chrome/browser/chromeos/file_manager/volume_manager.cc

// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "chrome/browser/chromeos/file_manager/volume_manager.h"

#include <stddef.h>
#include <stdint.h>

#include "base/bind.h"
#include "base/command_line.h"
#include "base/feature_list.h"
#include "base/files/file_path.h"
#include "base/logging.h"
#include "base/memory/weak_ptr.h"
#include "base/metrics/histogram_macros.h"
#include "base/strings/string_util.h"
#include "base/strings/stringprintf.h"
#include "base/strings/utf_string_conversions.h"
#include "chrome/browser/chromeos/arc/arc_util.h"
#include "chrome/browser/chromeos/arc/fileapi/arc_documents_provider_util.h"
#include "chrome/browser/chromeos/arc/fileapi/arc_file_system_service.h"
#include "chrome/browser/chromeos/arc/fileapi/arc_media_view_util.h"
#include "chrome/browser/chromeos/drive/drive_integration_service.h"
#include "chrome/browser/chromeos/drive/file_system_util.h"
#include "chrome/browser/chromeos/file_manager/path_util.h"
#include "chrome/browser/chromeos/file_manager/snapshot_manager.h"
#include "chrome/browser/chromeos/file_manager/volume_manager_factory.h"
#include "chrome/browser/chromeos/file_manager/volume_manager_observer.h"
#include "chrome/browser/chromeos/file_system_provider/provided_file_system_info.h"
#include "chrome/browser/chromeos/profiles/profile_helper.h"
#include "chrome/browser/media_galleries/fileapi/mtp_device_map_service.h"
#include "chrome/browser/profiles/profile.h"
#include "chrome/common/pref_names.h"
#include "chromeos/chromeos_switches.h"
#include "chromeos/disks/disk_mount_manager.h"
#include "components/drive/chromeos/file_system_interface.h"
#include "components/drive/file_system_core_util.h"
#include "components/prefs/pref_service.h"
#include "components/storage_monitor/storage_monitor.h"
#include "content/public/browser/browser_context.h"
#include "content/public/browser/browser_thread.h"
#include "device/media_transfer_protocol/media_transfer_protocol_manager.h"
#include "storage/browser/fileapi/external_mount_points.h"

namespace file_manager {
namespace {

const uint32_t kAccessCapabilityReadWrite = 0;
const uint32_t kFilesystemTypeGenericHierarchical = 2;
const char kFileManagerMTPMountNamePrefix[] = "fileman-mtp-";
const char kMtpVolumeIdPrefix[] = "mtp:";
const char kRootPath[] = "/";

// Registers |path| as the "Downloads" folder to the FileSystem API backend.
// If another folder is already mounted. It revokes and overrides the old one.
bool RegisterDownloadsMountPoint(Profile* profile, const base::FilePath& path) {
  // Although we show only profile's own "Downloads" folder in the Files app,
  // in the backend we need to mount all profile's download directory globally.
  // Otherwise, the Files app cannot support cross-profile file copies, etc.
  // For this reason, we need to register to the global GetSystemInstance().
  const std::string mount_point_name =
      file_manager::util::GetDownloadsMountPointName(profile);
  storage::ExternalMountPoints* const mount_points =
      storage::ExternalMountPoints::GetSystemInstance();

  // In some tests we want to override existing Downloads mount point, so we
  // first revoke the existing mount point (if any).
  mount_points->RevokeFileSystem(mount_point_name);
  return mount_points->RegisterFileSystem(mount_point_name,
                                          storage::kFileSystemTypeNativeLocal,
                                          storage::FileSystemMountOption(),
                                          path);
}

// Finds the path register as the "Downloads" folder to FileSystem API backend.
// Returns false if it is not registered.
bool FindDownloadsMountPointPath(Profile* profile, base::FilePath* path) {
  const std::string mount_point_name =
      util::GetDownloadsMountPointName(profile);
  storage::ExternalMountPoints* const mount_points =
      storage::ExternalMountPoints::GetSystemInstance();

  return mount_points->GetRegisteredPath(mount_point_name, path);
}

VolumeType MountTypeToVolumeType(chromeos::MountType type) {
  switch (type) {
    case chromeos::MOUNT_TYPE_INVALID:
      // We don't expect this value, but list here, so that when any value
      // is added to the enum definition but this is not edited, the compiler
      // warns it.
      break;
    case chromeos::MOUNT_TYPE_DEVICE:
      return VOLUME_TYPE_REMOVABLE_DISK_PARTITION;
    case chromeos::MOUNT_TYPE_ARCHIVE:
      return VOLUME_TYPE_MOUNTED_ARCHIVE_FILE;
  }

  NOTREACHED();
  return VOLUME_TYPE_DOWNLOADS_DIRECTORY;
}

// Returns a string representation of the given volume type.
std::string VolumeTypeToString(VolumeType type) {
  switch (type) {
    case VOLUME_TYPE_GOOGLE_DRIVE:
      return "drive";
    case VOLUME_TYPE_DOWNLOADS_DIRECTORY:
      return "downloads";
    case VOLUME_TYPE_REMOVABLE_DISK_PARTITION:
      return "removable";
    case VOLUME_TYPE_MOUNTED_ARCHIVE_FILE:
      return "archive";
    case VOLUME_TYPE_PROVIDED:
      return "provided";
    case VOLUME_TYPE_MTP:
      return "mtp";
    case VOLUME_TYPE_MEDIA_VIEW:
      return "media_view";
    case VOLUME_TYPE_TESTING:
      return "testing";
    case NUM_VOLUME_TYPE:
      break;
  }
  NOTREACHED();
  return "";
}

