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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. | |
4 | |
5 #include "chrome/common/json_pref_store.h" | |
6 | |
7 #include <algorithm> | |
8 | |
9 #include "base/bind.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_proxy.h" | |
16 #include "base/values.h" | |
17 | |
18 namespace { | |
19 | |
20 // Some extensions we'll tack on to copies of the Preferences files. | |
21 const FilePath::CharType* kBadExtension = FILE_PATH_LITERAL("bad"); | |
22 | |
23 // Differentiates file loading between origin thread and passed | |
24 // (aka file) thread. | |
25 class FileThreadDeserializer | |
26 : public base::RefCountedThreadSafe<FileThreadDeserializer> { | |
27 public: | |
28 FileThreadDeserializer(JsonPrefStore* delegate, | |
29 base::MessageLoopProxy* file_loop_proxy) | |
30 : no_dir_(false), | |
31 error_(PersistentPrefStore::PREF_READ_ERROR_NONE), | |
32 delegate_(delegate), | |
33 file_loop_proxy_(file_loop_proxy), | |
34 origin_loop_proxy_(base::MessageLoopProxy::current()) { | |
35 } | |
36 | |
37 void Start(const FilePath& path) { | |
38 DCHECK(origin_loop_proxy_->BelongsToCurrentThread()); | |
39 file_loop_proxy_->PostTask( | |
40 FROM_HERE, | |
41 base::Bind(&FileThreadDeserializer::ReadFileAndReport, | |
42 this, path)); | |
43 } | |
44 | |
45 // Deserializes JSON on the file thread. | |
46 void ReadFileAndReport(const FilePath& path) { | |
47 DCHECK(file_loop_proxy_->BelongsToCurrentThread()); | |
48 | |
49 value_.reset(DoReading(path, &error_, &no_dir_)); | |
50 | |
51 origin_loop_proxy_->PostTask( | |
52 FROM_HERE, | |
53 base::Bind(&FileThreadDeserializer::ReportOnOriginThread, this)); | |
54 } | |
55 | |
56 // Reports deserialization result on the origin thread. | |
57 void ReportOnOriginThread() { | |
58 DCHECK(origin_loop_proxy_->BelongsToCurrentThread()); | |
59 delegate_->OnFileRead(value_.release(), error_, no_dir_); | |
60 } | |
61 | |
62 static Value* DoReading(const FilePath& path, | |
63 PersistentPrefStore::PrefReadError* error, | |
64 bool* no_dir) { | |
65 int error_code; | |
66 std::string error_msg; | |
67 JSONFileValueSerializer serializer(path); | |
68 Value* value = serializer.Deserialize(&error_code, &error_msg); | |
69 HandleErrors(value, path, error_code, error_msg, error); | |
70 *no_dir = !file_util::PathExists(path.DirName()); | |
71 return value; | |
72 } | |
73 | |
74 static void HandleErrors(const Value* value, | |
75 const FilePath& path, | |
76 int error_code, | |
77 const std::string& error_msg, | |
78 PersistentPrefStore::PrefReadError* error); | |
79 | |
80 private: | |
81 friend class base::RefCountedThreadSafe<FileThreadDeserializer>; | |
82 ~FileThreadDeserializer() {} | |
83 | |
84 bool no_dir_; | |
85 PersistentPrefStore::PrefReadError error_; | |
86 scoped_ptr<Value> value_; | |
87 scoped_refptr<JsonPrefStore> delegate_; | |
88 scoped_refptr<base::MessageLoopProxy> file_loop_proxy_; | |
89 scoped_refptr<base::MessageLoopProxy> origin_loop_proxy_; | |
90 }; | |
91 | |
92 // static | |
93 void FileThreadDeserializer::HandleErrors( | |
94 const Value* value, | |
95 const FilePath& path, | |
96 int error_code, | |
97 const std::string& error_msg, | |
98 PersistentPrefStore::PrefReadError* error) { | |
99 *error = PersistentPrefStore::PREF_READ_ERROR_NONE; | |
100 if (!value) { | |
101 DVLOG(1) << "Error while loading JSON file: " << error_msg; | |
102 switch (error_code) { | |
103 case JSONFileValueSerializer::JSON_ACCESS_DENIED: | |
104 *error = PersistentPrefStore::PREF_READ_ERROR_ACCESS_DENIED; | |
105 break; | |
106 case JSONFileValueSerializer::JSON_CANNOT_READ_FILE: | |
107 *error = PersistentPrefStore::PREF_READ_ERROR_FILE_OTHER; | |
108 break; | |
109 case JSONFileValueSerializer::JSON_FILE_LOCKED: | |
110 *error = PersistentPrefStore::PREF_READ_ERROR_FILE_LOCKED; | |
111 break; | |
112 case JSONFileValueSerializer::JSON_NO_SUCH_FILE: | |
113 *error = PersistentPrefStore::PREF_READ_ERROR_NO_FILE; | |
114 break; | |
115 default: | |
116 *error = PersistentPrefStore::PREF_READ_ERROR_JSON_PARSE; | |
