified { get; private set; }
+        internal int? Crc { get; private set; }
+        internal int? UncompressedSize { get; private set; }
 
         internal override string FilePartName => _name!;
 
@@ -37,11 +46,21 @@ namespace SharpCompress.Common.GZip
             return _stream;
         }
 
-        private void ReadAndValidateGzipHeader(Stream stream)
+        private void ReadTrailer()
+        {
+            // Read and potentially verify the GZIP trailer: CRC32 and  size mod 2^32
+            Span<byte> trailer = stackalloc byte[8];
+            int n = _stream.Read(trailer);
+
+            Crc = BinaryPrimitives.ReadInt32LittleEndian(trailer);
+            UncompressedSize = BinaryPrimitives.ReadInt32LittleEndian(trailer.Slice(4));
+        }
+
+        private void ReadAndValidateGzipHeader()
         {
             // read the header on the first read
-            byte[] header = new byte[10];
-            int n = stream.Read(header, 0, header.Length);
+            Span<byte> header = stackalloc byte[10];
+            int n = _stream.Read(header);
 
             // workitem 8501: handle edge case (decompress empty stream)
             if (n == 0)
@@ -59,17 +78,17 @@ namespace SharpCompress.Common.GZip
                 throw new ZlibException("Bad GZIP header.");
             }
 
-            int timet = BinaryPrimitives.ReadInt32LittleEndian(header.AsSpan(4));
+            int timet = BinaryPrimitives.ReadInt32LittleEndian(header.Slice(4));
             DateModified = TarHeader.EPOCH.AddSeconds(timet);
             if ((header[3] & 0x04) == 0x04)
             {
                 // read and discard extra field
-                n = stream.Read(header, 0, 2); // 2-byte length field
+                n = _stream.Read(header.Slice(0, 2)); // 2-byte length field
 
-                Int16 extraLength = (Int16)(header[0] + header[1] * 256);
+                short extraLength = (short)(header[0] + header[1] * 256);
                 byte[] extra = new byte[extraLength];
 
-                if (!stream.ReadFully(extra))
+                if (!_stream.ReadFully(extra))
                 {
                     throw new ZlibException("Unexpected end-of-file reading GZIP header.");
                 }
@@ -77,27 +96,27 @@ namespace SharpCompress.Common.GZip
             }
             if ((header[3] & 0x08) == 0x08)
             {
-                _name = ReadZeroTerminatedString(stream);
+                _name = ReadZeroTerminatedString(_stream);
             }
             if ((header[3] & 0x10) == 0x010)
             {
-                ReadZeroTerminatedString(stream);
+                ReadZeroTerminatedString(_stream);
             }
             if ((header[3] & 0x02) == 0x02)
             {
-                stream.ReadByte(); // CRC16, ignore
+                _stream.ReadByte(); // CRC16, ignore
             }
         }
 
         private string ReadZeroTerminatedString(Stream stream)
         {
-            byte[] buf1 = new byte[1];
+            Span<byte> buf1 = stackalloc byte[1];
             var list = new List<byte>();
             bool done = false;
             do
             {
                 // workitem 7740
-                int n = stream.Read(buf1, 0, 1);
+                int n = stream.Read(buf1);
                 if (n != 1)
                 {
                     throw new ZlibException("Unexpected EOF reading GZIP header.");

src/SharpCompress/Common/IncompleteArchiveException.cs

@@ -1,4 +1,6 @@
-namespace SharpCompress.Common
+using System;
+
+namespace SharpCompress.Common
 {
     public class IncompleteArchiveException : ArchiveException
     {
@@ -6,5 +8,10 @@
             : base(message)
         {
         }
+
+        public IncompleteArchiveException(string message, Exception inner)
+            : base(message, inner)
+        {
+        }
     }
 }

src/SharpCompress/Common/Rar/Headers/AVHeader.cs

@@ -4,8 +4,8 @@ namespace SharpCompress.Common.Rar.Headers
 {
     internal class AvHeader : RarHeader
     {
-        public AvHeader(RarHeader header, RarCrcBinaryReader reader) 
-            : base(header, reader, HeaderType.Av) 
+        public AvHeader(RarHeader header, RarCrcBinaryReader reader)
+            : base(header, reader, HeaderType.Av)
         {
             if (IsRar5)
             {

src/SharpCompress/Common/Rar/Headers/ArchiveCryptHeader.cs

@@ -6,7 +6,7 @@ namespace SharpCompress.Common.Rar.Headers
 {
     internal class ArchiveCryptHeader : RarHeader
     {
-        
+
         private const int CRYPT_VERSION = 0; // Supported encryption version.
         private const int SIZE_SALT50 = 16;
         private const int SIZE_SALT30 = 8;
@@ -15,14 +15,14 @@ namespace SharpCompress.Common.Rar.Headers
         private const int SIZE_PSWCHECK_CSUM = 4;
         private const int CRYPT5_KDF_LG2_COUNT = 15; // LOG2 of PDKDF2 iteration count.
         private const int CRYPT5_KDF_LG2_COUNT_MAX = 24; // LOG2 of maximum accepted iteration count.
-        
-        
+
+
         private bool _usePswCheck;
         private uint _lg2Count; // Log2 of PBKDF2 repetition count.
         private byte[] _salt;
         private byte[] _pswCheck;
         private byte[] _pswCheckCsm;
-        
+
         public ArchiveCryptHeader(RarHeader header, RarCrcBinaryReader reader)
             : base(header, reader, HeaderType.Crypt)
         {
@@ -35,12 +35,12 @@ namespace SharpCompress.Common.Rar.Headers
             {
                 //error?
                 return;
-            } 
+            }
             var encryptionFlags = reader.ReadRarVIntUInt32();
             _usePswCheck = FlagUtility.HasFlag(encryptionFlags, EncryptionFlagsV5.CHFL_CRYPT_PSWCHECK);
             _lg2Count = reader.ReadRarVIntByte(1);
 
-            
+
             //UsePswCheck = HasHeaderFlag(EncryptionFlagsV5.CHFL_CRYPT_PSWCHECK);
             if (_lg2Count > CRYPT5_KDF_LG2_COUNT_MAX)
             {

src/SharpCompress/Common/Rar/Headers/ArchiveHeader.cs

@@ -4,14 +4,14 @@ namespace SharpCompress.Common.Rar.Headers
 {
     internal sealed class ArchiveHeader : RarHeader
     {
-        public ArchiveHeader(RarHeader header, RarCrcBinaryReader reader) 
-            : base(header, reader, HeaderType.Archive) 
+        public ArchiveHeader(RarHeader header, RarCrcBinaryReader reader)
+            : base(header, reader, HeaderType.Archive)
         {
         }
 
         protected override void ReadFinish(MarkingBinaryReader reader)
         {
-            if (IsRar5) 
+            if (IsRar5)
             {
                 Flags = reader.ReadRarVIntUInt16();
                 if (HasFlag(ArchiveFlagsV5.HAS_VOLUME_NUMBER))
@@ -22,8 +22,8 @@ namespace SharpCompress.Common.Rar.Headers
                 //if (ExtraSize != 0) {
                 //    ReadLocator(reader);
                 //}
-            } 
-            else 
+            }
+            else
             {
                 Flags = HeaderFlags;
                 HighPosAv = reader.ReadInt16();
@@ -35,7 +35,8 @@ namespace SharpCompress.Common.Rar.Headers
             }
         }
 
-        private void ReadLocator(MarkingBinaryReader reader) {
+        private void ReadLocator(MarkingBinaryReader reader)
+        {
             var size = reader.ReadRarVIntUInt16();
             var type = reader.ReadRarVIntUInt16();
             if (type != 1)
@@ -47,18 +48,20 @@ namespace SharpCompress.Common.Rar.Headers
             const ushort hasQuickOpenOffset = 0x01;
             const ushort hasRecoveryOffset = 0x02;
             ulong quickOpenOffset = 0;
-            if ((flags & hasQuickOpenOffset) == hasQuickOpenOffset) { 
+            if ((flags & hasQuickOpenOffset) == hasQuickOpenOffset)
+            {
                 quickOpenOffset = reader.ReadRarVInt();
             }
             ulong recoveryOffset = 0;
-            if ((flags & hasRecoveryOffset) == hasRecoveryOffset) { 
+            if ((flags & hasRecoveryOffset) == hasRecoveryOffset)
+            {
                 recoveryOffset = reader.ReadRarVInt();
             }
         }
 
-        private ushort Flags  { get; set; }
+        private ushort Flags { get; set; }
 
-        private bool HasFlag(ushort flag) 
+        private bool HasFlag(ushort flag)
         {
             return (Flags & flag) == flag;
         }

src/SharpCompress/Common/Rar/Headers/CommentHeader.cs

@@ -5,8 +5,8 @@ namespace SharpCompress.Common.Rar.Headers
     internal class CommentHeader : RarHeader
     {
         protected CommentHeader(RarHeader header, RarCrcBinaryReader reader)
-            : base(header, reader, HeaderType.Comment) 
-        { 
+            : base(header, reader, HeaderType.Comment)
+        {
             if (IsRar5)
             {
                 throw new InvalidFormatException("unexpected rar5 record");

src/SharpCompress/Common/Rar/Headers/EndArchiveHeader.cs

@@ -4,14 +4,14 @@ namespace SharpCompress.Common.Rar.Headers
 {
     internal class EndArchiveHeader : RarHeader
     {
-        public EndArchiveHeader(RarHeader header, RarCrcBinaryReader reader) 
-            : base(header, reader, HeaderType.EndArchive) 
+        public EndArchiveHeader(RarHeader header, RarCrcBinaryReader reader)
+            : base(header, reader, HeaderType.EndArchive)
         {
         }
 
         protected override void ReadFinish(MarkingBinaryReader reader)
         {
-            if (IsRar5) 
+            if (IsRar5)
             {
                 Flags = reader.ReadRarVIntUInt16();
             }
@@ -31,7 +31,7 @@ namespace SharpCompress.Common.Rar.Headers
 
         private ushort Flags { get; set; }
 
-        private bool HasFlag(ushort flag) 
+        private bool HasFlag(ushort flag)
         {
             return (Flags & flag) == flag;
         }

src/SharpCompress/Common/Rar/Headers/FileHeader.cs

@@ -21,18 +21,18 @@ namespace SharpCompress.Common.Rar.Headers
     {
         private uint _fileCrc;
 