// Generates a unique volume ID for the given volume info.
std::string GenerateVolumeId(const Volume& volume) {
  // For the same volume type, base names are unique, as mount points are
  // flat for the same volume type.
  return (VolumeTypeToString(volume.type()) + ":" +
          volume.mount_path().BaseName().AsUTF8Unsafe());
}

std::string GetMountPointNameForMediaStorage(
    const storage_monitor::StorageInfo& info) {
  std::string name(kFileManagerMTPMountNamePrefix);
  name += info.device_id();
  return name;
}

chromeos::MountAccessMode GetExternalStorageAccessMode(const Profile* profile) {
  return profile->GetPrefs()->GetBoolean(prefs::kExternalStorageReadOnly)
             ? chromeos::MOUNT_ACCESS_MODE_READ_ONLY
             : chromeos::MOUNT_ACCESS_MODE_READ_WRITE;
}

}  // namespace

Volume::Volume()
    : source_(SOURCE_FILE),
      type_(VOLUME_TYPE_GOOGLE_DRIVE),
      device_type_(chromeos::DEVICE_TYPE_UNKNOWN),
      mount_condition_(chromeos::disks::MOUNT_CONDITION_NONE),
      mount_context_(MOUNT_CONTEXT_UNKNOWN),
      is_parent_(false),
      is_read_only_(false),
      is_read_only_removable_device_(false),
      has_media_(false),
      configurable_(false),
      watchable_(false) {
}

Volume::~Volume() {
}

// static
Volume* Volume::CreateForDrive(Profile* profile) {
  const base::FilePath& drive_path =
      drive::util::GetDriveMountPointPath(profile);
  Volume* const volume = new Volume;
  volume->type_ = VOLUME_TYPE_GOOGLE_DRIVE;
  volume->device_type_ = chromeos::DEVICE_TYPE_UNKNOWN;
  volume->source_path_ = drive_path;
  volume->source_ = SOURCE_NETWORK;
  volume->mount_path_ = drive_path;
  volume->mount_condition_ = chromeos::disks::MOUNT_CONDITION_NONE;
  volume->volume_id_ = GenerateVolumeId(*volume);
  volume->watchable_ = true;
  return volume;
}

// static
Volume* Volume::CreateForDownloads(const base::FilePath& downloads_path) {
  Volume* const volume = new Volume;
  volume->type_ = VOLUME_TYPE_DOWNLOADS_DIRECTORY;
  volume->device_type_ = chromeos::DEVICE_TYPE_UNKNOWN;
  // Keep source_path empty.
  volume->source_ = SOURCE_SYSTEM;
  volume->mount_path_ = downloads_path;
  volume->mount_condition_ = chromeos::disks::MOUNT_CONDITION_NONE;
  volume->volume_id_ = GenerateVolumeId(*volume);
  volume->watchable_ = true;
  return volume;
}

// static
Volume* Volume::CreateForRemovable(
    const chromeos::disks::DiskMountManager::MountPointInfo& mount_point,
    const chromeos::disks::DiskMountManager::Disk* disk) {
  Volume* const volume = new Volume;
  volume->type_ = MountTypeToVolumeType(mount_point.mount_type);
  volume->source_path_ = base::FilePath(mount_point.source_path);
  volume->source_ = mount_point.mount_type == chromeos::MOUNT_TYPE_ARCHIVE
                        ? SOURCE_FILE
                        : SOURCE_DEVICE;
  volume->mount_path_ = base::FilePath(mount_point.mount_path);
  volume->mount_condition_ = mount_point.mount_condition;
  volume->volume_label_ = volume->mount_path().BaseName().AsUTF8Unsafe();
  if (disk) {
    volume->device_type_ = disk->device_type();
    volume->system_path_prefix_ = base::FilePath(disk->system_path_prefix());
    volume->is_parent_ = disk->is_parent();
    volume->is_read_only_ = disk->is_read_only();
    volume->is_read_only_removable_device_ = disk->is_read_only_hardware();
    volume->has_media_ = disk->has_media();
  } else {
    volume->device_type_ = chromeos::DEVICE_TYPE_UNKNOWN;
    volume->is_read_only_ =
        (mount_point.mount_type == chromeos::MOUNT_TYPE_ARCHIVE);
  }
  volume->volume_id_ = GenerateVolumeId(*volume);
  volume->watchable_ = true;
  return volume;
}

