src/chrome/browser/download/download_target_determiner.cc

   1 // Copyright 2013 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/browser/download/download_target_determiner.h"
   6
   7 #include "base/prefs/pref_service.h"
   8 #include "base/rand_util.h"
   9 #include "base/strings/stringprintf.h"
  10 #include "base/time/time.h"
  11 #include "chrome/browser/download/chrome_download_manager_delegate.h"
  12 #include "chrome/browser/download/download_crx_util.h"
  13 #include "chrome/browser/download/download_extensions.h"
  14 #include "chrome/browser/download/download_prefs.h"
  15 #include "chrome/browser/history/history_service.h"
  16 #include "chrome/browser/history/history_service_factory.h"
  17 #include "chrome/browser/profiles/profile.h"
  18 #include "chrome/common/pref_names.h"
  19 #include "chrome/grit/generated_resources.h"
  20 #include "content/public/browser/browser_context.h"
  21 #include "content/public/browser/browser_thread.h"
  22 #include "content/public/browser/download_interrupt_reasons.h"
  23 #include "extensions/common/constants.h"
  24 #include "net/base/filename_util.h"
  25 #include "net/base/mime_util.h"
  26 #include "ui/base/l10n/l10n_util.h"
  27
  28 #if defined(ENABLE_EXTENSIONS)
  29 #include "chrome/browser/extensions/webstore_installer.h"
  30 #include "extensions/common/feature_switch.h"
  31 #endif
  32
  33 #if defined(ENABLE_PLUGINS)
  34 #include "chrome/browser/plugins/plugin_prefs.h"
  35 #include "content/public/browser/plugin_service.h"
  36 #include "content/public/common/webplugininfo.h"
  37 #endif
  38
  39 #if defined(OS_WIN)
  40 #include "chrome/browser/ui/pdf/adobe_reader_info_win.h"
  41 #endif
  42
  43 using content::BrowserThread;
  44 using content::DownloadItem;
  45
  46 namespace {
  47
  48 const base::FilePath::CharType kCrdownloadSuffix[] =
  49     FILE_PATH_LITERAL(".crdownload");
  50
  51 // Condenses the results from HistoryService::GetVisibleVisitCountToHost() to a
  52 // single bool. A host is considered visited before if prior visible visits were
  53 // found in history and the first such visit was earlier than the most recent
  54 // midnight.
  55 void VisitCountsToVisitedBefore(
  56     const base::Callback<void(bool)>& callback,
  57     bool found_visits,
  58     int count,
  59     base::Time first_visit) {
  60   callback.Run(
  61       found_visits && count > 0 &&
  62       (first_visit.LocalMidnight() < base::Time::Now().LocalMidnight()));
  63 }
  64
  65 #if defined(OS_WIN)
  66 // Keeps track of whether Adobe Reader is up to date.
  67 bool g_is_adobe_reader_up_to_date_ = false;
  68 #endif
  69
  70 }  // namespace
  71
  72 DownloadTargetInfo::DownloadTargetInfo()
  73     : is_filetype_handled_safely(false) {}
  74
  75 DownloadTargetInfo::~DownloadTargetInfo() {}
  76
  77 DownloadTargetDeterminerDelegate::~DownloadTargetDeterminerDelegate() {
  78 }
  79
  80 DownloadTargetDeterminer::DownloadTargetDeterminer(
  81     DownloadItem* download,
  82     const base::FilePath& initial_virtual_path,
  83     DownloadPrefs* download_prefs,
  84     DownloadTargetDeterminerDelegate* delegate,
  85     const CompletionCallback& callback)
  86     : next_state_(STATE_GENERATE_TARGET_PATH),
  87       should_prompt_(false),
  88       should_notify_extensions_(false),
  89       create_target_directory_(false),
  90       conflict_action_(DownloadPathReservationTracker::OVERWRITE),
  91       danger_type_(download->GetDangerType()),
  92       is_dangerous_file_(false),
  93       virtual_path_(initial_virtual_path),
  94       is_filetype_handled_safely_(false),
  95       download_(download),
  96       is_resumption_(download_->GetLastReason() !=
  97                          content::DOWNLOAD_INTERRUPT_REASON_NONE &&
  98                      !initial_virtual_path.empty()),
  99       download_prefs_(download_prefs),
 100       delegate_(delegate),
 101       completion_callback_(callback),
 102       weak_ptr_factory_(this) {
 103   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 104   DCHECK(download_);
 105   DCHECK(delegate);
 106   download_->AddObserver(this);
 107
 108   DoLoop();
 109 }
 110
 111 DownloadTargetDeterminer::~DownloadTargetDeterminer() {
 112   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 113   DCHECK(download_);
 114   DCHECK(completion_callback_.is_null());
 115   download_->RemoveObserver(this);
 116 }
 117
 118 void DownloadTargetDeterminer::DoLoop() {
 119   Result result = CONTINUE;
 120   do {
 121     State current_state = next_state_;
 122     next_state_ = STATE_NONE;
 123
 124     switch (current_state) {
 125       case STATE_GENERATE_TARGET_PATH:
 126         result = DoGenerateTargetPath();
 127         break;
 128       case STATE_NOTIFY_EXTENSIONS:
 129         result = DoNotifyExtensions();
