blob: ef86d9386dd30e5510f81dff31a52d99962416f0 [file] [log] [blame]
// Copyright (c) 2012 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 "components/prefs/json_pref_store.h"
#include <stddef.h>
#include <algorithm>
#include <utility>
#include "base/bind.h"
#include "base/bind_helpers.h"
#include "base/callback.h"
#include "base/files/file_path.h"
#include "base/files/file_util.h"
#include "base/json/json_file_value_serializer.h"
#include "base/json/json_string_value_serializer.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/metrics/histogram.h"
#include "base/sequenced_task_runner.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_util.h"
#include "base/task_runner_util.h"
#include "base/threading/sequenced_task_runner_handle.h"
#include "base/time/default_clock.h"
#include "base/values.h"
#include "components/prefs/pref_filter.h"
// Result returned from internal read tasks.
struct JsonPrefStore::ReadResult {
public:
ReadResult();
~ReadResult();
std::unique_ptr<base::Value> value;
PrefReadError error;
bool no_dir;
private:
DISALLOW_COPY_AND_ASSIGN(ReadResult);
};
JsonPrefStore::ReadResult::ReadResult()
: error(PersistentPrefStore::PREF_READ_ERROR_NONE), no_dir(false) {}
JsonPrefStore::ReadResult::~ReadResult() {}
namespace {
// Some extensions we'll tack on to copies of the Preferences files.
const base::FilePath::CharType kBadExtension[] = FILE_PATH_LITERAL("bad");
PersistentPrefStore::PrefReadError HandleReadErrors(
const base::Value* value,
const base::FilePath& path,
int error_code,
const std::string& error_msg) {
if (!value) {
DVLOG(1) << "Error while loading JSON file: " << error_msg
<< ", file: " << path.value();
switch (error_code) {
case JSONFileValueDeserializer::JSON_ACCESS_DENIED:
return PersistentPrefStore::PREF_READ_ERROR_ACCESS_DENIED;
case JSONFileValueDeserializer::JSON_CANNOT_READ_FILE:
return PersistentPrefStore::PREF_READ_ERROR_FILE_OTHER;
case JSONFileValueDeserializer::JSON_FILE_LOCKED:
return PersistentPrefStore::PREF_READ_ERROR_FILE_LOCKED;
case JSONFileValueDeserializer::JSON_NO_SUCH_FILE:
return PersistentPrefStore::PREF_READ_ERROR_NO_FILE;
default:
// JSON errors indicate file corruption of some sort.
// Since the file is corrupt, move it to the side and continue with
// empty preferences. This will result in them losing their settings.
// We keep the old file for possible support and debugging assistance
// as well as to detect if they're seeing these errors repeatedly.
// TODO(erikkay) Instead, use the last known good file.
base::FilePath bad = path.ReplaceExtension(kBadExtension);
// If they've ever had a parse error before, put them in another bucket.
// TODO(erikkay) if we keep this error checking for very long, we may
// want to differentiate between recent and long ago errors.
bool bad_existed = base::PathExists(bad);
base::CopyFile(path, bad);
base::DeleteFile(path, false);
return bad_existed ? PersistentPrefStore::PREF_READ_ERROR_JSON_REPEAT
: PersistentPrefStore::PREF_READ_ERROR_JSON_PARSE;
}
}
if (!value->is_dict())
return PersistentPrefStore::PREF_READ_ERROR_JSON_TYPE;
return PersistentPrefStore::PREF_READ_ERROR_NONE;
}
// Records a sample for |size| in the Settings.JsonDataReadSizeKilobytes
// histogram suffixed with the base name of the JSON file under |path|.
void RecordJsonDataSizeHistogram(const base::FilePath& path, size_t size) {
std::string spaceless_basename;
base::ReplaceChars(path.BaseName().MaybeAsASCII(), " ", "_",
&spaceless_basename);
// The histogram below is an expansion of the UMA_HISTOGRAM_CUSTOM_COUNTS
// macro adapted to allow for a dynamically suffixed histogram name.
// Note: The factory creates and owns the histogram.
