Fix a usage of ReadOnly that use dispose in 7Zip

src/SharpCompress/Common/SevenZip/SevenZipFilePart.cs

@@ -55,7 +55,7 @@ internal override Stream GetCompressedStream()
         {
             folderStream.Skip(skipSize);
         }
-        return new ReadOnlySubStream(folderStream, Header.Size);
+        return new ReadOnlySubStream(folderStream, Header.Size, leaveOpen: false);
     }
 
     public CompressionType CompressionType

src/SharpCompress/Compressors/LZMA/LZipStream.cs

@@ -45,10 +45,12 @@ void IStreamStack.SetPosition(long position) { }
     private bool _finished;
 
     private long _writeCount;
+    private readonly Stream? _originalStream;
 
     public LZipStream(Stream stream, CompressionMode mode)
     {
         Mode = mode;
+        _originalStream = stream;
 
         if (mode == CompressionMode.Decompress)
         {
@@ -125,6 +127,10 @@ protected override void Dispose(bool disposing)
         {
             Finish();
             _stream.Dispose();
+            if (Mode == CompressionMode.Compress)
+            {
+                _originalStream?.Dispose();
+            }
         }
     }
 

src/SharpCompress/IO/ReadOnlySubStream.cs

@@ -16,11 +16,11 @@ internal class ReadOnlySubStream : SharpCompressStream, IStreamStack
 
     private long _position;
 
-    public ReadOnlySubStream(Stream stream, long bytesToRead)
-        : this(stream, null, bytesToRead) { }
+    public ReadOnlySubStream(Stream stream, long bytesToRead, bool leaveOpen = true)
+        : this(stream, null, bytesToRead, leaveOpen) { }
 
-    public ReadOnlySubStream(Stream stream, long? origin, long bytesToRead)
-        : base(stream, leaveOpen: true, throwOnDispose: false)
+    public ReadOnlySubStream(Stream stream, long? origin, long bytesToRead, bool leaveOpen = true)
+        : base(stream, leaveOpen, throwOnDispose: false)
     {
         if (origin != null && stream.Position != origin.Value)
         {

src/SharpCompress/IO/SharpCompressStream.cs

@@ -138,8 +138,6 @@ public SharpCompressStream(
 #endif
     }
 
-    internal bool IsRecording { get; private set; }
-
     protected override void Dispose(bool disposing)
     {
 #if DEBUG_STREAMS

src/SharpCompress/Utility.cs

@@ -71,48 +71,16 @@ public static void Skip(this Stream source, long advanceAmount)
             return;
         }
 
-        using var buffer = MemoryPool<byte>.Shared.Rent(TEMP_BUFFER_SIZE);
-        while (advanceAmount > 0)
-        {
-            var toRead = (int)Math.Min(buffer.Memory.Length, advanceAmount);
-            var read = source.Read(buffer.Memory.Slice(0, toRead).Span);
-            if (read <= 0)
-            {
-                break;
-            }
-            advanceAmount -= read;
-        }
+        using var readOnlySubStream = new IO.ReadOnlySubStream(source, advanceAmount);
+        readOnlySubStream.CopyTo(Stream.Null);
     }
 
-    public static void Skip(this Stream source)
-    {
-        using var buffer = MemoryPool<byte>.Shared.Rent(TEMP_BUFFER_SIZE);
-        while (source.Read(buffer.Memory.Span) > 0) { }
-    }
+    public static void Skip(this Stream source) => source.CopyTo(Stream.Null);
 
-    public static async Task SkipAsync(
-        this Stream source,
-        CancellationToken cancellationToken = default
-    )
+    public static Task SkipAsync(this Stream source, CancellationToken cancellationToken = default)
     {
-        var array = ArrayPool<byte>.Shared.Rent(TEMP_BUFFER_SIZE);
-        try
-        {
-            while (true)
-            {
-                var read = await source
-                    .ReadAsync(array, 0, array.Length, cancellationToken)
-                    .ConfigureAwait(false);
-                if (read <= 0)
-                {
-                    break;
-                }
-            }
-        }
-        finally
-        {
-            ArrayPool<byte>.Shared.Return(array);
-        }
+        cancellationToken.ThrowIfCancellationRequested();
+        return source.CopyToAsync(Stream.Null);
     }
 
     public static DateTime DosDateToDateTime(ushort iDate, ushort iTime)