117 // JSON errors indicate file corruption of some sort. | |
118 // Since the file is corrupt, move it to the side and continue with | |
119 // empty preferences. This will result in them losing their settings. | |
120 // We keep the old file for possible support and debugging assistance | |
121 // as well as to detect if they're seeing these errors repeatedly. | |
122 // TODO(erikkay) Instead, use the last known good file. | |
123 FilePath bad = path.ReplaceExtension(kBadExtension); | |
124 | |
125 // If they've ever had a parse error before, put them in another bucket. | |
126 // TODO(erikkay) if we keep this error checking for very long, we may | |
127 // want to differentiate between recent and long ago errors. | |
128 if (file_util::PathExists(bad)) | |
129 *error = PersistentPrefStore::PREF_READ_ERROR_JSON_REPEAT; | |
130 file_util::Move(path, bad); | |
131 break; | |
132 } | |
133 } else if (!value->IsType(Value::TYPE_DICTIONARY)) { | |
134 *error = PersistentPrefStore::PREF_READ_ERROR_JSON_TYPE; | |
135 } | |
136 } | |
137 | |
138 } // namespace | |
139 | |
140 JsonPrefStore::JsonPrefStore(const FilePath& filename, | |
141 base::MessageLoopProxy* file_message_loop_proxy) | |
142 : path_(filename), | |
143 file_message_loop_proxy_(file_message_loop_proxy), | |
144 prefs_(new DictionaryValue()), | |
145 read_only_(false), | |
146 writer_(filename, file_message_loop_proxy), | |
147 error_delegate_(NULL), | |
148 initialized_(false), | |
149 read_error_(PREF_READ_ERROR_OTHER) { | |
150 } | |
151 | |
152 PrefStore::ReadResult JsonPrefStore::GetValue(const std::string& key, | |
153 const Value** result) const { | |
154 Value* tmp = NULL; | |
155 if (prefs_->Get(key, &tmp)) { | |
156 if (result) | |
157 *result = tmp; | |
158 return READ_OK; | |
159 } | |
160 return READ_NO_VALUE; | |
161 } | |
162 | |
163 void JsonPrefStore::AddObserver(PrefStore::Observer* observer) { | |
164 observers_.AddObserver(observer); | |
165 } | |
166 | |
167 void JsonPrefStore::RemoveObserver(PrefStore::Observer* observer) { | |
168 observers_.RemoveObserver(observer); | |
169 } | |
170 | |
171 size_t JsonPrefStore::NumberOfObservers() const { | |
172 return observers_.size(); | |
173 } | |
174 | |
175 bool JsonPrefStore::IsInitializationComplete() const { | |
176 return initialized_; | |
177 } | |
178 | |
179 PrefStore::ReadResult JsonPrefStore::GetMutableValue(const std::string& key, | |
180 Value** result) { | |
181 return prefs_->Get(key, result) ? READ_OK : READ_NO_VALUE; | |
182 } | |
183 | |
184 void JsonPrefStore::SetValue(const std::string& key, Value* value) { | |
185 DCHECK(value); | |
186 scoped_ptr<Value> new_value(value); | |
187 Value* old_value = NULL; | |
188 prefs_->Get(key, &old_value); | |
189 if (!old_value || !value->Equals(old_value)) { | |
190 prefs_->Set(key, new_value.release()); | |
191 ReportValueChanged(key); | |
192 } | |
193 } | |
194 | |
195 void JsonPrefStore::SetValueSilently(const std::string& key, Value* value) { | |
196 DCHECK(value); | |
197 scoped_ptr<Value> new_value(value); | |
198 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 if (!read_only_) | |
203 writer_.ScheduleWrite(this); | |
204 } | |
205 } | |
206 | |
207 void JsonPrefStore::RemoveValue(const std::string& key) { | |
208 if (prefs_->Remove(key, NULL)) | |
209 ReportValueChanged(key); | |
210 } | |
211 | |
212 void JsonPrefStore::MarkNeedsEmptyValue(const std::string& key) { | |
213 keys_need_empty_value_.insert(key); | |
214 } | |
215 | |
216 bool JsonPrefStore::ReadOnly() const { | |
217 return read_only_; | |
218 } | |
219 | |
220 PersistentPrefStore::PrefReadError JsonPrefStore::GetReadError() const { | |
221 return read_error_; | |
222 } | |
223 | |
224 PersistentPrefStore::PrefReadError JsonPrefStore::ReadPrefs() { | |
225 if (path_.empty()) { | |
226 OnFileRead(NULL, PREF_READ_ERROR_FILE_NOT_SPECIFIED, false); | |
227 return PREF_READ_ERROR_FILE_NOT_SPECIFIED; | |
228 } | |
229 | |
230 PrefReadError error; | |
231 bool no_dir; | |