-        public FileHeader(RarHeader header, RarCrcBinaryReader reader, HeaderType headerType) 
-            : base(header, reader, headerType) 
+        public FileHeader(RarHeader header, RarCrcBinaryReader reader, HeaderType headerType)
+            : base(header, reader, headerType)
         {
         }
 
-        protected override void ReadFinish(MarkingBinaryReader reader) 
+        protected override void ReadFinish(MarkingBinaryReader reader)
         {
-            if (IsRar5) 
+            if (IsRar5)
             {
                 ReadFromReaderV5(reader);
-            } 
-            else 
+            }
+            else
             {
                 ReadFromReaderV4(reader);
             }
@@ -49,11 +49,13 @@ namespace SharpCompress.Common.Rar.Headers
 
             FileAttributes = reader.ReadRarVIntUInt32();
 
-            if (HasFlag(FileFlagsV5.HAS_MOD_TIME)) {
+            if (HasFlag(FileFlagsV5.HAS_MOD_TIME))
+            {
                 FileLastModifiedTime = Utility.UnixTimeToDateTime(reader.ReadUInt32());
             }
 
-            if (HasFlag(FileFlagsV5.HAS_CRC32)) {
+            if (HasFlag(FileFlagsV5.HAS_CRC32))
+            {
                 FileCrc = reader.ReadUInt32();
             }
 
@@ -65,7 +67,7 @@ namespace SharpCompress.Common.Rar.Headers
             // but it was already used in RAR 1.5 and Unpack needs to distinguish
             // them.
             CompressionAlgorithm = (byte)((compressionInfo & 0x3f) + 50);
-            
+
             // 7th bit (0x0040) defines the solid flag. If it is set, RAR continues to use the compression dictionary left after processing preceding files. 
             // It can be set only for file headers and is never set for service headers.
             IsSolid = (compressionInfo & 0x40) == 0x40;
@@ -74,7 +76,7 @@ namespace SharpCompress.Common.Rar.Headers
             CompressionMethod = (byte)((compressionInfo >> 7) & 0x7);
 
             // Bits 11 - 14 (0x3c00) define the minimum size of dictionary size required to extract data. Value 0 means 128 KB, 1 - 256 KB, ..., 14 - 2048 MB, 15 - 4096 MB.
-            WindowSize = IsDirectory ? 0 : ((size_t)0x20000) << ((compressionInfo>>10) & 0xf);
+            WindowSize = IsDirectory ? 0 : ((size_t)0x20000) << ((compressionInfo >> 10) & 0xf);
 
             HostOs = reader.ReadRarVIntByte();
 
@@ -101,18 +103,20 @@ namespace SharpCompress.Common.Rar.Headers
             FileName = ConvertPathV5(Encoding.UTF8.GetString(b, 0, b.Length));
 
             // extra size seems to be redudant since we know the total header size
-            if (ExtraSize != RemainingHeaderBytes(reader)) 
+            if (ExtraSize != RemainingHeaderBytes(reader))
             {
                 throw new InvalidFormatException("rar5 header size / extra size inconsistency");
             }
 
             isEncryptedRar5 = false;
 
-            while (RemainingHeaderBytes(reader) > 0) {
+            while (RemainingHeaderBytes(reader) > 0)
+            {
                 var size = reader.ReadRarVIntUInt16();
                 int n = RemainingHeaderBytes(reader);
                 var type = reader.ReadRarVIntUInt16();
-                switch (type) {
+                switch (type)
+                {
                     //TODO
                     case 1: // file encryption
                         {
@@ -120,7 +124,7 @@ namespace SharpCompress.Common.Rar.Headers
 
                             //var version = reader.ReadRarVIntByte();
                             //if (version != 0) throw new InvalidFormatException("unknown encryption algorithm " + version);
-                                                    }
+                        }
                         break;
                     //                    case 2: // file hash
                     //                        {
@@ -131,38 +135,41 @@ namespace SharpCompress.Common.Rar.Headers
                         {
                             ushort flags = reader.ReadRarVIntUInt16();
                             var isWindowsTime = (flags & 1) == 0;
-                            if ((flags & 0x2) == 0x2) {
+                            if ((flags & 0x2) == 0x2)
+                            {
                                 FileLastModifiedTime = ReadExtendedTimeV5(reader, isWindowsTime);
                             }
-                            if ((flags & 0x4) == 0x4) {
+                            if ((flags & 0x4) == 0x4)
+                            {
                                 FileCreatedTime = ReadExtendedTimeV5(reader, isWindowsTime);
                             }
-                            if ((flags & 0x8) == 0x8) {
+                            if ((flags & 0x8) == 0x8)
+                            {
                                 FileLastAccessedTime = ReadExtendedTimeV5(reader, isWindowsTime);
                             }
                         }
                         break;
-//TODO
-//                    case 4: // file version
-//                        {
-//
-//                        }
-//                        break;
-//                    case 5: // file system redirection
-//                        {
-//
-//                        }
-//                        break;
-//                    case 6: // unix owner
-//                        {
-//
-//                        }
-//                        break;
-//                    case 7: // service data
-//                        {
-//
-//                        }
-//                        break;
+                    //TODO
+                    //                    case 4: // file version
+                    //                        {
+                    //
+                    //                        }
+                    //                        break;
+                    //                    case 5: // file system redirection
+                    //                        {
+                    //
+                    //                        }
+                    //                        break;
+                    //                    case 6: // unix owner
+                    //                        {
+                    //
+                    //                        }
+                    //                        break;
+                    //                    case 7: // service data
+                    //                        {
+                    //
+                    //                        }
+                    //                        break;
 
                     default:
                         // skip unknown record types to allow new record types to be added in the future
@@ -171,25 +178,26 @@ namespace SharpCompress.Common.Rar.Headers
                 // drain any trailing bytes of extra record
                 int did = n - RemainingHeaderBytes(reader);
                 int drain = size - did;
-                if (drain > 0) 
+                if (drain > 0)
                 {
                     reader.ReadBytes(drain);
                 }
             }
 
-            if (AdditionalDataSize != 0) {
+            if (AdditionalDataSize != 0)
+            {
                 CompressedSize = AdditionalDataSize;
             }
         }
 
 
-        private static DateTime ReadExtendedTimeV5(MarkingBinaryReader reader, bool isWindowsTime) 
+        private static DateTime ReadExtendedTimeV5(MarkingBinaryReader reader, bool isWindowsTime)
         {
-            if (isWindowsTime) 
+            if (isWindowsTime)
             {
                 return DateTime.FromFileTime(reader.ReadInt64());
-            } 
-            else 
+            }
+            else
             {
                 return Utility.UnixTimeToDateTime(reader.ReadUInt32());
             }
@@ -201,7 +209,7 @@ namespace SharpCompress.Common.Rar.Headers
             {
                 // replace embedded \\ with valid filename char
                 return path.Replace('\\', '-').Replace('/', '\\');
-            } 
+            }
             return path;
         }
 
@@ -376,20 +384,22 @@ namespace SharpCompress.Common.Rar.Headers
 
         private ushort Flags { get; set; }
 
-        private bool HasFlag(ushort flag) 
+        private bool HasFlag(ushort flag)
         {
             return (Flags & flag) == flag;
         }
 
-        internal uint FileCrc 
-        { 
-            get { 
-                if (IsRar5 && !HasFlag(FileFlagsV5.HAS_CRC32)) {
-//!!! rar5: 
+        internal uint FileCrc
+        {
+            get
+            {
+                if (IsRar5 && !HasFlag(FileFlagsV5.HAS_CRC32))
+                {
+                    //!!! rar5: 
                     throw new InvalidOperationException("TODO rar5");
                 }
-                return _fileCrc; 
-            } 
+                return _fileCrc;
+            }
             private set => _fileCrc = value;
         }
 
@@ -409,7 +419,7 @@ namespace SharpCompress.Common.Rar.Headers
         //case 29: // rar 3.x compression
         //case 50: // RAR 5.0 compression algorithm.
         internal byte CompressionAlgorithm { get; private set; }
-        
+
         public bool IsSolid { get; private set; }
 
         // unused for UnpackV1 implementation (limitation)
@@ -427,13 +437,14 @@ namespace SharpCompress.Common.Rar.Headers
         internal long DataStartPosition { get; set; }
         public Stream PackedStream { get; set; }
 
+        public bool IsSplitBefore => IsRar5 ? HasHeaderFlag(HeaderFlagsV5.SPLIT_BEFORE) : HasFlag(FileFlagsV4.SPLIT_BEFORE);
         public bool IsSplitAfter => IsRar5 ? HasHeaderFlag(HeaderFlagsV5.SPLIT_AFTER) : HasFlag(FileFlagsV4.SPLIT_AFTER);
 
         public bool IsDirectory => HasFlag(IsRar5 ? FileFlagsV5.DIRECTORY : FileFlagsV4.DIRECTORY);
 
         private bool isEncryptedRar5 = false;
-        public bool IsEncrypted => IsRar5 ? isEncryptedRar5: HasFlag(FileFlagsV4.PASSWORD);
-        
+        public bool IsEncrypted => IsRar5 ? isEncryptedRar5 : HasFlag(FileFlagsV4.PASSWORD);
+
         internal DateTime? FileLastModifiedTime { get; private set; }
 
         internal DateTime? FileCreatedTime { get; private set; }

src/SharpCompress/Common/Rar/Headers/Flags.cs

@@ -42,10 +42,10 @@ namespace SharpCompress.Common.Rar.Headers
     }
 
     internal static class EncryptionFlagsV5
-    {   
+    {
         // RAR 5.0 archive encryption header specific flags.
         public const uint CHFL_CRYPT_PSWCHECK = 0x01; // Password check data is present.
-        
+
         public const uint FHEXTRA_CRYPT_PSWCHECK = 0x01; // Password check data is present.
         public const uint FHEXTRA_CRYPT_HASHMAC = 0x02;
     }

src/SharpCompress/Common/Rar/Headers/IRarHeader.cs

@@ -1,6 +1,6 @@
 namespace SharpCompress.Common.Rar.Headers
 {
-    internal interface IRarHeader 
+    internal interface IRarHeader
     {
         HeaderType HeaderType { get; }
     }

src/SharpCompress/Common/Rar/Headers/MarkHeader.cs

@@ -11,39 +11,39 @@ namespace SharpCompress.Common.Rar.Headers
 
         public bool IsRar5 { get; }
 
-        private MarkHeader(bool isRar5) 
-        { 
+        private MarkHeader(bool isRar5)
+        {
             IsRar5 = isRar5;
         }
 
         public HeaderType HeaderType => HeaderType.Mark;
 
