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// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CHROME_BROWSER_DOWNGRADE_DOWNGRADE_MANAGER_H_
#define CHROME_BROWSER_DOWNGRADE_DOWNGRADE_MANAGER_H_
namespace base {
class FilePath;
class Version;
} // namespace base
namespace downgrade {
// An encapsulation of processing relating to the handling of browser launches
// where the User Data directory was last written by a higher version of the
// browser (a "downgrade"). It can detect if downgrade processing is needed,
// drop a breadcrumb for future launches indicating the current browser version,
// delete leftover state from a previous downgrade, and perform processing on
// state deposited on the device by the browser (e.g., the User Data directory)
// following a downgrade.
class DowngradeManager {
public:
DowngradeManager() = default;
DowngradeManager(const DowngradeManager&) = delete;
DowngradeManager& operator=(const DowngradeManager&) = delete;
// Inspects the contents of |user_data_dir| to determine whether a downgrade
// or an upgrade has happened since the last launch. Takes a Snapshot in case
// of upgrade, and sets the appropriate |type_| in case of downgrade. Returns
// |true| if the data from |user_data_dir| requires migration processing,
// |false| if it is usable by the current version. Note: this must be called
// within the protection of the process singleton.
bool PrepareUserDataDirectoryForCurrentVersion(
const base::FilePath& user_data_dir);
// Writes the current version number into the "Last Version" file in
// |user_data_dir|.
void UpdateLastVersion(const base::FilePath& user_data_dir);
// Schedules a search for the removal of any directories moved aside by
// PrepareUserDataDirectoryForCurrentVersion or ProcessDowngrade. This
// operation is idempotent, and may be safely called when no such directories
// exist.
void DeleteMovedUserDataSoon(const base::FilePath& user_data_dir);
// Process a previously-detected downgrade of |user_data_dir|. This must be
// called late in shutdown while the process singleton is still held.
void ProcessDowngrade(const base::FilePath& user_data_dir);
static void EnableSnapshotsForTesting(bool enable);
private:
enum class Type {
kNone = 0, // Same version or upgrade.
kAdministrativeWipe = 1, // Admin-driven downgrade with no snapshot.
kUnsupported = 2, // Unsupported downgrade with no data processing.
kSnapshotRestore = 3, // Downgrade with snapshot restoration.
kMinorDowngrade = 4, // Minor version downgrade; no data processing.
kMaxValue = kMinorDowngrade
};
static Type GetDowngradeType(const base::FilePath& user_data_dir,
const base::Version& current_version,
const base::Version& last_version);
static Type GetDowngradeTypeWithSnapshot(const base::FilePath& user_data_dir,
const base::Version& current_version,
const base::Version& last_version);
Type type_ = Type::kNone;
};
} // namespace downgrade
#endif // CHROME_BROWSER_DOWNGRADE_DOWNGRADE_MANAGER_H_
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