More misc send fixes

kittens/transfer/ftc.go

@@ -330,15 +330,15 @@ func NewFileTransmissionCommand(serialized string) (ans *FileTransmissionCommand
 func split_for_transfer(data []byte, file_id string, mark_last bool, callback func(*FileTransmissionCommand)) {
 	const chunk_size = 4096
 	for len(data) > 0 {
-		ac := Action_data
-		if mark_last && len(data) <= chunk_size {
-			ac = Action_end_data
-		}
 		chunk := data
 		if len(chunk) > chunk_size {
 			chunk = data[:chunk_size]
 		}
-		callback(&FileTransmissionCommand{Action: ac, File_id: file_id, Data: chunk})
 		data = data[len(chunk):]
+		ac := Action_data
+		if mark_last && len(data) == 0 {
+			ac = Action_end_data
+		}
+		callback(&FileTransmissionCommand{Action: ac, File_id: file_id, Data: chunk})
 	}
 }

kittens/transfer/send.go

@@ -70,6 +70,7 @@ func (self *ZlibCompressor) Compress(data []byte) []byte {
 	if err != nil {
 		panic(err)
 	}
+	defer self.b.Reset()
 	return utils.UnsafeStringToBytes(self.b.String())
 }
 
@@ -979,7 +980,12 @@ func (self *SendManager) next_chunks(callback func(string)) error {
 			split_for_transfer(utils.UnsafeStringToBytes(chunk), af.file_id, is_last, func(ftc *FileTransmissionCommand) { callback(ftc.Serialize()) })
 		} else if is_last {
 			callback(FileTransmissionCommand{Action: Action_end_data, File_id: af.file_id}.Serialize())
+		}
+		if is_last {
 			self.activate_next_ready_file()
+			if self.active_file() == nil {
+				return nil
+			}
 		}
 	}
 }