// This histogram is expired but the code was intentionally left behind so
// it can be re-enabled on Stable in a single config tweak if needed.
base::HistogramBase* histogram = base::Histogram::FactoryGet(
"Settings.JsonDataReadSizeKilobytes." + spaceless_basename, 1, 10000, 50,
base::HistogramBase::kUmaTargetedHistogramFlag);
histogram->Add(static_cast<int>(size) / 1024);
}
std::unique_ptr<JsonPrefStore::ReadResult> ReadPrefsFromDisk(
const base::FilePath& path) {
int error_code;
std::string error_msg;
std::unique_ptr<JsonPrefStore::ReadResult> read_result(
new JsonPrefStore::ReadResult);
JSONFileValueDeserializer deserializer(path);
read_result->value = deserializer.Deserialize(&error_code, &error_msg);
read_result->error =
HandleReadErrors(read_result->value.get(), path, error_code, error_msg);
read_result->no_dir = !base::PathExists(path.DirName());
if (read_result->error == PersistentPrefStore::PREF_READ_ERROR_NONE)
RecordJsonDataSizeHistogram(path, deserializer.get_last_read_size());
return read_result;
}
} // namespace
JsonPrefStore::JsonPrefStore(
const base::FilePath& pref_filename,
std::unique_ptr<PrefFilter> pref_filter,
scoped_refptr<base::SequencedTaskRunner> file_task_runner)
: path_(pref_filename),
file_task_runner_(std::move(file_task_runner)),
prefs_(new base::DictionaryValue()),
read_only_(false),
writer_(pref_filename, file_task_runner_),
pref_filter_(std::move(pref_filter)),
initialized_(false),
filtering_in_progress_(false),
pending_lossy_write_(false),
read_error_(PREF_READ_ERROR_NONE),
has_pending_write_reply_(false) {
DCHECK(!path_.empty());
}
bool JsonPrefStore::GetValue(const std::string& key,
const base::Value** result) const {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
base::Value* tmp = nullptr;
if (!prefs_->Get(key, &tmp))
return false;
if (result)
*result = tmp;
return true;
}
std::unique_ptr<base::DictionaryValue> JsonPrefStore::GetValues() const {
return prefs_->CreateDeepCopy();
}
void JsonPrefStore::AddObserver(PrefStore::Observer* observer) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
observers_.AddObserver(observer);
}
void JsonPrefStore::RemoveObserver(PrefStore::Observer* observer) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
observers_.RemoveObserver(observer);
}
bool JsonPrefStore::HasObservers() const {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
return observers_.might_have_observers();
}
bool JsonPrefStore::IsInitializationComplete() const {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
return initialized_;
}
bool JsonPrefStore::GetMutableValue(const std::string& key,
base::Value** result) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
return prefs_->Get(key, result);
}
void JsonPrefStore::SetValue(const std::string& key,
std::unique_ptr<base::Value> value,
uint32_t flags) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
DCHECK(value);
base::Value* old_value = nullptr;
prefs_->Get(key, &old_value);
if (!old_value || !value->Equals(old_value)) {
prefs_->Set(key, std::move(value));
ReportValueChanged(key, flags);
}
}
void JsonPrefStore::SetValueSilently(const std::string& key,
std::unique_ptr<base::Value> value,
uint32_t flags) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
DCHECK(value);
base::Value* old_value = nullptr;
prefs_->Get(key, &old_value);
if (!old_value || !value->Equals(old_value)) {
prefs_->Set(key, std::move(value));
ScheduleWrite(flags);
}
}
void JsonPrefStore::RemoveValue(const std::string& key, uint32_t flags) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
if (prefs_->RemovePath(key, nullptr))
ReportValueChanged(key, flags);
}
void JsonPrefStore::RemoveValueSilently(const std::string& key,
uint32_t flags) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
prefs_->RemovePath(key, nullptr);
ScheduleWrite(flags);
}
bool JsonPrefStore::ReadOnly() const {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
return read_only_;
}
PersistentPrefStore::PrefReadError JsonPrefStore::GetReadError() const {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
return read_error_;
}
PersistentPrefStore::PrefReadError JsonPrefStore::ReadPrefs() {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
OnFileRead(ReadPrefsFromDisk(path_));
return filtering_in_progress_ ? PREF_READ_ERROR_ASYNCHRONOUS_TASK_INCOMPLETE
: read_error_;
}
void JsonPrefStore::ReadPrefsAsync(ReadErrorDelegate* error_delegate) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
initialized_ = false;
error_delegate_.reset(error_delegate);
// Weakly binds the read task so that it doesn't kick in during shutdown.