 130         break;
 131       case STATE_RESERVE_VIRTUAL_PATH:
 132         result = DoReserveVirtualPath();
 133         break;
 134       case STATE_PROMPT_USER_FOR_DOWNLOAD_PATH:
 135         result = DoPromptUserForDownloadPath();
 136         break;
 137       case STATE_DETERMINE_LOCAL_PATH:
 138         result = DoDetermineLocalPath();
 139         break;
 140       case STATE_DETERMINE_MIME_TYPE:
 141         result = DoDetermineMimeType();
 142         break;
 143       case STATE_DETERMINE_IF_HANDLED_SAFELY_BY_BROWSER:
 144         result = DoDetermineIfHandledSafely();
 145         break;
 146       case STATE_DETERMINE_IF_ADOBE_READER_UP_TO_DATE:
 147         result = DoDetermineIfAdobeReaderUpToDate();
 148         break;
 149       case STATE_CHECK_DOWNLOAD_URL:
 150         result = DoCheckDownloadUrl();
 151         break;
 152       case STATE_DETERMINE_INTERMEDIATE_PATH:
 153         result = DoDetermineIntermediatePath();
 154         break;
 155       case STATE_CHECK_VISITED_REFERRER_BEFORE:
 156         result = DoCheckVisitedReferrerBefore();
 157         break;
 158       case STATE_NONE:
 159         NOTREACHED();
 160         return;
 161     }
 162   } while (result == CONTINUE);
 163   // Note that if a callback completes synchronously, the handler will still
 164   // return QUIT_DOLOOP. In this case, an inner DoLoop() may complete the target
 165   // determination and delete |this|.
 166
 167   if (result == COMPLETE)
 168     ScheduleCallbackAndDeleteSelf();
 169 }
 170
 171 DownloadTargetDeterminer::Result
 172     DownloadTargetDeterminer::DoGenerateTargetPath() {
 173   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 174   DCHECK(local_path_.empty());
 175   DCHECK(!should_prompt_);
 176   DCHECK(!should_notify_extensions_);
 177   DCHECK_EQ(DownloadPathReservationTracker::OVERWRITE, conflict_action_);
 178   bool is_forced_path = !download_->GetForcedFilePath().empty();
 179
 180   next_state_ = STATE_NOTIFY_EXTENSIONS;
 181
 182   if (!virtual_path_.empty() && HasPromptedForPath() && !is_forced_path) {
 183     // The download is being resumed and the user has already been prompted for
 184     // a path. Assume that it's okay to overwrite the file if there's a conflict
 185     // and reuse the selection.
 186     should_prompt_ = ShouldPromptForDownload(virtual_path_);
 187   } else if (!is_forced_path) {
 188     // If we don't have a forced path, we should construct a path for the
 189     // download. Forced paths are only specified for programmatic downloads
 190     // (WebStore, Drag&Drop). Treat the path as a virtual path. We will
 191     // eventually determine whether this is a local path and if not, figure out
 192     // a local path.
 193     std::string default_filename(
 194         l10n_util::GetStringUTF8(IDS_DEFAULT_DOWNLOAD_FILENAME));
 195     base::FilePath generated_filename = net::GenerateFileName(
 196         download_->GetURL(),
 197         download_->GetContentDisposition(),
 198         GetProfile()->GetPrefs()->GetString(prefs::kDefaultCharset),
 199         download_->GetSuggestedFilename(),
 200         download_->GetMimeType(),
 201         default_filename);
 202     should_prompt_ = ShouldPromptForDownload(generated_filename);
 203     base::FilePath target_directory;
 204     if (should_prompt_) {
 205       DCHECK(!download_prefs_->IsDownloadPathManaged());
 206       // If the user is going to be prompted and the user has been prompted
 207       // before, then always prefer the last directory that the user selected.
 208       target_directory = download_prefs_->SaveFilePath();
 209     } else {
 210       target_directory = download_prefs_->DownloadPath();
 211     }
 212     virtual_path_ = target_directory.Append(generated_filename);
 213     conflict_action_ = DownloadPathReservationTracker::UNIQUIFY;
 214     should_notify_extensions_ = true;
 215   } else {
 216     virtual_path_ = download_->GetForcedFilePath();
 217     // If this is a resumed download which was previously interrupted due to an
 218     // issue with the forced path, the user is still not prompted. If the path
 219     // supplied to a programmatic download is invalid, then the caller needs to
 220     // intervene.
 221   }
 222   DCHECK(virtual_path_.IsAbsolute());
 223   DVLOG(20) << "Generated virtual path: " << virtual_path_.AsUTF8Unsafe();
 224
 225   // If the download is DOA, don't bother going any further. This would be the
 226   // case for a download that failed to initialize (e.g. the initial temporary
 227   // file couldn't be created because both the downloads directory and the
 228   // temporary directory are unwriteable).
 229   //
 230   // A virtual path is determined for DOA downloads for display purposes. This
 231   // is why this check is performed here instead of at the start.