// static
Volume* Volume::CreateForProvidedFileSystem(
    const chromeos::file_system_provider::ProvidedFileSystemInfo&
        file_system_info,
    MountContext mount_context) {
  Volume* const volume = new Volume;
  volume->file_system_id_ = file_system_info.file_system_id();
  volume->extension_id_ = file_system_info.extension_id();
  switch (file_system_info.source()) {
    case extensions::SOURCE_FILE:
      volume->source_ = SOURCE_FILE;
      break;
    case extensions::SOURCE_DEVICE:
      volume->source_ = SOURCE_DEVICE;
      break;
    case extensions::SOURCE_NETWORK:
      volume->source_ = SOURCE_NETWORK;
      break;
  }
  volume->volume_label_ = file_system_info.display_name();
  volume->type_ = VOLUME_TYPE_PROVIDED;
  volume->mount_path_ = file_system_info.mount_path();
  volume->mount_condition_ = chromeos::disks::MOUNT_CONDITION_NONE;
  volume->mount_context_ = mount_context;
  volume->is_parent_ = true;
  volume->is_read_only_ = !file_system_info.writable();
  volume->configurable_ = file_system_info.configurable();
  volume->watchable_ = file_system_info.watchable();
  volume->volume_id_ = GenerateVolumeId(*volume);
  return volume;
}

// static
Volume* Volume::CreateForMTP(const base::FilePath& mount_path,
                             const std::string& label,
                             bool read_only) {
  Volume* const volume = new Volume;
  volume->type_ = VOLUME_TYPE_MTP;
  volume->mount_path_ = mount_path;
  volume->mount_condition_ = chromeos::disks::MOUNT_CONDITION_NONE;
  volume->is_parent_ = true;
  volume->is_read_only_ = read_only;
  volume->volume_id_ = kMtpVolumeIdPrefix + label;
  volume->volume_label_ = label;
  volume->source_path_ = mount_path;
  volume->source_ = SOURCE_DEVICE;
  volume->device_type_ = chromeos::DEVICE_TYPE_MOBILE;
  return volume;
}

// static
Volume* Volume::CreateForMediaView(const std::string& root_document_id) {
  Volume* const volume = new Volume;
  volume->type_ = VOLUME_TYPE_MEDIA_VIEW;
  volume->device_type_ = chromeos::DEVICE_TYPE_UNKNOWN;
  volume->source_ = SOURCE_SYSTEM;
  volume->mount_path_ = arc::GetDocumentsProviderMountPath(
      arc::kMediaDocumentsProviderAuthority, root_document_id);
  volume->mount_condition_ = chromeos::disks::MOUNT_CONDITION_NONE;
  volume->volume_label_ = root_document_id;
  volume->is_read_only_ = true;
  volume->watchable_ = false;
  volume->volume_id_ = arc::GetMediaViewVolumeId(root_document_id);
  return volume;
}

// static
Volume* Volume::CreateForTesting(const base::FilePath& path,
                                 VolumeType volume_type,
                                 chromeos::DeviceType device_type,
                                 bool read_only) {
  Volume* const volume = new Volume;
  volume->type_ = volume_type;
  volume->device_type_ = device_type;
  // Keep source_path empty.
  volume->source_ = SOURCE_DEVICE;
  volume->mount_path_ = path;
  volume->mount_condition_ = chromeos::disks::MOUNT_CONDITION_NONE;
  volume->is_read_only_ = read_only;
  volume->volume_id_ = GenerateVolumeId(*volume);
  return volume;
}

// static
Volume* Volume::CreateForTesting(const base::FilePath& device_path,
                                 const base::FilePath& mount_path) {
  Volume* const volume = new Volume;
  volume->system_path_prefix_ = device_path;
  volume->mount_path_ = mount_path;
  return volume;
}

VolumeManager::VolumeManager(
    Profile* profile,
    drive::DriveIntegrationService* drive_integration_service,
    chromeos::PowerManagerClient* power_manager_client,
    chromeos::disks::DiskMountManager* disk_mount_manager,
    chromeos::file_system_provider::Service* file_system_provider_service,
    GetMtpStorageInfoCallback get_mtp_storage_info_callback)
    : profile_(profile),
      drive_integration_service_(drive_integration_service),
      disk_mount_manager_(disk_mount_manager),
      file_system_provider_service_(file_system_provider_service),
      get_mtp_storage_info_callback_(get_mtp_storage_info_callback),
      snapshot_manager_(new SnapshotManager(profile_)),
      weak_ptr_factory_(this) {
  DCHECK(disk_mount_manager);
}

VolumeManager::~VolumeManager() {
}

VolumeManager* VolumeManager::Get(content::BrowserContext* context) {
  return VolumeManagerFactory::Get(context);
}

void VolumeManager::Initialize() {
  // If in Sign in profile, then skip mounting and listening for mount events.
  if (chromeos::ProfileHelper::IsSigninProfile(profile_))
    return;

  // Register 'Downloads' folder for the profile to the file system.
  const base::FilePath downloads =
      file_manager::util::GetDownloadsFolderForProfile(profile_);
  const bool success = RegisterDownloadsMountPoint(profile_, downloads);
  DCHECK(success);

  DoMountEvent(chromeos::MOUNT_ERROR_NONE,
               make_linked_ptr(Volume::CreateForDownloads(downloads)));

