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1 //
2 // Copyright (C) 2015 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_BOOT_CONTROL_CHROMEOS_H_
18 #define UPDATE_ENGINE_BOOT_CONTROL_CHROMEOS_H_
19 
20 #include <string>
21 
22 #include <base/callback.h>
23 #include <gtest/gtest_prod.h>  // for FRIEND_TEST
24 
25 #include "update_engine/common/boot_control_interface.h"
26 
27 namespace chromeos_update_engine {
28 
29 // The Chrome OS implementation of the BootControlInterface. This interface
30 // assumes the partition names and numbers used in Chrome OS devices.
31 class BootControlChromeOS : public BootControlInterface {
32  public:
33   BootControlChromeOS() = default;
34   ~BootControlChromeOS() = default;
35 
36   // Initialize the BootControl instance loading the constant values. Returns
37   // whether the operation succeeded. In case of failure, normally meaning
38   // some critical failure such as we couldn't determine the slot that we
39   // booted from, the implementation will pretend that there's only one slot and
40   // therefore A/B updates are disabled.
41   bool Init();
42 
43   // BootControlInterface overrides.
44   unsigned int GetNumSlots() const override;
45   BootControlInterface::Slot GetCurrentSlot() const override;
46   bool GetPartitionDevice(const std::string& partition_name,
47                           BootControlInterface::Slot slot,
48                           std::string* device) const override;
49   bool IsSlotBootable(BootControlInterface::Slot slot) const override;
50   bool MarkSlotUnbootable(BootControlInterface::Slot slot) override;
51   bool SetActiveBootSlot(BootControlInterface::Slot slot) override;
52   bool MarkBootSuccessfulAsync(base::Callback<void(bool)> callback) override;
53 
54  private:
55   friend class BootControlChromeOSTest;
56   FRIEND_TEST(BootControlChromeOSTest, SysfsBlockDeviceTest);
57   FRIEND_TEST(BootControlChromeOSTest, GetPartitionNumberTest);
58 
59   // Returns the sysfs block device for a root block device. For example,
60   // SysfsBlockDevice("/dev/sda") returns "/sys/block/sda". Returns an empty
61   // string if the input device is not of the "/dev/xyz" form.
62   static std::string SysfsBlockDevice(const std::string& device);
63 
64   // Returns true if the root |device| (e.g., "/dev/sdb") is known to be
65   // removable, false otherwise.
66   static bool IsRemovableDevice(const std::string& device);
67 
68   // Return the hard-coded partition number used in Chrome OS for the passed
69   // |partition_name| and |slot|. In case of invalid data, returns -1.
70   int GetPartitionNumber(const std::string partition_name,
71                          BootControlInterface::Slot slot) const;
72 
73   // Cached values for GetNumSlots() and GetCurrentSlot().
74   BootControlInterface::Slot num_slots_{1};
75   BootControlInterface::Slot current_slot_{BootControlInterface::kInvalidSlot};
76 
77   // The block device of the disk we booted from, without the partition number.
78   std::string boot_disk_name_;
79 
80   DISALLOW_COPY_AND_ASSIGN(BootControlChromeOS);
81 };
82 
83 }  // namespace chromeos_update_engine
84 
85 #endif  // UPDATE_ENGINE_BOOT_CONTROL_CHROMEOS_H_
86