-        private static byte GetByte(Stream stream) 
+        private static byte GetByte(Stream stream)
         {
             var b = stream.ReadByte();
-            if (b != -1) 
+            if (b != -1)
             {
                 return (byte)b;
             }
             throw new EndOfStreamException();
         }
 
-        public static MarkHeader Read(Stream stream, bool leaveStreamOpen, bool lookForHeader) 
+        public static MarkHeader Read(Stream stream, bool leaveStreamOpen, bool lookForHeader)
         {
             int maxScanIndex = lookForHeader ? MAX_SFX_SIZE : 0;
             try
             {
                 int start = -1;
                 var b = GetByte(stream); start++;
-                while (start <= maxScanIndex) 
+                while (start <= maxScanIndex)
                 {
                     // Rar old signature: 52 45 7E 5E
                     // Rar4 signature:    52 61 72 21 1A 07 00
                     // Rar5 signature:    52 61 72 21 1A 07 01 00
-                    if (b == 0x52) 
+                    if (b == 0x52)
                     {
                         b = GetByte(stream); start++;
-                        if (b == 0x61) 
+                        if (b == 0x61)
                         {
                             b = GetByte(stream); start++;
                             if (b != 0x72)
@@ -70,7 +70,7 @@ namespace SharpCompress.Common.Rar.Headers
                             }
 
                             b = GetByte(stream); start++;
-                            if (b == 1) 
+                            if (b == 1)
                             {
                                 b = GetByte(stream); start++;
                                 if (b != 0)
@@ -79,13 +79,13 @@ namespace SharpCompress.Common.Rar.Headers
                                 }
 
                                 return new MarkHeader(true); // Rar5
-                            } 
-                            else if (b == 0) 
+                            }
+                            else if (b == 0)
                             {
                                 return new MarkHeader(false); // Rar4
-                            } 
-                        } 
-                        else if (b == 0x45) 
+                            }
+                        }
+                        else if (b == 0x45)
                         {
                             b = GetByte(stream); start++;
                             if (b != 0x7e)
@@ -100,9 +100,9 @@ namespace SharpCompress.Common.Rar.Headers
                             }
 
                             throw new InvalidFormatException("Rar format version pre-4 is unsupported.");
-                        } 
-                    } 
-                    else 
+                        }
+                    }
+                    else
                     {
                         b = GetByte(stream); start++;
                     }

src/SharpCompress/Common/Rar/Headers/NewSubHeaderType.cs

@@ -2,23 +2,23 @@
 
 namespace SharpCompress.Common.Rar.Headers
 {
-    internal class NewSubHeaderType : IEquatable<NewSubHeaderType>
+    internal sealed class NewSubHeaderType : IEquatable<NewSubHeaderType>
     {
-        internal static readonly NewSubHeaderType SUBHEAD_TYPE_CMT = new NewSubHeaderType('C', 'M', 'T');
+        internal static readonly NewSubHeaderType SUBHEAD_TYPE_CMT = new('C', 'M', 'T');
 
-        //internal static final NewSubHeaderType SUBHEAD_TYPE_ACL = new NewSubHeaderType(new byte[]{'A','C','L'});
+        //internal static final NewSubHeaderType SUBHEAD_TYPE_ACL = new (new byte[]{'A','C','L'});
 
-        //internal static final NewSubHeaderType SUBHEAD_TYPE_STREAM = new NewSubHeaderType(new byte[]{'S','T','M'});
+        //internal static final NewSubHeaderType SUBHEAD_TYPE_STREAM = new (new byte[]{'S','T','M'});
 
-        //internal static final NewSubHeaderType SUBHEAD_TYPE_UOWNER = new NewSubHeaderType(new byte[]{'U','O','W'});
+        //internal static final NewSubHeaderType SUBHEAD_TYPE_UOWNER = new (new byte[]{'U','O','W'});
 
-        //internal static final NewSubHeaderType SUBHEAD_TYPE_AV = new NewSubHeaderType(new byte[]{'A','V'});
+        //internal static final NewSubHeaderType SUBHEAD_TYPE_AV = new (new byte[]{'A','V'});
 
-        internal static readonly NewSubHeaderType SUBHEAD_TYPE_RR = new NewSubHeaderType('R', 'R');
+        internal static readonly NewSubHeaderType SUBHEAD_TYPE_RR = new('R', 'R');
 
-        //internal static final NewSubHeaderType SUBHEAD_TYPE_OS2EA = new NewSubHeaderType(new byte[]{'E','A','2'});
+        //internal static final NewSubHeaderType SUBHEAD_TYPE_OS2EA = new (new byte[]{'E','A','2'});
 
-        //internal static final NewSubHeaderType SUBHEAD_TYPE_BEOSEA = new NewSubHeaderType(new byte[]{'E','A','B','E'});
+        //internal static final NewSubHeaderType SUBHEAD_TYPE_BEOSEA = new (new byte[]{'E','A','B','E'});
 
         private readonly byte[] _bytes;
 
@@ -37,19 +37,13 @@ namespace SharpCompress.Common.Rar.Headers
             {
                 return false;
             }
-            for (int i = 0; i < bytes.Length; ++i)
-            {
-                if (_bytes[i] != bytes[i])
-                {
-                    return false;
-                }
-            }
-            return true;
+
+            return _bytes.AsSpan().SequenceEqual(bytes);
         }
 
-        public bool Equals(NewSubHeaderType other)
+        public bool Equals(NewSubHeaderType? other)
         {
-            return Equals(other._bytes);
+            return other is not null && Equals(other._bytes);
         }
     }
 }

src/SharpCompress/Common/Rar/Headers/ProtectHeader.cs

@@ -5,8 +5,8 @@ namespace SharpCompress.Common.Rar.Headers
     // ProtectHeader is part of the Recovery Record feature
     internal sealed class ProtectHeader : RarHeader
     {
-        public ProtectHeader(RarHeader header, RarCrcBinaryReader reader) 
-            : base(header, reader, HeaderType.Protect) 
+        public ProtectHeader(RarHeader header, RarCrcBinaryReader reader)
+            : base(header, reader, HeaderType.Protect)
         {
             if (IsRar5)
             {

src/SharpCompress/Common/Rar/Headers/RarHeader.cs

@@ -23,12 +23,12 @@ namespace SharpCompress.Common.Rar.Headers
             }
         }
 
-        private RarHeader(RarCrcBinaryReader reader, bool isRar5, ArchiveEncoding archiveEncoding) 
+        private RarHeader(RarCrcBinaryReader reader, bool isRar5, ArchiveEncoding archiveEncoding)
         {
             _headerType = HeaderType.Null;
             _isRar5 = isRar5;
             ArchiveEncoding = archiveEncoding;
-            if (IsRar5) 
+            if (IsRar5)
             {
                 HeaderCrc = reader.ReadUInt32();
                 reader.ResetCrc();
@@ -45,7 +45,9 @@ namespace SharpCompress.Common.Rar.Headers
                 {
                     AdditionalDataSize = (long)reader.ReadRarVInt();
                 }
-            } else {
+            }
+            else
+            {
                 reader.Mark();
                 HeaderCrc = reader.ReadUInt16();
                 reader.ResetCrc();
@@ -59,7 +61,8 @@ namespace SharpCompress.Common.Rar.Headers
             }
         }
 
-        protected RarHeader(RarHeader header, RarCrcBinaryReader reader, HeaderType headerType) {
+        protected RarHeader(RarHeader header, RarCrcBinaryReader reader, HeaderType headerType)
+        {
             _headerType = headerType;
             _isRar5 = header.IsRar5;
             HeaderCrc = header.HeaderCrc;
@@ -80,7 +83,8 @@ namespace SharpCompress.Common.Rar.Headers
             VerifyHeaderCrc(reader.GetCrc32());
         }
 
-        protected int RemainingHeaderBytes(MarkingBinaryReader reader) {
+        protected int RemainingHeaderBytes(MarkingBinaryReader reader)
+        {
             return checked(HeaderSize - (int)reader.CurrentReadByteCount);
         }
 
@@ -108,7 +112,7 @@ namespace SharpCompress.Common.Rar.Headers
 
         protected ushort HeaderFlags { get; }
 
-        protected bool HasHeaderFlag(ushort flag) 
+        protected bool HasHeaderFlag(ushort flag)
         {
             return (HeaderFlags & flag) == flag;
         }

src/SharpCompress/Common/Rar/Headers/RarHeaderFactory.cs

@@ -41,11 +41,11 @@ namespace SharpCompress.Common.Rar.Headers
         private RarHeader? TryReadNextHeader(Stream stream)
         {
             RarCrcBinaryReader reader;
-            if (!IsEncrypted) 
+            if (!IsEncrypted)
             {
                 reader = new RarCrcBinaryReader(stream);
-            } 
-            else 
+            }
+            else
             {
                 if (Options.Password is null)
                 {
@@ -65,7 +65,7 @@ namespace SharpCompress.Common.Rar.Headers
                 case HeaderCodeV.RAR4_ARCHIVE_HEADER:
                     {
                         var ah = new ArchiveHeader(header, reader);
-                        if (ah.IsEncrypted == true) 
+                        if (ah.IsEncrypted == true)
                         {
                             //!!! rar5 we don't know yet
                             IsEncrypted = true;
@@ -150,11 +150,11 @@ namespace SharpCompress.Common.Rar.Headers
                         return new EndArchiveHeader(header, reader);
                     }
                 case HeaderCodeV.RAR5_ARCHIVE_ENCRYPTION_HEADER:
-                {
-                    var ch = new ArchiveCryptHeader(header, reader);
-                    IsEncrypted = true;
-                    return ch;
-                }
+                    {
+                        var ch = new ArchiveCryptHeader(header, reader);
+                        IsEncrypted = true;
+                        return ch;
+                    }
                 default:
                     {
                         throw new InvalidFormatException("Unknown Rar Header: " + header.HeaderCode);
@@ -162,21 +162,26 @@ namespace SharpCompress.Common.Rar.Headers
             }
         }
 
