Array usage optimizations etc

Library/DiscUtils.BootConfig/DeviceElementValue.cs

@@ -100,7 +100,7 @@ public override string ToString()
 
     internal byte[] GetBytes()
     {
-        var buffer = new byte[_record.Size + 0x10];
+        var buffer = StreamUtilities.GetUninitializedArray<byte>(_record.Size + 0x10);
 
         EndianUtilities.WriteBytesLittleEndian(_parentObject, buffer, 0);
         _record.GetBytes(buffer, 0x10);

Library/DiscUtils.BootConfig/IntegerElementValue.cs

@@ -51,7 +51,7 @@ public IntegerElementValue(ulong value)
 
     internal byte[] GetBytes()
     {
-        var bytes = new byte[8];
+        var bytes = StreamUtilities.GetUninitializedArray<byte>(sizeof(ulong));
         EndianUtilities.WriteBytesLittleEndian(_value, bytes, 0);
         return bytes;
     }

Library/DiscUtils.BootConfig/IntegerListElementValue.cs

@@ -68,7 +68,7 @@ public override string ToString()
 
     internal byte[] GetBytes()
     {
-        var bytes = new byte[_values.Length * 8];
+        var bytes = StreamUtilities.GetUninitializedArray<byte>(_values.Length * 8);
         for (var i = 0; i < _values.Length; ++i)
         {
             EndianUtilities.WriteBytesLittleEndian(_values[i], bytes, i * 8);

Library/DiscUtils.Core/Archives/TarFile.cs

@@ -196,7 +196,7 @@ public IEnumerable<TarFileRecord> GetFiles(string dir)
 
     public static IEnumerable<TarFileData> EnumerateFiles(Stream archive)
     {
-        var hdrBuf = new byte[512];
+        var hdrBuf = StreamUtilities.GetUninitializedArray<byte>(512);
 
         string long_path = null;
 
@@ -275,7 +275,7 @@ public static IEnumerable<TarFileData> EnumerateFiles(Stream archive)
                 }
                 else
                 {
-                    var data = new byte[hdr.FileLength];
+                    var data = StreamUtilities.GetUninitializedArray<byte>((int)hdr.FileLength);
 
                     archive.ReadExactly(data, 0, data.Length);
 
@@ -297,7 +297,7 @@ public static IEnumerable<TarFileData> EnumerateFiles(Stream archive)
 #if NETSTANDARD2_1_OR_GREATER || NETCOREAPP
     public static async IAsyncEnumerable<TarFileData> EnumerateFilesAsync(Stream archive, [EnumeratorCancellation] CancellationToken cancellationToken)
     {
-        var hdrBuf = new byte[512];
+        var hdrBuf = StreamUtilities.GetUninitializedArray<byte>(512);
 
         string long_path = null;
 
@@ -376,7 +376,7 @@ public static async IAsyncEnumerable<TarFileData> EnumerateFilesAsync(Stream arc
                 }
                 else
                 {
-                    var data = new byte[hdr.FileLength];
+                    var data = StreamUtilities.GetUninitializedArray<byte>((int)hdr.FileLength);
 
                     await archive.ReadExactlyAsync(data, cancellationToken).ConfigureAwait(false);
 

Library/DiscUtils.Core/Compression/BZip2CombinedHuffmanTrees.cs

@@ -24,6 +24,7 @@
 // Based on "libbzip2", Copyright (C) 1996-2007 Julian R Seward.
 //
 
+using DiscUtils.Streams;
 using System.IO;
 
 namespace DiscUtils.Compression;
@@ -76,7 +77,7 @@ private void Initialize(int maxSymbols)
             throw new InvalidDataException("Invalid number of selectors");
         }
 
-        _selectors = new byte[numSelectors];
+        _selectors = StreamUtilities.GetUninitializedArray<byte>(numSelectors);
         var mtf = new MoveToFront(numTrees, true);
         for (var i = 0; i < numSelectors; ++i)
         {

Library/DiscUtils.Core/Compression/BZip2DecoderStream.cs

@@ -87,7 +87,7 @@ public BZip2DecoderStream(Stream stream, Ownership ownsStream)
 
         _rleStream = new BZip2RleStream();
         _blockDecoder = new BZip2BlockDecoder(blockSize);
-        _blockBuffer = new byte[blockSize];
+        _blockBuffer = StreamUtilities.GetUninitializedArray<byte>(blockSize);
 
         if (ReadBlock() == 0)
         {

Library/DiscUtils.Core/Compression/LZNT1.cs

@@ -300,7 +300,7 @@ public override int Decompress(ReadOnlySpan<byte> source, Span<byte> decompresse
 
     private static byte[] CalcCompressionBits()
     {
-        var result = new byte[4096];
+        var result = StreamUtilities.GetUninitializedArray<byte>(4096);
         byte offsetBits = 0;
 
         var y = 0x10;

