[Resumption 9/11] Handle filename determination for resumed downloads.

chrome/browser/download/download_target_determiner.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/download/download_target_determiner.h"
 
 #include "base/prefs/pref_service.h"
 #include "base/rand_util.h"
 #include "base/stringprintf.h"
 #include "base/time.h"
 #include "chrome/browser/download/chrome_download_manager_delegate.h"
 #include "chrome/browser/download/download_crx_util.h"
 #include "chrome/browser/download/download_extensions.h"
 #include "chrome/browser/download/download_prefs.h"
 #include "chrome/browser/download/download_util.h"
 #include "chrome/browser/extensions/webstore_installer.h"
 #include "chrome/browser/history/history_service.h"
 #include "chrome/browser/history/history_service_factory.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/extensions/extension.h"
 #include "chrome/common/extensions/feature_switch.h"
 #include "chrome/common/pref_names.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/browser_thread.h"
+#include "content/public/browser/download_interrupt_reasons.h"
 #include "grit/generated_resources.h"
 #include "net/base/net_util.h"
 #include "ui/base/l10n/l10n_util.h"
 
 #if defined(OS_CHROMEOS)
 #include "chrome/browser/chromeos/drive/download_handler.h"
 #include "chrome/browser/chromeos/drive/file_system_util.h"
 #endif
 
 using content::BrowserThread;
@@ skipping 16 matching lines @@
       (first_visit.LocalMidnight() < base::Time::Now().LocalMidnight()));
 }
 
 } // namespace
 
 DownloadTargetDeterminerDelegate::~DownloadTargetDeterminerDelegate() {
 }
 
 DownloadTargetDeterminer::DownloadTargetDeterminer(
     DownloadItem* download,
+    const base::FilePath& initial_virtual_path,
     DownloadPrefs* download_prefs,
     const base::FilePath& last_selected_directory,
     DownloadTargetDeterminerDelegate* delegate,
     const content::DownloadTargetCallback& callback)
     : next_state_(STATE_GENERATE_TARGET_PATH),
       should_prompt_(false),
+      should_notify_extensions_(false),
       create_directory_(false),
-      conflict_action_(download->GetForcedFilePath().empty() ?
-                       DownloadPathReservationTracker::UNIQUIFY :
-                       DownloadPathReservationTracker::OVERWRITE),
+      conflict_action_(DownloadPathReservationTracker::OVERWRITE),
       danger_type_(download->GetDangerType()),
+      virtual_path_(initial_virtual_path),
       download_(download),
+      is_resumption_(download_->GetLastReason() !=
+                     content::DOWNLOAD_INTERRUPT_REASON_NONE &&
+                     !initial_virtual_path.empty()),
       download_prefs_(download_prefs),
       delegate_(delegate),
       last_selected_directory_(last_selected_directory),
       completion_callback_(callback),
       weak_ptr_factory_(this) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DCHECK(download_);
   DCHECK(delegate);
   download_->AddObserver(this);
 
@@ skipping 47 matching lines @@
   // return QUIT_DOLOOP. In this case, an inner DoLoop() may complete the target
   // determination and delete |this|.
 
   if (result == COMPLETE)
     ScheduleCallbackAndDeleteSelf();
 }
 
 DownloadTargetDeterminer::Result
     DownloadTargetDeterminer::DoGenerateTargetPath() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  DCHECK(virtual_path_.empty());
   DCHECK(local_path_.empty());
+  DCHECK(!should_prompt_);
+  DCHECK(!should_notify_extensions_);

[Randy Smith (Not in Mondays), 2013/05/24 01:53:55]

Why is this a member variable rather than a local variable?  It looks like it's
just used in this routine.