-        private void SkipData(FileHeader fh, RarCrcBinaryReader reader) {
-            switch (StreamingMode) {
-                case StreamingMode.Seekable: {
-                    fh.DataStartPosition = reader.BaseStream.Position;
-                    reader.BaseStream.Position += fh.CompressedSize;
-                }
+        private void SkipData(FileHeader fh, RarCrcBinaryReader reader)
+        {
+            switch (StreamingMode)
+            {
+                case StreamingMode.Seekable:
+                    {
+                        fh.DataStartPosition = reader.BaseStream.Position;
+                        reader.BaseStream.Position += fh.CompressedSize;
+                    }
                     break;
-                case StreamingMode.Streaming: {
-                    //skip the data because it's useless?
-                    reader.BaseStream.Skip(fh.CompressedSize);
-                }
+                case StreamingMode.Streaming:
+                    {
+                        //skip the data because it's useless?
+                        reader.BaseStream.Skip(fh.CompressedSize);
+                    }
                     break;
-                default: {
-                    throw new InvalidFormatException("Invalid StreamingMode");
-                }
+                default:
+                    {
+                        throw new InvalidFormatException("Invalid StreamingMode");
+                    }
             }
         }
     }

src/SharpCompress/Common/Rar/Headers/SignHeader.cs

@@ -5,8 +5,8 @@ namespace SharpCompress.Common.Rar.Headers
     internal class SignHeader : RarHeader
     {
         protected SignHeader(RarHeader header, RarCrcBinaryReader reader)
-            : base(header, reader, HeaderType.Sign) 
-        { 
+            : base(header, reader, HeaderType.Sign)
+        {
             if (IsRar5)
             {
                 throw new InvalidFormatException("unexpected rar5 record");

src/SharpCompress/Common/Rar/RarCryptoWrapper.cs

@@ -50,11 +50,11 @@ namespace SharpCompress.Common.Rar
             if (sizeToRead > 0)
             {
                 int alignedSize = sizeToRead + ((~sizeToRead + 1) & 0xf);
-                byte[] cipherText = new byte[RarRijndael.CRYPTO_BLOCK_SIZE];
+                Span<byte> cipherText = stackalloc byte[RarRijndael.CRYPTO_BLOCK_SIZE];
                 for (int i = 0; i < alignedSize / 16; i++)
                 {
                     //long ax = System.currentTimeMillis();
-                    _actualStream.Read(cipherText, 0, RarRijndael.CRYPTO_BLOCK_SIZE);
+                    _actualStream.Read(cipherText);
 
                     var readBytes = _rijndael.ProcessBlock(cipherText);
                     foreach (var readByte in readBytes)

src/SharpCompress/Common/Rar/RarEntry.cs

@@ -11,7 +11,7 @@ namespace SharpCompress.Common.Rar
         /// As the V2017 port isn't complete, add this check to use the legacy Rar code.
         /// </summary>
         internal bool IsRarV3 => FileHeader.CompressionAlgorithm == 29 || FileHeader.CompressionAlgorithm == 36;
-        
+
         /// <summary>
         /// The File's 32 bit CRC Hash
         /// </summary>

src/SharpCompress/Common/Rar/RarRijndael.cs

@@ -27,13 +27,13 @@ namespace SharpCompress.Common.Rar
 
             _rijndael = new RijndaelEngine();
             _aesInitializationVector = new byte[CRYPTO_BLOCK_SIZE];
-            int rawLength = 2*_password.Length;
+            int rawLength = 2 * _password.Length;
             byte[] rawPassword = new byte[rawLength + 8];
             byte[] passwordBytes = Encoding.UTF8.GetBytes(_password);
             for (int i = 0; i < _password.Length; i++)
             {
-                rawPassword[i*2] = passwordBytes[i];
-                rawPassword[i*2 + 1] = 0;
+                rawPassword[i * 2] = passwordBytes[i];
+                rawPassword[i * 2 + 1] = 0;
             }
             for (int i = 0; i < _salt.Length; i++)
             {
@@ -68,11 +68,11 @@ namespace SharpCompress.Common.Rar
             {
                 for (int j = 0; j < 4; j++)
                 {
-                    aesKey[i*4 + j] = (byte)
-                        (((digest[i*4]*0x1000000) & 0xff000000 |
-                          (uint) ((digest[i*4 + 1]*0x10000) & 0xff0000) |
-                          (uint) ((digest[i*4 + 2]*0x100) & 0xff00) |
-                          (uint) (digest[i*4 + 3] & 0xff)) >> (j*8));
+                    aesKey[i * 4 + j] = (byte)
+                        (((digest[i * 4] * 0x1000000) & 0xff000000 |
+                          (uint)((digest[i * 4 + 1] * 0x10000) & 0xff0000) |
+                          (uint)((digest[i * 4 + 2] * 0x100) & 0xff00) |
+                          (uint)(digest[i * 4 + 3] & 0xff)) >> (j * 8));
                 }
             }
 
@@ -87,11 +87,11 @@ namespace SharpCompress.Common.Rar
             return rijndael;
         }
 
-        public byte[] ProcessBlock(byte[] cipherText)
+        public byte[] ProcessBlock(ReadOnlySpan<byte> cipherText)
         {
-            var plainText = new byte[CRYPTO_BLOCK_SIZE];
+            Span<byte> plainText = stackalloc byte[CRYPTO_BLOCK_SIZE]; // 16 bytes
             byte[] decryptedBytes = new byte[CRYPTO_BLOCK_SIZE];
-            _rijndael.ProcessBlock(cipherText, 0, plainText, 0);
+            _rijndael.ProcessBlock(cipherText, plainText);
 
             for (int j = 0; j < CRYPTO_BLOCK_SIZE; j++)
             {

src/SharpCompress/Common/Rar/RarVolume.cs

@@ -39,20 +39,20 @@ namespace SharpCompress.Common.Rar
                 switch (header.HeaderType)
                 {
                     case HeaderType.Mark:
-                    {
-                        lastMarkHeader = (MarkHeader)header;
-                    }
+                        {
+                            lastMarkHeader = (MarkHeader)header;
+                        }
                         break;
                     case HeaderType.Archive:
-                    {
-                        ArchiveHeader = (ArchiveHeader)header;
-                    }
+                        {
+                            ArchiveHeader = (ArchiveHeader)header;
+                        }
                         break;
                     case HeaderType.File:
-                    {
-                        var fh = (FileHeader)header;
-                        yield return CreateFilePart(lastMarkHeader!, fh);
-                    }
+                        {
+                            var fh = (FileHeader)header;
+                            yield return CreateFilePart(lastMarkHeader!, fh);
+                        }
                         break;
                 }
             }

src/SharpCompress/Common/SevenZip/ArchiveDatabase.cs

@@ -89,7 +89,7 @@ namespace SharpCompress.Common.SevenZip
                 {
                     // v3.13 incorrectly worked with empty folders
                     // v4.07: Loop for skipping empty folders
-                    for (;;)
+                    for (; ; )
                     {
                         if (folderIndex >= _folders.Count)
                         {

src/SharpCompress/Common/SevenZip/ArchiveReader.cs

@@ -90,7 +90,7 @@ namespace SharpCompress.Common.SevenZip
 
         private void WaitAttribute(BlockType attribute)
         {
-            for (;;)
+            for (; ; )
             {
                 BlockType? type = ReadId();
                 if (type == attribute)
@@ -452,7 +452,7 @@ namespace SharpCompress.Common.SevenZip
 #endif
 
                 BlockType? type;
-                for (;;)
+                for (; ; )
                 {
                     type = ReadId();
                     if (type == BlockType.End)
@@ -508,7 +508,7 @@ namespace SharpCompress.Common.SevenZip
                     int index = 0;
                     for (int i = 0; i < numFolders; i++)
                     {
-                        var f = new CFolder {_firstPackStreamId = index};
+                        var f = new CFolder { _firstPackStreamId = index };
                         folders.Add(f);
                         GetNextFolderItem(f);
                         index += f._packStreams.Count;
@@ -539,7 +539,7 @@ namespace SharpCompress.Common.SevenZip
 #endif
                 }
 
-                for (;;)
+                for (; ; )
                 {
                     BlockType? type = ReadId();
                     if (type == BlockType.End)
@@ -580,7 +580,7 @@ namespace SharpCompress.Common.SevenZip
                 numUnpackStreamsInFolders = null;
 
                 BlockType? type;
-                for (;;)
+                for (; ; )
                 {
                     type = ReadId();
                     if (type == BlockType.NumUnpackStream)
@@ -602,7 +602,7 @@ namespace SharpCompress.Common.SevenZip
 #endif
                         continue;
                     }
-                    if (type == BlockType.Crc || type == BlockType.Size)
+                    if (type is BlockType.Crc or BlockType.Size)
                     {
                         break;
                     }
@@ -672,7 +672,7 @@ namespace SharpCompress.Common.SevenZip
 
                 digests = null;
 
-                for (;;)
+                for (; ; )
                 {
                     if (type == BlockType.Crc)
                     {
@@ -755,7 +755,7 @@ namespace SharpCompress.Common.SevenZip
                 unpackSizes = null;
                 digests = null;
 
