default_policy.h revision d78caf9baf2026a356130f4754af2c504f423945 
1// Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef UPDATE_ENGINE_UPDATE_MANAGER_DEFAULT_POLICY_H_
6#define UPDATE_ENGINE_UPDATE_MANAGER_DEFAULT_POLICY_H_
7
8#include <string>
9
10#include <base/time/time.h>
11
12#include "update_engine/clock_interface.h"
13#include "update_engine/update_manager/policy.h"
14
15namespace chromeos_update_manager {
16
17// Auxiliary state class for DefaultPolicy evaluations.
18//
19// IMPORTANT: The use of a state object in policies is generally forbidden, as
20// it was a design decision to keep policy calls side-effect free. We make an
21// exception here to ensure that DefaultPolicy indeed serves as a safe (and
22// secure) fallback option. This practice should be avoided when imlpementing
23// other policies.
24class DefaultPolicyState {
25 public:
26  DefaultPolicyState() {}
27
28  bool IsLastCheckAllowedTimeSet() const {
29    return last_check_allowed_time_ != base::Time::Max();
30  }
31
32  // Sets/returns the point time on the monotonic time scale when the latest
33  // check allowed was recorded.
34  void set_last_check_allowed_time(base::Time timestamp) {
35    last_check_allowed_time_ = timestamp;
36  }
37  base::Time last_check_allowed_time() const {
38    return last_check_allowed_time_;
39  }
40
41 private:
42  base::Time last_check_allowed_time_ = base::Time::Max();
43};
44
45// The DefaultPolicy is a safe Policy implementation that doesn't fail. The
46// values returned by this policy are safe default in case of failure of the
47// actual policy being used by the UpdateManager.
48class DefaultPolicy : public Policy {
49 public:
50  explicit DefaultPolicy(chromeos_update_engine::ClockInterface* clock);
51  DefaultPolicy() : DefaultPolicy(nullptr) {}
52  virtual ~DefaultPolicy() {}
53
54  // Policy overrides.
55  EvalStatus UpdateCheckAllowed(
56      EvaluationContext* ec, State* state, std::string* error,
57      UpdateCheckParams* result) const override;
58
59  EvalStatus UpdateCanStart(
60      EvaluationContext* ec, State* state, std::string* error,
61      UpdateDownloadParams* result,
62      UpdateState update_state) const override;
63
64  EvalStatus UpdateDownloadAllowed(
65      EvaluationContext* ec, State* state, std::string* error,
66      bool* result) const override;
67
68 protected:
69  // Policy override.
70  std::string PolicyName() const override { return "DefaultPolicy"; }
71
72 private:
73  // A clock interface.
74  chromeos_update_engine::ClockInterface* clock_;
75
76  // An auxiliary state object.
77  scoped_ptr<DefaultPolicyState> aux_state_;
78
79  DISALLOW_COPY_AND_ASSIGN(DefaultPolicy);
80};
81
82}  // namespace chromeos_update_manager
83
84#endif  // UPDATE_ENGINE_UPDATE_MANAGER_DEFAULT_POLICY_H_
85