Fixes Async Writing by adamhathcock · Pull Request #1311 · adamhathcock/sharpcompress

adamhathcock · 2026-04-30T13:13:38Z

This pull request introduces several improvements and refactorings to the handling of TAR and 7z archives, focusing on modernizing async support and streamlining API usage. The main changes include updating the TAR archive factory to simplify how compression types are determined, adding asynchronous methods for writing 7z signature headers, and improving resource management in 7z compression streams.

Key changes:

TAR Archive Factory Refactoring

Refactored calls to TarFactory.GetCompressionType and GetCompressionTypeAsync in TarArchive.Factory.cs to pass the full ReaderOptions object instead of just the Providers property, simplifying the API and aligning with updated method signatures. [1] [2] [3] [4] [5] [6]

7z Archive Async Support

Added WritePlaceholderAsync and WriteFinalAsync methods to SevenZipSignatureHeader.cs to allow asynchronous writing of 7z signature headers, supporting cancellation tokens and non-blocking I/O. [1] [2]
Refactored header construction logic into a private BuildFinalHeader method to reduce code duplication and improve maintainability. [1] [2]

7z Compression Stream Improvements

Updated SevenZipStreamsCompressor.cs to use await using for Lzma2EncoderStream and, where supported, for LzmaStream, ensuring proper disposal of async streams and compatibility with newer .NET versions. [1] [2]

Dependency Management

Added a new .opencode/package-lock.json file to track and lock dependencies for the .opencode package, ensuring reproducible builds and consistent environments.

Agent-Logs-Url: https://github.com/adamhathcock/sharpcompress/sessions/6e4dec7d-12cd-4044-9935-4d354b911d11 Co-authored-by: adamhathcock <527620+adamhathcock@users.noreply.github.com>

… writers and compressors Agent-Logs-Url: https://github.com/adamhathcock/sharpcompress/sessions/6e4dec7d-12cd-4044-9935-4d354b911d11 Co-authored-by: adamhathcock <527620+adamhathcock@users.noreply.github.com>

…writes in async code paths Agent-Logs-Url: https://github.com/adamhathcock/sharpcompress/sessions/6e4dec7d-12cd-4044-9935-4d354b911d11 Co-authored-by: adamhathcock <527620+adamhathcock@users.noreply.github.com>

…only-stream-writes

Copilot

Pull request overview

This PR modernizes async-writing behavior across multiple archive/compression writers (notably ZIP, TAR, and 7z) to better support async-only streams, adds async finalization APIs, and refactors TAR compression detection and writer construction to streamline options/provider usage.

Changes:

Added/extended async disposal + async write paths for writers and compressor streams (ZIP/TAR/7z, plus several compressor primitives).
Refactored TAR factory compression probing APIs to accept IReaderOptions (instead of just provider registries) and improved async writer creation for compressed TAR outputs.
Expanded test coverage and test utilities to enforce “async-only” stream behavior and validate new async methods.

