src/webkit/browser/fileapi/file_system_context.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 "webkit/browser/fileapi/file_system_context.h"
   6
   7 #include "base/bind.h"
   8 #include "base/single_thread_task_runner.h"
   9 #include "base/stl_util.h"
  10 #include "base/task_runner_util.h"
  11 #include "net/url_request/url_request.h"
  12 #include "url/gurl.h"
  13 #include "webkit/browser/blob/file_stream_reader.h"
  14 #include "webkit/browser/fileapi/copy_or_move_file_validator.h"
  15 #include "webkit/browser/fileapi/external_mount_points.h"
  16 #include "webkit/browser/fileapi/file_permission_policy.h"
  17 #include "webkit/browser/fileapi/file_stream_writer.h"
  18 #include "webkit/browser/fileapi/file_system_file_util.h"
  19 #include "webkit/browser/fileapi/file_system_operation.h"
  20 #include "webkit/browser/fileapi/file_system_operation_runner.h"
  21 #include "webkit/browser/fileapi/file_system_options.h"
  22 #include "webkit/browser/fileapi/file_system_quota_client.h"
  23 #include "webkit/browser/fileapi/file_system_url.h"
  24 #include "webkit/browser/fileapi/isolated_context.h"
  25 #include "webkit/browser/fileapi/isolated_file_system_backend.h"
  26 #include "webkit/browser/fileapi/mount_points.h"
  27 #include "webkit/browser/fileapi/quota/quota_reservation.h"
  28 #include "webkit/browser/fileapi/sandbox_file_system_backend.h"
  29 #include "webkit/browser/quota/quota_manager_proxy.h"
  30 #include "webkit/browser/quota/special_storage_policy.h"
  31 #include "webkit/common/fileapi/file_system_info.h"
  32 #include "webkit/common/fileapi/file_system_util.h"
  33
  34 using quota::QuotaClient;
  35
  36 namespace fileapi {
  37
  38 namespace {
  39
  40 QuotaClient* CreateQuotaClient(
  41     FileSystemContext* context,
  42     bool is_incognito) {
  43   return new FileSystemQuotaClient(context, is_incognito);
  44 }
  45
  46
  47 void DidGetMetadataForResolveURL(
  48     const base::FilePath& path,
  49     const FileSystemContext::ResolveURLCallback& callback,
  50     const FileSystemInfo& info,
  51     base::File::Error error,
  52     const base::File::Info& file_info) {
  53   if (error != base::File::FILE_OK) {
  54     if (error == base::File::FILE_ERROR_NOT_FOUND) {
  55       callback.Run(base::File::FILE_OK, info, path,
  56                    FileSystemContext::RESOLVED_ENTRY_NOT_FOUND);
  57     } else {
  58       callback.Run(error, FileSystemInfo(), base::FilePath(),
  59                    FileSystemContext::RESOLVED_ENTRY_NOT_FOUND);
  60     }
  61     return;
  62   }
  63   callback.Run(error, info, path, file_info.is_directory ?
  64       FileSystemContext::RESOLVED_ENTRY_DIRECTORY :
  65       FileSystemContext::RESOLVED_ENTRY_FILE);
  66 }
  67
  68 void RelayResolveURLCallback(
  69     scoped_refptr<base::MessageLoopProxy> message_loop,
  70     const FileSystemContext::ResolveURLCallback& callback,
  71     base::File::Error result,
  72     const FileSystemInfo& info,
  73     const base::FilePath& file_path,
  74     FileSystemContext::ResolvedEntryType type) {
  75   message_loop->PostTask(
  76       FROM_HERE, base::Bind(callback, result, info, file_path, type));
  77 }
  78
  79 }  // namespace
  80
  81 // static
  82 int FileSystemContext::GetPermissionPolicy(FileSystemType type) {
  83   switch (type) {
  84     case kFileSystemTypeTemporary:
  85     case kFileSystemTypePersistent:
  86     case kFileSystemTypeSyncable:
  87       return FILE_PERMISSION_SANDBOX;
  88
  89     case kFileSystemTypeDrive:
  90     case kFileSystemTypeNativeForPlatformApp:
  91     case kFileSystemTypeNativeLocal:
  92     case kFileSystemTypeCloudDevice:
  93     case kFileSystemTypeProvided:
  94     case kFileSystemTypeDeviceMediaAsFileStorage:
  95       return FILE_PERMISSION_USE_FILE_PERMISSION;
  96
  97     case kFileSystemTypeRestrictedNativeLocal:
  98       return FILE_PERMISSION_READ_ONLY |
  99              FILE_PERMISSION_USE_FILE_PERMISSION;
 100
 101     case kFileSystemTypeDeviceMedia:
 102     case kFileSystemTypeIphoto:
 103     case kFileSystemTypeItunes:
 104     case kFileSystemTypeNativeMedia:
 105     case kFileSystemTypePicasa:
 106       return FILE_PERMISSION_USE_FILE_PERMISSION;
 107
 108     // Following types are only accessed via IsolatedFileSystem, and
 109     // don't have their own permission policies.