 232   if (download_->GetState() != DownloadItem::IN_PROGRESS)
 233     return COMPLETE;
 234   return CONTINUE;
 235 }
 236
 237 DownloadTargetDeterminer::Result
 238     DownloadTargetDeterminer::DoNotifyExtensions() {
 239   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 240   DCHECK(!virtual_path_.empty());
 241
 242   next_state_ = STATE_RESERVE_VIRTUAL_PATH;
 243
 244   if (!should_notify_extensions_)
 245     return CONTINUE;
 246
 247   delegate_->NotifyExtensions(download_, virtual_path_,
 248       base::Bind(&DownloadTargetDeterminer::NotifyExtensionsDone,
 249                  weak_ptr_factory_.GetWeakPtr()));
 250   return QUIT_DOLOOP;
 251 }
 252
 253 void DownloadTargetDeterminer::NotifyExtensionsDone(
 254     const base::FilePath& suggested_path,
 255     DownloadPathReservationTracker::FilenameConflictAction conflict_action) {
 256   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 257   DVLOG(20) << "Extension suggested path: " << suggested_path.AsUTF8Unsafe();
 258
 259   // Extensions should not call back here more than once.
 260   DCHECK_EQ(STATE_RESERVE_VIRTUAL_PATH, next_state_);
 261
 262   if (!suggested_path.empty()) {
 263     // If an extension overrides the filename, then the target directory will be
 264     // forced to download_prefs_->DownloadPath() since extensions cannot place
 265     // downloaded files anywhere except there. This prevents subdirectories from
 266     // accumulating: if an extension is allowed to say that a file should go in
 267     // last_download_path/music/foo.mp3, then last_download_path will accumulate
 268     // the subdirectory /music/ so that the next download may end up in
 269     // Downloads/music/music/music/bar.mp3.
 270     base::FilePath new_path(download_prefs_->DownloadPath().Append(
 271         suggested_path).NormalizePathSeparators());
 272     // Do not pass a mime type to GenerateSafeFileName so that it does not force
 273     // the filename to have an extension if the (Chrome) extension does not
 274     // suggest it.
 275     net::GenerateSafeFileName(std::string(), false, &new_path);
 276     virtual_path_ = new_path;
 277     create_target_directory_ = true;
 278   }
 279   // An extension may set conflictAction without setting filename.
 280   if (conflict_action != DownloadPathReservationTracker::UNIQUIFY)
 281     conflict_action_ = conflict_action;
 282
 283   DoLoop();
 284 }
 285
 286 DownloadTargetDeterminer::Result
 287     DownloadTargetDeterminer::DoReserveVirtualPath() {
 288   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 289   DCHECK(!virtual_path_.empty());
 290
 291   next_state_ = STATE_PROMPT_USER_FOR_DOWNLOAD_PATH;
 292
 293   delegate_->ReserveVirtualPath(
 294       download_, virtual_path_, create_target_directory_, conflict_action_,
 295       base::Bind(&DownloadTargetDeterminer::ReserveVirtualPathDone,
 296                  weak_ptr_factory_.GetWeakPtr()));
 297   return QUIT_DOLOOP;
 298 }
 299
 300 void DownloadTargetDeterminer::ReserveVirtualPathDone(
 301     const base::FilePath& path, bool verified) {
 302   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 303   DVLOG(20) << "Reserved path: " << path.AsUTF8Unsafe()
 304             << " Verified:" << verified;
 305   DCHECK_EQ(STATE_PROMPT_USER_FOR_DOWNLOAD_PATH, next_state_);
 306
 307   should_prompt_ = (should_prompt_ || !verified);
 308   virtual_path_ = path;
 309   DoLoop();
 310 }
 311
 312 DownloadTargetDeterminer::Result
 313     DownloadTargetDeterminer::DoPromptUserForDownloadPath() {
 314   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 315   DCHECK(!virtual_path_.empty());
 316
 317   next_state_ = STATE_DETERMINE_LOCAL_PATH;
 318
 319   if (should_prompt_) {
 320     delegate_->PromptUserForDownloadPath(
 321         download_,
 322         virtual_path_,
 323         base::Bind(&DownloadTargetDeterminer::PromptUserForDownloadPathDone,
 324                    weak_ptr_factory_.GetWeakPtr()));
 325     return QUIT_DOLOOP;
 326   }
 327   return CONTINUE;
 328 }
 329
 330 void DownloadTargetDeterminer::PromptUserForDownloadPathDone(
 331     const base::FilePath& virtual_path) {
 332   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 333   DVLOG(20) << "User selected path:" << virtual_path.AsUTF8Unsafe();
 334   if (virtual_path.empty()) {
 335     CancelOnFailureAndDeleteSelf();
 336     return;
 337   }
 338   DCHECK_EQ(STATE_DETERMINE_LOCAL_PATH, next_state_);
 339
 340   virtual_path_ = virtual_path;
 341   download_prefs_->SetSaveFilePath(virtual_path_.DirName());
 342   DoLoop();
 343 }
 344
 345 DownloadTargetDeterminer::Result
 346     DownloadTargetDeterminer::DoDetermineLocalPath() {
 347   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 348   DCHECK(!virtual_path_.empty());
 349   DCHECK(local_path_.empty());
 350
 351   next_state_ = STATE_DETERMINE_MIME_TYPE;
 352
 353   delegate_->DetermineLocalPath(
 354       download_,
 355       virtual_path_,
 356       base::Bind(&DownloadTargetDeterminer::DetermineLocalPathDone,
 357                  weak_ptr_factory_.GetWeakPtr()));
 358   return QUIT_DOLOOP;
 359 }
 360
 361 void DownloadTargetDeterminer::DetermineLocalPathDone(
 362     const base::FilePath& local_path) {
 363   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 364   DVLOG(20) << "Local path: " << local_path.AsUTF8Unsafe();
 365   if (local_path.empty()) {
 366     // Path subsitution failed.
