boot_control/include/libboot_control/libboot_control.h

//
// Copyright (C) 2019 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

#pragma once

#include <string>

#include <android/hardware/boot/1.1/IBootControl.h>

namespace android {
namespace bootable {

// Helper library to implement the IBootControl HAL using the misc partition.
class BootControl {
  using MergeStatus = ::android::hardware::boot::V1_1::MergeStatus;

 public:
  bool Init();
  unsigned int GetNumberSlots();
  unsigned int GetCurrentSlot();
  bool MarkBootSuccessful();
  bool SetActiveBootSlot(unsigned int slot);
  bool SetSlotAsUnbootable(unsigned int slot);
  bool SetSlotBootable(unsigned int slot);
  bool IsSlotBootable(unsigned int slot);
  const char* GetSuffix(unsigned int slot);
  bool IsSlotMarkedSuccessful(unsigned int slot);
  bool SetSnapshotMergeStatus(MergeStatus status);
  MergeStatus GetSnapshotMergeStatus();

  bool IsValidSlot(unsigned int slot);

  const std::string& misc_device() const {
    return misc_device_;
  }

 private:
  // Whether this object was initialized with data from the bootloader message
  // that doesn't change until next reboot.
  bool initialized_ = false;

  // The path to the misc_device as reported in the fstab.
  std::string misc_device_;

  // The number of slots present on the device.
  unsigned int num_slots_ = 0;

  // The slot where we are running from.
  unsigned int current_slot_ = 0;
};

// Helper functions to write the Virtual A/B merge status message. These are
// separate because BootControl uses bootloader_control_ab in vendor space,
// whereas the Virtual A/B merge status is in system space. A HAL might not
// use bootloader_control_ab, but may want to use the AOSP method of maintaining
// the merge status.

// If the Virtual A/B message has not yet been initialized, then initialize it.
// This should be called when the BootControl HAL first loads.
//
// If the Virtual A/B message in misc was already initialized, true is returned.
// If initialization was attempted, but failed, false is returned, and the HAL
// should fail to load.
bool InitMiscVirtualAbMessageIfNeeded();

// Save the current merge status as well as the current slot.
bool SetMiscVirtualAbMergeStatus(unsigned int current_slot,
                                 android::hardware::boot::V1_1::MergeStatus status);

// Return the current merge status. If the saved status is SNAPSHOTTED but the
// slot hasn't changed, the status returned will be NONE.
bool GetMiscVirtualAbMergeStatus(unsigned int current_slot,
                                 android::hardware::boot::V1_1::MergeStatus* status);

}  // namespace bootable
}  // namespace android