Library/DiscUtils.Core/Compression/LzxBitStream.cs

@@ -133,7 +133,7 @@ public byte[] ReadBytes(int count)
             throw new InvalidOperationException("Attempt to read bytes when not byte-aligned");
         }
 
-        var buffer = new byte[count];
+        var buffer = StreamUtilities.GetUninitializedArray<byte>(count);
         ReadBytes(buffer, 0, count);
         return buffer;
     }

Library/DiscUtils.Core/LogicalDiskManager/DynamicDisk.cs

@@ -21,6 +21,7 @@
 //
 
 using System;
+using System.Buffers;
 using System.IO;
 using DiscUtils.Partitions;
 using DiscUtils.Streams;
@@ -113,16 +114,25 @@ internal static PrivateHeader GetPrivateHeader(VirtualDisk disk)
 
     private TocBlock GetTableOfContents()
     {
-        var buffer = new byte[_header.TocSizeLba * 512];
-        _disk.Content.Position = _header.ConfigurationStartLba * 512 + 1 * _header.TocSizeLba * 512;
+        var tocSize = (int)(_header.TocSizeLba * 512);
 
-        _disk.Content.ReadExactly(buffer, 0, buffer.Length);
-        var tocBlock = new TocBlock();
-        tocBlock.ReadFrom(buffer);
+        var buffer = ArrayPool<byte>.Shared.Rent(tocSize);
+        try
+        {
+            _disk.Content.Position = _header.ConfigurationStartLba * 512 + 1 * _header.TocSizeLba * 512;
+
+            _disk.Content.ReadExactly(buffer, 0, tocSize);
+            var tocBlock = new TocBlock();
+            tocBlock.ReadFrom(buffer);
 
-        if (tocBlock.Signature == "TOCBLOCK")
+            if (tocBlock.Signature == "TOCBLOCK")
+            {
+                return tocBlock;
+            }
+        }
+        finally
         {
-            return tocBlock;
+            ArrayPool<byte>.Shared.Return(buffer);
         }
 
         return null;

Library/DiscUtils.Core/Partitions/GuidPartitionTable.cs

@@ -130,7 +130,7 @@ public static GuidPartitionTable Initialize(Stream disk, Geometry diskGeometry)
         // Write the primary header
         var headerBuffer = diskGeometry.BytesPerSector <= 1024
             ? stackalloc byte[diskGeometry.BytesPerSector]
-            : new byte[diskGeometry.BytesPerSector];
+            : StreamUtilities.GetUninitializedArray<byte>(diskGeometry.BytesPerSector);
 
         header.WriteTo(headerBuffer);
         disk.Position = header.HeaderLba * diskGeometry.BytesPerSector;
@@ -312,9 +312,9 @@ internal SparseStream Open(GptEntry entry)
         return new SubStream(_diskData, start, end - start);
     }
 
-    private static uint CalcEntriesCrc(byte[] buffer)
+    private static uint CalcEntriesCrc(ReadOnlySpan<byte> buffer)
     {
-        return Crc32LittleEndian.Compute(Crc32Algorithm.Common, buffer, 0, buffer.Length);
+        return Crc32LittleEndian.Compute(Crc32Algorithm.Common, buffer);
     }
 
     private static int CountEntries<T>(ICollection<T> values, Func<T, bool> pred)
@@ -355,7 +355,7 @@ private void Init(Stream disk, Geometry diskGeometry)
         disk.Position = diskGeometry.BytesPerSector;
         var sector = diskGeometry.BytesPerSector <= 1024
             ? stackalloc byte[diskGeometry.BytesPerSector]
-            : new byte[diskGeometry.BytesPerSector];
+            : StreamUtilities.GetUninitializedArray<byte>(diskGeometry.BytesPerSector);
 
         disk.ReadExactly(sector);
 
@@ -536,7 +536,7 @@ private void WritePrimaryHeader()
     {
         var buffer = _diskGeometry.BytesPerSector <= 1024
             ? stackalloc byte[_diskGeometry.BytesPerSector]
-            : new byte[_diskGeometry.BytesPerSector];
+            : StreamUtilities.GetUninitializedArray<byte>(_diskGeometry.BytesPerSector);
 