 367     CancelOnFailureAndDeleteSelf();
 368     return;
 369   }
 370   DCHECK_EQ(STATE_DETERMINE_MIME_TYPE, next_state_);
 371
 372   local_path_ = local_path;
 373   DoLoop();
 374 }
 375
 376 DownloadTargetDeterminer::Result
 377     DownloadTargetDeterminer::DoDetermineMimeType() {
 378   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 379   DCHECK(!virtual_path_.empty());
 380   DCHECK(!local_path_.empty());
 381   DCHECK(mime_type_.empty());
 382
 383   next_state_ = STATE_DETERMINE_IF_HANDLED_SAFELY_BY_BROWSER;
 384
 385   if (virtual_path_ == local_path_) {
 386     delegate_->GetFileMimeType(
 387         local_path_,
 388         base::Bind(&DownloadTargetDeterminer::DetermineMimeTypeDone,
 389                    weak_ptr_factory_.GetWeakPtr()));
 390     return QUIT_DOLOOP;
 391   }
 392   return CONTINUE;
 393 }
 394
 395 void DownloadTargetDeterminer::DetermineMimeTypeDone(
 396     const std::string& mime_type) {
 397   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 398   DVLOG(20) << "MIME type: " << mime_type;
 399   DCHECK_EQ(STATE_DETERMINE_IF_HANDLED_SAFELY_BY_BROWSER, next_state_);
 400
 401   mime_type_ = mime_type;
 402   DoLoop();
 403 }
 404
 405 #if defined(ENABLE_PLUGINS)
 406 // The code below is used by DoDetermineIfHandledSafely to determine if the
 407 // file type is handled by a sandboxed plugin.
 408 namespace {
 409
 410 void InvokeClosureAfterGetPluginCallback(
 411     const base::Closure& closure,
 412     const std::vector<content::WebPluginInfo>& unused) {
 413   closure.Run();
 414 }
 415
 416 enum ActionOnStalePluginList {
 417   RETRY_IF_STALE_PLUGIN_LIST,
 418   IGNORE_IF_STALE_PLUGIN_LIST
 419 };
 420
 421 void IsHandledBySafePlugin(content::ResourceContext* resource_context,
 422                            const GURL& url,
 423                            const std::string& mime_type,
 424                            ActionOnStalePluginList stale_plugin_action,
 425                            const base::Callback<void(bool)>& callback) {
 426   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 427   DCHECK(!mime_type.empty());
 428   using content::WebPluginInfo;
 429
 430   std::string actual_mime_type;
 431   bool is_stale = false;
 432   WebPluginInfo plugin_info;
 433
 434   content::PluginService* plugin_service =
 435       content::PluginService::GetInstance();
 436   bool plugin_found = plugin_service->GetPluginInfo(-1, -1, resource_context,
 437                                                     url, GURL(), mime_type,
 438                                                     false, &is_stale,
 439                                                     &plugin_info,
 440                                                     &actual_mime_type);
 441   if (is_stale && stale_plugin_action == RETRY_IF_STALE_PLUGIN_LIST) {
 442     // The GetPlugins call causes the plugin list to be refreshed. Once that's
 443     // done we can retry the GetPluginInfo call. We break out of this cycle
 444     // after a single retry in order to avoid retrying indefinitely.
 445     plugin_service->GetPlugins(
 446         base::Bind(&InvokeClosureAfterGetPluginCallback,
 447                    base::Bind(&IsHandledBySafePlugin,
 448                               resource_context,
 449                               url,
 450                               mime_type,
 451                               IGNORE_IF_STALE_PLUGIN_LIST,
 452                               callback)));
 453     return;
 454   }
 455   // In practice, we assume that retrying once is enough.
