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.

common/stub_process.h

@@ -0,0 +1,78 @@
+/*
+ * 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 COMMON_STUB_PROCESS_H_
+#define COMMON_STUB_PROCESS_H_
+
+#include <vector>
+
+#include "absl/status/status.h"
+#include "common/process.h"
+
+namespace cdc_ft {
+
+// A stub process returns prefabricated stdout, stderr and exit codes to
+// predetermined commands.
+class StubProcessFactory : public ProcessFactory {
+ public:
+  using ProcessHandlerFn = std::function<void(
+      std::string* std_out, std::string* std_err, uint32_t* exit_code)>;
+
+  virtual StubProcessFactory::~StubProcessFactory();
+
+  // ProcessFactory:
+  std::unique_ptr<Process> Create(const ProcessStartInfo& start_info) override;
+
+  // Sets up a stub process that is returned by a call to Create() if the
+  // command contains |command_part|. The stub process exits on RunUntil(),
+  // writes the given |std_out| and |std_err| to the output stream and exits
+  // with |exit_code|.
+  void SetProcessOutput(std::string command_part, std::string std_out,
+                        std::string std_err, uint32_t exit_code);
+
+  // Sets up a stub process that is returned by a call to Create() if the
+  // command contains |command_part|. The process never exits. Useful for
+  // testing timeout conditions.
+  void SetProcessNeverExits(std::string command_part);
+
+  // Sets up a stub process that is returned by a call to Create() if the
+  // command contains |command_part|. The stub process is immediately in an
+  // exited state with code |exit_code| and does not write stdout or stderr.
+  void SetProcessExitsImmediately(std::string command_part, uint32_t exit_code);
+
+  // Sets up a stub process that is returned by a call to Create() if the
+  // command contains |command_part|. The stub process calls |handler| on
+  // RunUntil(), writes returned |std_out| and |std_err| to the output stream
+  // and exits with |exit_code|.
+  void SetProcessHandler(std::string command_part, ProcessHandlerFn handler);
+
+ private:
+  struct ProcessInfo {
+    std::string command_part;
+    std::string std_out;
+    std::string std_err;
+    uint32_t exit_code;
+    bool has_exited;
+    bool never_exits;
+    ProcessHandlerFn handler;
+  };
+
+  std::vector<ProcessInfo> process_info_;
+};
+
+}  // namespace cdc_ft
+
+#endif  // COMMON_STUB_PROCESS_H_