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/file_finder_and_sender.h

@@ -0,0 +1,90 @@
+/*
+ * 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_FILE_FINDER_AND_SENDER_H_
+#define CDC_RSYNC_FILE_FINDER_AND_SENDER_H_
+
+#include <string>
+#include <vector>
+
+#include "absl/status/status.h"
+#include "cdc_rsync/client_file_info.h"
+#include "cdc_rsync/protos/messages.pb.h"
+
+namespace cdc_ft {
+
+class MessagePump;
+class PathFilter;
+
+class ReportFindFilesProgress {
+ public:
+  virtual ~ReportFindFilesProgress() = default;
+  virtual void ReportFileFound() = 0;
+  virtual void ReportDirFound() = 0;
+};
+
+class FileFinderAndSender {
+ public:
+  // Send AddFileRequests in packets of roughly 10k max by default.
+  static constexpr size_t kDefaultRequestSizeThreshold = 10000;
+
+  FileFinderAndSender(
+      PathFilter* path_filter, MessagePump* message_pump,
+      ReportFindFilesProgress* progress_, std::string sources_dir,
+      bool recursive, bool relative,
+      size_t request_byte_threshold = kDefaultRequestSizeThreshold);
+  ~FileFinderAndSender();
+
+  absl::Status FindAndSendFiles(std::string source);
+
+  // Sends the remaining file batch to the client, followed by an EOF indicator.
+  // Should be called once all files have been deleted.
+  absl::Status Flush();
+
+  void ReleaseFiles(std::vector<ClientFileInfo>* files);
+  void ReleaseDirs(std::vector<ClientDirInfo>* dirs);
+
+ private:
+  absl::Status HandleFoundFileOrDir(std::string dir, std::string filename,
+                                    int64_t modified_time, uint64_t size,
+                                    bool is_directory);
+
+  // Sends the current file and directory batch to the server.
+  absl::Status SendFilesAndDirs();
+
+  PathFilter* const path_filter_;
+  MessagePump* const message_pump_;
+  ReportFindFilesProgress* const progress_;
+  std::string sources_dir_;
+  const bool recursive_;
+  const bool relative_;
+  const size_t request_size_threshold_;
+
+  // Prefix removed from found files before they are sent to the server.
+  std::string base_dir_;
+  AddFilesRequest request_;
+  size_t request_size_ = 0;
+
+  // Found files.
+  std::vector<ClientFileInfo> files_;
+
+  // Found directories.
+  std::vector<ClientDirInfo> dirs_;
+};
+
+}  // namespace cdc_ft
+
+#endif  // CDC_RSYNC_FILE_FINDER_AND_SENDER_H_