 456   DCHECK(!is_stale);
 457   bool is_handled_safely =
 458       plugin_found &&
 459       (plugin_info.type == WebPluginInfo::PLUGIN_TYPE_PEPPER_IN_PROCESS ||
 460        plugin_info.type == WebPluginInfo::PLUGIN_TYPE_PEPPER_OUT_OF_PROCESS);
 461   BrowserThread::PostTask(
 462       BrowserThread::UI, FROM_HERE, base::Bind(callback, is_handled_safely));
 463 }
 464
 465 }  // namespace
 466 #endif  // defined(ENABLE_PLUGINS)
 467
 468 DownloadTargetDeterminer::Result
 469     DownloadTargetDeterminer::DoDetermineIfHandledSafely() {
 470   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 471   DCHECK(!virtual_path_.empty());
 472   DCHECK(!local_path_.empty());
 473   DCHECK(!is_filetype_handled_safely_);
 474
 475   next_state_ = STATE_DETERMINE_IF_ADOBE_READER_UP_TO_DATE;
 476
 477   if (mime_type_.empty())
 478     return CONTINUE;
 479
 480   if (net::IsSupportedMimeType(mime_type_)) {
 481     is_filetype_handled_safely_ = true;
 482     return CONTINUE;
 483   }
 484
 485 #if defined(ENABLE_PLUGINS)
 486   BrowserThread::PostTask(
 487       BrowserThread::IO,
 488       FROM_HERE,
 489       base::Bind(
 490           &IsHandledBySafePlugin,
 491           GetProfile()->GetResourceContext(),
 492           net::FilePathToFileURL(local_path_),
 493           mime_type_,
 494           RETRY_IF_STALE_PLUGIN_LIST,
 495           base::Bind(&DownloadTargetDeterminer::DetermineIfHandledSafelyDone,
 496                      weak_ptr_factory_.GetWeakPtr())));
 497   return QUIT_DOLOOP;
 498 #else
 499   return CONTINUE;
 500 #endif
 501 }
 502
 503 #if defined(ENABLE_PLUGINS)
 504 void DownloadTargetDeterminer::DetermineIfHandledSafelyDone(
 505     bool is_handled_safely) {
 506   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 507   DVLOG(20) << "Is file type handled safely: " << is_filetype_handled_safely_;
 508   DCHECK_EQ(STATE_DETERMINE_IF_ADOBE_READER_UP_TO_DATE, next_state_);
 509   is_filetype_handled_safely_ = is_handled_safely;
 510   DoLoop();
 511 }
 512 #endif
 513
 514 DownloadTargetDeterminer::Result
 515     DownloadTargetDeterminer::DoDetermineIfAdobeReaderUpToDate() {
 516   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 517
 518   next_state_ = STATE_CHECK_DOWNLOAD_URL;
 519
 520 #if defined(OS_WIN)
 521   if (!local_path_.MatchesExtension(FILE_PATH_LITERAL(".pdf")))
 522     return CONTINUE;
 523   if (!IsAdobeReaderDefaultPDFViewer()) {
 524     g_is_adobe_reader_up_to_date_ = false;
 525     return CONTINUE;
 526   }
 527
 528   base::PostTaskAndReplyWithResult(
 529       BrowserThread::GetBlockingPool(),
 530       FROM_HERE,
 531       base::Bind(&::IsAdobeReaderUpToDate),
 532       base::Bind(&DownloadTargetDeterminer::DetermineIfAdobeReaderUpToDateDone,
 533                  weak_ptr_factory_.GetWeakPtr()));
 534   return QUIT_DOLOOP;
 535 #else
 536   return CONTINUE;
 537 #endif
 538 }
 539
 540 #if defined(OS_WIN)
 541 void DownloadTargetDeterminer::DetermineIfAdobeReaderUpToDateDone(
 542     bool adobe_reader_up_to_date) {
 543   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 544   DVLOG(20) << "Is Adobe Reader Up To Date: " << adobe_reader_up_to_date;
 545   DCHECK_EQ(STATE_CHECK_DOWNLOAD_URL, next_state_);
 546   g_is_adobe_reader_up_to_date_ = adobe_reader_up_to_date;
 547   DoLoop();
 548 }
 549 #endif
 550
 551 DownloadTargetDeterminer::Result
 552     DownloadTargetDeterminer::DoCheckDownloadUrl() {
 553   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 554   DCHECK(!virtual_path_.empty());
 555   next_state_ = STATE_CHECK_VISITED_REFERRER_BEFORE;
 556   delegate_->CheckDownloadUrl(
 557       download_,
 558       virtual_path_,
 559       base::Bind(&DownloadTargetDeterminer::CheckDownloadUrlDone,
 560                  weak_ptr_factory_.GetWeakPtr()));
 561   return QUIT_DOLOOP;
 562 }
 563
 564 void DownloadTargetDeterminer::CheckDownloadUrlDone(
 565     content::DownloadDangerType danger_type) {
 566   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 567   DVLOG(20) << "URL Check Result:" << danger_type;
 568   DCHECK_EQ(STATE_CHECK_VISITED_REFERRER_BEFORE, next_state_);
 569   danger_type_ = danger_type;
 570   DoLoop();
 571 }
 572
 573 DownloadTargetDeterminer::Result
 574     DownloadTargetDeterminer::DoCheckVisitedReferrerBefore() {
 575   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 576
 577   next_state_ = STATE_DETERMINE_INTERMEDIATE_PATH;
 578
 579   // Checking if there are prior visits to the referrer is only necessary if the
 580   // danger level of the download depends on the file type.