tests/SharpCompress.Test/Streams/DisposalTests.cs

@@ -0,0 +1,189 @@
+using System;
+using System.IO;
+using SharpCompress.Common;
+using SharpCompress.Compressors;
+using SharpCompress.Compressors.Deflate;
+using SharpCompress.Compressors.LZMA;
+using SharpCompress.Compressors.Lzw;
+using SharpCompress.Compressors.PPMd;
+using SharpCompress.Compressors.Reduce;
+using SharpCompress.Compressors.ZStandard;
+using SharpCompress.IO;
+using SharpCompress.Readers;
+using SharpCompress.Test.Mocks;
+using Xunit;
+
+namespace SharpCompress.Test.Streams;
+
+public class DisposalTests
+{
+    private void VerifyStreamDisposal(
+        Func<Stream, bool, Stream> createStream,
+        bool supportsLeaveOpen = true
+    )
+    {
+        // 1. Test Dispose behavior (should dispose inner stream)
+        {
+            using var innerStream = new TestStream(new MemoryStream());
+            // createStream(stream, leaveOpen: false)
+            var stream = createStream(innerStream, false);
+            stream.Dispose();
+
+            // Some streams might not support disposal of inner stream (e.g. PpmdStream apparently)
+            // But for those that satisfy the pattern, we assert true.
+            Assert.True(
+                innerStream.IsDisposed,
+                "Stream should have been disposed when leaveOpen=false"
+            );
+        }
+
+        // 2. Test LeaveOpen behavior (should NOT dispose inner stream)
+        if (supportsLeaveOpen)
+        {
+            using var innerStream = new TestStream(new MemoryStream());
+            // createStream(stream, leaveOpen: true)
+            var stream = createStream(innerStream, true);
+            stream.Dispose();
+            Assert.False(
+                innerStream.IsDisposed,
+                "Stream should NOT have been disposed when leaveOpen=true"
+            );
+        }
+    }
+
+    private void VerifyAlwaysDispose(Func<Stream, Stream> createStream)
+    {
+        using var innerStream = new TestStream(new MemoryStream());
+        var stream = createStream(innerStream);
+        stream.Dispose();
+        Assert.True(innerStream.IsDisposed, "Stream should have been disposed (AlwaysDispose)");
+    }
+
+    private void VerifyNeverDispose(Func<Stream, Stream> createStream)
+    {
+        using var innerStream = new TestStream(new MemoryStream());
+        var stream = createStream(innerStream);
+        stream.Dispose();
+        Assert.False(innerStream.IsDisposed, "Stream should NOT have been disposed (NeverDispose)");
+    }
+
+    [Fact]
+    public void SourceStream_Disposal()
+    {
+        VerifyStreamDisposal(
+            (stream, leaveOpen) =>
+                new SourceStream(
+                    stream,
+                    i => null,
+                    new ReaderOptions { LeaveStreamOpen = leaveOpen }
+                )
+        );
+    }
+
+    [Fact]
+    public void ProgressReportingStream_Disposal()
+    {
+        VerifyStreamDisposal(
+            (stream, leaveOpen) =>
+                new ProgressReportingStream(
+                    stream,
+                    new Progress<ProgressReport>(),
+                    "",
+                    0,
+                    leaveOpen: leaveOpen
+                )
+        );
+    }
+
+    [Fact]
+    public void DataDescriptorStream_Disposal()
+    {
+        // DataDescriptorStream DOES dispose inner stream
+        VerifyAlwaysDispose(stream => new DataDescriptorStream(stream));
+    }
+
+    [Fact]
+    public void DeflateStream_Disposal()
+    {
+        // DeflateStream in SharpCompress always disposes inner stream
+        VerifyAlwaysDispose(stream => new DeflateStream(stream, CompressionMode.Compress));
+    }
+
+    [Fact]
+    public void GZipStream_Disposal()
+    {
+        // GZipStream in SharpCompress always disposes inner stream
+        VerifyAlwaysDispose(stream => new GZipStream(stream, CompressionMode.Compress));
+    }
+
+    [Fact]
+    public void LzwStream_Disposal()
+    {
+        VerifyStreamDisposal(
+            (stream, leaveOpen) =>
+            {
+                var lzw = new LzwStream(stream);
+                lzw.IsStreamOwner = !leaveOpen;
+                return lzw;
+            }
+        );
+    }
+
+    [Fact]
+    public void PpmdStream_Disposal()
+    {
+        // PpmdStream seems to not dispose inner stream based on code analysis
+        // It takes PpmdProperties which we need to mock or create.
+        var props = new PpmdProperties();
+        VerifyNeverDispose(stream => new PpmdStream(props, stream, false));
+    }
+
+    [Fact]
+    public void LzmaStream_Disposal()
+    {
+        // LzmaStream always disposes inner stream
+        // Need to provide valid properties to avoid crash in constructor (invalid window size)
+        // 5 bytes: 1 byte properties + 4 bytes dictionary size (little endian)
+        // Dictionary size = 1024 (0x400) -> 00 04 00 00
+        var lzmaProps = new byte[] { 0, 0, 4, 0, 0 };
+        VerifyAlwaysDispose(stream => new LzmaStream(lzmaProps, stream));
+    }
+
+    [Fact]
+    public void LZipStream_Disposal()
+    {
+        // LZipStream always disposes inner stream
+        // Use Compress mode to avoid need for valid input header
+        VerifyAlwaysDispose(stream => new LZipStream(stream, CompressionMode.Compress));
+    }
+
+    [Fact]
+    public void ReduceStream_Disposal()
+    {
+        // ReduceStream does not dispose inner stream
+        VerifyNeverDispose(stream => new ReduceStream(stream, 0, 0, 1));
+    }
+
+    [Fact]
+    public void ZStandard_CompressionStream_Disposal()
+    {
+        VerifyStreamDisposal(
+            (stream, leaveOpen) =>
+                new CompressionStream(stream, level: 0, bufferSize: 0, leaveOpen: leaveOpen)
+        );
+    }
+
+    [Fact]
+    public void ZStandard_DecompressionStream_Disposal()
+    {
+        VerifyStreamDisposal(
+            (stream, leaveOpen) =>
+                new DecompressionStream(
+                    stream,
+                    bufferSize: 0,
+                    checkEndOfStream: false,
+                    leaveOpen: leaveOpen
+                )
+        );
+    }
+}