-                for (;;)
+                for (; ; )
                 {
                     switch (ReadId())
                     {
@@ -791,22 +791,14 @@ namespace SharpCompress.Common.SevenZip
 #endif
             try
             {
-                long dataStartPos;
-                List<long> packSizes;
-                List<uint?> packCrCs;
-                List<CFolder> folders;
-                List<int> numUnpackStreamsInFolders;
-                List<long> unpackSizes;
-                List<uint?> digests;
-
                 ReadStreamsInfo(null,
-                                out dataStartPos,
-                                out packSizes,
-                                out packCrCs,
-                                out folders,
-                                out numUnpackStreamsInFolders,
-                                out unpackSizes,
-                                out digests);
+                                out long dataStartPos,
+                                out List<long> packSizes,
+                                out List<uint?> packCrCs,
+                                out List<CFolder> folders,
+                                out List<int> numUnpackStreamsInFolders,
+                                out List<long> unpackSizes,
+                                out List<uint?> digests);
 
                 dataStartPos += baseOffset;
 
@@ -934,7 +926,7 @@ namespace SharpCompress.Common.SevenZip
                 BitVector antiFileVector = null;
                 int numEmptyStreams = 0;
 
-                for (;;)
+                for (; ; )
                 {
                     type = ReadId();
                     if (type == BlockType.End)
@@ -969,7 +961,7 @@ namespace SharpCompress.Common.SevenZip
 #if DEBUG
                             Log.Write("WinAttributes:");
 #endif
-                            ReadAttributeVector(dataVector, numFiles, delegate(int i, uint? attr)
+                            ReadAttributeVector(dataVector, numFiles, delegate (int i, uint? attr)
                                                                       {
                                                                           // Some third party implementations established an unofficial extension
                                                                           // of the 7z archive format by placing posix file attributes in the high
@@ -1057,7 +1049,7 @@ namespace SharpCompress.Common.SevenZip
 #if DEBUG
                             Log.Write("StartPos:");
 #endif
-                            ReadNumberVector(dataVector, numFiles, delegate(int i, long? startPos)
+                            ReadNumberVector(dataVector, numFiles, delegate (int i, long? startPos)
                                                                    {
                                                                        db._files[i].StartPos = startPos;
 #if DEBUG
@@ -1072,7 +1064,7 @@ namespace SharpCompress.Common.SevenZip
 #if DEBUG
                             Log.Write("CTime:");
 #endif
-                            ReadDateTimeVector(dataVector, numFiles, delegate(int i, DateTime? time)
+                            ReadDateTimeVector(dataVector, numFiles, delegate (int i, DateTime? time)
                                                                      {
                                                                          db._files[i].CTime = time;
 #if DEBUG
@@ -1087,7 +1079,7 @@ namespace SharpCompress.Common.SevenZip
 #if DEBUG
                             Log.Write("ATime:");
 #endif
-                            ReadDateTimeVector(dataVector, numFiles, delegate(int i, DateTime? time)
+                            ReadDateTimeVector(dataVector, numFiles, delegate (int i, DateTime? time)
                                                                      {
                                                                          db._files[i].ATime = time;
 #if DEBUG
@@ -1102,7 +1094,7 @@ namespace SharpCompress.Common.SevenZip
 #if DEBUG
                             Log.Write("MTime:");
 #endif
-                            ReadDateTimeVector(dataVector, numFiles, delegate(int i, DateTime? time)
+                            ReadDateTimeVector(dataVector, numFiles, delegate (int i, DateTime? time)
                                                                      {
                                                                          db._files[i].MTime = time;
 #if DEBUG
@@ -1445,8 +1437,7 @@ namespace SharpCompress.Common.SevenZip
 
         private Stream GetCachedDecoderStream(ArchiveDatabase db, int folderIndex)
         {
-            Stream s;
-            if (!_cachedStreams.TryGetValue(folderIndex, out s))
+            if (!_cachedStreams.TryGetValue(folderIndex, out Stream s))
             {
                 CFolder folderInfo = db._folders[folderIndex];
                 int packStreamIndex = db._folders[folderIndex]._firstPackStreamId;
@@ -1494,7 +1485,7 @@ namespace SharpCompress.Common.SevenZip
             int numItems = allFilesMode
                 ? db._files.Count
                 : indices.Length;
-            
+
             if (numItems == 0)
             {
                 return;
@@ -1526,6 +1517,7 @@ namespace SharpCompress.Common.SevenZip
                 }
             }
 
+            byte[] buffer = null;
             foreach (CExtractFolderInfo efi in extractFolderInfoVector)
             {
                 int startIndex;
@@ -1562,8 +1554,8 @@ namespace SharpCompress.Common.SevenZip
 
                 Stream s = DecoderStreamHelper.CreateDecoderStream(_stream, folderStartPackPos, packSizes,
                                                                    folderInfo, db.PasswordProvider);
-                byte[] buffer = new byte[4 << 10];
-                for (;;)
+                buffer ??= new byte[4 << 10];
+                for (; ; )
                 {
                     int processed = s.Read(buffer, 0, buffer.Length);
                     if (processed == 0)

src/SharpCompress/Common/SevenZip/CMethodId.cs

@@ -1,6 +1,6 @@
 namespace SharpCompress.Common.SevenZip
 {
-    internal struct CMethodId
+    internal readonly struct CMethodId
     {
         public const ulong K_COPY_ID = 0;
         public const ulong K_LZMA_ID = 0x030101;
@@ -24,9 +24,9 @@
             return _id.GetHashCode();
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
-            return obj is CMethodId && (CMethodId)obj == this;
+            return obj is CMethodId other && Equals(other);
         }
 
         public bool Equals(CMethodId other)

src/SharpCompress/Common/SevenZip/DataReader.cs

@@ -161,7 +161,7 @@ namespace SharpCompress.Common.SevenZip
         {
             int ending = Offset;
 
-            for (;;)
+            for (; ; )
             {
                 if (ending + 2 > _ending)
                 {

src/SharpCompress/Common/SevenZip/SevenZipEntry.cs

@@ -32,7 +32,7 @@ namespace SharpCompress.Common.SevenZip
 
         public override DateTime? ArchivedTime => null;
 
-        public override bool IsEncrypted => false;
+        public override bool IsEncrypted => FilePart.IsEncrypted;
 
         public override bool IsDirectory => FilePart.Header.IsDir;
 

src/SharpCompress/Common/SevenZip/SevenZipFilePart.cs

@@ -84,23 +84,25 @@ namespace SharpCompress.Common.SevenZip
         {
             var coder = Folder!._coders.First();
             switch (coder._methodId._id)
-            {                
+            {
                 case K_LZMA:
                 case K_LZMA2:
-                {
-                    return CompressionType.LZMA;
-                }
+                    {
+                        return CompressionType.LZMA;
+                    }
                 case K_PPMD:
-                {
-                    return CompressionType.PPMd;
-                }
+                    {
+                        return CompressionType.PPMd;
+                    }
                 case K_B_ZIP2:
-                {
-                    return CompressionType.BZip2;
-                }
+                    {
+                        return CompressionType.BZip2;
+                    }
                 default:
                     throw new NotImplementedException();
             }
         }
+
+        internal bool IsEncrypted => Folder!._coders.FindIndex(c => c._methodId._id == CMethodId.K_AES_ID) != -1;
     }
 }

src/SharpCompress/Common/Tar/Headers/TarHeader.cs

@@ -7,7 +7,7 @@ using System.Text;
 
 namespace SharpCompress.Common.Tar.Headers
 {
-    internal class TarHeader
+    internal sealed class TarHeader
     {
         internal static readonly DateTime EPOCH = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
 
@@ -97,7 +97,7 @@ namespace SharpCompress.Common.Tar.Headers
             {
                 numPaddingBytes = BLOCK_SIZE;
             }
-            output.Write(new byte[numPaddingBytes], 0, numPaddingBytes);
+            output.Write(stackalloc byte[numPaddingBytes]);
         }
 
         internal bool Read(BinaryReader reader)
@@ -260,10 +260,16 @@ namespace SharpCompress.Common.Tar.Headers
             return Convert.ToInt64(s);
         }
 
+
+        private static readonly byte[] eightSpaces = {
+            (byte)' ', (byte)' ', (byte)' ', (byte)' ',
+            (byte)' ', (byte)' ', (byte)' ', (byte)' '
+        };
+
         internal static int RecalculateChecksum(byte[] buf)
         {
             // Set default value for checksum. That is 8 spaces.
-            Encoding.UTF8.GetBytes("        ").CopyTo(buf, 148);
+            eightSpaces.CopyTo(buf, 148);
 
             // Calculate checksum
             int headerChecksum = 0;
@@ -276,7 +282,7 @@ namespace SharpCompress.Common.Tar.Headers
 
         internal static int RecalculateAltChecksum(byte[] buf)
         {
-            Encoding.UTF8.GetBytes("        ").CopyTo(buf, 148);
+            eightSpaces.CopyTo(buf, 148);
             int headerChecksum = 0;
             foreach (byte b in buf)
             {

src/SharpCompress/Common/Zip/Headers/DirectoryEntryHeader.cs

@@ -32,7 +32,7 @@ namespace SharpCompress.Common.Zip.Headers
             byte[] name = reader.ReadBytes(nameLength);
             byte[] extra = reader.ReadBytes(extraLength);
             byte[] comment = reader.ReadBytes(commentLength);
-            
+
             // According to .ZIP File Format Specification
             //
             // For example: https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT
@@ -40,7 +40,7 @@ namespace SharpCompress.Common.Zip.Headers
             // Bit 11: Language encoding flag (EFS).  If this bit is set,
             //         the filename and comment fields for this file
             //         MUST be encoded using UTF-8. (see APPENDIX D)
-            
+
             if (Flags.HasFlag(HeaderFlags.Efs))
             {
                 Name = ArchiveEncoding.DecodeUTF8(name);
@@ -63,6 +63,8 @@ namespace SharpCompress.Common.Zip.Headers
             var zip64ExtraData = Extra.OfType<Zip64ExtendedInformationExtraField>().FirstOrDefault();
             if (zip64ExtraData != null)
             {
+                zip64ExtraData.Process(UncompressedSize, CompressedSize, RelativeOffsetOfEntryHeader, DiskNumberStart);
+
                 if (CompressedSize == uint.MaxValue)
                 {
                     CompressedSize = zip64ExtraData.CompressedSize;