 581   if (danger_type_ != content::DOWNLOAD_DANGER_TYPE_NOT_DANGEROUS &&
 582       danger_type_ != content::DOWNLOAD_DANGER_TYPE_MAYBE_DANGEROUS_CONTENT)
 583     return CONTINUE;
 584
 585   // Assume that:
 586   // IsDangerousFile(VISITED_REFERRER) => IsDangerousFile(NO_VISITS_...)
 587   // I.e. having visited a referrer only lowers a file's danger level.
 588   if (IsDangerousFile(NO_VISITS_TO_REFERRER)) {
 589     // Only need to ping the history DB if the download would be considered safe
 590     // if there are prior visits and is considered dangerous otherwise.
 591     if (!IsDangerousFile(VISITED_REFERRER)) {
 592       // HistoryServiceFactory redirects incognito profiles to on-record
 593       // profiles.  There's no history for on-record profiles in unit_tests.
 594       HistoryService* history_service = HistoryServiceFactory::GetForProfile(
 595           GetProfile(), Profile::EXPLICIT_ACCESS);
 596
 597       if (history_service && download_->GetReferrerUrl().is_valid()) {
 598         history_service->GetVisibleVisitCountToHost(
 599             download_->GetReferrerUrl(),
 600             base::Bind(
 601                 &VisitCountsToVisitedBefore,
 602                 base::Bind(
 603                     &DownloadTargetDeterminer::CheckVisitedReferrerBeforeDone,
 604                     weak_ptr_factory_.GetWeakPtr())),
 605             &history_tracker_);
 606         return QUIT_DOLOOP;
 607       }
 608     }
 609
 610     // If the danger level doesn't depend on having visited the refererrer URL
 611     // or if original profile doesn't have a HistoryService or the referrer url
 612     // is invalid, then assume the referrer has not been visited before.
 613     is_dangerous_file_ = true;
 614     if (danger_type_ == content::DOWNLOAD_DANGER_TYPE_NOT_DANGEROUS)
 615       danger_type_ = content::DOWNLOAD_DANGER_TYPE_DANGEROUS_FILE;
 616   }
 617   return CONTINUE;
 618 }
 619
 620 void DownloadTargetDeterminer::CheckVisitedReferrerBeforeDone(
 621     bool visited_referrer_before) {
 622   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 623   DCHECK_EQ(STATE_DETERMINE_INTERMEDIATE_PATH, next_state_);
 624   if (IsDangerousFile(visited_referrer_before ? VISITED_REFERRER
 625                                               : NO_VISITS_TO_REFERRER)) {
 626     is_dangerous_file_ = true;
 627     if (danger_type_ == content::DOWNLOAD_DANGER_TYPE_NOT_DANGEROUS)
 628       danger_type_ = content::DOWNLOAD_DANGER_TYPE_DANGEROUS_FILE;
 629   }
 630   DoLoop();
 631 }
 632
 633 DownloadTargetDeterminer::Result
 634     DownloadTargetDeterminer::DoDetermineIntermediatePath() {
 635   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 636   DCHECK(!virtual_path_.empty());
 637   DCHECK(!local_path_.empty());
 638   DCHECK(intermediate_path_.empty());
 639   DCHECK(!virtual_path_.MatchesExtension(kCrdownloadSuffix));
 640   DCHECK(!local_path_.MatchesExtension(kCrdownloadSuffix));
 641
 642   next_state_ = STATE_NONE;
 643
 644   // Note that the intermediate filename is always uniquified (i.e. if a file by
 645   // the same name exists, it is never overwritten). Therefore the code below
 646   // does not attempt to find a name that doesn't conflict with an existing
 647   // file.
 648
 649   // If the actual target of the download is a virtual path, then the local path
 650   // is considered to point to a temporary path. A separate intermediate path is
 651   // unnecessary since the local path already serves that purpose.
 652   if (virtual_path_.BaseName() != local_path_.BaseName()) {
 653     intermediate_path_ = local_path_;
 654     return COMPLETE;
 655   }
 656
 657   // If the download has a forced path and is safe, then just use the
 658   // target path. In practice the temporary download file that was created prior
 659   // to download filename determination is already named
 660   // download_->GetForcedFilePath().
 661   if (danger_type_ == content::DOWNLOAD_DANGER_TYPE_NOT_DANGEROUS &&
 662       !download_->GetForcedFilePath().empty()) {
 663     DCHECK_EQ(download_->GetForcedFilePath().value(), local_path_.value());
 664     intermediate_path_ = local_path_;
 665     return COMPLETE;
 666   }
 667
 668   // Other safe downloads get a .crdownload suffix for their intermediate name.
 669   if (danger_type_ == content::DOWNLOAD_DANGER_TYPE_NOT_DANGEROUS) {
 670     intermediate_path_ = GetCrDownloadPath(local_path_);
 671     return COMPLETE;
 672   }
 673
 674   // If this is a resumed download, then re-use the existing intermediate path
 675   // if one is available. A resumed download shouldn't cause a non-dangerous
 676   // download to be considered dangerous upon resumption. Therefore the
 677   // intermediate file should already be in the correct form.
