Google OAuth Device Flow support for FNL

services/authentication/accounts_db_manager.h

+// Copyright 2015 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 SERVICES_AUTHENTICATION_ACCOUNTS_DB_MANAGER_H_
+#define SERVICES_AUTHENTICATION_ACCOUNTS_DB_MANAGER_H_
+
+#include <type_traits>
+
+#include "base/macros.h"
+#include "mojo/services/files/interfaces/files.mojom.h"
+
+namespace authentication {
+
+// TODO(ukode): Stuff copied from mojo/public/cpp/bindings/lib/template_util.h.
+typedef char YesType;
+
+struct NoType {
+  YesType dummy[2];
+};
+
+template <typename T>
+struct IsMoveOnlyType {
+  template <typename U>
+  static YesType Test(const typename U::MoveOnlyTypeForCPP03*);
+
+  template <typename U>
+  static NoType Test(...);
+
+  static const bool value =
+      sizeof(Test<T>(0)) == sizeof(YesType) && !std::is_const<T>::value;
+};
+
+template <typename T>
+typename std::enable_if<!IsMoveOnlyType<T>::value, T>::type& Forward(T& t) {
+  return t;
+}
+
+template <typename T>
+typename std::enable_if<IsMoveOnlyType<T>::value, T>::type Forward(T& t) {
+  return t.Pass();
+}
+// TODO(ukode): (End of stuff copied from template_util.h.)
+
+template <typename T1>
+mojo::Callback<void(T1)> Capture(T1* t1) {
+  return [t1](T1 got_t1) { *t1 = Forward(got_t1); };
+}
+
+template <typename T1, typename T2>
+mojo::Callback<void(T1, T2)> Capture(T1* t1, T2* t2) {
+  return [t1, t2](T1 got_t1, T2 got_t2) {
+    *t1 = Forward(got_t1);
+    *t2 = Forward(got_t2);
+  };
+}
+
+// Implementation of user account management service on systems like FNL. This
+// uses native mojo files service as the underlying mechanism to store user
+// credentials and supports operations such as to add a new user account, update
+// existing user credentials and fetching current credentials for a given user.
+class AccountsDbManager {
+ public:
+  AccountsDbManager();
+  explicit AccountsDbManager(mojo::files::FilesPtr files);
+  ~AccountsDbManager();
+  // Updates account credentials for a given user.
+  bool UpdateAccount(const mojo::String& username,
+                     const mojo::String& account_data);
+  // Fetches account credentials for a given user.
+  void GetAccountDataForUser(const mojo::String& username,
+                             mojo::String& user_data);
+  // Fetches all user credentials.
+  mojo::Array<uint8_t> FetchAllAccounts();
+
+ private:
+  // Generates new contents of the accounts database during an update operation.
+  // Performs one of the two operations:
+  //   1. If the user already exists, updates the existing record in database.
+  //   2. If its a new user, adds a new record to the existing database content.
+  void GetUpdatedDbContents(const mojo::String& username,
+                            const mojo::String& new_account_data,
+                            const bool user_exists,
+                            mojo::String& new_db_contents);
+
+  // Directory pointer to the stored accounts db file.
+  mojo::files::DirectoryPtr directory_;
+  // Stores the cached account data in between account operations.
+  std::string contents_;
+
+  DISALLOW_COPY_AND_ASSIGN(AccountsDbManager);
+};
+
+}  // namespace authentication
+
+#endif  // SERVICES_AUTHENTICATION_ACCOUNTS_DB_MANAGER_H_