  // Subscribe to DriveIntegrationService.
  if (drive_integration_service_) {
    drive_integration_service_->AddObserver(this);
    if (drive_integration_service_->IsMounted()) {
      DoMountEvent(chromeos::MOUNT_ERROR_NONE,
                   make_linked_ptr(Volume::CreateForDrive(profile_)));
    }
  }

  // Subscribe to DiskMountManager.
  disk_mount_manager_->AddObserver(this);
  disk_mount_manager_->EnsureMountInfoRefreshed(
      base::Bind(&VolumeManager::OnDiskMountManagerRefreshed,
                 weak_ptr_factory_.GetWeakPtr()),
      false /* force */);

  // Subscribe to FileSystemProviderService and register currently mounted
  // volumes for the profile.
  if (file_system_provider_service_) {
    using chromeos::file_system_provider::ProvidedFileSystemInfo;
    file_system_provider_service_->AddObserver(this);

    std::vector<ProvidedFileSystemInfo> file_system_info_list =
        file_system_provider_service_->GetProvidedFileSystemInfoList();
    for (size_t i = 0; i < file_system_info_list.size(); ++i) {
      linked_ptr<Volume> volume(Volume::CreateForProvidedFileSystem(
          file_system_info_list[i], MOUNT_CONTEXT_AUTO));
      DoMountEvent(chromeos::MOUNT_ERROR_NONE, volume);
    }
  }

  // Subscribe to Profile Preference change.
  pref_change_registrar_.Init(profile_->GetPrefs());
  pref_change_registrar_.Add(
      prefs::kExternalStorageDisabled,
      base::Bind(&VolumeManager::OnExternalStorageDisabledChanged,
                 weak_ptr_factory_.GetWeakPtr()));
  pref_change_registrar_.Add(
      prefs::kExternalStorageReadOnly,
      base::Bind(&VolumeManager::OnExternalStorageReadOnlyChanged,
                 weak_ptr_factory_.GetWeakPtr()));

  // Subscribe to storage monitor for MTP notifications.
  if (storage_monitor::StorageMonitor::GetInstance()) {
    storage_monitor::StorageMonitor::GetInstance()->EnsureInitialized(
        base::Bind(&VolumeManager::OnStorageMonitorInitialized,
                   weak_ptr_factory_.GetWeakPtr()));
  }

  // Subscribe to ARC file system events.
  if (base::FeatureList::IsEnabled(arc::kMediaViewFeature) &&
      arc::IsArcAllowedForProfile(profile_)) {
    arc::ArcSessionManager::Get()->AddObserver(this);
    OnArcPlayStoreEnabledChanged(
        arc::IsArcPlayStoreEnabledForProfile(profile_));
  }
}

void VolumeManager::Shutdown() {
  weak_ptr_factory_.InvalidateWeakPtrs();

  snapshot_manager_.reset();
  pref_change_registrar_.RemoveAll();
  disk_mount_manager_->RemoveObserver(this);
  if (storage_monitor::StorageMonitor::GetInstance())
    storage_monitor::StorageMonitor::GetInstance()->RemoveObserver(this);

  if (drive_integration_service_)
    drive_integration_service_->RemoveObserver(this);

  if (file_system_provider_service_)
    file_system_provider_service_->RemoveObserver(this);

  // Unsubscribe from ARC file system events.
  if (base::FeatureList::IsEnabled(arc::kMediaViewFeature) &&
      arc::IsArcAllowedForProfile(profile_)) {
    auto* session_manager = arc::ArcSessionManager::Get();
    // TODO(crbug.com/672829): We need nullptr check here because
    // ArcSessionManager may or may not be alive at this point.
    if (session_manager)
      session_manager->RemoveObserver(this);
  }
}

void VolumeManager::AddObserver(VolumeManagerObserver* observer) {
  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
  DCHECK(observer);
  observers_.AddObserver(observer);
}

void VolumeManager::RemoveObserver(VolumeManagerObserver* observer) {
  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
  DCHECK(observer);
  observers_.RemoveObserver(observer);
}

std::vector<base::WeakPtr<Volume>> VolumeManager::GetVolumeList() {
  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);

  std::vector<base::WeakPtr<Volume>> result;
  for (const auto& pair : mounted_volumes_) {
    result.push_back(pair.second->AsWeakPtr());
  }
  return result;
}

base::WeakPtr<Volume> VolumeManager::FindVolumeById(
    const std::string& volume_id) {
  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);

  const auto it = mounted_volumes_.find(volume_id);
  if (it != mounted_volumes_.end())
    return it->second->AsWeakPtr();
  return base::WeakPtr<Volume>();
}

bool VolumeManager::RegisterDownloadsDirectoryForTesting(
    const base::FilePath& path) {
  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);

  base::FilePath old_path;
  if (FindDownloadsMountPointPath(profile_, &old_path)) {
    DoUnmountEvent(chromeos::MOUNT_ERROR_NONE,
                   make_linked_ptr(Volume::CreateForDownloads(old_path)));
  }

  bool success = RegisterDownloadsMountPoint(profile_, path);
  DoMountEvent(
      success ? chromeos::MOUNT_ERROR_NONE : chromeos::MOUNT_ERROR_INVALID_PATH,
      make_linked_ptr(Volume::CreateForDownloads(path)));
  return success;
}

void VolumeManager::AddVolumeForTesting(const base::FilePath& path,
                                        VolumeType volume_type,
                                        chromeos::DeviceType device_type,
                                        bool read_only) {
  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
  DoMountEvent(chromeos::MOUNT_ERROR_NONE,
               make_linked_ptr(Volume::CreateForTesting(
                   path, volume_type, device_type, read_only)));
}

void VolumeManager::AddVolumeForTesting(const linked_ptr<Volume>& volume) {
  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
  DoMountEvent(chromeos::MOUNT_ERROR_NONE, volume);
}

void VolumeManager::OnFileSystemMounted() {
  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);

