content/child/v8_value_converter_impl.cc

   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 "content/child/v8_value_converter_impl.h"
   6
   7 #include <cmath>
   8 #include <string>
   9
  10 #include "base/bind.h"
  11 #include "base/bind_helpers.h"
  12 #include "base/logging.h"
  13 #include "base/memory/scoped_ptr.h"
  14 #include "base/values.h"
  15 #include "third_party/WebKit/public/web/WebArrayBuffer.h"
  16 #include "third_party/WebKit/public/web/WebArrayBufferConverter.h"
  17 #include "third_party/WebKit/public/web/WebArrayBufferView.h"
  18 #include "v8/include/v8.h"
  19
  20 namespace content {
  21
  22 // Default implementation of V8ValueConverter::Strategy
  23
  24 bool V8ValueConverter::Strategy::FromV8Object(
  25     v8::Local<v8::Object> value,
  26     base::Value** out,
  27     v8::Isolate* isolate,
  28     const FromV8ValueCallback& callback) const {
  29   return false;
  30 }
  31
  32 bool V8ValueConverter::Strategy::FromV8Array(
  33     v8::Local<v8::Array> value,
  34     base::Value** out,
  35     v8::Isolate* isolate,
  36     const FromV8ValueCallback& callback) const {
  37   return false;
  38 }
  39
  40 bool V8ValueConverter::Strategy::FromV8ArrayBuffer(v8::Local<v8::Object> value,
  41                                                    base::Value** out,
  42                                                    v8::Isolate* isolate) const {
  43   return false;
  44 }
  45
  46 bool V8ValueConverter::Strategy::FromV8Number(v8::Local<v8::Number> value,
  47                                               base::Value** out) const {
  48   return false;
  49 }
  50
  51 bool V8ValueConverter::Strategy::FromV8Undefined(base::Value** out) const {
  52   return false;
  53 }
  54
  55
  56 namespace {
  57
  58 // For the sake of the storage API, make this quite large.
  59 const int kMaxRecursionDepth = 100;
  60
  61 }  // namespace
  62
  63 // The state of a call to FromV8Value.
  64 class V8ValueConverterImpl::FromV8ValueState {
  65  public:
  66   // Level scope which updates the current depth of some FromV8ValueState.
  67   class Level {
  68    public:
  69     explicit Level(FromV8ValueState* state) : state_(state) {
  70       state_->max_recursion_depth_--;
  71     }
  72     ~Level() {
  73       state_->max_recursion_depth_++;
  74     }
  75
  76    private:
  77     FromV8ValueState* state_;
  78   };
  79
  80   explicit FromV8ValueState(bool avoid_identity_hash_for_testing)
  81       : max_recursion_depth_(kMaxRecursionDepth),
  82         avoid_identity_hash_for_testing_(avoid_identity_hash_for_testing) {}
  83
  84   // If |handle| is not in |unique_map_|, then add it to |unique_map_| and
  85   // return true.
  86   //
  87   // Otherwise do nothing and return false. Here "A is unique" means that no
  88   // other handle B in the map points to the same object as A. Note that A can
  89   // be unique even if there already is another handle with the same identity
  90   // hash (key) in the map, because two objects can have the same hash.
  91   bool UpdateAndCheckUniqueness(v8::Local<v8::Object> handle) {
  92     typedef HashToHandleMap::const_iterator Iterator;
  93     int hash = avoid_identity_hash_for_testing_ ? 0 : handle->GetIdentityHash();
  94     // We only compare using == with handles to objects with the same identity
  95     // hash. Different hash obviously means different objects, but two objects
  96     // in a couple of thousands could have the same identity hash.
  97     std::pair<Iterator, Iterator> range = unique_map_.equal_range(hash);
  98     for (Iterator it = range.first; it != range.second; ++it) {
  99       // Operator == for handles actually compares the underlying objects.