src/SharpCompress/Common/Zip/Headers/LocalEntryHeader.cs

@@ -24,7 +24,7 @@ namespace SharpCompress.Common.Zip.Headers
             ushort extraLength = reader.ReadUInt16();
             byte[] name = reader.ReadBytes(nameLength);
             byte[] extra = reader.ReadBytes(extraLength);
-            
+
             // According to .ZIP File Format Specification
             //
             // For example: https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT
@@ -32,7 +32,7 @@ namespace SharpCompress.Common.Zip.Headers
             // Bit 11: Language encoding flag (EFS).  If this bit is set,
             //         the filename and comment fields for this file
             //         MUST be encoded using UTF-8. (see APPENDIX D)
-            
+
             if (Flags.HasFlag(HeaderFlags.Efs))
             {
                 Name = ArchiveEncoding.DecodeUTF8(name);
@@ -41,7 +41,7 @@ namespace SharpCompress.Common.Zip.Headers
             {
                 Name = ArchiveEncoding.Decode(name);
             }
-            
+
             LoadExtra(extra);
 
             var unicodePathExtra = Extra.FirstOrDefault(u => u.Type == ExtraDataType.UnicodePathExtraField);
@@ -53,6 +53,8 @@ namespace SharpCompress.Common.Zip.Headers
             var zip64ExtraData = Extra.OfType<Zip64ExtendedInformationExtraField>().FirstOrDefault();
             if (zip64ExtraData != null)
             {
+                zip64ExtraData.Process(UncompressedSize, CompressedSize, 0, 0);
+
                 if (CompressedSize == uint.MaxValue)
                 {
                     CompressedSize = zip64ExtraData.CompressedSize;

src/SharpCompress/Common/Zip/Headers/LocalEntryHeaderExtraFactory.cs

@@ -1,6 +1,4 @@
-#nullable disable
-
-using System;
+using System;
 using System.Buffers.Binary;
 using System.Text;
 
@@ -20,13 +18,25 @@ namespace SharpCompress.Common.Zip.Headers
 
     internal class ExtraData
     {
-        internal ExtraDataType Type { get; set; }
-        internal ushort Length { get; set; }
-        internal byte[] DataBytes { get; set; }
+        public ExtraData(ExtraDataType type, ushort length, byte[] dataBytes)
+        {
+            Type = type;
+            Length = length;
+            DataBytes = dataBytes;
+        }
+
+        internal ExtraDataType Type { get; }
+        internal ushort Length { get; }
+        internal byte[] DataBytes { get; }
     }
 
-    internal class ExtraUnicodePathExtraField : ExtraData
+    internal sealed class ExtraUnicodePathExtraField : ExtraData
     {
+        public ExtraUnicodePathExtraField(ExtraDataType type, ushort length, byte[] dataBytes)
+            : base(type, length, dataBytes)
+        {
+        }
+
         internal byte Version => DataBytes[0];
 
         internal byte[] NameCrc32
@@ -51,70 +61,79 @@ namespace SharpCompress.Common.Zip.Headers
         }
     }
 
-    internal class Zip64ExtendedInformationExtraField : ExtraData
+    internal sealed class Zip64ExtendedInformationExtraField : ExtraData
     {
-
         public Zip64ExtendedInformationExtraField(ExtraDataType type, ushort length, byte[] dataBytes)
+            : base(type, length, dataBytes)
         {
-            Type = type;
-            Length = length;
-            DataBytes = dataBytes;
-            Process();
         }
 
-        //From the spec values are only in the extradata if the standard
-        //value is set to 0xFFFF, but if one of the sizes are present, both are.
-        //Hence if length == 4 volume only
-        //      if length == 8 offset only
-        //      if length == 12 offset + volume
-        //      if length == 16 sizes only
-        //      if length == 20 sizes + volume
-        //      if length == 24 sizes + offset
-        //      if length == 28 everything.
-        //It is unclear how many of these are used in the wild.
-
-        private void Process()
+        // From the spec, values are only in the extradata if the standard
+        // value is set to 0xFFFFFFFF (or 0xFFFF for the Disk Start Number).
+        // Values, if present, must appear in the following order:
+        // - Original Size
+        // - Compressed Size
+        // - Relative Header Offset
+        // - Disk Start Number
+        public void Process(long uncompressedFileSize, long compressedFileSize, long relativeHeaderOffset, ushort diskNumber)
         {
-            switch (DataBytes.Length)
+            var bytesRequired = ((uncompressedFileSize == uint.MaxValue) ? 8 : 0)
+                + ((compressedFileSize == uint.MaxValue) ? 8 : 0)
+                + ((relativeHeaderOffset == uint.MaxValue) ? 8 : 0)
+                + ((diskNumber == ushort.MaxValue) ? 4 : 0);
+            var currentIndex = 0;
+
+            if (bytesRequired > DataBytes.Length)
             {
-                case 4:
-                    VolumeNumber = BinaryPrimitives.ReadUInt32LittleEndian(DataBytes);
-                    return;
-                case 8:
-                    RelativeOffsetOfEntryHeader = BinaryPrimitives.ReadInt64LittleEndian(DataBytes);
-                    return;
-                case 12:
-                    RelativeOffsetOfEntryHeader = BinaryPrimitives.ReadInt64LittleEndian(DataBytes);
-                    VolumeNumber = BinaryPrimitives.ReadUInt32LittleEndian(DataBytes.AsSpan(8));
-                    return;
-                case 16:
-                    UncompressedSize = BinaryPrimitives.ReadInt64LittleEndian(DataBytes);
-                    CompressedSize = BinaryPrimitives.ReadInt64LittleEndian(DataBytes.AsSpan(8));
-                    return;
-                case 20:
-                    UncompressedSize = BinaryPrimitives.ReadInt64LittleEndian(DataBytes);
-                    CompressedSize = BinaryPrimitives.ReadInt64LittleEndian(DataBytes.AsSpan(8));
-                    VolumeNumber = BinaryPrimitives.ReadUInt32LittleEndian(DataBytes.AsSpan(16));
-                    return;
-                case 24:
-                    UncompressedSize = BinaryPrimitives.ReadInt64LittleEndian(DataBytes);
-                    CompressedSize = BinaryPrimitives.ReadInt64LittleEndian(DataBytes.AsSpan(8));
-                    RelativeOffsetOfEntryHeader = BinaryPrimitives.ReadInt64LittleEndian(DataBytes.AsSpan(16));
-                    return;
-                case 28:
-                    UncompressedSize = BinaryPrimitives.ReadInt64LittleEndian(DataBytes);
-                    CompressedSize = BinaryPrimitives.ReadInt64LittleEndian(DataBytes.AsSpan(8));
-                    RelativeOffsetOfEntryHeader = BinaryPrimitives.ReadInt64LittleEndian(DataBytes.AsSpan(16));
-                    VolumeNumber = BinaryPrimitives.ReadUInt32LittleEndian(DataBytes.AsSpan(24));
-                    return;
-                default:
-                throw new ArchiveException("Unexpected size of of Zip64 extended information extra field");
+                throw new ArchiveException("Zip64 extended information extra field is not large enough for the required information");
+            }
+
+            if (uncompressedFileSize == uint.MaxValue)
+            {
+                UncompressedSize = BinaryPrimitives.ReadInt64LittleEndian(DataBytes.AsSpan(currentIndex));
+                currentIndex += 8;
+            }
+
+            if (compressedFileSize == uint.MaxValue)
+            {
+                CompressedSize = BinaryPrimitives.ReadInt64LittleEndian(DataBytes.AsSpan(currentIndex));
+                currentIndex += 8;
+            }
+
+            if (relativeHeaderOffset == uint.MaxValue)
+            {
+                RelativeOffsetOfEntryHeader = BinaryPrimitives.ReadInt64LittleEndian(DataBytes.AsSpan(currentIndex));
+                currentIndex += 8;
+            }
+
+            if (diskNumber == ushort.MaxValue)
+            {
+                VolumeNumber = BinaryPrimitives.ReadUInt32LittleEndian(DataBytes.AsSpan(currentIndex));
             }
         }
 
+        /// <summary>
+        /// Uncompressed file size. Only valid after <see cref="Process(long, long, long, ushort)"/> has been called and if the
+        /// original entry header had a corresponding 0xFFFFFFFF value.
+        /// </summary>
         public long UncompressedSize { get; private set; }
+
+        /// <summary>
+        /// Compressed file size. Only valid after <see cref="Process(long, long, long, ushort)"/> has been called and if the
+        /// original entry header had a corresponding 0xFFFFFFFF value.
+        /// </summary>
         public long CompressedSize { get; private set; }
+
+        /// <summary>
+        /// Relative offset of the entry header. Only valid after <see cref="Process(long, long, long, ushort)"/> has been called and if the
+        /// original entry header had a corresponding 0xFFFFFFFF value.
+        /// </summary>
         public long RelativeOffsetOfEntryHeader { get; private set; }
+
+        /// <summary>
+        /// Volume number. Only valid after <see cref="Process(long, long, long, ushort)"/> has been called and if the
+        /// original entry header had a corresponding 0xFFFF value.
+        /// </summary>
         public uint VolumeNumber { get; private set; }
     }
 
@@ -122,30 +141,12 @@ namespace SharpCompress.Common.Zip.Headers
     {
         internal static ExtraData Create(ExtraDataType type, ushort length, byte[] extraData)
         {
-            switch (type)
+            return type switch
             {
-                case ExtraDataType.UnicodePathExtraField:
-                    return new ExtraUnicodePathExtraField
-                           {
-                               Type = type,
-                               Length = length,
-                               DataBytes = extraData
-                           };
-                case ExtraDataType.Zip64ExtendedInformationExtraField:
-                    return new Zip64ExtendedInformationExtraField
-                            (
-                                type,
-                                length,
-                                extraData
-                           );
-                default:
-                    return new ExtraData
-                           {
-                               Type = type,
-                               Length = length,
-                               DataBytes = extraData
-                           };
-            }
+                ExtraDataType.UnicodePathExtraField => new ExtraUnicodePathExtraField(type, length, extraData),
+                ExtraDataType.Zip64ExtendedInformationExtraField => new Zip64ExtendedInformationExtraField(type, length, extraData),
+                _ => new ExtraData(type, length, extraData)
+            };
         }
     }
 }

src/SharpCompress/Common/Zip/Headers/ZipFileEntry.cs

@@ -20,7 +20,7 @@ namespace SharpCompress.Common.Zip.Headers
         {
             get
             {
-                if (Name.EndsWith("/"))
+                if (Name.EndsWith('/'))
                 {
                     return true;
                 }
@@ -28,7 +28,7 @@ namespace SharpCompress.Common.Zip.Headers
                 //.NET Framework 4.5 : System.IO.Compression::CreateFromDirectory() probably writes backslashes to headers
                 return CompressedSize == 0
                        && UncompressedSize == 0
-                       && Name.EndsWith("\\");
+                       && Name.EndsWith('\\');
             }
         }
 
