Base Reader implementation of .ARC format

src/SharpCompress/Common/Arc/ArcEntry.cs

@@ -0,0 +1,60 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using SharpCompress.Common.GZip;
+using SharpCompress.Common.Tar;
+
+namespace SharpCompress.Common.Arc
+{
+    public class ArcEntry : Entry
+    {
+        private readonly ArcFilePart? _filePart;
+
+        internal ArcEntry(ArcFilePart? filePart)
+        {
+            _filePart = filePart;
+        }
+
+        public override long Crc
+        {
+            get
+            {
+                if (_filePart == null)
+                {
+                    return 0;
+                }
+                return _filePart.Header.Crc16;
+            }
+        }
+
+        public override string? Key => _filePart?.Header.Name;
+
+        public override string? LinkTarget => null;
+
+        public override long CompressedSize => _filePart?.Header.CompressedSize ?? 0;
+
+        public override CompressionType CompressionType =>
+            _filePart?.Header.CompressionMethod ?? CompressionType.Unknown;
+
+        public override long Size => throw new NotImplementedException();
+
+        public override DateTime? LastModifiedTime => null;
+
+        public override DateTime? CreatedTime => null;
+
+        public override DateTime? LastAccessedTime => null;
+
+        public override DateTime? ArchivedTime => null;
+
+        public override bool IsEncrypted => false;
+
+        public override bool IsDirectory => false;
+
+        public override bool IsSplitAfter => false;
+
+        internal override IEnumerable<FilePart> Parts => _filePart.Empty();
+    }
+}

src/SharpCompress/Common/Arc/ArcEntryHeader.cs

@@ -0,0 +1,83 @@
+using System;
+using System.IO;
+using System.Linq;
+using System.Text;
+
+namespace SharpCompress.Common.Arc
+{
+    public class ArcEntryHeader
+    {
+        public ArchiveEncoding ArchiveEncoding { get; }
+        public CompressionType CompressionMethod { get; private set; }
+        public string? Name { get; private set; }
+        public long CompressedSize { get; private set; }
+        public DateTime DateTime { get; private set; }
+        public int Crc16 { get; private set; }
+        public long OriginalSize { get; private set; }
+        public long DataStartPosition { get; private set; }
+
+        public ArcEntryHeader(ArchiveEncoding archiveEncoding)
+        {
+            this.ArchiveEncoding = archiveEncoding;
+        }
+
+        public ArcEntryHeader? ReadHeader(Stream stream)
+        {
+            byte[] headerBytes = new byte[29];
+            if (stream.Read(headerBytes, 0, headerBytes.Length) != headerBytes.Length)
+            {
+                return null;
+            }
+            return LoadFrom(headerBytes);
+        }
+
+        public ArcEntryHeader LoadFrom(byte[] headerBytes)
+        {
+            CompressionMethod = GetCompressionType(headerBytes[1]);
+
+            // Read name
+            int nameEnd = Array.IndexOf(headerBytes, (byte)0, 1); // Find null terminator
+            Name = Encoding.UTF8.GetString(headerBytes, 2, nameEnd > 0 ? nameEnd - 2 : 12);
+
+            int offset = 15;
+            CompressedSize = BitConverter.ToUInt32(headerBytes, offset);
+            offset += 4;
+            uint rawDateTime = BitConverter.ToUInt32(headerBytes, offset);
+            DateTime = ConvertToDateTime(rawDateTime);
+            offset += 4;
+            Crc16 = BitConverter.ToUInt16(headerBytes, offset);
+            offset += 2;
+            OriginalSize = BitConverter.ToUInt32(headerBytes, offset);
+            return this;
+        }
+
+        private CompressionType GetCompressionType(byte value)
+        {
+            return value switch
+            {
+                1 or 2 => CompressionType.None,
+                //3 => CompressionType.RLE90,
+                //4 => CompressionType.Squeezed,
+                //5 or 6 or 7 or 8 => CompressionType.Crunched,
+                //9 => CompressionType.Squashed,
+                //10 => CompressionType.Crushed,
+                //11 => CompressionType.Distilled,
+                _ => CompressionType.Unknown,
+            };
+        }
+
+        public static DateTime ConvertToDateTime(long rawDateTime)
+        {
+            // Extract components using bit manipulation
+            int year = (int)((rawDateTime >> 25) & 0x7F) + 1980;
+            int month = (int)((rawDateTime >> 21) & 0xF);
+            int day = (int)((rawDateTime >> 16) & 0x1F);
+            int hour = (int)((rawDateTime >> 11) & 0x1F);
+            int minute = (int)((rawDateTime >> 5) & 0x3F);
+            int second = (int)((rawDateTime & 0x1F) * 2); // Multiply by 2 since DOS seconds are stored as halves
+
+            // Return as a DateTime object
+            return new DateTime(year, month, day, hour, minute, second);
+        }
+    }
+}

src/SharpCompress/Common/Arc/ArcFilePart.cs

@@ -0,0 +1,41 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using SharpCompress.Common.GZip;
+using SharpCompress.Common.Tar;
+using SharpCompress.Common.Tar.Headers;
+using SharpCompress.Common.Zip.Headers;
+using SharpCompress.IO;
+
+namespace SharpCompress.Common.Arc
+{
+    public class ArcFilePart : FilePart
+    {
+        private readonly Stream? _stream;
+
+        internal ArcFilePart(ArcEntryHeader localArcHeader, Stream? seekableStream)
+            : base(localArcHeader.ArchiveEncoding)
+        {
+            _stream = seekableStream;
+            Header = localArcHeader;
+        }
+
+        internal ArcEntryHeader Header { get; set; }
+
+        internal override string? FilePartName => Header.Name;
+
+        internal override Stream GetCompressedStream()
+        {
+            if (_stream != null)
+            {
+                return new ReadOnlySubStream(_stream, Header.CompressedSize);
+            }
+            return _stream.NotNull();
+        }
+
+        internal override Stream? GetRawStream() => _stream;
+    }
+}