232 Value* value = FileThreadDeserializer::DoReading(path_, &error, &no_dir); | |
233 OnFileRead(value, error, no_dir); | |
234 return error; | |
235 } | |
236 | |
237 void JsonPrefStore::ReadPrefsAsync(ReadErrorDelegate *error_delegate) { | |
238 initialized_ = false; | |
239 error_delegate_.reset(error_delegate); | |
240 if (path_.empty()) { | |
241 OnFileRead(NULL, PREF_READ_ERROR_FILE_NOT_SPECIFIED, false); | |
242 return; | |
243 } | |
244 | |
245 // Start async reading of the preferences file. It will delete itself | |
246 // in the end. | |
247 scoped_refptr<FileThreadDeserializer> deserializer( | |
248 new FileThreadDeserializer(this, file_message_loop_proxy_.get())); | |
249 deserializer->Start(path_); | |
250 } | |
251 | |
252 void JsonPrefStore::CommitPendingWrite() { | |
253 if (writer_.HasPendingWrite() && !read_only_) | |
254 writer_.DoScheduledWrite(); | |
255 } | |
256 | |
257 void JsonPrefStore::ReportValueChanged(const std::string& key) { | |
258 FOR_EACH_OBSERVER(PrefStore::Observer, observers_, OnPrefValueChanged(key)); | |
259 if (!read_only_) | |
260 writer_.ScheduleWrite(this); | |
261 } | |
262 | |
263 void JsonPrefStore::OnFileRead(Value* value_owned, | |
264 PersistentPrefStore::PrefReadError error, | |
265 bool no_dir) { | |
266 scoped_ptr<Value> value(value_owned); | |
267 read_error_ = error; | |
268 | |
269 if (no_dir) { | |
270 FOR_EACH_OBSERVER(PrefStore::Observer, | |
271 observers_, | |
272 OnInitializationCompleted(false)); | |
273 return; | |
274 } | |
275 | |
276 initialized_ = true; | |
277 | |
278 switch (error) { | |
279 case PREF_READ_ERROR_ACCESS_DENIED: | |
280 case PREF_READ_ERROR_FILE_OTHER: | |
281 case PREF_READ_ERROR_FILE_LOCKED: | |
282 case PREF_READ_ERROR_JSON_TYPE: | |
283 case PREF_READ_ERROR_FILE_NOT_SPECIFIED: | |
284 read_only_ = true; | |
285 break; | |
286 case PREF_READ_ERROR_NONE: | |
287 DCHECK(value.get()); | |
288 prefs_.reset(static_cast<DictionaryValue*>(value.release())); | |
289 break; | |
290 case PREF_READ_ERROR_NO_FILE: | |
291 // If the file just doesn't exist, maybe this is first run. In any case | |
292 // there's no harm in writing out default prefs in this case. | |
293 break; | |
294 case PREF_READ_ERROR_JSON_PARSE: | |
295 case PREF_READ_ERROR_JSON_REPEAT: | |
296 break; | |
297 default: | |
298 NOTREACHED() << "Unknown error: " << error; | |
299 } | |
300 | |
301 if (error_delegate_.get() && error != PREF_READ_ERROR_NONE) | |
302 error_delegate_->OnError(error); | |
303 | |
304 FOR_EACH_OBSERVER(PrefStore::Observer, | |
305 observers_, | |
306 OnInitializationCompleted(true)); | |
307 } | |
308 | |
309 JsonPrefStore::~JsonPrefStore() { | |
310 CommitPendingWrite(); | |
311 } | |
312 | |
313 bool JsonPrefStore::SerializeData(std::string* output) { | |
314 // TODO(tc): Do we want to prune webkit preferences that match the default | |
315 // value? | |
316 JSONStringValueSerializer serializer(output); | |
317 serializer.set_pretty_print(true); | |
318 scoped_ptr<DictionaryValue> copy(prefs_->DeepCopyWithoutEmptyChildren()); | |
319 | |
320 // Iterates |keys_need_empty_value_| and if the key exists in |prefs_|, | |
321 // ensure its empty ListValue or DictonaryValue is preserved. | |
322 for (std::set<std::string>::const_iterator | |
323 it = keys_need_empty_value_.begin(); | |
324 it != keys_need_empty_value_.end(); | |
325 ++it) { | |
326 const std::string& key = *it; | |
327 | |
328 base::Value* value = NULL; | |
329 if (!prefs_->Get(key, &value)) | |
330 continue; | |
331 | |
332 if (value->IsType(base::Value::TYPE_LIST)) { | |
333 const base::ListValue* list = NULL; | |
334 if (value->GetAsList(&list) && list->empty()) | |
335 copy->Set(key, new base::ListValue); | |
336 } else if (value->IsType(base::Value::TYPE_DICTIONARY)) { | |
337 const base::DictionaryValue* dict = NULL; | |
338 if (value->GetAsDictionary(&dict) && dict->empty()) | |
339 copy->Set(key, new base::DictionaryValue); | |
340 } | |
341 } | |
342 | |
343 return serializer.Serialize(*(copy.get())); | |
344 } | |
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