Add async/await support for all Stream I/O operations

[Copilot]

All I/O operations now support async/await with CancellationToken. Methods performing async operations are suffixed with Async.

Changes

Core Infrastructure

• SharpCompressStream, SourceStream - Added ReadAsync(), WriteAsync(), FlushAsync()
• Utility methods - Added TransferToAsync(), SkipAsync() with CancellationToken support

Public APIs

• IReader.WriteEntryToAsync() - Extract entries asynchronously
• IWriter.WriteAsync() - Write entries asynchronously
• IArchiveEntry.OpenEntryStreamAsync() - Open entry streams asynchronously

Extension Methods

• reader.WriteAllToDirectoryAsync() - Bulk async extraction
• writer.WriteAllAsync() - Bulk async compression
• All methods accept optional CancellationToken

Archive Format Support

• All formats (GZip, Tar, Zip, Rar, SevenZip) implement async entry stream opening

Usage

Async Reading:

using var reader = ReaderFactory.Open(stream);
await reader.WriteAllToDirectoryAsync(@"C:\output", options, cancellationToken);

Async Writing:

using var writer = WriterFactory.Open(stream, ArchiveType.Zip, CompressionType.Deflate);
await writer.WriteAllAsync(@"D:\files", "*", SearchOption.AllDirectories, cancellationToken);

Async Entry Access:

using var entryStream = await entry.OpenEntryStreamAsync(cancellationToken);
await entryStream.CopyToAsync(outputStream, cancellationToken);

Compatibility

• All synchronous methods remain unchanged - no breaking changes
• Framework support: net48, net481, netstandard2.0, net6.0, net8.0
• Older frameworks use Microsoft.Bcl.AsyncInterfaces polyfill (already referenced)

Documentation

• README.md - Added async overview and examples
• USAGE.md - Added comprehensive async patterns section
• New test file AsyncTests.cs with 6 async scenarios

Original prompt

Convert all Stream access to be async. All IO should go through asynchronous methods now. Methods using async should be renamed to be Async. .NET legacy (.net framework 4.8 and 4.8.1 and .net standard) might need something different. Use compiler flags if necessary. Update the README when done.

---

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.

[adamhathcock]

Tests should also pass

[adamhathcock]

Go deeper, EntryStream should be changed to be asynchronous as well as classes like ZlibStream

[adamhathcock]

Derived classes should be forced to implement this