  // Raise mount event.
  // We can pass chromeos::MOUNT_ERROR_NONE even when authentication is failed
  // or network is unreachable. These two errors will be handled later.
  linked_ptr<Volume> volume(Volume::CreateForDrive(profile_));
  DoMountEvent(chromeos::MOUNT_ERROR_NONE, volume);
}

void VolumeManager::OnFileSystemBeingUnmounted() {
  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);

  linked_ptr<Volume> volume(Volume::CreateForDrive(profile_));
  DoUnmountEvent(chromeos::MOUNT_ERROR_NONE, volume);
}

void VolumeManager::OnDiskEvent(
    chromeos::disks::DiskMountManager::DiskEvent event,
    const chromeos::disks::DiskMountManager::Disk* disk) {
  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);

  // Disregard hidden devices.
  if (disk->is_hidden())
    return;

  switch (event) {
    case chromeos::disks::DiskMountManager::DISK_ADDED:
    case chromeos::disks::DiskMountManager::DISK_CHANGED: {
      if (disk->device_path().empty()) {
        DVLOG(1) << "Empty system path for " << disk->device_path();
        return;
      }

      bool mounting = false;
      if (disk->mount_path().empty() && disk->has_media() &&
          !profile_->GetPrefs()->GetBoolean(prefs::kExternalStorageDisabled)) {
        // If disk is not mounted yet and it has media and there is no policy
        // forbidding external storage, give it a try.
        // Initiate disk mount operation. MountPath auto-detects the filesystem
        // format if the second argument is empty. The third argument (mount
        // label) is not used in a disk mount operation.
        disk_mount_manager_->MountPath(disk->device_path(), std::string(),
                                       std::string(),
                                       chromeos::MOUNT_TYPE_DEVICE,
                                       GetExternalStorageAccessMode(profile_));
        mounting = true;
      }

      // Notify to observers.
      for (auto& observer : observers_)
        observer.OnDiskAdded(*disk, mounting);
      return;
    }

    case chromeos::disks::DiskMountManager::DISK_REMOVED:
      // If the disk is already mounted, unmount it.
      if (!disk->mount_path().empty()) {
        disk_mount_manager_->UnmountPath(
            disk->mount_path(),
            chromeos::UNMOUNT_OPTIONS_LAZY,
            chromeos::disks::DiskMountManager::UnmountPathCallback());
      }

      // Notify to observers.
      for (auto& observer : observers_)
        observer.OnDiskRemoved(*disk);
      return;
  }
  NOTREACHED();
}

void VolumeManager::OnDeviceEvent(
    chromeos::disks::DiskMountManager::DeviceEvent event,
    const std::string& device_path) {
  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);

  DVLOG(1) << "OnDeviceEvent: " << event << ", " << device_path;
  switch (event) {
    case chromeos::disks::DiskMountManager::DEVICE_ADDED:
      for (auto& observer : observers_)
        observer.OnDeviceAdded(device_path);
      return;
    case chromeos::disks::DiskMountManager::DEVICE_REMOVED: {
      for (auto& observer : observers_)
        observer.OnDeviceRemoved(device_path);
      return;
    }
    case chromeos::disks::DiskMountManager::DEVICE_SCANNED:
      DVLOG(1) << "Ignore SCANNED event: " << device_path;
      return;
  }
  NOTREACHED();
}

void VolumeManager::OnMountEvent(
    chromeos::disks::DiskMountManager::MountEvent event,
    chromeos::MountError error_code,
    const chromeos::disks::DiskMountManager::MountPointInfo& mount_info) {
  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
  DCHECK_NE(chromeos::MOUNT_TYPE_INVALID, mount_info.mount_type);

  if (mount_info.mount_type == chromeos::MOUNT_TYPE_ARCHIVE) {
    // If the file is not mounted now, tell it to drive file system so that
    // it can handle file caching correctly.
    // Note that drive file system knows if the file is managed by drive file
    // system or not, so here we report all paths.
    if ((event == chromeos::disks::DiskMountManager::MOUNTING &&
         error_code != chromeos::MOUNT_ERROR_NONE) ||
        (event == chromeos::disks::DiskMountManager::UNMOUNTING &&
         error_code == chromeos::MOUNT_ERROR_NONE)) {
      drive::FileSystemInterface* const file_system =
          drive::util::GetFileSystemByProfile(profile_);
      if (file_system) {
        file_system->MarkCacheFileAsUnmounted(
            base::FilePath(mount_info.source_path),
            base::Bind(&drive::util::EmptyFileOperationCallback));
      }
    }
  }

