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/file_deleter_and_sender.cc

@@ -0,0 +1,111 @@
+// 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.
+
+#include "cdc_rsync_server/file_deleter_and_sender.h"
+
+#include "cdc_rsync/base/message_pump.h"
+#include "common/log.h"
+#include "common/path.h"
+#include "common/status.h"
+
+namespace cdc_ft {
+
+FileDeleterAndSender::FileDeleterAndSender(MessagePump* message_pump,
+                                           size_t request_size_threshold)
+    : message_pump_(message_pump),
+      request_size_threshold_(request_size_threshold) {
+  assert(message_pump_);
+}
+
+FileDeleterAndSender::~FileDeleterAndSender() = default;
+
+absl::Status FileDeleterAndSender::DeleteAndSendFileOrDir(
+    const std::string& base_dir, const std::string& relative_path, bool dry_run,
+    bool is_directory) {
+  std::string filepath = path::Join(base_dir, relative_path);
+  if (!dry_run) {
+    LOG_INFO("Removing %s", filepath.c_str());
+    absl::Status status = path::RemoveFile(filepath);
+    if (!status.ok()) {
+      return WrapStatus(status, "Failed to remove '%s'", filepath);
+    }
+  }
+
+  std::string relative_dir = path::DirName(relative_path);
+  if (!relative_dir.empty()) path::EnsureEndsWithPathSeparator(&relative_dir);
+  if (response_.directory() != relative_dir) {
+    // Flush files in previous directory.
+    absl::Status status = SendFilesAndDirs();
+    if (!status.ok()) {
+      return WrapStatus(
+          status, "Failed to send deleted files and directories to client");
+    }
+
+    // Set new directory.
+    response_.set_directory(relative_dir);
+    response_size_ = response_.directory().length();
+  }
+
+  std::string filename = path::BaseName(relative_path);
+  if (is_directory) {
+    *response_.add_dirs() = filename;
+  } else {
+    *response_.add_files() = filename;
+  }
+  response_size_ += filename.size();
+
+  if (response_size_ >= request_size_threshold_) {
+    absl::Status status = SendFilesAndDirs();
+    if (!status.ok()) {
+      return WrapStatus(
+          status, "Failed to send deleted files and directories to client");
+    }
+  }
+
+  return absl::OkStatus();
+}
+
+absl::Status FileDeleterAndSender::Flush() {
+  absl::Status status = SendFilesAndDirs();
+  if (!status.ok()) {
+    return WrapStatus(status,
+                      "Failed to send deleted files and directories to client");
+  }
+
+  // Send an empty batch as EOF indicator.
+  assert(response_.files_size() == 0 && response_.dirs_size() == 0);
+  status = message_pump_->SendMessage(PacketType::kAddDeletedFiles, response_);
+  if (!status.ok()) {
+    return WrapStatus(status, "Failed to send EOF indicator");
+  }
+
+  return absl::OkStatus();
+}
+
+absl::Status FileDeleterAndSender::SendFilesAndDirs() {
+  if (response_.files_size() == 0 && response_.dirs_size() == 0) {
+    return absl::OkStatus();
+  }
+
+  absl::Status status =
+      message_pump_->SendMessage(PacketType::kAddDeletedFiles, response_);
+  if (!status.ok()) {
+    return WrapStatus(status, "Failed to send AddDeletedFilesResponse");
+  }
+  response_.Clear();
+  response_size_ = response_.directory().length();
+  return absl::OkStatus();
+}
+
+}  // namespace cdc_ft