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// 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.
#ifndef COMPONENTS_USER_PREFS_TRACKED_PREF_HASH_FILTER_H_
#define COMPONENTS_USER_PREFS_TRACKED_PREF_HASH_FILTER_H_
#include <stddef.h>
#include <map>
#include <memory>
#include <set>
#include <vector>
#include "base/callback.h"
#include "base/compiler_specific.h"
#include "base/containers/scoped_ptr_hash_map.h"
#include "base/files/file_path.h"
#include "base/macros.h"
#include "base/optional.h"
#include "components/user_prefs/tracked/hash_store_contents.h"
#include "components/user_prefs/tracked/interceptable_pref_filter.h"
#include "components/user_prefs/tracked/tracked_preference.h"
class PrefHashStore;
class PrefService;
class PrefStore;
class TrackedPreferenceValidationDelegate;
namespace base {
class DictionaryValue;
class Time;
class Value;
} // namespace base
namespace user_prefs {
class PrefRegistrySyncable;
} // namespace user_prefs
// Intercepts preference values as they are loaded from disk and verifies them
// using a PrefHashStore. Keeps the PrefHashStore contents up to date as values
// are changed.
class PrefHashFilter : public InterceptablePrefFilter {
public:
enum EnforcementLevel { NO_ENFORCEMENT, ENFORCE_ON_LOAD };
enum PrefTrackingStrategy {
// Atomic preferences are tracked as a whole.
TRACKING_STRATEGY_ATOMIC,
// Split preferences are dictionaries for which each top-level entry is
// tracked independently. Note: preferences using this strategy must be kept
// in sync with TrackedSplitPreferences in histograms.xml.
TRACKING_STRATEGY_SPLIT,
};
enum ValueType {
VALUE_IMPERSONAL,
// The preference value may contain personal information.
VALUE_PERSONAL,
};
struct TrackedPreferenceMetadata {
size_t reporting_id;
const char* name;
EnforcementLevel enforcement_level;
PrefTrackingStrategy strategy;
ValueType value_type;
};
using StoreContentsPair = std::pair<std::unique_ptr<PrefHashStore>,
std::unique_ptr<HashStoreContents>>;
// Constructs a PrefHashFilter tracking the specified |tracked_preferences|
// using |pref_hash_store| to check/store hashes. An optional |delegate| is
// notified of the status of each preference as it is checked.
// If |on_reset_on_load| is provided, it will be invoked if a reset occurs in
// FilterOnLoad.
// |reporting_ids_count| is the count of all possible IDs (possibly greater
// than |tracked_preferences.size()|). If |report_super_mac_validity| is true,
// the state of the super MAC will be reported via UMA during
// FinalizeFilterOnLoad.
// |external_validation_hash_store_pair_| will be used (if non-null) to
// perform extra validations without triggering resets.
PrefHashFilter(
std::unique_ptr<PrefHashStore> pref_hash_store,
StoreContentsPair external_validation_hash_store_pair_,
const std::vector<TrackedPreferenceMetadata>& tracked_preferences,
const base::Closure& on_reset_on_load,
TrackedPreferenceValidationDelegate* delegate,
size_t reporting_ids_count,
bool report_super_mac_validity);
~PrefHashFilter() override;
// Registers required user preferences.
static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
// Retrieves the time of the last reset event, if any, for the provided user
// preferences. If no reset has occurred, Returns a null |Time|.
static base::Time GetResetTime(PrefService* user_prefs);
// Clears the time of the last reset event, if any, for the provided user
// preferences.
static void ClearResetTime(PrefService* user_prefs);
// Initializes the PrefHashStore with hashes of the tracked preferences in
// |pref_store_contents|. |pref_store_contents| will be the |storage| passed
// to PrefHashStore::BeginTransaction().
void Initialize(base::DictionaryValue* pref_store_contents);
// PrefFilter remaining implementation.
void FilterUpdate(const std::string& path) override;
OnWriteCallbackPair FilterSerializeData(
base::DictionaryValue* pref_store_contents) override;
private:
// InterceptablePrefFilter implementation.
void FinalizeFilterOnLoad(
const PostFilterOnLoadCallback& post_filter_on_load_callback,
std::unique_ptr<base::DictionaryValue> pref_store_contents,
bool prefs_altered) override;
// Helper function to generate FilterSerializeData()'s pre-write and
// post-write callbacks. The returned callbacks are thread-safe.
OnWriteCallbackPair GetOnWriteSynchronousCallbacks(
base::DictionaryValue* pref_store_contents);
// Clears the MACs contained in |external_validation_hash_store_contents|
// which are present in |paths_to_clear|.
static void ClearFromExternalStore(
HashStoreContents* external_validation_hash_store_contents,
const base::DictionaryValue* changed_paths_and_macs);
// Flushes the MACs contained in |changed_paths_and_mac| to
// external_hash_store_contents if |write_success|, otherwise discards the
// changes.
static void FlushToExternalStore(
std::unique_ptr<HashStoreContents> external_hash_store_contents,
std::unique_ptr<base::DictionaryValue> changed_paths_and_macs,
bool write_success);
// Callback to be invoked only once (and subsequently reset) on the next
// FilterOnLoad event. It will be allowed to modify the |prefs| handed to
// FilterOnLoad before handing them back to this PrefHashFilter.
FilterOnLoadInterceptor filter_on_load_interceptor_;
// A map of paths to TrackedPreferences; this map owns this individual
// TrackedPreference objects.
typedef base::ScopedPtrHashMap<std::string,
std::unique_ptr<TrackedPreference>>
TrackedPreferencesMap;
// A map from changed paths to their corresponding TrackedPreferences (which
// aren't owned by this map).
typedef std::map<std::string, const TrackedPreference*> ChangedPathsMap;
std::unique_ptr<PrefHashStore> pref_hash_store_;
// A store and contents on which to perform extra validations without
// triggering resets.
// Will be null if the platform does not support external validation.
const base::Optional<StoreContentsPair> external_validation_hash_store_pair_;
// Invoked if a reset occurs in a call to FilterOnLoad.
const base::Closure on_reset_on_load_;
TrackedPreferencesMap tracked_paths_;
// The set of all paths whose value has changed since the last call to
// FilterSerializeData.
ChangedPathsMap changed_paths_;
// Whether to report the validity of the super MAC at load time (via UMA).
bool report_super_mac_validity_;
DISALLOW_COPY_AND_ASSIGN(PrefHashFilter);
};
#endif // COMPONENTS_PREFS_TRACKED_PREF_HASH_FILTER_H_
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