 110     case kFileSystemTypeDragged:
 111     case kFileSystemTypeForTransientFile:
 112     case kFileSystemTypePluginPrivate:
 113       return FILE_PERMISSION_ALWAYS_DENY;
 114
 115     // Following types only appear as mount_type, and will not be
 116     // queried for their permission policies.
 117     case kFileSystemTypeIsolated:
 118     case kFileSystemTypeExternal:
 119       return FILE_PERMISSION_ALWAYS_DENY;
 120
 121     // Following types should not be used to access files by FileAPI clients.
 122     case kFileSystemTypeTest:
 123     case kFileSystemTypeSyncableForInternalSync:
 124     case kFileSystemInternalTypeEnumEnd:
 125     case kFileSystemInternalTypeEnumStart:
 126     case kFileSystemTypeUnknown:
 127       return FILE_PERMISSION_ALWAYS_DENY;
 128   }
 129   NOTREACHED();
 130   return FILE_PERMISSION_ALWAYS_DENY;
 131 }
 132
 133 FileSystemContext::FileSystemContext(
 134     base::SingleThreadTaskRunner* io_task_runner,
 135     base::SequencedTaskRunner* file_task_runner,
 136     ExternalMountPoints* external_mount_points,
 137     quota::SpecialStoragePolicy* special_storage_policy,
 138     quota::QuotaManagerProxy* quota_manager_proxy,
 139     ScopedVector<FileSystemBackend> additional_backends,
 140     const std::vector<URLRequestAutoMountHandler>& auto_mount_handlers,
 141     const base::FilePath& partition_path,
 142     const FileSystemOptions& options)
 143     : io_task_runner_(io_task_runner),
 144       default_file_task_runner_(file_task_runner),
 145       quota_manager_proxy_(quota_manager_proxy),
 146       sandbox_delegate_(new SandboxFileSystemBackendDelegate(
 147           quota_manager_proxy,
 148           file_task_runner,
 149           partition_path,
 150           special_storage_policy,
 151           options)),
 152       sandbox_backend_(new SandboxFileSystemBackend(
 153           sandbox_delegate_.get())),
 154       isolated_backend_(new IsolatedFileSystemBackend()),
 155       plugin_private_backend_(new PluginPrivateFileSystemBackend(
 156           file_task_runner,
 157           partition_path,
 158           special_storage_policy,
 159           options)),
 160       additional_backends_(additional_backends.Pass()),
 161       auto_mount_handlers_(auto_mount_handlers),
 162       external_mount_points_(external_mount_points),
 163       partition_path_(partition_path),
 164       is_incognito_(options.is_incognito()),
 165       operation_runner_(new FileSystemOperationRunner(this)) {
 166   RegisterBackend(sandbox_backend_.get());
 167   RegisterBackend(isolated_backend_.get());
 168   RegisterBackend(plugin_private_backend_.get());
 169
 170   for (ScopedVector<FileSystemBackend>::const_iterator iter =
 171           additional_backends_.begin();
 172        iter != additional_backends_.end(); ++iter) {
 173     RegisterBackend(*iter);
 174   }
 175
 176   if (quota_manager_proxy) {
 177     // Quota client assumes all backends have registered.
 178     quota_manager_proxy->RegisterClient(CreateQuotaClient(
 179             this, options.is_incognito()));
 180   }
 181
 182   sandbox_backend_->Initialize(this);
 183   isolated_backend_->Initialize(this);
 184   plugin_private_backend_->Initialize(this);
 185   for (ScopedVector<FileSystemBackend>::const_iterator iter =
 186           additional_backends_.begin();
 187        iter != additional_backends_.end(); ++iter) {
 188     (*iter)->Initialize(this);
 189   }
 190
 191   // Additional mount points must be added before regular system-wide
 192   // mount points.