 100       if (it->second == handle)
 101         return false;
 102     }
 103     unique_map_.insert(std::make_pair(hash, handle));
 104     return true;
 105   }
 106
 107   bool HasReachedMaxRecursionDepth() {
 108     return max_recursion_depth_ < 0;
 109   }
 110
 111  private:
 112   typedef std::multimap<int, v8::Local<v8::Object> > HashToHandleMap;
 113   HashToHandleMap unique_map_;
 114
 115   int max_recursion_depth_;
 116
 117   bool avoid_identity_hash_for_testing_;
 118 };
 119
 120 V8ValueConverter* V8ValueConverter::create() {
 121   return new V8ValueConverterImpl();
 122 }
 123
 124 V8ValueConverterImpl::V8ValueConverterImpl()
 125     : date_allowed_(false),
 126       reg_exp_allowed_(false),
 127       function_allowed_(false),
 128       strip_null_from_objects_(false),
 129       avoid_identity_hash_for_testing_(false),
 130       strategy_(NULL) {}
 131
 132 void V8ValueConverterImpl::SetDateAllowed(bool val) {
 133   date_allowed_ = val;
 134 }
 135
 136 void V8ValueConverterImpl::SetRegExpAllowed(bool val) {
 137   reg_exp_allowed_ = val;
 138 }
 139
 140 void V8ValueConverterImpl::SetFunctionAllowed(bool val) {
 141   function_allowed_ = val;
 142 }
 143
 144 void V8ValueConverterImpl::SetStripNullFromObjects(bool val) {
 145   strip_null_from_objects_ = val;
 146 }
 147
 148 void V8ValueConverterImpl::SetStrategy(Strategy* strategy) {
 149   strategy_ = strategy;
 150 }
 151
 152 v8::Local<v8::Value> V8ValueConverterImpl::ToV8Value(
 153     const base::Value* value, v8::Local<v8::Context> context) const {
 154   v8::Context::Scope context_scope(context);
 155   v8::EscapableHandleScope handle_scope(context->GetIsolate());
 156   return handle_scope.Escape(
 157       ToV8ValueImpl(context->GetIsolate(), context->Global(), value));
 158 }
 159
 160 base::Value* V8ValueConverterImpl::FromV8Value(
 161     v8::Local<v8::Value> val,
 162     v8::Local<v8::Context> context) const {
 163   v8::Context::Scope context_scope(context);
 164   v8::HandleScope handle_scope(context->GetIsolate());
 165   FromV8ValueState state(avoid_identity_hash_for_testing_);
 166   return FromV8ValueImpl(&state, val, context->GetIsolate());
 167 }
 168
 169 v8::Local<v8::Value> V8ValueConverterImpl::ToV8ValueImpl(
 170     v8::Isolate* isolate,
 171     v8::Local<v8::Object> creation_context,
 172     const base::Value* value) const {
 173   CHECK(value);
 174   switch (value->GetType()) {
 175     case base::Value::TYPE_NULL:
 176       return v8::Null(isolate);
 177
 178     case base::Value::TYPE_BOOLEAN: {
 179       bool val = false;
 180       CHECK(value->GetAsBoolean(&val));
 181       return v8::Boolean::New(isolate, val);
 182     }
 183
 184     case base::Value::TYPE_INTEGER: {
 185       int val = 0;
 186       CHECK(value->GetAsInteger(&val));
 187       return v8::Integer::New(isolate, val);
 188     }
 189
 190     case base::Value::TYPE_DOUBLE: {
 191       double val = 0.0;
 192       CHECK(value->GetAsDouble(&val));
 193       return v8::Number::New(isolate, val);
 194     }
 195
 196     case base::Value::TYPE_STRING: {
 197       std::string val;
 198       CHECK(value->GetAsString(&val));
 199       return v8::String::NewFromUtf8(
 200           isolate, val.c_str(), v8::String::kNormalString, val.length());
 201     }
 202
 203     case base::Value::TYPE_LIST:
 204       return ToV8Array(isolate,
 205                        creation_context,
 206                        static_cast<const base::ListValue*>(value));
 207
 208     case base::Value::TYPE_DICTIONARY:
 209       return ToV8Object(isolate,
 210                         creation_context,
 211                         static_cast<const base::DictionaryValue*>(value));
 212
 213     case base::Value::TYPE_BINARY:
 214       return ToArrayBuffer(isolate,
 215                            creation_context,
 216                            static_cast<const base::BinaryValue*>(value));
 217
 218     default:
 219       LOG(ERROR) << "Unexpected value type: " << value->GetType();
 220       return v8::Null(isolate);
 221   }
 222 }
 223
 224 v8::Local<v8::Value> V8ValueConverterImpl::ToV8Array(
