1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
5 #include "base/prefs/json_pref_store.h"
10 #include "base/callback.h"
11 #include "base/file_util.h"
12 #include "base/json/json_file_value_serializer.h"
13 #include "base/json/json_string_value_serializer.h"
14 #include "base/memory/ref_counted.h"
15 #include "base/message_loop/message_loop_proxy.h"
16 #include "base/sequenced_task_runner.h"
17 #include "base/threading/sequenced_worker_pool.h"
18 #include "base/values.h"
22 // Some extensions we'll tack on to copies of the Preferences files.
23 const base::FilePath::CharType* kBadExtension = FILE_PATH_LITERAL("bad");
25 // Differentiates file loading between origin thread and passed
27 class FileThreadDeserializer
28 : public base::RefCountedThreadSafe<FileThreadDeserializer> {
30 FileThreadDeserializer(JsonPrefStore* delegate,
31 base::SequencedTaskRunner* sequenced_task_runner)
33 error_(PersistentPrefStore::PREF_READ_ERROR_NONE),
35 sequenced_task_runner_(sequenced_task_runner),
36 origin_loop_proxy_(base::MessageLoopProxy::current()) {
39 void Start(const base::FilePath& path) {
40 DCHECK(origin_loop_proxy_->BelongsToCurrentThread());
41 sequenced_task_runner_->PostTask(
43 base::Bind(&FileThreadDeserializer::ReadFileAndReport,
47 // Deserializes JSON on the sequenced task runner.
48 void ReadFileAndReport(const base::FilePath& path) {
49 DCHECK(sequenced_task_runner_->RunsTasksOnCurrentThread());
51 value_.reset(DoReading(path, &error_, &no_dir_));
53 origin_loop_proxy_->PostTask(
55 base::Bind(&FileThreadDeserializer::ReportOnOriginThread, this));
58 // Reports deserialization result on the origin thread.
59 void ReportOnOriginThread() {
60 DCHECK(origin_loop_proxy_->BelongsToCurrentThread());
61 delegate_->OnFileRead(value_.release(), error_, no_dir_);
64 static base::Value* DoReading(const base::FilePath& path,
65 PersistentPrefStore::PrefReadError* error,
68 std::string error_msg;
69 JSONFileValueSerializer serializer(path);
70 base::Value* value = serializer.Deserialize(&error_code, &error_msg);
71 HandleErrors(value, path, error_code, error_msg, error);
72 *no_dir = !base::PathExists(path.DirName());
76 static void HandleErrors(const base::Value* value,
77 const base::FilePath& path,
79 const std::string& error_msg,
80 PersistentPrefStore::PrefReadError* error);
83 friend class base::RefCountedThreadSafe<FileThreadDeserializer>;
84 ~FileThreadDeserializer() {}
87 PersistentPrefStore::PrefReadError error_;
88 scoped_ptr<base::Value> value_;
89 const scoped_refptr<JsonPrefStore> delegate_;
90 const scoped_refptr<base::SequencedTaskRunner> sequenced_task_runner_;
91 const scoped_refptr<base::MessageLoopProxy> origin_loop_proxy_;
95 void FileThreadDeserializer::HandleErrors(
96 const base::Value* value,
97 const base::FilePath& path,
99 const std::string& error_msg,
100 PersistentPrefStore::PrefReadError* error) {
101 *error = PersistentPrefStore::PREF_READ_ERROR_NONE;
103 DVLOG(1) << "Error while loading JSON file: " << error_msg
104 << ", file: " << path.value();
105 switch (error_code) {
106 case JSONFileValueSerializer::JSON_ACCESS_DENIED:
107 *error = PersistentPrefStore::PREF_READ_ERROR_ACCESS_DENIED;
109 case JSONFileValueSerializer::JSON_CANNOT_READ_FILE:
110 *error = PersistentPrefStore::PREF_READ_ERROR_FILE_OTHER;
112 case JSONFileValueSerializer::JSON_FILE_LOCKED:
113 *error = PersistentPrefStore::PREF_READ_ERROR_FILE_LOCKED;
115 case JSONFileValueSerializer::JSON_NO_SUCH_FILE:
116 *error = PersistentPrefStore::PREF_READ_ERROR_NO_FILE;
119 *error = PersistentPrefStore::PREF_READ_ERROR_JSON_PARSE;
120 // JSON errors indicate file corruption of some sort.
