Releasing the former Stadia file transfer tools

The tools allow efficient and fast synchronization of large directory
trees from a Windows workstation to a Linux target machine.

cdc_rsync* support efficient copy of files by using content-defined
chunking (CDC) to identify chunks within files that can be reused.

asset_stream_manager + cdc_fuse_fs support efficient streaming of a
local directory to a remote virtual file system based on FUSE. It also
employs CDC to identify and reuse unchanged data chunks.

cdc_rsync_server/cdc_rsync_server.h

@@ -0,0 +1,121 @@
+/*
+ * Copyright 2022 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef CDC_RSYNC_SERVER_CDC_RSYNC_SERVER_H_
+#define CDC_RSYNC_SERVER_CDC_RSYNC_SERVER_H_
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "absl/status/status.h"
+#include "cdc_rsync/base/message_pump.h"
+#include "cdc_rsync_server/file_diff_generator.h"
+#include "cdc_rsync_server/file_info.h"
+#include "common/gamelet_component.h"
+#include "common/path_filter.h"
+
+namespace cdc_ft {
+
+class MessagePump;
+class ServerSocket;
+
+class GgpRsyncServer {
+ public:
+  GgpRsyncServer();
+  ~GgpRsyncServer();
+
+  // Checks that the gamelet components (cdc_rsync_server binary etc.) are
+  // up-to-date by checking their sizes and timestamps.
+  bool CheckComponents(const std::vector<GameletComponent>& components);
+
+  // Listens to |port|, accepts a connection from the client and runs the rsync
+  // procedure.
+  absl::Status Run(int port);
+
+  // Returns the verbosity sent from the client. 0 by default.
+  int GetVerbosity() const { return verbosity_; }
+
+ private:
+  // Runs the rsync procedure.
+  absl::Status Sync();
+
+  // Receives options from the client.
+  absl::Status HandleSetOptions();
+
+  // Finds all server-side files in the |destination_| folder.
+  absl::Status FindFiles();
+
+  // Receives all client-side files.
+  absl::Status HandleSendAllFiles();
+
+  // Diffs client- and server-side files.
+  absl::Status DiffFiles();
+
+  // Deletes files and directories present on the server, but not on the client.
+  absl::Status RemoveExtraneousFilesAndDirs();
+
+  // Creates missing directories.
+  absl::Status CreateMissingDirs();
+
+  // Sends file indices to the client. Used for missing and changed files.
+  template <typename T>
+  absl::Status SendFileIndices(const char* file_type,
+                               const std::vector<T>& files);
+
+  // Receives missing files from the client.
+  absl::Status HandleSendMissingFileData();
+
+  // Core rsync algorithm. Sends signatures of changed files to the client,
+  // receives diffs and applies them.
+  absl::Status SyncChangedFiles();
+
+  // Waits for the shutdown message and send an ack.
+  absl::Status HandleShutdown();
+
+  // Called on |message_pump_|'s receiver thread whenever a package is received.
+  // Used to toggle decompression.
+  void Thread_OnPackageReceived(PacketType type);
+
+  std::unique_ptr<ServerSocket> socket_;
+  std::unique_ptr<MessagePump> message_pump_;
+
+  std::string destination_;
+
+  // Options.
+  bool delete_ = false;
+  bool recursive_ = false;
+  int verbosity_ = 0;
+  bool whole_file_ = false;
+  bool compress_ = false;
+  bool checksum_ = false;
+  bool relative_ = false;
+  bool dry_run_ = false;
+  bool existing_ = false;
+  std::string copy_dest_;
+
+  PathFilter path_filter_;
+
+  std::vector<FileInfo> client_files_;
+  std::vector<DirInfo> client_dirs_;
+  std::vector<FileInfo> server_files_;
+  std::vector<DirInfo> server_dirs_;
+  file_diff::Result diff_;
+};
+
+}  // namespace cdc_ft
+
+#endif  // CDC_RSYNC_SERVER_CDC_RSYNC_SERVER_H_