 225     v8::Isolate* isolate,
 226     v8::Local<v8::Object> creation_context,
 227     const base::ListValue* val) const {
 228   v8::Local<v8::Array> result(v8::Array::New(isolate, val->GetSize()));
 229
 230   for (size_t i = 0; i < val->GetSize(); ++i) {
 231     const base::Value* child = NULL;
 232     CHECK(val->Get(i, &child));
 233
 234     v8::Local<v8::Value> child_v8 =
 235         ToV8ValueImpl(isolate, creation_context, child);
 236     CHECK(!child_v8.IsEmpty());
 237
 238     v8::TryCatch try_catch;
 239     result->Set(static_cast<uint32>(i), child_v8);
 240     if (try_catch.HasCaught())
 241       LOG(ERROR) << "Setter for index " << i << " threw an exception.";
 242   }
 243
 244   return result;
 245 }
 246
 247 v8::Local<v8::Value> V8ValueConverterImpl::ToV8Object(
 248     v8::Isolate* isolate,
 249     v8::Local<v8::Object> creation_context,
 250     const base::DictionaryValue* val) const {
 251   v8::Local<v8::Object> result(v8::Object::New(isolate));
 252
 253   for (base::DictionaryValue::Iterator iter(*val);
 254        !iter.IsAtEnd(); iter.Advance()) {
 255     const std::string& key = iter.key();
 256     v8::Local<v8::Value> child_v8 =
 257         ToV8ValueImpl(isolate, creation_context, &iter.value());
 258     CHECK(!child_v8.IsEmpty());
 259
 260     v8::TryCatch try_catch;
 261     result->Set(
 262         v8::String::NewFromUtf8(
 263             isolate, key.c_str(), v8::String::kNormalString, key.length()),
 264         child_v8);
 265     if (try_catch.HasCaught()) {
 266       LOG(ERROR) << "Setter for property " << key.c_str() << " threw an "
 267                  << "exception.";
 268     }
 269   }
 270
 271   return result;
 272 }
 273
 274 v8::Local<v8::Value> V8ValueConverterImpl::ToArrayBuffer(
 275     v8::Isolate* isolate,
 276     v8::Local<v8::Object> creation_context,
 277     const base::BinaryValue* value) const {
 278   blink::WebArrayBuffer buffer =
 279       blink::WebArrayBuffer::create(value->GetSize(), 1);
 280   memcpy(buffer.data(), value->GetBuffer(), value->GetSize());
 281   return blink::WebArrayBufferConverter::toV8Value(
 282       &buffer, creation_context, isolate);
 283 }
 284
 285 base::Value* V8ValueConverterImpl::FromV8ValueImpl(
 286     FromV8ValueState* state,
 287     v8::Local<v8::Value> val,
 288     v8::Isolate* isolate) const {
 289   CHECK(!val.IsEmpty());
 290
 291   FromV8ValueState::Level state_level(state);
 292   if (state->HasReachedMaxRecursionDepth())
 293     return NULL;
 294
 295   if (val->IsNull())
 296     return base::Value::CreateNullValue().release();
 297
 298   if (val->IsBoolean())
 299     return new base::FundamentalValue(val->ToBoolean(isolate)->Value());
 300
 301   if (val->IsNumber() && strategy_) {
 302     base::Value* out = NULL;
 303     if (strategy_->FromV8Number(val.As<v8::Number>(), &out))
 304       return out;
 305   }
 306
 307   if (val->IsInt32())
 308     return new base::FundamentalValue(val->ToInt32(isolate)->Value());
 309
 310   if (val->IsNumber()) {
 311     double val_as_double = val.As<v8::Number>()->Value();
 312     if (!std::isfinite(val_as_double))
 313       return NULL;
 314     return new base::FundamentalValue(val_as_double);
 315   }
 316
 317   if (val->IsString()) {
 318     v8::String::Utf8Value utf8(val);
 319     return new base::StringValue(std::string(*utf8, utf8.length()));
 320   }
 321
 322   if (val->IsUndefined()) {
 323     if (strategy_) {
 324       base::Value* out = NULL;
 325       if (strategy_->FromV8Undefined(&out))
 326         return out;
 327     }
 328     // JSON.stringify ignores undefined.
 329     return NULL;
 330   }
 331
 332   if (val->IsDate()) {
 333     if (!date_allowed_)
 334       // JSON.stringify would convert this to a string, but an object is more
 335       // consistent within this class.
 336       return FromV8Object(val->ToObject(isolate), state, isolate);
 337     v8::Date* date = v8::Date::Cast(*val);
 338     return new base::FundamentalValue(date->ValueOf() / 1000.0);
 339   }
 340
 341   if (val->IsRegExp()) {
 342     if (!reg_exp_allowed_)
 343       // JSON.stringify converts to an object.