 193   if (external_mount_points)
 194     url_crackers_.push_back(external_mount_points);
 195   url_crackers_.push_back(ExternalMountPoints::GetSystemInstance());
 196   url_crackers_.push_back(IsolatedContext::GetInstance());
 197 }
 198
 199 bool FileSystemContext::DeleteDataForOriginOnFileTaskRunner(
 200     const GURL& origin_url) {
 201   DCHECK(default_file_task_runner()->RunsTasksOnCurrentThread());
 202   DCHECK(origin_url == origin_url.GetOrigin());
 203
 204   bool success = true;
 205   for (FileSystemBackendMap::iterator iter = backend_map_.begin();
 206        iter != backend_map_.end();
 207        ++iter) {
 208     FileSystemBackend* backend = iter->second;
 209     if (!backend->GetQuotaUtil())
 210       continue;
 211     if (backend->GetQuotaUtil()->DeleteOriginDataOnFileTaskRunner(
 212             this, quota_manager_proxy(), origin_url, iter->first)
 213             != base::File::FILE_OK) {
 214       // Continue the loop, but record the failure.
 215       success = false;
 216     }
 217   }
 218
 219   return success;
 220 }
 221
 222 scoped_refptr<QuotaReservation>
 223 FileSystemContext::CreateQuotaReservationOnFileTaskRunner(
 224     const GURL& origin_url,
 225     FileSystemType type) {
 226   DCHECK(default_file_task_runner()->RunsTasksOnCurrentThread());
 227   FileSystemBackend* backend = GetFileSystemBackend(type);
 228   if (!backend || !backend->GetQuotaUtil())
 229     return scoped_refptr<QuotaReservation>();
 230   return backend->GetQuotaUtil()->CreateQuotaReservationOnFileTaskRunner(
 231       origin_url, type);
 232 }
 233
 234 void FileSystemContext::Shutdown() {
 235   if (!io_task_runner_->RunsTasksOnCurrentThread()) {
 236     io_task_runner_->PostTask(
 237         FROM_HERE, base::Bind(&FileSystemContext::Shutdown,
 238                               make_scoped_refptr(this)));
 239     return;
 240   }
 241   operation_runner_->Shutdown();
 242 }
 243
 244 FileSystemQuotaUtil*
 245 FileSystemContext::GetQuotaUtil(FileSystemType type) const {
 246   FileSystemBackend* backend = GetFileSystemBackend(type);
 247   if (!backend)
 248     return NULL;
 249   return backend->GetQuotaUtil();
 250 }
 251
 252 AsyncFileUtil* FileSystemContext::GetAsyncFileUtil(
 253     FileSystemType type) const {
 254   FileSystemBackend* backend = GetFileSystemBackend(type);
 255   if (!backend)
 256     return NULL;
 257   return backend->GetAsyncFileUtil(type);
 258 }
 259
 260 CopyOrMoveFileValidatorFactory*
 261 FileSystemContext::GetCopyOrMoveFileValidatorFactory(
 262     FileSystemType type, base::File::Error* error_code) const {
 263   DCHECK(error_code);
 264   *error_code = base::File::FILE_OK;
 265   FileSystemBackend* backend = GetFileSystemBackend(type);
 266   if (!backend)
 267     return NULL;
 268   return backend->GetCopyOrMoveFileValidatorFactory(
 269       type, error_code);
 270 }
 271
 272 FileSystemBackend* FileSystemContext::GetFileSystemBackend(
 273     FileSystemType type) const {
 274   FileSystemBackendMap::const_iterator found = backend_map_.find(type);
 275   if (found != backend_map_.end())
 276     return found->second;
 277   NOTREACHED() << "Unknown filesystem type: " << type;
 278   return NULL;
 279 }
 280
 281 bool FileSystemContext::IsSandboxFileSystem(FileSystemType type) const {
 282   FileSystemBackendMap::const_iterator found = backend_map_.find(type);
 283   return found != backend_map_.end() && found->second->GetQuotaUtil();
 284 }
 285
 286 const UpdateObserverList* FileSystemContext::GetUpdateObservers(
 287     FileSystemType type) const {
 288   FileSystemBackend* backend = GetFileSystemBackend(type);
 289   if (backend->GetQuotaUtil())
 290     return backend->GetQuotaUtil()->GetUpdateObservers(type);
 291   return NULL;
 292 }
 293
 294 const AccessObserverList* FileSystemContext::GetAccessObservers(
 295     FileSystemType type) const {
 296   FileSystemBackend* backend = GetFileSystemBackend(type);
 297   if (backend->GetQuotaUtil())
 298     return backend->GetQuotaUtil()->GetAccessObservers(type);
 299   return NULL;
 300 }
 301
 302 void FileSystemContext::GetFileSystemTypes(
 303     std::vector<FileSystemType>* types) const {
 304   types->clear();
 305   for (FileSystemBackendMap::const_iterator iter = backend_map_.begin();
 306        iter != backend_map_.end(); ++iter)
 307     types->push_back(iter->first);
 308 }
 309
 310 ExternalFileSystemBackend*
 311 FileSystemContext::external_backend() const {
 312   return static_cast<ExternalFileSystemBackend*>(
 313       GetFileSystemBackend(kFileSystemTypeExternal));
 314 }
 315
 316 void FileSystemContext::OpenFileSystem(
 317     const GURL& origin_url,
 318     FileSystemType type,
 319     OpenFileSystemMode mode,
 320     const OpenFileSystemCallback& callback) {
 321   DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
 322   DCHECK(!callback.is_null());
 323
 324   if (!FileSystemContext::IsSandboxFileSystem(type)) {
 325     // Disallow opening a non-sandboxed filesystem.