src/SharpCompress/Common/Arc/ArcVolume.cs

@@ -0,0 +1,16 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using SharpCompress.Readers;
+
+namespace SharpCompress.Common.Arc
+{
+    public class ArcVolume : Volume
+    {
+        public ArcVolume(Stream stream, ReaderOptions readerOptions, int index = 0)
+            : base(stream, readerOptions, index) { }
+    }
+}

src/SharpCompress/Common/ArchiveType.cs

@@ -7,4 +7,5 @@ public enum ArchiveType
     Tar,
     SevenZip,
     GZip,
+    Arc,
 }

src/SharpCompress/Factories/ArcFactory.cs

@@ -0,0 +1,42 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Security.Cryptography;
+using System.Text;
+using System.Threading.Tasks;
+using SharpCompress.Common;
+using SharpCompress.Readers;
+using SharpCompress.Readers.Arc;
+using static System.Net.Mime.MediaTypeNames;
+
+namespace SharpCompress.Factories
+{
+    public class ArcFactory : Factory, IReaderFactory
+    {
+        public override string Name => "Arc";
+
+        public override ArchiveType? KnownArchiveType => ArchiveType.Arc;
+
+        public override IEnumerable<string> GetSupportedExtensions()
+        {
+            yield return "arc";
+        }
+
+        public override bool IsArchive(Stream stream, string? password = null)
+        {
+            //You may have to use some(paranoid) checks to ensure that you actually are
+            //processing an ARC file, since other archivers also adopted the idea of putting
+            //a 01Ah byte at offset 0, namely the Hyper archiver. To check if you have a
+            //Hyper - archive, check the next two bytes for "HP" or "ST"(or look below for
+            //"HYP").Also the ZOO archiver also does put a 01Ah at the start of the file,
+            //see the ZOO entry below.
+            var bytes = new byte[2];
+            stream.Read(bytes, 0, 2);
+            return bytes[0] == 0x1A && bytes[1] < 10; //rather thin, but this is all we have
+        }
+
+        public IReader OpenReader(Stream stream, ReaderOptions? options) =>
+            ArcReader.Open(stream, options);
+    }
+}

src/SharpCompress/Factories/Factory.cs

@@ -17,6 +17,7 @@ static Factory()
         RegisterFactory(new SevenZipFactory());
         RegisterFactory(new GZipFactory());
         RegisterFactory(new TarFactory());
+        RegisterFactory(new ArcFactory());
     }
 
     private static readonly HashSet<Factory> _factories = new();

src/SharpCompress/Readers/Arc/ArcReader.cs

@@ -0,0 +1,41 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using SharpCompress.Common;
+using SharpCompress.Common.Arc;
+
+namespace SharpCompress.Readers.Arc
+{
+    public class ArcReader : AbstractReader<ArcEntry, ArcVolume>
+    {
+        private ArcReader(Stream stream, ReaderOptions options)
+            : base(options, ArchiveType.Arc) => Volume = new ArcVolume(stream, options, 0);
+
+        public override ArcVolume Volume { get; }
+
+        /// <summary>
+        /// Opens an ArcReader for Non-seeking usage with a single volume
+        /// </summary>
+        /// <param name="stream"></param>
+        /// <param name="options"></param>
+        /// <returns></returns>
+        public static ArcReader Open(Stream stream, ReaderOptions? options = null)
+        {
+            stream.CheckNotNull(nameof(stream));
+            return new ArcReader(stream, options ?? new ReaderOptions());
+        }
+
+        protected override IEnumerable<ArcEntry> GetEntries(Stream stream)
+        {
+            ArcEntryHeader headerReader = new ArcEntryHeader(new ArchiveEncoding());
+            ArcEntryHeader? header;
+            while ((header = headerReader.ReadHeader(stream)) != null)
+            {
+                yield return new ArcEntry(new ArcFilePart(header, stream));
+            }
+        }
+    }
+}

src/SharpCompress/Readers/ReaderFactory.cs

@@ -30,7 +30,7 @@ public static IReader Open(Stream stream, ReaderOptions? options = null)
         }
 
         throw new InvalidOperationException(
-            "Cannot determine compressed stream type.  Supported Reader Formats: Zip, GZip, BZip2, Tar, Rar, LZip, XZ"
+            "Cannot determine compressed stream type.  Supported Reader Formats: Arc, Zip, GZip, BZip2, Tar, Rar, LZip, XZ"
         );
     }
 }

tests/SharpCompress.Test/Arc/ArcReaderTests.cs

@@ -0,0 +1,22 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using SharpCompress.Common;
+using Xunit;
+
+namespace SharpCompress.Test.Arc
+{
+    public class ArcReaderTests : ReaderTests
+    {
+        public ArcReaderTests()
+        {
+            UseExtensionInsteadOfNameToVerify = true;
+            UseCaseInsensitiveToVerify = true;
+        }
+
+        [Fact]
+        public void Arc_Uncompressed_Read() => Read("Arc.uncompressed.arc", CompressionType.None);
+    }
+}