  // Notify a mounting/unmounting event to observers.
  const chromeos::disks::DiskMountManager::Disk* const disk =
      disk_mount_manager_->FindDiskBySourcePath(mount_info.source_path);
  linked_ptr<Volume> volume(Volume::CreateForRemovable(mount_info, disk));
  switch (event) {
    case chromeos::disks::DiskMountManager::MOUNTING: {
      DoMountEvent(error_code, volume);
      return;
    }
    case chromeos::disks::DiskMountManager::UNMOUNTING:
      DoUnmountEvent(error_code, volume);
      return;
  }
  NOTREACHED();
}

void VolumeManager::OnFormatEvent(
    chromeos::disks::DiskMountManager::FormatEvent event,
    chromeos::FormatError error_code,
    const std::string& device_path) {
  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
  DVLOG(1) << "OnDeviceEvent: " << event << ", " << error_code
           << ", " << device_path;

  switch (event) {
    case chromeos::disks::DiskMountManager::FORMAT_STARTED:
      for (auto& observer : observers_) {
        observer.OnFormatStarted(device_path,
                                 error_code == chromeos::FORMAT_ERROR_NONE);
      }
      return;
    case chromeos::disks::DiskMountManager::FORMAT_COMPLETED:
      if (error_code == chromeos::FORMAT_ERROR_NONE) {
        // If format is completed successfully, try to mount the device.
        // MountPath auto-detects filesystem format if second argument is
        // empty. The third argument (mount label) is not used in a disk mount
        // operation.
        disk_mount_manager_->MountPath(device_path, std::string(),
                                       std::string(),
                                       chromeos::MOUNT_TYPE_DEVICE,
                                       GetExternalStorageAccessMode(profile_));
      }

      for (auto& observer : observers_) {
        observer.OnFormatCompleted(device_path,
                                   error_code == chromeos::FORMAT_ERROR_NONE);
      }

      return;
  }
  NOTREACHED();
}

void VolumeManager::OnProvidedFileSystemMount(
    const chromeos::file_system_provider::ProvidedFileSystemInfo&
        file_system_info,
    chromeos::file_system_provider::MountContext context,
    base::File::Error error) {
  MountContext volume_context = MOUNT_CONTEXT_UNKNOWN;
  switch (context) {
    case chromeos::file_system_provider::MOUNT_CONTEXT_USER:
      volume_context = MOUNT_CONTEXT_USER;
      break;
    case chromeos::file_system_provider::MOUNT_CONTEXT_RESTORE:
      volume_context = MOUNT_CONTEXT_AUTO;
      break;
  }

  linked_ptr<Volume> volume(
      Volume::CreateForProvidedFileSystem(file_system_info, volume_context));

  // TODO(mtomasz): Introduce own type, and avoid using MountError internally,
  // since it is related to cros disks only.
  chromeos::MountError mount_error;
  switch (error) {
    case base::File::FILE_OK:
      mount_error = chromeos::MOUNT_ERROR_NONE;
      break;
    case base::File::FILE_ERROR_EXISTS:
      mount_error = chromeos::MOUNT_ERROR_PATH_ALREADY_MOUNTED;
      break;
    default:
      mount_error = chromeos::MOUNT_ERROR_UNKNOWN;
      break;
  }

  DoMountEvent(mount_error, volume);
}

void VolumeManager::OnProvidedFileSystemUnmount(
    const chromeos::file_system_provider::ProvidedFileSystemInfo&
        file_system_info,
    base::File::Error error) {
  // TODO(mtomasz): Introduce own type, and avoid using MountError internally,
  // since it is related to cros disks only.
  const chromeos::MountError mount_error = error == base::File::FILE_OK
                                               ? chromeos::MOUNT_ERROR_NONE
                                               : chromeos::MOUNT_ERROR_UNKNOWN;
  linked_ptr<Volume> volume(Volume::CreateForProvidedFileSystem(
      file_system_info, MOUNT_CONTEXT_UNKNOWN));
  DoUnmountEvent(mount_error, volume);
}

void VolumeManager::OnExternalStorageDisabledChangedUnmountCallback(
    chromeos::MountError error_code) {
  if (disk_mount_manager_->mount_points().empty())
    return;
  // Repeat until unmount all paths
  const std::string& mount_path =
      disk_mount_manager_->mount_points().begin()->second.mount_path;
  disk_mount_manager_->UnmountPath(
      mount_path, chromeos::UNMOUNT_OPTIONS_NONE,
      base::Bind(
          &VolumeManager::OnExternalStorageDisabledChangedUnmountCallback,
          weak_ptr_factory_.GetWeakPtr()));
}

void VolumeManager::OnArcPlayStoreEnabledChanged(bool enabled) {
  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
  DCHECK(base::FeatureList::IsEnabled(arc::kMediaViewFeature));
  DCHECK(arc::IsArcAllowedForProfile(profile_));

  if (enabled == arc_volumes_mounted_)
    return;