 344       return FromV8Object(val.As<v8::Object>(), state, isolate);
 345     return new base::StringValue(*v8::String::Utf8Value(val));
 346   }
 347
 348   // v8::Value doesn't have a ToArray() method for some reason.
 349   if (val->IsArray())
 350     return FromV8Array(val.As<v8::Array>(), state, isolate);
 351
 352   if (val->IsFunction()) {
 353     if (!function_allowed_)
 354       // JSON.stringify refuses to convert function(){}.
 355       return NULL;
 356     return FromV8Object(val.As<v8::Object>(), state, isolate);
 357   }
 358
 359   if (val->IsArrayBuffer() || val->IsArrayBufferView())
 360     return FromV8ArrayBuffer(val.As<v8::Object>(), isolate);
 361
 362   if (val->IsObject())
 363     return FromV8Object(val.As<v8::Object>(), state, isolate);
 364
 365   LOG(ERROR) << "Unexpected v8 value type encountered.";
 366   return NULL;
 367 }
 368
 369 base::Value* V8ValueConverterImpl::FromV8Array(
 370     v8::Local<v8::Array> val,
 371     FromV8ValueState* state,
 372     v8::Isolate* isolate) const {
 373   if (!state->UpdateAndCheckUniqueness(val))
 374     return base::Value::CreateNullValue().release();
 375
 376   scoped_ptr<v8::Context::Scope> scope;
 377   // If val was created in a different context than our current one, change to
 378   // that context, but change back after val is converted.
 379   if (!val->CreationContext().IsEmpty() &&
 380       val->CreationContext() != isolate->GetCurrentContext())
 381     scope.reset(new v8::Context::Scope(val->CreationContext()));
 382
 383   if (strategy_) {
 384     // These base::Unretained's are safe, because Strategy::FromV8Value should
 385     // be synchronous, so this object can't be out of scope.
 386     V8ValueConverter::Strategy::FromV8ValueCallback callback =
 387         base::Bind(&V8ValueConverterImpl::FromV8ValueImpl,
 388                    base::Unretained(this),
 389                    base::Unretained(state));
 390     base::Value* out = NULL;
 391     if (strategy_->FromV8Array(val, &out, isolate, callback))
 392       return out;
 393   }
 394
 395   base::ListValue* result = new base::ListValue();
 396
 397   // Only fields with integer keys are carried over to the ListValue.
 398   for (uint32 i = 0; i < val->Length(); ++i) {
 399     v8::TryCatch try_catch;
 400     v8::Local<v8::Value> child_v8 = val->Get(i);
 401     if (try_catch.HasCaught()) {
 402       LOG(ERROR) << "Getter for index " << i << " threw an exception.";
 403       child_v8 = v8::Null(isolate);
 404     }
 405
 406     if (!val->HasRealIndexedProperty(i)) {
 407       result->Append(base::Value::CreateNullValue());
 408       continue;
 409     }
 410
 411     base::Value* child = FromV8ValueImpl(state, child_v8, isolate);
 412     if (child)
 413       result->Append(child);
 414     else
 415       // JSON.stringify puts null in places where values don't serialize, for
 416       // example undefined and functions. Emulate that behavior.
 417       result->Append(base::Value::CreateNullValue());
 418   }
 419   return result;
 420 }
 421
 422 base::Value* V8ValueConverterImpl::FromV8ArrayBuffer(
 423     v8::Local<v8::Object> val,
 424     v8::Isolate* isolate) const {
 425   if (strategy_) {
 426     base::Value* out = NULL;
 427     if (strategy_->FromV8ArrayBuffer(val, &out, isolate))
 428       return out;
 429   }
 430
 431   char* data = NULL;
 432   size_t length = 0;
 433
 434   scoped_ptr<blink::WebArrayBuffer> array_buffer(
 435       blink::WebArrayBufferConverter::createFromV8Value(val, isolate));
 436   scoped_ptr<blink::WebArrayBufferView> view;
 437   if (array_buffer) {
 438     data = reinterpret_cast<char*>(array_buffer->data());
 439     length = array_buffer->byteLength();
 440   } else {
 441     view.reset(blink::WebArrayBufferView::createFromV8Value(val));
 442     if (view) {
 443       data = reinterpret_cast<char*>(view->baseAddress()) + view->byteOffset();
 444       length = view->byteLength();
 445     }
 446   }
 447
 448   if (data)
 449     return base::BinaryValue::CreateWithCopiedBuffer(data, length);
 450   else
 451     return NULL;
 452 }
 453
 454 base::Value* V8ValueConverterImpl::FromV8Object(
 455     v8::Local<v8::Object> val,
 456     FromV8ValueState* state,
 457     v8::Isolate* isolate) const {
 458   if (!state->UpdateAndCheckUniqueness(val))
 459     return base::Value::CreateNullValue().release();
 460
 461   scoped_ptr<v8::Context::Scope> scope;
 462   // If val was created in a different context than our current one, change to
 463   // that context, but change back after val is converted.