Reviewed changes

Copilot reviewed 47 out of 48 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
tests/SharpCompress.Test/Zip/ZipMemoryArchiveWithCrcAsyncTests.cs	Switches writer usage to `await using` for async disposal correctness.
tests/SharpCompress.Test/Tar/TarWriterAsyncTests.cs	Uses `await using` and updates `AsyncOnlyStream` usage to control underlying disposal.
tests/SharpCompress.Test/Tar/TarArchiveAsyncTests.cs	Uses `await using` for async writer lifetime in TAR async tests.
tests/SharpCompress.Test/Streams/LzmaStreamAsyncTests.cs	Validates async disposal and async-only output stream behavior for LZMA encoding.
tests/SharpCompress.Test/Streams/LeaveOpenBehaviorTests.cs	Updates LZip tests to use new `LZipStream.Create(...)` factory API.
tests/SharpCompress.Test/Streams/DisposalTests.cs	Updates disposal tests to use new LZip creation API.
tests/SharpCompress.Test/Mocks/AsyncOnlyStream.cs	Strengthens mock to throw on sync APIs and adds `disposeStream` control.
tests/SharpCompress.Test/GZip/GZipWriterAsyncTests.cs	Updates writer lifetimes to `await using` for async disposal.
tests/SharpCompress.Test/GZip/AsyncTests.cs	Uses `await using` for async writer usage.
tests/SharpCompress.Test/BZip2/BZip2StreamAsyncTests.cs	Switches to `FinishAsync` in async BZip2 tests.
tests/SharpCompress.Test/ADCTest.cs	Adds CRC32 async write tests for `Crc32Stream`.
src/SharpCompress/Writers/Zip/ZipWriter.cs	Refactors header/footer writing to accept explicit streams; adds async-capable `ZipWritingStream` write/limit logic.
src/SharpCompress/Writers/Zip/ZipWriter.Async.cs	Adds async `DisposeAsync`, async header emission, and async entry writing path.
src/SharpCompress/Writers/Tar/TarWriter.cs	Refactors TAR writer initialization and disposal semantics; stream creation extracted.
src/SharpCompress/Writers/Tar/TarWriter.Async.cs	Adds async `DisposeAsync` and async TAR writing helpers.
src/SharpCompress/Writers/SevenZip/SevenZipWriter.cs	Makes 7z placeholder header lazy and introduces sync/async placeholder helpers.
src/SharpCompress/Writers/SevenZip/SevenZipWriter.Async.cs	Adds async `DisposeAsync` and async finalize/header writing path.
src/SharpCompress/Writers/IWriter.cs	Removes embedded `IAsyncWriter` definition (moved to its own file).
src/SharpCompress/Writers/IAsyncWriter.cs	Introduces standalone async writer interface.
src/SharpCompress/Writers/GZip/GZipWriter.cs	Adds async disposal path for GZip writer output stream.
src/SharpCompress/Writers/AbstractWriter.cs	Makes disposal respect `LeaveStreamOpen` and exposes `_isDisposed` to derived writers.
src/SharpCompress/Writers/AbstractWriter.Async.cs	Makes `DisposeAsync` virtual for derived overrides.
src/SharpCompress/Providers/IFinishable.cs	Adds `FinishAsync` for async finalization hooks.
src/SharpCompress/Providers/Default/LZipCompressionProvider.cs	Adds async create methods and switches to `LZipStream.Create/CreateAsync`.
src/SharpCompress/IO/CountingStream.cs	Adds async flush/write overrides that track written byte counts.
src/SharpCompress/Factories/TarWrapper.cs	Updates LZip wrapper to use new LZip factory APIs (sync + async).
src/SharpCompress/Factories/TarFactory.cs	Refactors compression probing to use reader options; implements async-compressed TAR writer construction.
src/SharpCompress/Crypto/Crc32Stream.cs	Adds async write/flush overrides to support async-only pipelines and new tests.
src/SharpCompress/Compressors/ZStandard/CompressionStream.cs	Adjusts async-disposal interface implementation for legacy TFMs.
src/SharpCompress/Compressors/ZStandard/CompressionStream.Async.cs	Fixes partial class declaration to avoid duplicate base type.
src/SharpCompress/Compressors/LZMA/LzmaStream.cs	Adds `IAsyncDisposable` to LZMA stream type.
src/SharpCompress/Compressors/LZMA/LzmaStream.Async.cs	Implements real async write + async disposal behavior for LZMA encoding streams.
src/SharpCompress/Compressors/LZMA/LzmaEncoder.cs	Adds async encoding primitives and async coding loop support.
src/SharpCompress/Compressors/LZMA/Lzma2EncoderStream.cs	Adds async writes and async disposal; async chunk flush path.
src/SharpCompress/Compressors/LZMA/LZipStream.cs	Makes constructor private and removes header write from ctor (moved to factory).
src/SharpCompress/Compressors/LZMA/LZipStream.Async.cs	Adds `Create/CreateAsync` and `FinishAsync` for LZip; async header write helper.
src/SharpCompress/Compressors/Deflate/ZlibBaseStream.cs	Improves async disposal compatibility across TFMs and stream types.
src/SharpCompress/Compressors/Deflate/GZipStream.cs	Refactors header writing into reusable builder and introduces async header emission.
src/SharpCompress/Compressors/Deflate/GZipStream.Async.cs	Uses async header emission and improves async disposal compatibility.
src/SharpCompress/Compressors/Deflate/DeflateStream.cs	Adds legacy-TFM async-disposable support.
src/SharpCompress/Compressors/Deflate/DeflateStream.Async.cs	Expands async disposal support for legacy TFMs.
src/SharpCompress/Compressors/BZip2/CBZip2OutputStream.cs	Defers header emission; adds async header write + async finish buffering strategy.
src/SharpCompress/Compressors/BZip2/BZip2Stream.cs	Adds `FinishAsync` forwarding.
src/SharpCompress/Compressors/BZip2/BZip2Stream.Async.cs	Adds async `FinishAsync` helper.
src/SharpCompress/Common/SevenZip/SevenZipStreamsCompressor.cs	Uses `await using` for async-disposable LZMA/LZMA2 encoder streams.
src/SharpCompress/Common/SevenZip/SevenZipSignatureHeader.cs	Adds async placeholder/final header writing and refactors shared header construction.
src/SharpCompress/Archives/Tar/TarArchive.Factory.cs	Updates TAR compression detection calls to pass `ReaderOptions`.
.opencode/package-lock.json	Adds dependency lockfile for `.opencode` package reproducibility.