@@ -105,6 +105,6 @@ namespace SharpCompress.Common.Zip.Headers
 
         internal ZipFilePart Part { get; set; }
 
-        internal bool IsZip64 => CompressedSize == uint.MaxValue;
+        internal bool IsZip64 => CompressedSize >= uint.MaxValue;
     }
 }

src/SharpCompress/Common/Zip/PkwareTraditionalEncryptionData.cs

@@ -7,7 +7,7 @@ namespace SharpCompress.Common.Zip
     internal class PkwareTraditionalEncryptionData
     {
         private static readonly CRC32 CRC32 = new CRC32();
-        private readonly UInt32[] _keys = {0x12345678, 0x23456789, 0x34567890};
+        private readonly UInt32[] _keys = { 0x12345678, 0x23456789, 0x34567890 };
         private readonly ArchiveEncoding _archiveEncoding;
 
         private PkwareTraditionalEncryptionData(string password, ArchiveEncoding archiveEncoding)

src/SharpCompress/Common/Zip/SeekableZipHeaderFactory.cs

@@ -8,7 +8,10 @@ namespace SharpCompress.Common.Zip
 {
     internal sealed class SeekableZipHeaderFactory : ZipHeaderFactory
     {
-        private const int MAX_ITERATIONS_FOR_DIRECTORY_HEADER = 4096;
+        private const int MINIMUM_EOCD_LENGTH = 22;
+        private const int ZIP64_EOCD_LENGTH = 20;
+        // Comment may be within 64kb + structure 22 bytes
+        private const int MAX_SEARCH_LENGTH_FOR_EOCD = 65557;
         private bool _zip64;
 
         internal SeekableZipHeaderFactory(string? password, ArchiveEncoding archiveEncoding)
@@ -20,14 +23,24 @@ namespace SharpCompress.Common.Zip
         {
             var reader = new BinaryReader(stream);
 
-            SeekBackToHeader(stream, reader, DIRECTORY_END_HEADER_BYTES);
+            SeekBackToHeader(stream, reader);
+
+            var eocd_location = stream.Position;
             var entry = new DirectoryEndHeader();
             entry.Read(reader);
 
             if (entry.IsZip64)
             {
                 _zip64 = true;
-                SeekBackToHeader(stream, reader, ZIP64_END_OF_CENTRAL_DIRECTORY_LOCATOR);
+
+                // ZIP64_END_OF_CENTRAL_DIRECTORY_LOCATOR should be before the EOCD
+                stream.Seek(eocd_location - ZIP64_EOCD_LENGTH - 4, SeekOrigin.Begin);
+                uint zip64_locator = reader.ReadUInt32();
+                if( zip64_locator != ZIP64_END_OF_CENTRAL_DIRECTORY_LOCATOR )
+                {
+                    throw new ArchiveException("Failed to locate the Zip64 Directory Locator");
+                }
+
                 var zip64Locator = new Zip64DirectoryEndLocatorHeader();
                 zip64Locator.Read(reader);
 
@@ -73,27 +86,49 @@ namespace SharpCompress.Common.Zip
             }
         }
 
-        private static void SeekBackToHeader(Stream stream, BinaryReader reader, uint headerSignature)
+        private static bool IsMatch( byte[] haystack, int position, byte[] needle)
         {
-            long offset = 0;
-            uint signature;
-            int iterationCount = 0;
-            do
+            for( int i = 0; i < needle.Length; i++ )
             {
-                if ((stream.Length + offset) - 4 < 0)
+                if( haystack[ position + i ] != needle[ i ] )
                 {
-                    throw new ArchiveException("Failed to locate the Zip Header");
-                }
-                stream.Seek(offset - 4, SeekOrigin.End);
-                signature = reader.ReadUInt32();
-                offset--;
-                iterationCount++;
-                if (iterationCount > MAX_ITERATIONS_FOR_DIRECTORY_HEADER)
-                {
-                    throw new ArchiveException("Could not find Zip file Directory at the end of the file.  File may be corrupted.");
+                    return false;
                 }
             }
-            while (signature != headerSignature);
+
+            return true;
+        }
+        private static void SeekBackToHeader(Stream stream, BinaryReader reader)
+        {
+            // Minimum EOCD length
+            if (stream.Length < MINIMUM_EOCD_LENGTH)
+            {
+                throw new ArchiveException("Could not find Zip file Directory at the end of the file. File may be corrupted.");
+            }
+
+            int len = stream.Length < MAX_SEARCH_LENGTH_FOR_EOCD ? (int)stream.Length : MAX_SEARCH_LENGTH_FOR_EOCD;
+            // We search for marker in reverse to find the first occurance
+            byte[] needle = { 0x06, 0x05, 0x4b, 0x50 };
+
+            stream.Seek(-len, SeekOrigin.End);
+
+            byte[] seek = reader.ReadBytes(len);
+
+            // Search in reverse
+            Array.Reverse(seek);
+
+            var max_search_area = len - MINIMUM_EOCD_LENGTH;
+
+            for( int pos_from_end = 0; pos_from_end < max_search_area; ++pos_from_end)
+            {
+                if( IsMatch(seek, pos_from_end, needle) )
+                {
+                    stream.Seek(-pos_from_end, SeekOrigin.End);
+                    return;
+                }
+            }
+
+            throw new ArchiveException("Failed to locate the Zip Header");
         }
 
         internal LocalEntryHeader GetLocalHeader(Stream stream, DirectoryEntryHeader directoryEntryHeader)

src/SharpCompress/Common/Zip/StreamingZipFilePart.cs

@@ -42,7 +42,7 @@ namespace SharpCompress.Common.Zip
             if (Header.HasData && !Skipped)
             {
                 _decompressionStream ??= GetCompressedStream();
-                
+
                 _decompressionStream.Skip();
 
                 if (_decompressionStream is DeflateStream deflateStream)

src/SharpCompress/Common/Zip/StreamingZipHeaderFactory.cs

@@ -49,7 +49,10 @@ namespace SharpCompress.Common.Zip
                 _lastEntryHeader = null;
                 uint headerBytes = reader.ReadUInt32();
                 header = ReadHeader(headerBytes, reader);
-                if (header is null) { yield break; }
+                if (header is null)
+                {
+                    yield break;
+                }
 
                 //entry could be zero bytes so we need to know that.
                 if (header.ZipHeaderType == ZipHeaderType.LocalEntry)
@@ -57,11 +60,11 @@ namespace SharpCompress.Common.Zip
                     var local_header = ((LocalEntryHeader)header);
 
                     // If we have CompressedSize, there is data to be read
-                    if( local_header.CompressedSize > 0 )
+                    if (local_header.CompressedSize > 0)
                     {
                         header.HasData = true;
                     } // Check if zip is streaming ( Length is 0 and is declared in PostDataDescriptor )
-                    else if( local_header.Flags.HasFlag(HeaderFlags.UsePostDataDescriptor) )
+                    else if (local_header.Flags.HasFlag(HeaderFlags.UsePostDataDescriptor))
                     {
                         bool isRecording = rewindableStream.IsRecording;
                         if (!isRecording)

src/SharpCompress/Common/Zip/WinzipAesCryptoStream.cs

@@ -75,7 +75,7 @@ namespace SharpCompress.Common.Zip
             if (disposing)
             {
                 //read out last 10 auth bytes
-                var ten = new byte[10];
+                Span<byte> ten = stackalloc byte[10];
                 _stream.ReadFully(ten);
                 _stream.Dispose();
             }

src/SharpCompress/Common/Zip/WinzipAesEncryptionData.cs

@@ -33,8 +33,10 @@ namespace SharpCompress.Common.Zip
 
         private int KeySizeInBytes
         {
-            get { return KeyLengthInBytes(_keySize);
-}
+            get
+            {
+                return KeyLengthInBytes(_keySize);
+            }
         }
 
         internal static int KeyLengthInBytes(WinzipAesKeySize keySize)

src/SharpCompress/Common/Zip/ZipEntry.cs

@@ -27,33 +27,33 @@ namespace SharpCompress.Common.Zip
                 switch (_filePart.Header.CompressionMethod)
                 {
                     case ZipCompressionMethod.BZip2:
-                    {
-                        return CompressionType.BZip2;
-                    }
+                        {
+                            return CompressionType.BZip2;
+                        }
                     case ZipCompressionMethod.Deflate:
-                    {
-                        return CompressionType.Deflate;
-                    }
+                        {
+                            return CompressionType.Deflate;
+                        }
                     case ZipCompressionMethod.Deflate64:
-                    {
-                        return CompressionType.Deflate64;
-                    }
+                        {
+                            return CompressionType.Deflate64;
+                        }
                     case ZipCompressionMethod.LZMA:
-                    {
-                        return CompressionType.LZMA;
-                    }
+                        {
+                            return CompressionType.LZMA;
+                        }
                     case ZipCompressionMethod.PPMd:
-                    {
-                        return CompressionType.PPMd;
-                    }
+                        {
+                            return CompressionType.PPMd;
+                        }
                     case ZipCompressionMethod.None:
-                    {
-                        return CompressionType.None;
-                    }
+                        {
+                            return CompressionType.None;
+                        }
                     default:
-                    {
-                        return CompressionType.Unknown;
-                    }
+                        {
+                            return CompressionType.Unknown;
+                        }
                 }
             }
         }

