gzipwriter async

src/SharpCompress/Writers/AbstractWriter.Async.cs

@@ -8,30 +8,18 @@ namespace SharpCompress.Writers;
 
 public abstract partial class AbstractWriter
 {
-    public virtual async ValueTask WriteAsync(
+    public abstract ValueTask WriteAsync(
         string filename,
         Stream source,
         DateTime? modificationTime,
         CancellationToken cancellationToken = default
-    )
-    {
-        // Default implementation calls synchronous version
-        // Derived classes should override for true async behavior
-        Write(filename, source, modificationTime);
-        await Task.CompletedTask.ConfigureAwait(false);
-    }
+    );
 
-    public virtual async ValueTask WriteDirectoryAsync(
+    public abstract ValueTask WriteDirectoryAsync(
         string directoryName,
         DateTime? modificationTime,
         CancellationToken cancellationToken = default
-    )
-    {
-        // Default implementation calls synchronous version
-        // Derived classes should override for true async behavior
-        WriteDirectory(directoryName, modificationTime);
-        await Task.CompletedTask.ConfigureAwait(false);
-    }
+    );
 
     public ValueTask DisposeAsync()
     {

src/SharpCompress/Writers/GZip/GZipWriter.Async.cs

@@ -0,0 +1,31 @@
+using System;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+using SharpCompress.Compressors.Deflate;
+
+namespace SharpCompress.Writers.GZip;
+
+public partial class GZipWriter
+{
+    public override async ValueTask WriteAsync(string filename, Stream source, DateTime? modificationTime, CancellationToken cancellationToken = default)
+    {
+        if (_wroteToStream)
+        {
+            throw new ArgumentException("Can only write a single stream to a GZip file.");
+        }
+        var stream = (GZipStream)OutputStream;
+        stream.FileName = filename;
+        stream.LastModified = modificationTime;
+        var progressStream = WrapWithProgress(source, filename);
+#if LEGACY_DOTNET
+        await progressStream.CopyToAsync(stream);
+        #else
+        await progressStream.CopyToAsync(stream, cancellationToken);
+#endif
+        _wroteToStream = true;
+    }
+
+    public override ValueTask WriteDirectoryAsync(string directoryName, DateTime? modificationTime, CancellationToken cancellationToken = default) =>
+        throw new NotSupportedException("GZip archives do not support directory entries.");
+}