121 // Since the file is corrupt, move it to the side and continue with
122 // empty preferences. This will result in them losing their settings.
123 // We keep the old file for possible support and debugging assistance
124 // as well as to detect if they're seeing these errors repeatedly.
125 // TODO(erikkay) Instead, use the last known good file.
126 base::FilePath bad = path.ReplaceExtension(kBadExtension);
128 // If they've ever had a parse error before, put them in another bucket.
129 // TODO(erikkay) if we keep this error checking for very long, we may
130 // want to differentiate between recent and long ago errors.
131 if (base::PathExists(bad))
132 *error = PersistentPrefStore::PREF_READ_ERROR_JSON_REPEAT;
133 base::Move(path, bad);
136 } else if (!value->IsType(base::Value::TYPE_DICTIONARY)) {
137 *error = PersistentPrefStore::PREF_READ_ERROR_JSON_TYPE;
143 scoped_refptr<base::SequencedTaskRunner> JsonPrefStore::GetTaskRunnerForFile(
144 const base::FilePath& filename,
145 base::SequencedWorkerPool* worker_pool) {
146 std::string token("json_pref_store-");
147 token.append(filename.AsUTF8Unsafe());
148 return worker_pool->GetSequencedTaskRunnerWithShutdownBehavior(
149 worker_pool->GetNamedSequenceToken(token),
150 base::SequencedWorkerPool::BLOCK_SHUTDOWN);
153 JsonPrefStore::JsonPrefStore(const base::FilePath& filename,
154 base::SequencedTaskRunner* sequenced_task_runner)
156 sequenced_task_runner_(sequenced_task_runner),
157 prefs_(new base::DictionaryValue()),
159 writer_(filename, sequenced_task_runner),
161 read_error_(PREF_READ_ERROR_OTHER) {}
163 bool JsonPrefStore::GetValue(const std::string& key,
164 const base::Value** result) const {
165 base::Value* tmp = NULL;
166 if (!prefs_->Get(key, &tmp))
174 void JsonPrefStore::AddObserver(PrefStore::Observer* observer) {
175 observers_.AddObserver(observer);
178 void JsonPrefStore::RemoveObserver(PrefStore::Observer* observer) {
179 observers_.RemoveObserver(observer);
182 bool JsonPrefStore::HasObservers() const {
183 return observers_.might_have_observers();
186 bool JsonPrefStore::IsInitializationComplete() const {
190 bool JsonPrefStore::GetMutableValue(const std::string& key,
191 base::Value** result) {
192 return prefs_->Get(key, result);
195 void JsonPrefStore::SetValue(const std::string& key, base::Value* value) {
197 scoped_ptr<base::Value> new_value(value);
198 base::Value* old_value = NULL;
199 prefs_->Get(key, &old_value);
200 if (!old_value || !value->Equals(old_value)) {
201 prefs_->Set(key, new_value.release());
202 ReportValueChanged(key);
206 void JsonPrefStore::SetValueSilently(const std::string& key,
207 base::Value* value) {
209 scoped_ptr<base::Value> new_value(value);
210 base::Value* old_value = NULL;
211 prefs_->Get(key, &old_value);
212 if (!old_value || !value->Equals(old_value)) {
213 prefs_->Set(key, new_value.release());
215 writer_.ScheduleWrite(this);
219 void JsonPrefStore::RemoveValue(const std::string& key) {
220 if (prefs_->Remove(key, NULL))
221 ReportValueChanged(key);
224 void JsonPrefStore::MarkNeedsEmptyValue(const std::string& key) {
225 keys_need_empty_value_.insert(key);
228 bool JsonPrefStore::ReadOnly() const {
232 PersistentPrefStore::PrefReadError JsonPrefStore::GetReadError() const {