  if (enabled) {
    DoMountEvent(chromeos::MOUNT_ERROR_NONE,
                 linked_ptr<Volume>(
                     Volume::CreateForMediaView(arc::kImagesRootDocumentId)));
    DoMountEvent(chromeos::MOUNT_ERROR_NONE,
                 linked_ptr<Volume>(
                     Volume::CreateForMediaView(arc::kVideosRootDocumentId)));
    DoMountEvent(chromeos::MOUNT_ERROR_NONE,
                 linked_ptr<Volume>(
                     Volume::CreateForMediaView(arc::kAudioRootDocumentId)));
  } else {
    DoUnmountEvent(chromeos::MOUNT_ERROR_NONE,
                   linked_ptr<Volume>(
                       Volume::CreateForMediaView(arc::kImagesRootDocumentId)));
    DoUnmountEvent(chromeos::MOUNT_ERROR_NONE,
                   linked_ptr<Volume>(
                       Volume::CreateForMediaView(arc::kVideosRootDocumentId)));
    DoUnmountEvent(chromeos::MOUNT_ERROR_NONE,
                   linked_ptr<Volume>(
                       Volume::CreateForMediaView(arc::kAudioRootDocumentId)));
  }

  arc_volumes_mounted_ = enabled;
}

void VolumeManager::OnExternalStorageDisabledChanged() {
  // If the policy just got disabled we have to unmount every device currently
  // mounted. The opposite is fine - we can let the user re-plug their device to
  // make it available.
  if (profile_->GetPrefs()->GetBoolean(prefs::kExternalStorageDisabled)) {
    // We do not iterate on mount_points directly, because mount_points can
    // be changed by UnmountPath().
    // TODO(hidehiko): Is it necessary to unmount mounted archives, too, here?
    if (disk_mount_manager_->mount_points().empty())
      return;
    const std::string& mount_path =
        disk_mount_manager_->mount_points().begin()->second.mount_path;
    disk_mount_manager_->UnmountPath(
        mount_path, chromeos::UNMOUNT_OPTIONS_NONE,
        base::Bind(
            &VolumeManager::OnExternalStorageDisabledChangedUnmountCallback,
            weak_ptr_factory_.GetWeakPtr()));
  }
}

void VolumeManager::OnExternalStorageReadOnlyChanged() {
  disk_mount_manager_->RemountAllRemovableDrives(
      GetExternalStorageAccessMode(profile_));
}

void VolumeManager::OnRemovableStorageAttached(
    const storage_monitor::StorageInfo& info) {
  if (!storage_monitor::StorageInfo::IsMTPDevice(info.device_id()))
    return;
  if (profile_->GetPrefs()->GetBoolean(prefs::kExternalStorageDisabled))
    return;

  const base::FilePath path = base::FilePath::FromUTF8Unsafe(info.location());
  const std::string fsid = GetMountPointNameForMediaStorage(info);
  const std::string base_name = base::UTF16ToUTF8(info.model_name());

  // Assign a fresh volume ID based on the volume name.
  std::string label = base_name;
  for (int i = 2; mounted_volumes_.count(kMtpVolumeIdPrefix + label); ++i)
    label = base_name + base::StringPrintf(" (%d)", i);

  bool result =
      storage::ExternalMountPoints::GetSystemInstance()->RegisterFileSystem(
          fsid,
          storage::kFileSystemTypeDeviceMediaAsFileStorage,
          storage::FileSystemMountOption(),
          path);
  DCHECK(result);

  // Resolve mtp storage name and get MtpStorageInfo.
  std::string storage_name;
  base::RemoveChars(info.location(), kRootPath, &storage_name);
  DCHECK(!storage_name.empty());

  const MtpStorageInfo* mtp_storage_info;
  if (get_mtp_storage_info_callback_.is_null()) {
    mtp_storage_info = storage_monitor::StorageMonitor::GetInstance()
                           ->media_transfer_protocol_manager()
                           ->GetStorageInfo(storage_name);
  } else {
    mtp_storage_info = get_mtp_storage_info_callback_.Run(storage_name);
  }
  DCHECK(mtp_storage_info);

  // Mtp write is enabled only when the device is writable, supports generic
  // hierarchical file system, and writing to external storage devices is not
  // prohibited by the preference.
  const bool read_only =
      base::CommandLine::ForCurrentProcess()->HasSwitch(
          chromeos::switches::kDisableMtpWriteSupport) ||
      mtp_storage_info->access_capability() != kAccessCapabilityReadWrite ||
      mtp_storage_info->filesystem_type() !=
          kFilesystemTypeGenericHierarchical ||
      GetExternalStorageAccessMode(profile_) ==
          chromeos::MOUNT_ACCESS_MODE_READ_ONLY;

  content::BrowserThread::PostTask(
      content::BrowserThread::IO, FROM_HERE,
      base::Bind(&MTPDeviceMapService::RegisterMTPFileSystem,
                 base::Unretained(MTPDeviceMapService::GetInstance()),
                 info.location(), fsid, read_only));

  linked_ptr<Volume> volume(Volume::CreateForMTP(path, label, read_only));
  DoMountEvent(chromeos::MOUNT_ERROR_NONE, volume);
}

void VolumeManager::OnRemovableStorageDetached(
    const storage_monitor::StorageInfo& info) {
  if (!storage_monitor::StorageInfo::IsMTPDevice(info.device_id()))
    return;