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Copilot · 2026-04-30T14:36:39Z

+    private void EnsurePlaceholderWritten()
+    {
+        if (!_placeholderWritten)
+        {
+            _placeholderWritten = true;
+            // Write placeholder signature header (32 bytes) - will be back-patched on finalize
+            SevenZipSignatureHeaderWriter.WritePlaceholder(OutputStream.NotNull());
+        }
+    }


SevenZipWriter now writes the 7z signature header placeholder lazily, but FinalizeArchive()/WriteFinal always seek to position 0 and assume the 32-byte placeholder already exists. If the first operation is WriteDirectory (or if the writer is disposed without any Write/WriteAsync), the placeholder is never written, so finalization will back-patch over real data and compute a negative nextHeaderOffset (cast to ulong). Ensure the placeholder is written before any entry (including directory entries) and before finalization when no entries were written.

Copilot · 2026-04-30T14:36:40Z

+    private async Task EnsurePlaceholderWrittenAsync(CancellationToken cancellationToken)
+    {
+        if (!_placeholderWritten)
+        {
+            _placeholderWritten = true;
+            // Write placeholder signature header (32 bytes) - will be back-patched on finalize
+            await SevenZipSignatureHeaderWriter
+                .WritePlaceholderAsync(OutputStream.NotNull(), cancellationToken)
+                .ConfigureAwait(false);
+        }


EnsurePlaceholderWrittenAsync sets _placeholderWritten=true before awaiting the actual write. If the write is canceled or fails, the flag remains true and the archive will later finalize by back-patching a header that was never reserved (corrupt output). Set the flag only after the placeholder write completes successfully (or reset it on failure).

Copilot AI and others added 17 commits April 28, 2026 09:33

Initial plan

2b7faac

Fix AsyncOnlyStream to throw on sync operations

01273b7

Agent-Logs-Url: https://github.com/adamhathcock/sharpcompress/sessions/6e4dec7d-12cd-4044-9935-4d354b911d11 Co-authored-by: adamhathcock <527620+adamhathcock@users.noreply.github.com>

Merge remote-tracking branch 'origin/release' into copilot/fix-async-…

56bf786

…only-stream-writes

fix up disposal for legacy frameworks

afc2730

Fully implement FInishAsync

06a70fd

tar can write async

14ad6a8

LZip might work if SCS writes are done

998853c

forgot a disposal change

818735d

fix writing of headers

29744b3

Small fixes and format

2aec75a

add Crc32Stream write async

29f06b7

fix LzmaStream writing async

6172bd3

Fix more async stream disposal

de36344

Rationalize AsyncDisposable

2f3d11c

fixed providers in TarWriter and TarArchive.

48afb4d

adamhathcock mentioned this pull request Apr 30, 2026

fix: dispose source streams in writable archive async add entry #1310

Closed

Figure out more async usage for legacy

ee02924

adamhathcock requested a review from Copilot April 30, 2026 14:27

Copilot started reviewing on behalf of adamhathcock April 30, 2026 14:28 View session

Copilot AI reviewed Apr 30, 2026

View reviewed changes

adamhathcock and others added 6 commits May 5, 2026 08:19

BZip2 fixed?

25a5b7b

Merge remote-tracking branch 'origin/release' into adam/write-async

9e2aac2

fixed zip writing for PPMD

270b018

BZip2 now is async

d3fb640

use ValueTask where possible

da20f51

fix legacy type issues

9faf6fe

adamhathcock closed this May 14, 2026

adamhathcock mentioned this pull request May 14, 2026

Finish Write Async #1323

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Fixes Async Writing#1311

Fixes Async Writing#1311
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adamhathcock commented Apr 30, 2026

TAR Archive Factory Refactoring

7z Archive Async Support

7z Compression Stream Improvements

Dependency Management

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Pull request overview

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