base::PostTaskAndReplyWithResult(
file_task_runner_.get(), FROM_HERE, base::Bind(&ReadPrefsFromDisk, path_),
base::Bind(&JsonPrefStore::OnFileRead, AsWeakPtr()));
}
void JsonPrefStore::CommitPendingWrite(
base::OnceClosure reply_callback,
base::OnceClosure synchronous_done_callback) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
// Schedule a write for any lossy writes that are outstanding to ensure that
// they get flushed when this function is called.
SchedulePendingLossyWrites();
if (writer_.HasPendingWrite() && !read_only_)
writer_.DoScheduledWrite();
// Since disk operations occur on |file_task_runner_|, the reply of a task
// posted to |file_task_runner_| will run after currently pending disk
// operations. Also, by definition of PostTaskAndReply(), the reply (in the
// |reply_callback| case will run on the current sequence.
if (synchronous_done_callback) {
file_task_runner_->PostTask(FROM_HERE,
std::move(synchronous_done_callback));
}
if (reply_callback) {
file_task_runner_->PostTaskAndReply(FROM_HERE, base::DoNothing(),
std::move(reply_callback));
}
}
void JsonPrefStore::SchedulePendingLossyWrites() {
if (pending_lossy_write_)
writer_.ScheduleWrite(this);
}
void JsonPrefStore::ReportValueChanged(const std::string& key, uint32_t flags) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
if (pref_filter_)
pref_filter_->FilterUpdate(key);
for (PrefStore::Observer& observer : observers_)
observer.OnPrefValueChanged(key);
ScheduleWrite(flags);
}
void JsonPrefStore::RunOrScheduleNextSuccessfulWriteCallback(
bool write_success) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
has_pending_write_reply_ = false;
if (!on_next_successful_write_reply_.is_null()) {
base::Closure on_successful_write =
std::move(on_next_successful_write_reply_);
if (write_success) {
on_successful_write.Run();
} else {
RegisterOnNextSuccessfulWriteReply(on_successful_write);
}
}
}
// static
void JsonPrefStore::PostWriteCallback(
const base::Callback<void(bool success)>& on_next_write_callback,
const base::Callback<void(bool success)>& on_next_write_reply,
scoped_refptr<base::SequencedTaskRunner> reply_task_runner,
bool write_success) {
if (!on_next_write_callback.is_null())
on_next_write_callback.Run(write_success);
// We can't run |on_next_write_reply| on the current thread. Bounce back to
// the |reply_task_runner| which is the correct sequenced thread.
reply_task_runner->PostTask(
FROM_HERE, base::BindOnce(on_next_write_reply, write_success));
}
void JsonPrefStore::RegisterOnNextSuccessfulWriteReply(
const base::Closure& on_next_successful_write_reply) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
DCHECK(on_next_successful_write_reply_.is_null());
on_next_successful_write_reply_ = on_next_successful_write_reply;
// If there are pending callbacks, avoid erasing them; the reply will be used
// as we set |on_next_successful_write_reply_|. Otherwise, setup a reply with
// an empty callback.