  for (const auto mounted_volume : mounted_volumes_) {
    if (mounted_volume.second->source_path().value() == info.location()) {
      DoUnmountEvent(chromeos::MOUNT_ERROR_NONE, mounted_volume.second);

      const std::string fsid = GetMountPointNameForMediaStorage(info);
      storage::ExternalMountPoints::GetSystemInstance()->RevokeFileSystem(fsid);
      content::BrowserThread::PostTask(
          content::BrowserThread::IO, FROM_HERE, base::Bind(
              &MTPDeviceMapService::RevokeMTPFileSystem,
              base::Unretained(MTPDeviceMapService::GetInstance()),
              fsid));
      return;
    }
  }
}

void VolumeManager::OnDiskMountManagerRefreshed(bool success) {
  if (!success) {
    LOG(ERROR) << "Failed to refresh disk mount manager";
    return;
  }

  std::vector<linked_ptr<Volume>> archives;

  const chromeos::disks::DiskMountManager::MountPointMap& mount_points =
      disk_mount_manager_->mount_points();
  for (chromeos::disks::DiskMountManager::MountPointMap::const_iterator it =
           mount_points.begin();
       it != mount_points.end();
       ++it) {
    if (it->second.mount_type == chromeos::MOUNT_TYPE_ARCHIVE) {
      // Archives are mounted after other types of volume. See below.
      archives.push_back(
          make_linked_ptr(Volume::CreateForRemovable(it->second, NULL)));
      continue;
    }
    DoMountEvent(chromeos::MOUNT_ERROR_NONE,
                 make_linked_ptr(Volume::CreateForRemovable(
                     it->second, disk_mount_manager_->FindDiskBySourcePath(
                                     it->second.source_path))));
  }

  // We mount archives only if they are opened from currently mounted volumes.
  // To check the condition correctly in DoMountEvent, we care about the order.
  std::vector<bool> done(archives.size(), false);
  for (size_t i = 0; i < archives.size(); ++i) {
    if (done[i])
      continue;

    std::vector<linked_ptr<Volume>> chain;
    done[i] = true;
    chain.push_back(archives[i]);

    // If archives[i]'s source_path is in another archive, mount it first.
    for (size_t parent = i + 1; parent < archives.size(); ++parent) {
      if (!done[parent] &&
          archives[parent]->mount_path().IsParent(
              chain.back()->source_path())) {
        done[parent] = true;
        chain.push_back(archives[parent]);
        parent = i + 1;  // Search archives[parent]'s parent from the beginning.
      }
    }

    // Mount from the tail of chain.
    for (size_t i = chain.size(); i > 0; --i) {
      DoMountEvent(chromeos::MOUNT_ERROR_NONE, chain[i - 1]);
    }
  }
}

void VolumeManager::OnStorageMonitorInitialized() {
  std::vector<storage_monitor::StorageInfo> storages =
      storage_monitor::StorageMonitor::GetInstance()->GetAllAvailableStorages();
  for (size_t i = 0; i < storages.size(); ++i)
    OnRemovableStorageAttached(storages[i]);
  storage_monitor::StorageMonitor::GetInstance()->AddObserver(this);
}

void VolumeManager::DoMountEvent(chromeos::MountError error_code,
                                 const linked_ptr<Volume>& volume) {
  // Archive files are mounted globally in system. We however don't want to show
  // archives from profile-specific folders (Drive/Downloads) of other users in
  // multi-profile session. To this end, we filter out archives not on the
  // volumes already mounted on this VolumeManager instance.
  if (volume->type() == VOLUME_TYPE_MOUNTED_ARCHIVE_FILE) {
    // Source may be in Drive cache folder under the current profile directory.
    bool from_current_profile =
        profile_->GetPath().IsParent(volume->source_path());
    for (const auto& mounted_volume : mounted_volumes_) {
      if (mounted_volume.second->mount_path().IsParent(volume->source_path())) {
        from_current_profile = true;
        break;
      }
    }
    if (!from_current_profile)
      return;
  }

  // Filter out removable disks if forbidden by policy for this profile.
  if (volume->type() == VOLUME_TYPE_REMOVABLE_DISK_PARTITION &&
      profile_->GetPrefs()->GetBoolean(prefs::kExternalStorageDisabled)) {
    return;
  }

  if (error_code == chromeos::MOUNT_ERROR_NONE || volume->mount_condition()) {
    mounted_volumes_[volume->volume_id()] = volume;
    UMA_HISTOGRAM_ENUMERATION("FileBrowser.VolumeType", volume->type(),
                              NUM_VOLUME_TYPE);
  }

  for (auto& observer : observers_)
    observer.OnVolumeMounted(error_code, *volume);
}

void VolumeManager::DoUnmountEvent(chromeos::MountError error_code,
                                   const linked_ptr<Volume>& volume) {
  if (mounted_volumes_.find(volume->volume_id()) == mounted_volumes_.end())
    return;
  if (error_code == chromeos::MOUNT_ERROR_NONE)
    mounted_volumes_.erase(volume->volume_id());

  for (auto& observer : observers_)
    observer.OnVolumeUnmounted(error_code, *volume.get());
}

}  // namespace file_manager