236 PersistentPrefStore::PrefReadError JsonPrefStore::ReadPrefs() {
238 OnFileRead(NULL, PREF_READ_ERROR_FILE_NOT_SPECIFIED, false);
239 return PREF_READ_ERROR_FILE_NOT_SPECIFIED;
245 FileThreadDeserializer::DoReading(path_, &error, &no_dir);
246 OnFileRead(value, error, no_dir);
250 void JsonPrefStore::ReadPrefsAsync(ReadErrorDelegate *error_delegate) {
251 initialized_ = false;
252 error_delegate_.reset(error_delegate);
254 OnFileRead(NULL, PREF_READ_ERROR_FILE_NOT_SPECIFIED, false);
258 // Start async reading of the preferences file. It will delete itself
260 scoped_refptr<FileThreadDeserializer> deserializer(
261 new FileThreadDeserializer(this, sequenced_task_runner_.get()));
262 deserializer->Start(path_);
265 void JsonPrefStore::CommitPendingWrite() {
266 if (writer_.HasPendingWrite() && !read_only_)
267 writer_.DoScheduledWrite();
270 void JsonPrefStore::ReportValueChanged(const std::string& key) {
271 FOR_EACH_OBSERVER(PrefStore::Observer, observers_, OnPrefValueChanged(key));
273 writer_.ScheduleWrite(this);
276 void JsonPrefStore::OnFileRead(base::Value* value_owned,
277 PersistentPrefStore::PrefReadError error,
279 scoped_ptr<base::Value> value(value_owned);
283 FOR_EACH_OBSERVER(PrefStore::Observer,
285 OnInitializationCompleted(false));
292 case PREF_READ_ERROR_ACCESS_DENIED:
293 case PREF_READ_ERROR_FILE_OTHER:
294 case PREF_READ_ERROR_FILE_LOCKED:
295 case PREF_READ_ERROR_JSON_TYPE:
296 case PREF_READ_ERROR_FILE_NOT_SPECIFIED:
299 case PREF_READ_ERROR_NONE:
301 prefs_.reset(static_cast<base::DictionaryValue*>(value.release()));
303 case PREF_READ_ERROR_NO_FILE:
304 // If the file just doesn't exist, maybe this is first run. In any case
305 // there's no harm in writing out default prefs in this case.
307 case PREF_READ_ERROR_JSON_PARSE:
308 case PREF_READ_ERROR_JSON_REPEAT:
311 NOTREACHED() << "Unknown error: " << error;
314 if (error_delegate_.get() && error != PREF_READ_ERROR_NONE)
315 error_delegate_->OnError(error);
317 FOR_EACH_OBSERVER(PrefStore::Observer,
319 OnInitializationCompleted(true));
322 JsonPrefStore::~JsonPrefStore() {
323 CommitPendingWrite();
326 bool JsonPrefStore::SerializeData(std::string* output) {
327 // TODO(tc): Do we want to prune webkit preferences that match the default
329 JSONStringValueSerializer serializer(output);
330 serializer.set_pretty_print(true);
331 scoped_ptr<base::DictionaryValue> copy(
332 prefs_->DeepCopyWithoutEmptyChildren());
334 // Iterates |keys_need_empty_value_| and if the key exists in |prefs_|,
335 // ensure its empty ListValue or DictonaryValue is preserved.
336 for (std::set<std::string>::const_iterator
337 it = keys_need_empty_value_.begin();
338 it != keys_need_empty_value_.end();
340 const std::string& key = *it;
342 base::Value* value = NULL;
343 if (!prefs_->Get(key, &value))
346 if (value->IsType(base::Value::TYPE_LIST)) {
347 const base::ListValue* list = NULL;
348 if (value->GetAsList(&list) && list->empty())
349 copy->Set(key, new base::ListValue);
350 } else if (value->IsType(base::Value::TYPE_DICTIONARY)) {
351 const base::DictionaryValue* dict = NULL;
352 if (value->GetAsDictionary(&dict) && dict->empty())
353 copy->Set(key, new base::DictionaryValue);
357 return serializer.Serialize(*(copy.get()));