add extract all test

FORMATS.md

@@ -24,14 +24,26 @@
 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. See [Zip Format Notes](#zip-format-notes) for details on multi-volume archives and streaming behavior.
 3. The Tar format requires a file size in the header. If no size is specified to the TarWriter and the stream is not seekable, then an exception will be thrown.
-4. The 7Zip format doesn't allow for reading as a forward-only stream so 7Zip is only supported through the Archive API
+4. The 7Zip format doesn't allow for reading as a forward-only stream so 7Zip is only supported through the Archive API. See [7Zip Format Notes](#7zip-format-notes) for details on async extraction behavior.
 5. LZip has no support for extra data like the file name or timestamp. There is a default filename used when looking at the entry Key on the archive.
 
 ### Zip Format Notes
 
 - Multi-volume/split ZIP archives require ZipArchive (seekable streams) as ZipReader cannot seek across volume files.
 - ZipReader processes entries from LocalEntry headers (which include directory entries ending with `/`) and intentionally skips DirectoryEntry headers from the central directory, as they are redundant in streaming mode - all entry data comes from LocalEntry headers which ZipReader has already processed.
 
+### 7Zip Format Notes
+
+- **Async Extraction Performance**: When using async extraction methods (e.g., `ExtractAllEntries()` with `MoveToNextEntryAsync()`), each file creates its own decompression stream to avoid state corruption in the LZMA decoder. This is less efficient than synchronous extraction, which can reuse a single decompression stream for multiple files in the same folder.
+
+  **Performance Impact**: For archives with many small files in the same compression folder, async extraction will be slower than synchronous extraction because it must:
+  1. Create a new LZMA decoder for each file
+  2. Skip through the decompressed data to reach each file's starting position
+
+  **Recommendation**: For best performance with 7Zip archives, use synchronous extraction methods (`MoveToNextEntry()` and `WriteEntryToDirectory()`) when possible. Use async methods only when you need to avoid blocking the thread (e.g., in UI applications or async-only contexts).
+
+  **Technical Details**: 7Zip archives group files into "folders" (compression units), where all files in a folder share one continuous LZMA-compressed stream. The LZMA decoder maintains internal state (dictionary window, decoder positions) that assumes sequential, non-interruptible processing. Async operations can yield control during awaits, which would corrupt this shared state. To avoid this, async extraction creates a fresh decoder stream for each file.
+
 ## Compression Streams
 
 For those who want to directly compress/decompress bits. The single file formats are represented here as well. However, BZip2, LZip and XZ have no metadata (GZip has a little) so using them without something like a Tar file makes little sense.

src/SharpCompress/Archives/SevenZip/SevenZipArchive.cs

@@ -2,6 +2,8 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
 using SharpCompress.Common;
 using SharpCompress.Common.SevenZip;
 using SharpCompress.Compressors.LZMA.Utilites;
@@ -213,9 +215,7 @@ protected override IReader CreateReaderForSolidExtraction() =>
     private sealed class SevenZipReader : AbstractReader<SevenZipEntry, SevenZipVolume>
     {
         private readonly SevenZipArchive _archive;
-        private CFolder? _currentFolder;
-        private Stream? _currentStream;
-        private CFileItem? _currentItem;
+        private SevenZipEntry? _currentEntry;
 
         internal SevenZipReader(ReaderOptions readerOptions, SevenZipArchive archive)
             : base(readerOptions, ArchiveType.SevenZip) => this._archive = archive;
@@ -228,40 +228,135 @@ protected override IEnumerable<SevenZipEntry> GetEntries(Stream stream)
             stream.Position = 0;
             foreach (var dir in entries.Where(x => x.IsDirectory))
             {
+                _currentEntry = dir;
                 yield return dir;
             }
-            foreach (
-                var group in entries.Where(x => !x.IsDirectory).GroupBy(x => x.FilePart.Folder)
-            )
+            // For non-directory entries, yield them without creating shared streams
+            // Each call to GetEntryStream() will create a fresh decompression stream
+            // to avoid state corruption issues with async operations
+            foreach (var entry in entries.Where(x => !x.IsDirectory))
             {
-                _currentFolder = group.Key;
-                if (group.Key is null)
-                {
-                    _currentStream = Stream.Null;
-                }
-                else
-                {
-                    _currentStream = _archive._database?.GetFolderStream(
-                        stream,
-                        _currentFolder,
-                        new PasswordProvider(Options.Password)
-                    );
-                }
-                foreach (var entry in group)
-                {
-                    _currentItem = entry.FilePart.Header;
-                    yield return entry;
-                }
+                _currentEntry = entry;
+                yield return entry;
             }
         }
 