         _primaryHeader.EntriesCrc = CalcEntriesCrc(_entryBuffer);
         _primaryHeader.WriteTo(buffer);
@@ -551,7 +551,7 @@ private void WriteSecondaryHeader()
     {
         var buffer = _diskGeometry.BytesPerSector <= 1024
             ? stackalloc byte[_diskGeometry.BytesPerSector]
-            : new byte[_diskGeometry.BytesPerSector];
+            : StreamUtilities.GetUninitializedArray<byte>(_diskGeometry.BytesPerSector);
 
         _secondaryHeader.EntriesCrc = CalcEntriesCrc(_entryBuffer);
         _secondaryHeader.WriteTo(buffer);

Library/DiscUtils.Core/VirtualDisk.cs

@@ -29,6 +29,7 @@
 using DiscUtils.Internal;
 using DiscUtils.Partitions;
 using DiscUtils.Streams;
+using LTRData.Extensions.Buffers;
 
 namespace DiscUtils;
 
@@ -523,7 +524,7 @@ public static VirtualDisk OpenDisk(string path, string forceType, FileAccess acc
                 else
                 {
                     var extension = Path.GetExtension(uri.AbsolutePath);
-                    if (extension.StartsWith(".", StringComparison.Ordinal))
+                    if (extension.StartsWith('.'))
                     {
                         extension = extension.Substring(1);
                     }
@@ -566,7 +567,7 @@ public static VirtualDisk OpenDisk(DiscFileSystem fs, string path, FileAccess ac
         }
 
         var extension = Path.GetExtension(path);
-        if (extension.StartsWith(".", StringComparison.Ordinal))
+        if (extension.StartsWith('.'))
         {
             extension = extension.Substring(1);
         }
@@ -594,7 +595,7 @@ public void Dispose()
     /// <returns>The MBR as a byte array.</returns>
     public byte[] GetMasterBootRecord()
     {
-        var sector = new byte[Sizes.Sector];
+        var sector = StreamUtilities.GetUninitializedArray<byte>(Sizes.Sector);
 
         GetMasterBootRecord(sector);
 
@@ -687,7 +688,7 @@ public VirtualDisk CreateDifferencingDisk(string path)
     internal static VirtualDiskLayer OpenDiskLayer(FileLocator locator, string path, FileAccess access)
     {
         var extension = Path.GetExtension(path);
-        if (extension.StartsWith(".", StringComparison.Ordinal))
+        if (extension.StartsWith('.'))
         {
             extension = extension.Substring(1);
         }

Library/DiscUtils.Core/WindowsSecurity/AccessControl/GenericSecurityDescriptor.cs

@@ -1,3 +1,4 @@
+using DiscUtils.Streams;
 using System;
 using System.Globalization;
 using System.Text;
@@ -202,7 +203,7 @@ static void WriteInt(int val, byte[] buffer, int offset)
 
     public byte[] GetSecurityDescriptorBinaryForm()
     {
-        var buffer = new byte[BinaryLength];
+        var buffer = StreamUtilities.GetUninitializedArray<byte>(BinaryLength);
         GetBinaryForm(buffer, 0);
         return buffer;
     }

Library/DiscUtils.Core/WindowsSecurity/SecurityIdentifier.cs

@@ -3,6 +3,7 @@
 using System.Globalization;
 using System.Linq;
 using System.Runtime.InteropServices;
+using System.Security.Cryptography;
 using System.Text;
 
 namespace DiscUtils.Core.WindowsSecurity;
@@ -17,10 +18,14 @@ public sealed class SecurityIdentifier : IdentityReference, IComparable<Security
 
     public SecurityIdentifier(string sddlForm)
     {
+#if NET6_0_OR_GREATER
+        ArgumentNullException.ThrowIfNull(sddlForm);
+#else
         if (sddlForm == null)
         {
             throw new ArgumentNullException(nameof(sddlForm));
         }
+#endif
 
         buffer = ParseSddlForm(sddlForm);
     }
@@ -119,10 +124,14 @@ public SecurityIdentifier(WellKnownSidType sidType,
         }
         else
         {
+#if NET6_0_OR_GREATER
+            ArgumentNullException.ThrowIfNull(domainSid);
+#else
             if (domainSid == null)
             {
                 throw new ArgumentNullException(nameof(domainSid));
             }
+#endif
 