 678   if (is_resumption_ && !download_->GetFullPath().empty() &&
 679       local_path_.DirName() == download_->GetFullPath().DirName()) {
 680     DCHECK_NE(content::DOWNLOAD_DANGER_TYPE_NOT_DANGEROUS,
 681               download_->GetDangerType());
 682     DCHECK_EQ(kCrdownloadSuffix, download_->GetFullPath().Extension());
 683     intermediate_path_ = download_->GetFullPath();
 684     return COMPLETE;
 685   }
 686
 687   // Dangerous downloads receive a random intermediate name that looks like:
 688   // 'Unconfirmed <random>.crdownload'.
 689   const base::FilePath::CharType kUnconfirmedFormatSuffix[] =
 690       FILE_PATH_LITERAL(" %d.crdownload");
 691   // Range of the <random> uniquifier.
 692   const int kUnconfirmedUniquifierRange = 1000000;
 693 #if defined(OS_WIN)
 694   base::string16 unconfirmed_format =
 695       l10n_util::GetStringUTF16(IDS_DOWNLOAD_UNCONFIRMED_PREFIX);
 696 #else
 697   std::string unconfirmed_format =
 698       l10n_util::GetStringUTF8(IDS_DOWNLOAD_UNCONFIRMED_PREFIX);
 699 #endif
 700   unconfirmed_format.append(kUnconfirmedFormatSuffix);
 701
 702   base::FilePath::StringType file_name = base::StringPrintf(
 703       unconfirmed_format.c_str(),
 704       base::RandInt(0, kUnconfirmedUniquifierRange));
 705   intermediate_path_ = local_path_.DirName().Append(file_name);
 706   return COMPLETE;
 707 }
 708
 709 void DownloadTargetDeterminer::ScheduleCallbackAndDeleteSelf() {
 710   DCHECK(download_);
 711   DVLOG(20) << "Scheduling callback. Virtual:" << virtual_path_.AsUTF8Unsafe()
 712             << " Local:" << local_path_.AsUTF8Unsafe()
 713             << " Intermediate:" << intermediate_path_.AsUTF8Unsafe()
 714             << " Should prompt:" << should_prompt_
 715             << " Danger type:" << danger_type_
 716             << " Is dangerous file:" << is_dangerous_file_;
 717   scoped_ptr<DownloadTargetInfo> target_info(new DownloadTargetInfo);
 718
 719   target_info->target_path = local_path_;
 720   target_info->target_disposition =
 721       (HasPromptedForPath() || should_prompt_
 722            ? DownloadItem::TARGET_DISPOSITION_PROMPT
 723            : DownloadItem::TARGET_DISPOSITION_OVERWRITE);
 724   target_info->danger_type = danger_type_;
 725   target_info->is_dangerous_file = is_dangerous_file_;
 726   target_info->intermediate_path = intermediate_path_;
 727   target_info->mime_type = mime_type_;
 728   target_info->is_filetype_handled_safely = is_filetype_handled_safely_;
 729
 730   base::MessageLoop::current()->PostTask(
 731       FROM_HERE, base::Bind(completion_callback_, base::Passed(&target_info)));
 732   completion_callback_.Reset();
 733   delete this;
 734 }
 735
 736 void DownloadTargetDeterminer::CancelOnFailureAndDeleteSelf() {
 737   // Path substitution failed.
 738   virtual_path_.clear();
 739   local_path_.clear();
 740   intermediate_path_.clear();
 741   ScheduleCallbackAndDeleteSelf();
 742 }
 743
 744 Profile* DownloadTargetDeterminer::GetProfile() {
 745   DCHECK(download_->GetBrowserContext());
 746   return Profile::FromBrowserContext(download_->GetBrowserContext());
 747 }
 748
 749 bool DownloadTargetDeterminer::ShouldPromptForDownload(
 750     const base::FilePath& filename) const {
 751   if (is_resumption_) {
 752     // For resumed downloads, if the target disposition or prefs require
 753     // prompting, the user has already been prompted. Try to respect the user's
 754     // selection, unless we've discovered that the target path cannot be used
 755     // for some reason.
 756     content::DownloadInterruptReason reason = download_->GetLastReason();
 757     return (reason == content::DOWNLOAD_INTERRUPT_REASON_FILE_ACCESS_DENIED ||
 758             reason == content::DOWNLOAD_INTERRUPT_REASON_FILE_NO_SPACE ||
 759             reason == content::DOWNLOAD_INTERRUPT_REASON_FILE_TOO_LARGE);
 760   }
 761
 762   // If the download path is forced, don't prompt.
 763   if (!download_->GetForcedFilePath().empty()) {
 764     // 'Save As' downloads shouldn't have a forced path.
 765     DCHECK(DownloadItem::TARGET_DISPOSITION_PROMPT !=
 766            download_->GetTargetDisposition());
 767     return false;
 768   }
 769
 770   // Don't ask where to save if the download path is managed. Even if the user
 771   // wanted to be prompted for "all" downloads, or if this was a 'Save As'
 772   // download.
 773   if (download_prefs_->IsDownloadPathManaged())
 774     return false;
 775
 776   // Prompt if this is a 'Save As' download.