-        protected override EntryStream GetEntryStream() =>
-            CreateEntryStream(
-                new ReadOnlySubStream(
-                    _currentStream.NotNull("currentStream is not null"),
-                    _currentItem?.Size ?? 0
-                )
-            );
+        protected override EntryStream GetEntryStream()
+        {
+            // Create a fresh decompression stream for each file (no state sharing).
+            // However, the LZMA decoder has bugs in its async implementation that cause
+            // state corruption even on fresh streams. The SyncOnlyStream wrapper
+            // works around these bugs by forcing async operations to use sync equivalents.
+            //
+            // TODO: Fix the LZMA decoder async bugs (in LzmaStream, Decoder, OutWindow)
+            // so this wrapper is no longer necessary.
+            var entry = _currentEntry.NotNull("currentEntry is not null");
+            if (entry.IsDirectory)
+            {
+                return CreateEntryStream(Stream.Null);
+            }
+            return CreateEntryStream(new SyncOnlyStream(entry.FilePart.GetCompressedStream()));
+        }
+    }
+
+    /// <summary>
+    /// WORKAROUND: Forces async operations to use synchronous equivalents.
+    /// This is necessary because the LZMA decoder has bugs in its async implementation
+    /// that cause state corruption (IndexOutOfRangeException, DataErrorException).
+    ///
+    /// The proper fix would be to repair the LZMA decoder's async methods
+    /// (LzmaStream.ReadAsync, Decoder.CodeAsync, OutWindow async operations),
+    /// but that requires deep changes to the decoder state machine.
+    /// </summary>
+    private sealed class SyncOnlyStream : Stream
+    {
+        private readonly Stream _baseStream;
+
+        public SyncOnlyStream(Stream baseStream) => _baseStream = baseStream;
+
+        public override bool CanRead => _baseStream.CanRead;
+        public override bool CanSeek => _baseStream.CanSeek;
+        public override bool CanWrite => _baseStream.CanWrite;
+        public override long Length => _baseStream.Length;
+        public override long Position
+        {
+            get => _baseStream.Position;
+            set => _baseStream.Position = value;
+        }
+
+        public override void Flush() => _baseStream.Flush();
+
+        public override int Read(byte[] buffer, int offset, int count) =>
+            _baseStream.Read(buffer, offset, count);
+
+        public override long Seek(long offset, SeekOrigin origin) =>
+            _baseStream.Seek(offset, origin);
+
+        public override void SetLength(long value) => _baseStream.SetLength(value);
+
+        public override void Write(byte[] buffer, int offset, int count) =>
+            _baseStream.Write(buffer, offset, count);
+
+        // Force async operations to use sync equivalents to avoid LZMA decoder bugs
+        public override Task<int> ReadAsync(
+            byte[] buffer,
+            int offset,
+            int count,
+            CancellationToken cancellationToken
+        )
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+            return Task.FromResult(_baseStream.Read(buffer, offset, count));
+        }
+
+        public override Task WriteAsync(
+            byte[] buffer,
+            int offset,
+            int count,
+            CancellationToken cancellationToken
+        )
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+            _baseStream.Write(buffer, offset, count);
+            return Task.CompletedTask;
+        }
+
+        public override Task FlushAsync(CancellationToken cancellationToken)
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+            _baseStream.Flush();
+            return Task.CompletedTask;
+        }
+
+#if !NETFRAMEWORK && !NETSTANDARD2_0
+        public override ValueTask<int> ReadAsync(
+            Memory<byte> buffer,
+            CancellationToken cancellationToken = default
+        )
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+            return new ValueTask<int>(_baseStream.Read(buffer.Span));
+        }
+
+        public override ValueTask WriteAsync(
+            ReadOnlyMemory<byte> buffer,
+            CancellationToken cancellationToken = default
+        )
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+            _baseStream.Write(buffer.Span);
+            return ValueTask.CompletedTask;
+        }
+#endif
+
+        protected override void Dispose(bool disposing)
+        {
+            if (disposing)
+            {
+                _baseStream.Dispose();
+            }
+            base.Dispose(disposing);
+        }
     }
 
     private class PasswordProvider : IPasswordProvider

src/SharpCompress/Compressors/LZMA/LzmaStream.cs

@@ -428,7 +428,9 @@ private void DecodeChunkHeader()
     private async Task DecodeChunkHeaderAsync(CancellationToken cancellationToken = default)
     {
         var controlBuffer = new byte[1];
-        await _inputStream.ReadAsync(controlBuffer, 0, 1, cancellationToken).ConfigureAwait(false);
+        await _inputStream
+            .ReadExactlyAsync(controlBuffer, 0, 1, cancellationToken)
+            .ConfigureAwait(false);
         var control = controlBuffer[0];
         _inputPosition++;
 
@@ -455,19 +457,23 @@ private async Task DecodeChunkHeaderAsync(CancellationToken cancellationToken =
 