 326     callback.Run(GURL(), std::string(), base::File::FILE_ERROR_SECURITY);
 327     return;
 328   }
 329
 330   FileSystemBackend* backend = GetFileSystemBackend(type);
 331   if (!backend) {
 332     callback.Run(GURL(), std::string(), base::File::FILE_ERROR_SECURITY);
 333     return;
 334   }
 335
 336   backend->ResolveURL(
 337       CreateCrackedFileSystemURL(origin_url, type, base::FilePath()),
 338       mode,
 339       callback);
 340 }
 341
 342 void FileSystemContext::ResolveURL(
 343     const FileSystemURL& url,
 344     const ResolveURLCallback& callback) {
 345   DCHECK(!callback.is_null());
 346
 347   // If not on IO thread, forward before passing the task to the backend.
 348   if (!io_task_runner_->RunsTasksOnCurrentThread()) {
 349     ResolveURLCallback relay_callback =
 350         base::Bind(&RelayResolveURLCallback,
 351                    base::MessageLoopProxy::current(), callback);
 352     io_task_runner_->PostTask(
 353         FROM_HERE,
 354         base::Bind(&FileSystemContext::ResolveURL, this, url, relay_callback));
 355     return;
 356   }
 357
 358   FileSystemBackend* backend = GetFileSystemBackend(url.type());
 359   if (!backend) {
 360     callback.Run(base::File::FILE_ERROR_SECURITY,
 361                  FileSystemInfo(), base::FilePath(),
 362                  FileSystemContext::RESOLVED_ENTRY_NOT_FOUND);
 363     return;
 364   }
 365
 366   backend->ResolveURL(
 367       url,
 368       OPEN_FILE_SYSTEM_FAIL_IF_NONEXISTENT,
 369       base::Bind(&FileSystemContext::DidOpenFileSystemForResolveURL,
 370                  this,
 371                  url,
 372                  callback));
 373 }
 374
 375 void FileSystemContext::AttemptAutoMountForURLRequest(
 376     const net::URLRequest* url_request,
 377     const std::string& storage_domain,
 378     const StatusCallback& callback) {
 379   FileSystemURL filesystem_url(url_request->url());
 380   if (filesystem_url.type() == kFileSystemTypeExternal) {
 381     for (size_t i = 0; i < auto_mount_handlers_.size(); i++) {
 382       if (auto_mount_handlers_[i].Run(url_request, filesystem_url,
 383                                       storage_domain, callback)) {
 384         return;
 385       }
 386     }
 387   }
 388   callback.Run(base::File::FILE_ERROR_NOT_FOUND);
 389 }
 390
 391 void FileSystemContext::DeleteFileSystem(
 392     const GURL& origin_url,
 393     FileSystemType type,
 394     const StatusCallback& callback) {
 395   DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
 396   DCHECK(origin_url == origin_url.GetOrigin());
 397   DCHECK(!callback.is_null());
 398
 399   FileSystemBackend* backend = GetFileSystemBackend(type);
 400   if (!backend) {
 401     callback.Run(base::File::FILE_ERROR_SECURITY);
 402     return;
 403   }
 404   if (!backend->GetQuotaUtil()) {
 405     callback.Run(base::File::FILE_ERROR_INVALID_OPERATION);
 406     return;
 407   }
 408
 409   base::PostTaskAndReplyWithResult(
 410       default_file_task_runner(),
 411       FROM_HERE,
 412       // It is safe to pass Unretained(quota_util) since context owns it.
