fix(storage): Current object generation takeover. (#12383)

cjc25 · web-flow · commit 9ca8e015405a · 2025-06-04T02:57:17.000-04:00
Correct handling when the caller specifies takeover for the current
object generation. The previous behavior was inconsistent: it opened a
writer when the user specified:

```
c.Bucket(b).Object(o).Generation(0).NewWriterFromAppendableObject(...)
```

But in the internal writer code would only perform takeovers for
generations greater than 0.
diff --git a/storage/grpc_writer.go b/storage/grpc_writer.go
@@ -114,7 +114,7 @@ func (c *grpcStorageClient) OpenWriter(params *openWriterParams, opts ...storage
 
 	// If we are taking over an appendable object, send the first message here
 	// to get the append offset.
-	if params.appendGen > 0 {
+	if params.append && params.appendGen >= 0 {
 		// Create the buffer sender. This opens a stream and blocks until we
 		// get a response that tells us what offset to write from.
 		wbs, err := gw.newGRPCAppendTakeoverWriteBufferSender(params.ctx)
@@ -223,7 +223,7 @@ func newGRPCWriter(c *grpcStorageClient, s *settings, params *openWriterParams,
 		Appendable: proto.Bool(params.append),
 	}
 	var appendSpec *storagepb.AppendObjectSpec
-	if params.appendGen > 0 {
+	if params.append && params.appendGen >= 0 {
 		appendSpec = &storagepb.AppendObjectSpec{
 			Bucket:     bucketResourceName(globalProjectAlias, params.bucket),
 			Object:     params.attrs.Name,
