Add 'flog' service implementation.

services/flog/flog_directory.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MOJO_SERVICES_FLOG_FLOG_DIRECTORY_H_
+#define MOJO_SERVICES_FLOG_FLOG_DIRECTORY_H_
+
+#include <map>
+
+#include "mojo/public/cpp/application/connect.h"
+#include "mojo/services/files/interfaces/directory.mojom.h"
+#include "mojo/services/files/interfaces/file.mojom.h"
+#include "mojo/services/files/interfaces/files.mojom.h"
+
+namespace mojo {
+namespace flog {
+
+// Flog directory management.
+class FlogDirectory {
+ public:
+  using GetExistingFilesCallback =
+      std::function<void(std::unique_ptr<std::map<uint32_t, std::string>>)>;
+
+  FlogDirectory(Shell* shell);
+
+  ~FlogDirectory();
+
+  // Calls back with a map (id -> label) of existing files.
+  void GetExistingFiles(GetExistingFilesCallback callback);
+
+  // Gets a FilePtr for the indicated file.
+  files::FilePtr GetFile(uint32_t id, const std::string& label, bool create);
+
+ private:
+  static const size_t kLogIdWidth = 8;
+
+  // Returns a log file name given the id and label of the log.
+  std::string LogFileName(uint32_t id, const std::string& label);
+
+  // Parses a log file name.
+  bool ParseLogFileName(const std::string& name,
+                        uint32_t* id_out,
+                        std::string* label_out);
+
+  files::FilesPtr files_;
+  files::DirectoryPtr file_system_;
+};
+
+}  // namespace flog
+}  // namespace mojo
+
+#endif  // MOJO_SERVICES_FLOG_FLOG_DIRECTORY_H_