 413       base::Bind(&FileSystemQuotaUtil::DeleteOriginDataOnFileTaskRunner,
 414                  base::Unretained(backend->GetQuotaUtil()),
 415                  make_scoped_refptr(this),
 416                  base::Unretained(quota_manager_proxy()),
 417                  origin_url,
 418                  type),
 419       callback);
 420 }
 421
 422 scoped_ptr<webkit_blob::FileStreamReader>
 423 FileSystemContext::CreateFileStreamReader(
 424     const FileSystemURL& url,
 425     int64 offset,
 426     const base::Time& expected_modification_time) {
 427   if (!url.is_valid())
 428     return scoped_ptr<webkit_blob::FileStreamReader>();
 429   FileSystemBackend* backend = GetFileSystemBackend(url.type());
 430   if (!backend)
 431     return scoped_ptr<webkit_blob::FileStreamReader>();
 432   return backend->CreateFileStreamReader(
 433       url, offset, expected_modification_time, this);
 434 }
 435
 436 scoped_ptr<FileStreamWriter> FileSystemContext::CreateFileStreamWriter(
 437     const FileSystemURL& url,
 438     int64 offset) {
 439   if (!url.is_valid())
 440     return scoped_ptr<FileStreamWriter>();
 441   FileSystemBackend* backend = GetFileSystemBackend(url.type());
 442   if (!backend)
 443     return scoped_ptr<FileStreamWriter>();
 444   return backend->CreateFileStreamWriter(url, offset, this);
 445 }
 446
 447 scoped_ptr<FileSystemOperationRunner>
 448 FileSystemContext::CreateFileSystemOperationRunner() {
 449   return make_scoped_ptr(new FileSystemOperationRunner(this));
 450 }
 451
 452 FileSystemURL FileSystemContext::CrackURL(const GURL& url) const {
 453   return CrackFileSystemURL(FileSystemURL(url));
 454 }
 455
 456 FileSystemURL FileSystemContext::CreateCrackedFileSystemURL(
 457     const GURL& origin,
 458     FileSystemType type,
 459     const base::FilePath& path) const {
 460   return CrackFileSystemURL(FileSystemURL(origin, type, path));
 461 }
 462
 463 #if defined(OS_CHROMEOS)
 464 void FileSystemContext::EnableTemporaryFileSystemInIncognito() {
 465   sandbox_backend_->set_enable_temporary_file_system_in_incognito(true);
 466 }
 467 #endif
 468
 469 bool FileSystemContext::CanServeURLRequest(const FileSystemURL& url) const {
 470   // We never support accessing files in isolated filesystems via an URL.
 471   if (url.mount_type() == kFileSystemTypeIsolated)
 472     return false;
 473 #if defined(OS_CHROMEOS)
 474   if (url.type() == kFileSystemTypeTemporary &&
 475       sandbox_backend_->enable_temporary_file_system_in_incognito()) {
 476     return true;
 477   }
 478 #endif
 479   return !is_incognito_ || !FileSystemContext::IsSandboxFileSystem(url.type());
 480 }
 481
 482 bool FileSystemContext::ShouldFlushOnWriteCompletion(
 483     FileSystemType type) const {
 484   if (IsSandboxFileSystem(type)) {
 485     // Disable Flush() for each write operation on SandboxFileSystems since it
 486     // hurts the performance, assuming the FileSystems are stored in a local
 487     // disk, we don't need to keep calling fsync() for it.
 488     // On the other hand, other FileSystems that may stored on a removable media
 489     // should be Flush()ed as soon as a write operation is completed, so that
 490     // written data is saved over sudden media removal.