 464   if (!val->CreationContext().IsEmpty() &&
 465       val->CreationContext() != isolate->GetCurrentContext())
 466     scope.reset(new v8::Context::Scope(val->CreationContext()));
 467
 468   if (strategy_) {
 469     // These base::Unretained's are safe, because Strategy::FromV8Value should
 470     // be synchronous, so this object can't be out of scope.
 471     V8ValueConverter::Strategy::FromV8ValueCallback callback =
 472         base::Bind(&V8ValueConverterImpl::FromV8ValueImpl,
 473                    base::Unretained(this),
 474                    base::Unretained(state));
 475     base::Value* out = NULL;
 476     if (strategy_->FromV8Object(val, &out, isolate, callback))
 477       return out;
 478   }
 479
 480   // Don't consider DOM objects. This check matches isHostObject() in Blink's
 481   // bindings/v8/V8Binding.h used in structured cloning. It reads:
 482   //
 483   // If the object has any internal fields, then we won't be able to serialize
 484   // or deserialize them; conveniently, this is also a quick way to detect DOM
 485   // wrapper objects, because the mechanism for these relies on data stored in
 486   // these fields.
 487   //
 488   // NOTE: check this after |strategy_| so that callers have a chance to
 489   // do something else, such as convert to the node's name rather than NULL.
 490   //
 491   // ANOTHER NOTE: returning an empty dictionary here to minimise surprise.
 492   // See also http://crbug.com/330559.
 493   if (val->InternalFieldCount())
 494     return new base::DictionaryValue();
 495
 496   scoped_ptr<base::DictionaryValue> result(new base::DictionaryValue());
 497   v8::Local<v8::Array> property_names(val->GetOwnPropertyNames());
 498
 499   for (uint32 i = 0; i < property_names->Length(); ++i) {
 500     v8::Local<v8::Value> key(property_names->Get(i));
 501
 502     // Extend this test to cover more types as necessary and if sensible.
 503     if (!key->IsString() &&
 504         !key->IsNumber()) {
 505       NOTREACHED() << "Key \"" << *v8::String::Utf8Value(key) << "\" "
 506                       "is neither a string nor a number";
 507       continue;
 508     }
 509
 510     v8::String::Utf8Value name_utf8(key);
 511
 512     v8::TryCatch try_catch;
 513     v8::Local<v8::Value> child_v8 = val->Get(key);
 514
 515     if (try_catch.HasCaught()) {
 516       LOG(WARNING) << "Getter for property " << *name_utf8
 517                    << " threw an exception.";
 518       child_v8 = v8::Null(isolate);
 519     }
 520
 521     scoped_ptr<base::Value> child(FromV8ValueImpl(state, child_v8, isolate));
 522     if (!child)
 523       // JSON.stringify skips properties whose values don't serialize, for
 524       // example undefined and functions. Emulate that behavior.
 525       continue;
 526
 527     // Strip null if asked (and since undefined is turned into null, undefined
 528     // too). The use case for supporting this is JSON-schema support,
 529     // specifically for extensions, where "optional" JSON properties may be
 530     // represented as null, yet due to buggy legacy code elsewhere isn't
 531     // treated as such (potentially causing crashes). For example, the
 532     // "tabs.create" function takes an object as its first argument with an
 533     // optional "windowId" property.
 534     //
 535     // Given just
 536     //
 537     //   tabs.create({})
 538     //
 539     // this will work as expected on code that only checks for the existence of
 540     // a "windowId" property (such as that legacy code). However given
 541     //
 542     //   tabs.create({windowId: null})
 543     //
 544     // there *is* a "windowId" property, but since it should be an int, code
 545     // on the browser which doesn't additionally check for null will fail.
 546     // We can avoid all bugs related to this by stripping null.
 547     if (strip_null_from_objects_ && child->IsType(base::Value::TYPE_NULL))
 548       continue;
 549
 550     result->SetWithoutPathExpansion(std::string(*name_utf8, name_utf8.length()),
 551                                     child.release());
 552   }
 553
 554   return result.release();
 555 }
 556
 557 }  // namespace content