dynamic_partition_control_android.cc

//
// Copyright (C) 2018 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.
//

#include "update_engine/dynamic_partition_control_android.h"

#include <memory>
#include <set>
#include <string>

#include <android-base/properties.h>
#include <android-base/strings.h>
#include <base/files/file_util.h>
#include <base/logging.h>
#include <bootloader_message/bootloader_message.h>
#include <fs_mgr_dm_linear.h>

#include "update_engine/common/boot_control_interface.h"
#include "update_engine/common/utils.h"

using android::base::GetBoolProperty;
using android::base::Join;
using android::dm::DeviceMapper;
using android::dm::DmDeviceState;
using android::fs_mgr::CreateLogicalPartition;
using android::fs_mgr::DestroyLogicalPartition;
using android::fs_mgr::MetadataBuilder;

namespace chromeos_update_engine {

constexpr char kUseDynamicPartitions[] = "ro.boot.logical_partitions";
constexpr uint64_t kMapTimeoutMillis = 1000;

DynamicPartitionControlAndroid::~DynamicPartitionControlAndroid() {
  CleanupInternal(false /* wait */);
}

bool DynamicPartitionControlAndroid::IsDynamicPartitionsEnabled() {
  return GetBoolProperty(kUseDynamicPartitions, false);
}

bool DynamicPartitionControlAndroid::MapPartitionOnDeviceMapper(
    const std::string& super_device,
    const std::string& target_partition_name,
    uint32_t slot,
    std::string* path) {
  if (!CreateLogicalPartition(super_device.c_str(),
                              slot,
                              target_partition_name,
                              true /* force_writable */,
                              std::chrono::milliseconds(kMapTimeoutMillis),
                              path)) {
    LOG(ERROR) << "Cannot map " << target_partition_name << " in "
               << super_device << " on device mapper.";
    return false;
  }
  LOG(INFO) << "Succesfully mapped " << target_partition_name
            << " to device mapper; device path at " << *path;
  mapped_devices_.insert(target_partition_name);
  return true;
}

bool DynamicPartitionControlAndroid::UnmapPartitionOnDeviceMapper(
    const std::string& target_partition_name, bool wait) {
  if (DeviceMapper::Instance().GetState(target_partition_name) !=
      DmDeviceState::INVALID) {
    if (!DestroyLogicalPartition(
            target_partition_name,
            std::chrono::milliseconds(wait ? kMapTimeoutMillis : 0))) {
      LOG(ERROR) << "Cannot unmap " << target_partition_name
                 << " from device mapper.";
      return false;
    }
    LOG(INFO) << "Successfully unmapped " << target_partition_name
              << " from device mapper.";
  }
  mapped_devices_.erase(target_partition_name);
  return true;
}

void DynamicPartitionControlAndroid::CleanupInternal(bool wait) {
  // UnmapPartitionOnDeviceMapper removes objects from mapped_devices_, hence
  // a copy is needed for the loop.
  std::set<std::string> mapped = mapped_devices_;
  LOG(INFO) << "Destroying [" << Join(mapped, ", ") << "] from device mapper";
  for (const auto& partition_name : mapped) {
    ignore_result(UnmapPartitionOnDeviceMapper(partition_name, wait));
  }
}

void DynamicPartitionControlAndroid::Cleanup() {
  CleanupInternal(true /* wait */);
}

bool DynamicPartitionControlAndroid::DeviceExists(const std::string& path) {
  return base::PathExists(base::FilePath(path));
}

android::dm::DmDeviceState DynamicPartitionControlAndroid::GetState(
    const std::string& name) {
  return DeviceMapper::Instance().GetState(name);
}

bool DynamicPartitionControlAndroid::GetDmDevicePathByName(
    const std::string& name, std::string* path) {
  return DeviceMapper::Instance().GetDmDevicePathByName(name, path);
}

std::unique_ptr<MetadataBuilder>
DynamicPartitionControlAndroid::LoadMetadataBuilder(
    const std::string& super_device, uint32_t source_slot) {
  auto builder = MetadataBuilder::New(super_device, source_slot);
  if (builder == nullptr) {
    LOG(WARNING) << "No metadata slot "
                 << BootControlInterface::SlotName(source_slot) << " in "
                 << super_device;
  }
  LOG(INFO) << "Loaded metadata from slot "
            << BootControlInterface::SlotName(source_slot) << " in "
            << super_device;
  return builder;
}

bool DynamicPartitionControlAndroid::StoreMetadata(
    const std::string& super_device,
    MetadataBuilder* builder,
    uint32_t target_slot) {
  auto metadata = builder->Export();
  if (metadata == nullptr) {
    LOG(ERROR) << "Cannot export metadata to slot "
               << BootControlInterface::SlotName(target_slot) << " in "
               << super_device;
    return false;
  }

  if (!UpdatePartitionTable(super_device, *metadata, target_slot)) {
    LOG(ERROR) << "Cannot write metadata to slot "
               << BootControlInterface::SlotName(target_slot) << " in "
               << super_device;
    return false;
  }

  LOG(INFO) << "Copied metadata to slot "
            << BootControlInterface::SlotName(target_slot) << " in "
            << super_device;
  return true;
}

bool DynamicPartitionControlAndroid::GetDeviceDir(std::string* out) {
  // We can't use fs_mgr to look up |partition_name| because fstab
  // doesn't list every slot partition (it uses the slotselect option
  // to mask the suffix).
  //
  // We can however assume that there's an entry for the /misc mount
  // point and use that to get the device file for the misc
  // partition. This helps us locate the disk that |partition_name|
  // resides on. From there we'll assume that a by-name scheme is used
  // so we can just replace the trailing "misc" by the given
  // |partition_name| and suffix corresponding to |slot|, e.g.
  //
  //   /dev/block/platform/soc.0/7824900.sdhci/by-name/misc ->
  //   /dev/block/platform/soc.0/7824900.sdhci/by-name/boot_a
  //
  // If needed, it's possible to relax the by-name assumption in the
  // future by trawling /sys/block looking for the appropriate sibling
  // of misc and then finding an entry in /dev matching the sysfs
  // entry.

  std::string err, misc_device = get_bootloader_message_blk_device(&err);
  if (misc_device.empty()) {
    LOG(ERROR) << "Unable to get misc block device: " << err;
    return false;
  }

  if (!utils::IsSymlink(misc_device.c_str())) {
    LOG(ERROR) << "Device file " << misc_device << " for /misc "
               << "is not a symlink.";
    return false;
  }
  *out = base::FilePath(misc_device).DirName().value();
  return true;
}
}  // namespace chromeos_update_engine