1 //
2 // Copyright (C) 2012 The Android Open Source Project
3 //
4 // Licensed under the Apache License, Version 2.0 (the "License");
5 // you may not use this file except in compliance with the License.
6 // You may obtain a copy of the License at
7 //
8 //      http://www.apache.org/licenses/LICENSE-2.0
9 //
10 // Unless required by applicable law or agreed to in writing, software
11 // distributed under the License is distributed on an "AS IS" BASIS,
12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 // See the License for the specific language governing permissions and
14 // limitations under the License.
15 //
16 
17 #ifndef UPDATE_ENGINE_COMMON_FAKE_PREFS_H_
18 #define UPDATE_ENGINE_COMMON_FAKE_PREFS_H_
19 
20 #include <functional>
21 #include <map>
22 #include <string>
23 #include <string_view>
24 #include <vector>
25 
26 #include <base/macros.h>
27 
28 #include "update_engine/common/prefs_interface.h"
29 
30 namespace chromeos_update_engine {
31 
32 // Implements a fake preference store by storing the value associated with
33 // a key in a std::map, suitable for testing. It doesn't allow to set a value on
34 // a key with a different type than the previously set type. This enforces the
35 // type of a given key to be fixed. Also the class checks that the Get*()
36 // methods aren't called on a key set with a different type.
37 
38 class FakePrefs : public PrefsInterface {
39  public:
40   FakePrefs() = default;
41   ~FakePrefs();
42 
43   // PrefsInterface methods.
44   bool GetString(std::string_view key, std::string* value) const override;
45   bool SetString(std::string_view key, std::string_view value) override;
46   bool GetInt64(std::string_view key, int64_t* value) const override;
47   bool SetInt64(std::string_view key, const int64_t value) override;
48   bool GetBoolean(std::string_view key, bool* value) const override;
49   bool SetBoolean(std::string_view key, const bool value) override;
50 
51   bool Exists(std::string_view key) const override;
52   bool Delete(std::string_view key) override;
53   bool Delete(std::string_view key,
54               const std::vector<std::string>& nss) override;
55 
56   bool GetSubKeys(std::string_view ns,
57                   std::vector<std::string>* keys) const override;
58 
59   void AddObserver(std::string_view key, ObserverInterface* observer) override;
60   void RemoveObserver(std::string_view key,
61                       ObserverInterface* observer) override;
StartTransaction()62   bool StartTransaction() override { return false; }
CancelTransaction()63   bool CancelTransaction() override { return false; }
SubmitTransaction()64   bool SubmitTransaction() override { return false; }
65 
66  private:
67   enum class PrefType {
68     kString,
69     kInt64,
70     kBool,
71   };
72   struct PrefValue {
73     std::string as_str;
74     int64_t as_int64;
75     bool as_bool;
76   };
77 
78   struct PrefTypeValue {
79     PrefType type;
80     PrefValue value;
81   };
82 
83   // Class to store compile-time type-dependent constants.
84   template <typename T>
85   class PrefConsts {
86    public:
87     // The PrefType associated with T.
88     static FakePrefs::PrefType const type;
89 
90     // The data member pointer to PrefValue associated with T.
91     static T FakePrefs::PrefValue::*const member;
92   };
93 
94   // Returns a string representation of the PrefType useful for logging.
95   static std::string GetTypeName(PrefType type);
96 
97   // Checks that the |key| is either not present or has the given |type|.
98   void CheckKeyType(std::string_view key, PrefType type) const;
99 
100   // Helper function to set a value of the passed |key|. It sets the type based
101   // on the template parameter T.
102   template <typename T>
103   void SetValue(std::string_view key, T value);
104 
105   // Helper function to get a value from the map checking for invalid calls.
106   // The function fails the test if you attempt to read a value  defined as a
107   // different type. Returns whether the get succeeded.
108   template <typename T>
109   bool GetValue(std::string_view key, T* value) const;
110 
111   // Container for all the key/value pairs.
112   std::map<std::string, PrefTypeValue, std::less<>> values_;
113 
114   // The registered observers watching for changes.
115   std::map<std::string, std::vector<ObserverInterface*>, std::less<>>
116       observers_;
117 
118   DISALLOW_COPY_AND_ASSIGN(FakePrefs);
119 };
120 
121 }  // namespace chromeos_update_engine
122 
123 #endif  // UPDATE_ENGINE_COMMON_FAKE_PREFS_H_
124