src/SharpCompress/Common/Zip/ZipFilePart.cs

@@ -60,72 +60,72 @@ namespace SharpCompress.Common.Zip
             switch (method)
             {
                 case ZipCompressionMethod.None:
-                {
-                    return stream;
-                }
+                    {
+                        return stream;
+                    }
                 case ZipCompressionMethod.Deflate:
-                {
-                    return new DeflateStream(stream, CompressionMode.Decompress);
-                }
+                    {
+                        return new DeflateStream(stream, CompressionMode.Decompress);
+                    }
                 case ZipCompressionMethod.Deflate64:
-                {
-                    return new Deflate64Stream(stream, CompressionMode.Decompress);
-                }
+                    {
+                        return new Deflate64Stream(stream, CompressionMode.Decompress);
+                    }
                 case ZipCompressionMethod.BZip2:
-                {
-                    return new BZip2Stream(stream, CompressionMode.Decompress, false);
-                }
+                    {
+                        return new BZip2Stream(stream, CompressionMode.Decompress, false);
+                    }
                 case ZipCompressionMethod.LZMA:
-                {
-                    if (FlagUtility.HasFlag(Header.Flags, HeaderFlags.Encrypted))
                     {
-                        throw new NotSupportedException("LZMA with pkware encryption.");
+                        if (FlagUtility.HasFlag(Header.Flags, HeaderFlags.Encrypted))
+                        {
+                            throw new NotSupportedException("LZMA with pkware encryption.");
+                        }
+                        var reader = new BinaryReader(stream);
+                        reader.ReadUInt16(); //LZMA version
+                        var props = new byte[reader.ReadUInt16()];
+                        reader.Read(props, 0, props.Length);
+                        return new LzmaStream(props, stream,
+                                              Header.CompressedSize > 0 ? Header.CompressedSize - 4 - props.Length : -1,
+                                              FlagUtility.HasFlag(Header.Flags, HeaderFlags.Bit1)
+                                                  ? -1
+                                                  : (long)Header.UncompressedSize);
                     }
-                    var reader = new BinaryReader(stream);
-                    reader.ReadUInt16(); //LZMA version
-                    var props = new byte[reader.ReadUInt16()];
-                    reader.Read(props, 0, props.Length);
-                    return new LzmaStream(props, stream,
-                                          Header.CompressedSize > 0 ? Header.CompressedSize - 4 - props.Length : -1,
-                                          FlagUtility.HasFlag(Header.Flags, HeaderFlags.Bit1)
-                                              ? -1
-                                              : (long)Header.UncompressedSize);
-                }
                 case ZipCompressionMethod.PPMd:
-                {
-                    var props = new byte[2];
-                    stream.ReadFully(props);
-                    return new PpmdStream(new PpmdProperties(props), stream, false);
-                }
+                    {
+                        Span<byte> props = stackalloc byte[2];
+                        stream.ReadFully(props);
+                        return new PpmdStream(new PpmdProperties(props), stream, false);
+                    }
                 case ZipCompressionMethod.WinzipAes:
-                {
-                    ExtraData data = Header.Extra.Where(x => x.Type == ExtraDataType.WinZipAes).SingleOrDefault();
-                    if (data is null)
                     {
-                        throw new InvalidFormatException("No Winzip AES extra data found.");
-                    }
-                    if (data.Length != 7)
-                    {
-                        throw new InvalidFormatException("Winzip data length is not 7.");
-                    }
-                    ushort compressedMethod = BinaryPrimitives.ReadUInt16LittleEndian(data.DataBytes);
+                        ExtraData? data = Header.Extra.SingleOrDefault(x => x.Type == ExtraDataType.WinZipAes);
+                        if (data is null)
+                        {
+                            throw new InvalidFormatException("No Winzip AES extra data found.");
+                        }
+                        if (data.Length != 7)
+                        {
+                            throw new InvalidFormatException("Winzip data length is not 7.");
+                        }
+                        ushort compressedMethod = BinaryPrimitives.ReadUInt16LittleEndian(data.DataBytes);
 
-                    if (compressedMethod != 0x01 && compressedMethod != 0x02)
-                    {
-                        throw new InvalidFormatException("Unexpected vendor version number for WinZip AES metadata");
-                    }
+                        if (compressedMethod != 0x01 && compressedMethod != 0x02)
+                        {
+                            throw new InvalidFormatException("Unexpected vendor version number for WinZip AES metadata");
+                        }
 
-                    ushort vendorId = BinaryPrimitives.ReadUInt16LittleEndian(data.DataBytes.AsSpan(2));
-                    if (vendorId != 0x4541)
-                    {
-                        throw new InvalidFormatException("Unexpected vendor ID for WinZip AES metadata");
+                        ushort vendorId = BinaryPrimitives.ReadUInt16LittleEndian(data.DataBytes.AsSpan(2));
+                        if (vendorId != 0x4541)
+                        {
+                            throw new InvalidFormatException("Unexpected vendor ID for WinZip AES metadata");
+                        }
+                        return CreateDecompressionStream(stream, (ZipCompressionMethod)BinaryPrimitives.ReadUInt16LittleEndian(data.DataBytes.AsSpan(5)));
                     }
-                    return CreateDecompressionStream(stream, (ZipCompressionMethod)BinaryPrimitives.ReadUInt16LittleEndian(data.DataBytes.AsSpan(5)));
-                }
                 default:
-                {
-                    throw new NotSupportedException("CompressionMethod: " + Header.CompressionMethod);
-                }
+                    {
+                        throw new NotSupportedException("CompressionMethod: " + Header.CompressionMethod);
+                    }
             }
         }
 
@@ -159,23 +159,23 @@ namespace SharpCompress.Common.Zip
                     case ZipCompressionMethod.BZip2:
                     case ZipCompressionMethod.LZMA:
                     case ZipCompressionMethod.PPMd:
-                    {
-                        return new PkwareTraditionalCryptoStream(plainStream, Header.ComposeEncryptionData(plainStream), CryptoMode.Decrypt);
-                    }
+                        {
+                            return new PkwareTraditionalCryptoStream(plainStream, Header.ComposeEncryptionData(plainStream), CryptoMode.Decrypt);
+                        }
 
                     case ZipCompressionMethod.WinzipAes:
-                    {
-                        if (Header.WinzipAesEncryptionData != null)
                         {
-                            return new WinzipAesCryptoStream(plainStream, Header.WinzipAesEncryptionData, Header.CompressedSize - 10);
+                            if (Header.WinzipAesEncryptionData != null)
+                            {
+                                return new WinzipAesCryptoStream(plainStream, Header.WinzipAesEncryptionData, Header.CompressedSize - 10);
+                            }
+                            return plainStream;
                         }
-                        return plainStream;
-                    }
 
                     default:
-                    {
-                        throw new ArgumentOutOfRangeException();
-                    }
+                        {
+                            throw new ArgumentOutOfRangeException();
+                        }
 
                 }
             }

src/SharpCompress/Common/Zip/ZipHeaderFactory.cs

@@ -35,20 +35,20 @@ namespace SharpCompress.Common.Zip
             switch (headerBytes)
             {
                 case ENTRY_HEADER_BYTES:
-                {
-                    var entryHeader = new LocalEntryHeader(_archiveEncoding);
-                    entryHeader.Read(reader);
-                    LoadHeader(entryHeader, reader.BaseStream);
+                    {
+                        var entryHeader = new LocalEntryHeader(_archiveEncoding);
+                        entryHeader.Read(reader);
+                        LoadHeader(entryHeader, reader.BaseStream);
 
-                    _lastEntryHeader = entryHeader;
-                    return entryHeader;
-                }
+                        _lastEntryHeader = entryHeader;
+                        return entryHeader;
+                    }
                 case DIRECTORY_START_HEADER_BYTES:
-                {
-                    var entry = new DirectoryEntryHeader(_archiveEncoding);
-                    entry.Read(reader);
-                    return entry;
-                }
+                    {
+                        var entry = new DirectoryEntryHeader(_archiveEncoding);
+                        entry.Read(reader);
+                        return entry;
+                    }
                 case POST_DATA_DESCRIPTOR:
                     {
                         if (FlagUtility.HasFlag(_lastEntryHeader!.Flags, HeaderFlags.UsePostDataDescriptor))
@@ -129,7 +129,7 @@ namespace SharpCompress.Common.Zip
 
                 if (entryHeader.CompressionMethod == ZipCompressionMethod.WinzipAes)
                 {
-                    ExtraData data = entryHeader.Extra.SingleOrDefault(x => x.Type == ExtraDataType.WinZipAes);
+                    ExtraData? data = entryHeader.Extra.SingleOrDefault(x => x.Type == ExtraDataType.WinZipAes);
                     if (data != null)
                     {
                         var keySize = (WinzipAesKeySize)data.DataBytes[4];

src/SharpCompress/Compressors/ADC/ADCBase.cs

@@ -52,32 +52,24 @@ namespace SharpCompress.Compressors.ADC
 
         private static int GetChunkSize(byte byt)
         {
-            switch (GetChunkType(byt))
+            return GetChunkType(byt) switch
             {
-                case PLAIN:
-                    return (byt & 0x7F) + 1;
-                case TWO_BYTE:
-                    return ((byt & 0x3F) >> 2) + 3;
-                case THREE_BYTE:
-                    return (byt & 0x3F) + 4;
-                default:
-                    return -1;
-            }
+                PLAIN => (byt & 0x7F) + 1,
+                TWO_BYTE => ((byt & 0x3F) >> 2) + 3,
+                THREE_BYTE => (byt & 0x3F) + 4,
+                _ => -1,
+            };
         }
 
         private static int GetOffset(ReadOnlySpan<byte> chunk)
         {
-            switch (GetChunkType(chunk[0]))
+            return GetChunkType(chunk[0]) switch
             {
-                case PLAIN:
-                    return 0;
-                case TWO_BYTE:
-                    return ((chunk[0] & 0x03) << 8) + chunk[1];
-                case THREE_BYTE:
-                    return (chunk[1] << 8) + chunk[2];
-                default:
-                    return -1;
-            }
+                PLAIN => 0,
+                TWO_BYTE => ((chunk[0] & 0x03) << 8) + chunk[1],
+                THREE_BYTE => (chunk[1] << 8) + chunk[2],
+                _ => -1,
+            };
         }
 
         /// <summary>