 777   if (download_->GetTargetDisposition() ==
 778       DownloadItem::TARGET_DISPOSITION_PROMPT)
 779     return true;
 780
 781   // Check if the user has the "Always prompt for download location" preference
 782   // set. If so we prompt for most downloads except for the following scenarios:
 783   // 1) Extension installation. Note that we only care here about the case where
 784   //    an extension is installed, not when one is downloaded with "save as...".
 785   // 2) Filetypes marked "always open." If the user just wants this file opened,
 786   //    don't bother asking where to keep it.
 787   if (download_prefs_->PromptForDownload() &&
 788       !download_crx_util::IsExtensionDownload(*download_) &&
 789       !filename.MatchesExtension(extensions::kExtensionFileExtension) &&
 790       !download_prefs_->IsAutoOpenEnabledBasedOnExtension(filename))
 791     return true;
 792
 793   // Otherwise, don't prompt. Note that the user might still be prompted if
 794   // there are unresolved conflicts during path reservation (e.g. due to the
 795   // target path being unwriteable or because there are too many conflicting
 796   // files), or if an extension signals that the user be prompted on a filename
 797   // conflict.
 798   return false;
 799 }
 800
 801 bool DownloadTargetDeterminer::HasPromptedForPath() const {
 802   return (is_resumption_ && download_->GetTargetDisposition() ==
 803                                 DownloadItem::TARGET_DISPOSITION_PROMPT);
 804 }
 805
 806 bool DownloadTargetDeterminer::IsDangerousFile(PriorVisitsToReferrer visits) {
 807   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 808
 809   // If the user has has been prompted or will be, assume that the user has
 810   // approved the download. A programmatic download is considered safe unless it
 811   // contains malware.
 812   if (HasPromptedForPath() || should_prompt_ ||
 813       !download_->GetForcedFilePath().empty())
 814     return false;
 815
 816   const bool is_extension_download =
 817       download_crx_util::IsExtensionDownload(*download_);
 818
 819   // User-initiated extension downloads from pref-whitelisted sources are not
 820   // considered dangerous.
 821   if (download_->HasUserGesture() &&
 822       is_extension_download &&
 823       download_crx_util::OffStoreInstallAllowedByPrefs(
 824           GetProfile(), *download_)) {
 825     return false;
 826   }
 827
 828 #if defined(ENABLE_EXTENSIONS)
 829   // Extensions that are not from the gallery are considered dangerous.
 830   // When off-store install is disabled we skip this, since in this case, we
 831   // will not offer to install the extension.
 832   if (extensions::FeatureSwitch::easy_off_store_install()->IsEnabled() &&
 833       is_extension_download &&
 834       !extensions::WebstoreInstaller::GetAssociatedApproval(*download_)) {
 835     return true;
 836   }
 837 #endif
 838
 839   // Anything the user has marked auto-open is OK if it's user-initiated.
 840   if (download_prefs_->IsAutoOpenEnabledBasedOnExtension(virtual_path_) &&
 841       download_->HasUserGesture())
 842     return false;
 843
 844   switch (download_util::GetFileDangerLevel(virtual_path_.BaseName())) {
 845     case download_util::NOT_DANGEROUS:
 846       return false;
 847
 848     case download_util::ALLOW_ON_USER_GESTURE:
 849       // "Allow on user gesture" is OK when we have a user gesture and the
 850       // hosting page has been visited before today.
 851       if (download_->GetTransitionType() &
 852           ui::PAGE_TRANSITION_FROM_ADDRESS_BAR) {
 853         return false;
 854       }
 855       return !download_->HasUserGesture() || visits == NO_VISITS_TO_REFERRER;
 856
 857     case download_util::DANGEROUS:
 858       return true;
 859   }
 860   NOTREACHED();
 861   return false;
 862 }
 863
 864 void DownloadTargetDeterminer::OnDownloadDestroyed(
 865     DownloadItem* download) {
 866   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 867   DCHECK_EQ(download_, download);
 868   CancelOnFailureAndDeleteSelf();
 869 }
 870
 871 // static
 872 void DownloadTargetDeterminer::Start(content::DownloadItem* download,
 873                                      const base::FilePath& initial_virtual_path,
 874                                      DownloadPrefs* download_prefs,
 875                                      DownloadTargetDeterminerDelegate* delegate,
 876                                      const CompletionCallback& callback) {
 877   // DownloadTargetDeterminer owns itself and will self destruct when the job is
 878   // complete or the download item is destroyed. The callback is always invoked
 879   // asynchronously.
 880   new DownloadTargetDeterminer(download, initial_virtual_path, download_prefs,
 881                                delegate, callback);
 882 }
 883
 884 // static
 885 base::FilePath DownloadTargetDeterminer::GetCrDownloadPath(
 886     const base::FilePath& suggested_path) {
 887   return base::FilePath(suggested_path.value() + kCrdownloadSuffix);
 888 }
 889
 890 #if defined(OS_WIN)
 891 // static
 892 bool DownloadTargetDeterminer::IsAdobeReaderUpToDate() {
 893   return g_is_adobe_reader_up_to_date_;
 894 }
 895 #endif