 491     return false;
 492   }
 493   return true;
 494 }
 495
 496 void FileSystemContext::OpenPluginPrivateFileSystem(
 497     const GURL& origin_url,
 498     FileSystemType type,
 499     const std::string& filesystem_id,
 500     const std::string& plugin_id,
 501     OpenFileSystemMode mode,
 502     const StatusCallback& callback) {
 503   DCHECK(plugin_private_backend_);
 504   plugin_private_backend_->OpenPrivateFileSystem(
 505       origin_url, type, filesystem_id, plugin_id, mode, callback);
 506 }
 507
 508 FileSystemContext::~FileSystemContext() {
 509 }
 510
 511 void FileSystemContext::DeleteOnCorrectThread() const {
 512   if (!io_task_runner_->RunsTasksOnCurrentThread() &&
 513       io_task_runner_->DeleteSoon(FROM_HERE, this)) {
 514     return;
 515   }
 516   delete this;
 517 }
 518
 519 FileSystemOperation* FileSystemContext::CreateFileSystemOperation(
 520     const FileSystemURL& url, base::File::Error* error_code) {
 521   if (!url.is_valid()) {
 522     if (error_code)
 523       *error_code = base::File::FILE_ERROR_INVALID_URL;
 524     return NULL;
 525   }
 526
 527   FileSystemBackend* backend = GetFileSystemBackend(url.type());
 528   if (!backend) {
 529     if (error_code)
 530       *error_code = base::File::FILE_ERROR_FAILED;
 531     return NULL;
 532   }
 533
 534   base::File::Error fs_error = base::File::FILE_OK;
 535   FileSystemOperation* operation =
 536       backend->CreateFileSystemOperation(url, this, &fs_error);
 537
 538   if (error_code)
 539     *error_code = fs_error;
 540   return operation;
 541 }
 542
 543 FileSystemURL FileSystemContext::CrackFileSystemURL(
 544     const FileSystemURL& url) const {
 545   if (!url.is_valid())
 546     return FileSystemURL();
 547
 548   // The returned value in case there is no crackers which can crack the url.
 549   // This is valid situation for non isolated/external file systems.
 550   FileSystemURL current = url;
 551
 552   // File system may be mounted multiple times (e.g., an isolated filesystem on
 553   // top of an external filesystem). Hence cracking needs to be iterated.
 554   for (;;) {
 555     FileSystemURL cracked = current;
 556     for (size_t i = 0; i < url_crackers_.size(); ++i) {
 557       if (!url_crackers_[i]->HandlesFileSystemMountType(current.type()))
 558         continue;
 559       cracked = url_crackers_[i]->CrackFileSystemURL(current);
 560       if (cracked.is_valid())
 561         break;
 562     }
 563     if (cracked == current)
 564       break;
 565     current = cracked;
 566   }
 567   return current;
 568 }
 569
 570 void FileSystemContext::RegisterBackend(FileSystemBackend* backend) {
 571   const FileSystemType mount_types[] = {
 572     kFileSystemTypeTemporary,
 573     kFileSystemTypePersistent,
 574     kFileSystemTypeIsolated,
 575     kFileSystemTypeExternal,
 576   };
 577   // Register file system backends for public mount types.
 578   for (size_t j = 0; j < ARRAYSIZE_UNSAFE(mount_types); ++j) {
 579     if (backend->CanHandleType(mount_types[j])) {
 580       const bool inserted = backend_map_.insert(
 581           std::make_pair(mount_types[j], backend)).second;
 582       DCHECK(inserted);
 583     }
 584   }
 585   // Register file system backends for internal types.
 586   for (int t = kFileSystemInternalTypeEnumStart + 1;
 587        t < kFileSystemInternalTypeEnumEnd; ++t) {
 588     FileSystemType type = static_cast<FileSystemType>(t);
 589     if (backend->CanHandleType(type)) {
 590       const bool inserted = backend_map_.insert(
 591           std::make_pair(type, backend)).second;
 592       DCHECK(inserted);
 593     }
 594   }
 595 }
 596
 597 void FileSystemContext::DidOpenFileSystemForResolveURL(
 598     const FileSystemURL& url,
 599     const FileSystemContext::ResolveURLCallback& callback,
 600     const GURL& filesystem_root,
 601     const std::string& filesystem_name,
 602     base::File::Error error) {
 603   DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
 604
 605   if (error != base::File::FILE_OK) {
 606     callback.Run(error, FileSystemInfo(), base::FilePath(),
 607                  FileSystemContext::RESOLVED_ENTRY_NOT_FOUND);
 608     return;
 609   }
 610
 611   fileapi::FileSystemInfo info(
 612       filesystem_name, filesystem_root, url.mount_type());
 613
 614   // Extract the virtual path not containing a filesystem type part from |url|.
 615   base::FilePath parent = CrackURL(filesystem_root).virtual_path();
 616   base::FilePath child = url.virtual_path();
 617   base::FilePath path;
 618
 619   if (parent.empty()) {
 620     path = child;
 621   } else if (parent != child) {
 622     bool result = parent.AppendRelativePath(child, &path);
 623     DCHECK(result);
 624   }
 625
 626   operation_runner()->GetMetadata(
 627       url, base::Bind(&DidGetMetadataForResolveURL, path, callback, info));
 628 }
 629
 630 }  // namespace fileapi