             buffer = domainSid.CreateSubSid(uint.Parse(acct.RidStr)).buffer;
         }
@@ -204,10 +213,14 @@ public uint GetSidSubAuthority(byte index)
     // The comparison was determined to be: authority, then subauthority count, then subauthority.
     public int CompareTo(SecurityIdentifier sid)
     {
+#if NET6_0_OR_GREATER
+        ArgumentNullException.ThrowIfNull(sid);
+#else
         if (sid == null)
         {
             throw new ArgumentNullException(nameof(sid));
         }
+#endif
 
         int result;
         if (0 != (result = SidAuthority.CompareTo(sid.SidAuthority)))
@@ -456,7 +469,7 @@ private static byte[] ParseSddlForm(string sddlForm)
             throw new ArgumentException("Only SIDs with revision 1 are supported");
         }
 
-        var buffer = new byte[8 + (numSubAuthorities * 4)];
+        var buffer = StreamUtilities.GetUninitializedArray<byte>(8 + (numSubAuthorities * 4));
         buffer[0] = 1;
         buffer[1] = (byte)numSubAuthorities;
 

Library/DiscUtils.Fat/ClusterStream.cs

@@ -61,7 +61,7 @@ internal ClusterStream(FatFileSystem fileSystem, FileAccess access, uint firstCl
         }
 
         _currentCluster = uint.MaxValue;
-        _clusterBuffer = new byte[_reader.ClusterSize];
+        _clusterBuffer = StreamUtilities.GetUninitializedArray<byte>(_reader.ClusterSize);
     }
 
     public override long? GetPositionInBaseStream(Stream baseStream, long virtualPosition)

Library/DiscUtils.HfsPlus/BTreeGenericRecord.cs

@@ -20,6 +20,7 @@
 // DEALINGS IN THE SOFTWARE.
 //
 
+using DiscUtils.Streams;
 using System;
 
 namespace DiscUtils.HfsPlus;
@@ -38,7 +39,7 @@ public BTreeGenericRecord(int size)
 
     public override int ReadFrom(ReadOnlySpan<byte> buffer)
     {
-        _data = new byte[_size];
+        _data = StreamUtilities.GetUninitializedArray<byte>(_size);
         buffer.Slice(0, _size).CopyTo(_data);
         return _size;
     }

Library/DiscUtils.HfsPlus/File.cs

@@ -144,8 +144,8 @@ public IBuffer FileContent
                         // The data is stored in the resource fork.
                         var buffer = new FileBuffer(Context, fileInfo.ResourceFork, fileInfo.FileId);
                         var compressionFork = new CompressionResourceHeader();
-                        var compressionForkData = new byte[CompressionResourceHeader.Size];
-                        buffer.Read(0, compressionForkData, 0, CompressionResourceHeader.Size);
+                        Span<byte> compressionForkData = stackalloc byte[CompressionResourceHeader.Size];
+                        buffer.Read(0, compressionForkData);
                         compressionFork.ReadFrom(compressionForkData);
 
                         // The data is compressed in a number of blocks. Each block originally accounted for
@@ -154,25 +154,25 @@ public IBuffer FileContent
                         // the zlib header but the others don't, so we read them directly as deflate streams.
                         // For each block, we create a separate stream which we later aggregate.
                         var blockHeader = new CompressionResourceBlockHead();
-                        var blockHeaderData = new byte[CompressionResourceBlockHead.Size];
-                        buffer.Read(compressionFork.HeaderSize, blockHeaderData, 0, CompressionResourceBlockHead.Size);
+                        Span<byte> blockHeaderData = stackalloc byte[CompressionResourceBlockHead.Size];
+                        buffer.Read(compressionFork.HeaderSize, blockHeaderData);
                         blockHeader.ReadFrom(blockHeaderData);
 
                         var blockCount = blockHeader.NumBlocks;
                         var blocks = new CompressionResourceBlock[blockCount];
                         var streams = new SparseStream[blockCount];
 
+                        Span<byte> blockData = stackalloc byte[CompressionResourceBlock.Size];
+
                         for (var i = 0; i < blockCount; i++)
                         {
                             // Read the block data, first into a buffer and the into the class.
                             blocks[i] = new CompressionResourceBlock();
-                            var blockData = new byte[CompressionResourceBlock.Size];
+
                             buffer.Read(
                                 compressionFork.HeaderSize + CompressionResourceBlockHead.Size +
                                 i * CompressionResourceBlock.Size,
-                                blockData,
-                                0,
-                                blockData.Length);
+                                blockData);
                             blocks[i].ReadFrom(blockData);
 
                             // Create a SubBuffer which points to the data window that corresponds to the block.