Update src/OrasProject.Oras/Content/File/TarUtilities.cs

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Signed-off-by: Xiaoxuan Wang <wangxiaoxuan119@gmail.com>

Author: wangxiaoxuan273

src/OrasProject.Oras/Content/File/TarUtilities.cs

@@ -176,54 +176,44 @@ internal static async Task ExtractTarGzipAsync(
         var decompressedStream = new GZipStream(gzipStream, CompressionMode.Decompress);
         await using var _2 = decompressedStream.ConfigureAwait(false);
 
-        Stream sourceStream = decompressedStream;
-        IncrementalHash? hash = null;
-        MemoryStream? bufferedStream = null;
-
-        try
+        if (string.IsNullOrEmpty(checksum))
         {
-            // If we have a checksum, we need to verify the content
-            if (!string.IsNullOrEmpty(checksum))
-            {
-                hash = IncrementalHash.CreateHash(HashAlgorithmName.SHA256);
-
-                // Read the entire decompressed content for hashing
-                bufferedStream = new MemoryStream();
-                var buffer = new byte[_bufferSize];
-                int bytesRead;
-                while ((bytesRead = await decompressedStream.ReadAsync(buffer.AsMemory(0, buffer.Length), cancellationToken).ConfigureAwait(false)) > 0)
-                {
-                    hash.AppendData(buffer.AsSpan(0, bytesRead));
-                    await bufferedStream.WriteAsync(buffer.AsMemory(0, bytesRead), cancellationToken).ConfigureAwait(false);
-                }
-
-                // Verify the checksum
-                var computedHash = hash.GetHashAndReset();
-                var computedDigest = $"sha256:{Convert.ToHexString(computedHash).ToLowerInvariant()}";
-                if (!string.Equals(computedDigest, checksum, StringComparison.OrdinalIgnoreCase))
-                {
-                    throw new InvalidOperationException($"Content digest mismatch: expected {checksum}, got {computedDigest}");
-                }
-
-                bufferedStream.Position = 0;
-                sourceStream = bufferedStream;
-            }
-
             await ExtractTarDirectoryAsync(
                 targetDirectory,
                 directoryName,
-                sourceStream,
+                decompressedStream,
                 preservePermissions,
                 cancellationToken).ConfigureAwait(false);
+            return;
         }
-        finally
+
+        using var hash = IncrementalHash.CreateHash(HashAlgorithmName.SHA256);
+        await using var bufferedStream = new MemoryStream();
+
+        var buffer = new byte[_bufferSize];
+        int bytesRead;
+        while ((bytesRead = await decompressedStream.ReadAsync(buffer.AsMemory(0, buffer.Length), cancellationToken).ConfigureAwait(false)) > 0)
         {
-            hash?.Dispose();
-            if (bufferedStream != null)
-            {
-                await bufferedStream.DisposeAsync().ConfigureAwait(false);
-            }
+            hash.AppendData(buffer.AsSpan(0, bytesRead));
+            await bufferedStream.WriteAsync(buffer.AsMemory(0, bytesRead), cancellationToken).ConfigureAwait(false);
         }
+
+        // Verify the checksum
+        var computedHash = hash.GetHashAndReset();
+        var computedDigest = $"sha256:{Convert.ToHexString(computedHash).ToLowerInvariant()}";
+        if (!string.Equals(computedDigest, checksum, StringComparison.OrdinalIgnoreCase))
+        {
+            throw new InvalidOperationException($"Content digest mismatch: expected {checksum}, got {computedDigest}");
+        }
+
+        bufferedStream.Position = 0;
+
+        await ExtractTarDirectoryAsync(
+            targetDirectory,
+            directoryName,
+            bufferedStream,
+            preservePermissions,
+            cancellationToken).ConfigureAwait(false);
     }
 
     /// <summary>