             _availableBytes = (control & 0x1F) << 16;
             var buffer = new byte[2];
-            await _inputStream.ReadAsync(buffer, 0, 2, cancellationToken).ConfigureAwait(false);
+            await _inputStream
+                .ReadExactlyAsync(buffer, 0, 2, cancellationToken)
+                .ConfigureAwait(false);
             _availableBytes += (buffer[0] << 8) + buffer[1] + 1;
             _inputPosition += 2;
 
-            await _inputStream.ReadAsync(buffer, 0, 2, cancellationToken).ConfigureAwait(false);
+            await _inputStream
+                .ReadExactlyAsync(buffer, 0, 2, cancellationToken)
+                .ConfigureAwait(false);
             _rangeDecoderLimit = (buffer[0] << 8) + buffer[1] + 1;
             _inputPosition += 2;
 
             if (control >= 0xC0)
             {
                 _needProps = false;
                 await _inputStream
-                    .ReadAsync(controlBuffer, 0, 1, cancellationToken)
+                    .ReadExactlyAsync(controlBuffer, 0, 1, cancellationToken)
                     .ConfigureAwait(false);
                 Properties[0] = controlBuffer[0];
                 _inputPosition++;
@@ -495,7 +501,9 @@ await _inputStream
         {
             _uncompressedChunk = true;
             var buffer = new byte[2];
-            await _inputStream.ReadAsync(buffer, 0, 2, cancellationToken).ConfigureAwait(false);
+            await _inputStream
+                .ReadExactlyAsync(buffer, 0, 2, cancellationToken)
+                .ConfigureAwait(false);
             _availableBytes = (buffer[0] << 8) + buffer[1] + 1;
             _inputPosition += 2;
         }

src/SharpCompress/Polyfills/StreamExtensions.cs

@@ -3,6 +3,8 @@
 using System;
 using System.Buffers;
 using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
 
 namespace SharpCompress;
 
@@ -41,6 +43,28 @@ internal static void Write(this Stream stream, ReadOnlySpan<byte> buffer)
             ArrayPool<byte>.Shared.Return(temp);
         }
     }
+
+    internal static async Task ReadExactlyAsync(
+        this Stream stream,
+        byte[] buffer,
+        int offset,
+        int count,
+        CancellationToken cancellationToken
+    )
+    {
+        var totalRead = 0;
+        while (totalRead < count)
+        {
+            var read = await stream
+                .ReadAsync(buffer, offset + totalRead, count - totalRead, cancellationToken)
+                .ConfigureAwait(false);
+            if (read == 0)
+            {
+                throw new EndOfStreamException();
+            }
+            totalRead += read;
+        }
+    }
 }
 
 #endif

tests/SharpCompress.Test/ExtractAll.cs

@@ -0,0 +1,46 @@
+using System.IO;
+using System.Linq;
+using System.Threading.Tasks;
+using SharpCompress.Archives;
+using SharpCompress.Common;
+using SharpCompress.Readers;
+using Xunit;
+
+namespace SharpCompress.Test;
+
+public class ExtractAllTests : TestBase
+{
+    [Theory]
+    [InlineData("Zip.deflate.zip")]
+    [InlineData("Rar5.rar")]
+    [InlineData("Rar.rar")]
+    [InlineData("Rar.solid.rar")]
+    [InlineData("7Zip.solid.7z")]
+    [InlineData("7Zip.nonsolid.7z")]
+    [InlineData("7Zip.LZMA.7z")]
+    public async Task ExtractAllEntriesAsync(string archivePath)
+    {
+        var testArchive = Path.Combine(TEST_ARCHIVES_PATH, archivePath);
+        var options = new ExtractionOptions() { ExtractFullPath = true, Overwrite = true };
+
+        using var archive = ArchiveFactory.Open(testArchive);
+        await archive.WriteToDirectoryAsync(SCRATCH_FILES_PATH, options);
+    }
+
+    [Theory]
+    [InlineData("Zip.deflate.zip")]
+    [InlineData("Rar5.rar")]
+    [InlineData("Rar.rar")]
+    [InlineData("Rar.solid.rar")]
+    [InlineData("7Zip.solid.7z")]
+    [InlineData("7Zip.nonsolid.7z")]
+    [InlineData("7Zip.LZMA.7z")]
+    public void ExtractAllEntriesSync(string archivePath)
+    {
+        var testArchive = Path.Combine(TEST_ARCHIVES_PATH, archivePath);
+        var options = new ExtractionOptions() { ExtractFullPath = true, Overwrite = true };
+
+        using var archive = ArchiveFactory.Open(testArchive);
+        archive.WriteToDirectory(SCRATCH_FILES_PATH, options);
+    }
+}