if (!has_pending_write_reply_) {
has_pending_write_reply_ = true;
writer_.RegisterOnNextWriteCallbacks(
base::Closure(),
base::Bind(
&PostWriteCallback, base::Callback<void(bool success)>(),
base::Bind(&JsonPrefStore::RunOrScheduleNextSuccessfulWriteCallback,
AsWeakPtr()),
base::SequencedTaskRunnerHandle::Get()));
}
}
void JsonPrefStore::RegisterOnNextWriteSynchronousCallbacks(
OnWriteCallbackPair callbacks) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
has_pending_write_reply_ = true;
writer_.RegisterOnNextWriteCallbacks(
callbacks.first,
base::Bind(
&PostWriteCallback, callbacks.second,
base::Bind(&JsonPrefStore::RunOrScheduleNextSuccessfulWriteCallback,
AsWeakPtr()),
base::SequencedTaskRunnerHandle::Get()));
}
void JsonPrefStore::ClearMutableValues() {
NOTIMPLEMENTED();
}
void JsonPrefStore::OnStoreDeletionFromDisk() {
if (pref_filter_)
pref_filter_->OnStoreDeletionFromDisk();
}
void JsonPrefStore::OnFileRead(std::unique_ptr<ReadResult> read_result) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
DCHECK(read_result);
std::unique_ptr<base::DictionaryValue> unfiltered_prefs(
new base::DictionaryValue);
read_error_ = read_result->error;
bool initialization_successful = !read_result->no_dir;
if (initialization_successful) {
switch (read_error_) {
case PREF_READ_ERROR_ACCESS_DENIED:
case PREF_READ_ERROR_FILE_OTHER:
case PREF_READ_ERROR_FILE_LOCKED:
case PREF_READ_ERROR_JSON_TYPE:
case PREF_READ_ERROR_FILE_NOT_SPECIFIED:
read_only_ = true;
break;
case PREF_READ_ERROR_NONE:
DCHECK(read_result->value);
unfiltered_prefs.reset(
static_cast<base::DictionaryValue*>(read_result->value.release()));
break;
case PREF_READ_ERROR_NO_FILE:
// If the file just doesn't exist, maybe this is first run. In any case
// there's no harm in writing out default prefs in this case.
case PREF_READ_ERROR_JSON_PARSE:
case PREF_READ_ERROR_JSON_REPEAT:
break;
case PREF_READ_ERROR_ASYNCHRONOUS_TASK_INCOMPLETE:
// This is a special error code to be returned by ReadPrefs when it
// can't complete synchronously, it should never be returned by the read
// operation itself.
case PREF_READ_ERROR_MAX_ENUM:
NOTREACHED();
break;
}
}
if (pref_filter_) {
filtering_in_progress_ = true;
const PrefFilter::PostFilterOnLoadCallback post_filter_on_load_callback(
base::Bind(&JsonPrefStore::FinalizeFileRead, AsWeakPtr(),
initialization_successful));
pref_filter_->FilterOnLoad(post_filter_on_load_callback,
std::move(unfiltered_prefs));
} else {
FinalizeFileRead(initialization_successful, std::move(unfiltered_prefs),
false);
}
}
JsonPrefStore::~JsonPrefStore() {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
CommitPendingWrite();
}
bool JsonPrefStore::SerializeData(std::string* output) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
pending_lossy_write_ = false;
if (pref_filter_) {
OnWriteCallbackPair callbacks =
pref_filter_->FilterSerializeData(prefs_.get());
if (!callbacks.first.is_null() || !callbacks.second.is_null())
RegisterOnNextWriteSynchronousCallbacks(callbacks);
}
JSONStringValueSerializer serializer(output);
// Not pretty-printing prefs shrinks pref file size by ~30%. To obtain
// readable prefs for debugging purposes, you can dump your prefs into any
// command-line or online JSON pretty printing tool.
serializer.set_pretty_print(false);
bool success = serializer.Serialize(*prefs_);
DCHECK(success);
return success;
}
void JsonPrefStore::FinalizeFileRead(
bool initialization_successful,
std::unique_ptr<base::DictionaryValue> prefs,
bool schedule_write) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
filtering_in_progress_ = false;
if (!initialization_successful) {
for (PrefStore::Observer& observer : observers_)
observer.OnInitializationCompleted(false);
return;
}
prefs_ = std::move(prefs);
initialized_ = true;
if (schedule_write)
ScheduleWrite(DEFAULT_PREF_WRITE_FLAGS);
if (error_delegate_ && read_error_ != PREF_READ_ERROR_NONE)
error_delegate_->OnError(read_error_);
for (PrefStore::Observer& observer : observers_)
observer.OnInitializationCompleted(true);
return;
}
void JsonPrefStore::ScheduleWrite(uint32_t flags) {
if (read_only_)
return;
if (flags & LOSSY_PREF_WRITE_FLAG)
pending_lossy_write_ = true;
else
writer_.ScheduleWrite(this);
}