[asanka, 2013/05/29 22:30:11]

It's set here, but is read in DoNotifyExtensions()

+  DCHECK_EQ(DownloadPathReservationTracker::OVERWRITE, conflict_action_);
   bool is_forced_path = !download_->GetForcedFilePath().empty();
 
   next_state_ = STATE_NOTIFY_EXTENSIONS;
 
-  // If we don't have a forced path, we should construct a path for the
-  // download. Forced paths are only specified for programmatic downloads
-  // (WebStore, Drag&Drop). Treat the path as a virtual path. We will eventually
-  // determine whether this is a local path and if not, figure out a local path.
-  if (!is_forced_path) {
-   std::string default_filename(
+  if (!virtual_path_.empty() && HasPromptedForPath() && !is_forced_path) {
+    // The download is being resumed and the user has already been prompted for
+    // a path. Assume that it's okay to overwrite the file if there's a
+    // conflict and reuse the selection.
+    // Note: |virtual_path_| may already be uniquified. In this case setting
+    // conflict_action_ to UNIQUIFY may cause additional levels of uniquifiers
+    // (e.g. "foo (1) (1).txt").

[Randy Smith (Not in Mondays), 2013/05/24 01:53:55]

Why is this comment still relevant?  If we prompted them, we're going to
overwrite, right?

[asanka, 2013/05/29 22:30:11]

Yes. The comment was explaining why we aren't setting conflict_action_ to
UNIQUIFY in case someone feels like doing so in the future.

Comment removed.

+    should_prompt_ = ShouldPromptForDownload(virtual_path_);
+  } else if (!is_forced_path) {
+    // If we don't have a forced path, we should construct a path for the
+    // download. Forced paths are only specified for programmatic downloads
+    // (WebStore, Drag&Drop). Treat the path as a virtual path. We will
+    // eventually determine whether this is a local path and if not, figure out
+    // a local path.
+    std::string default_filename(
         l10n_util::GetStringUTF8(IDS_DEFAULT_DOWNLOAD_FILENAME));
     base::FilePath generated_filename = net::GenerateFileName(
         download_->GetURL(),
         download_->GetContentDisposition(),
         GetProfile()->GetPrefs()->GetString(prefs::kDefaultCharset),
         download_->GetSuggestedFilename(),
         download_->GetMimeType(),
         default_filename);
     should_prompt_ = ShouldPromptForDownload(generated_filename);
     base::FilePath target_directory;
     if (should_prompt_ && !last_selected_directory_.empty()) {
       DCHECK(!download_prefs_->IsDownloadPathManaged());
       // If the user is going to be prompted and the user has been prompted
       // before, then always prefer the last directory that the user selected.
       target_directory = last_selected_directory_;
     } else {
       target_directory = download_prefs_->DownloadPath();
     }
     virtual_path_ = target_directory.Append(generated_filename);
+    conflict_action_ = DownloadPathReservationTracker::UNIQUIFY;
+    should_notify_extensions_ = true;
   } else {
     DCHECK(!should_prompt_);

[Randy Smith (Not in Mondays), 2013/05/24 01:53:55]

nit: Feels a little redundant with identical DCHECK() at top of function.

[asanka, 2013/05/29 22:30:11]

Done.

     virtual_path_ = download_->GetForcedFilePath();
+    // If this is a resumed download which was previously interrupted due to an
+    // issue with the forced path, the user is still not prompted. If the path
+    // supplied to a programmatic download is invalid, then the caller needs to
+    // intervene.
   }
   DCHECK(virtual_path_.IsAbsolute());
   DVLOG(20) << "Generated virtual path: " << virtual_path_.AsUTF8Unsafe();
 
   // If the download is DOA, don't bother going any further. This would be the
   // case for a download that failed to initialize (e.g. the initial temporary
   // file couldn't be created because both the downloads directory and the
   // temporary directory are unwriteable).
   //
   // A virtual path is determined for DOA downloads for display purposes. This
   // is why this check is performed here instead of at the start.
   if (!download_->IsInProgress())
     return COMPLETE;
   return CONTINUE;
 }
 
 DownloadTargetDeterminer::Result
     DownloadTargetDeterminer::DoNotifyExtensions() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DCHECK(!virtual_path_.empty());
 
   next_state_ = STATE_RESERVE_VIRTUAL_PATH;
 
-  // If the target path is forced or if we don't have an extensions event
-  // router, then proceed with the original path.
-  if (!download_->GetForcedFilePath().empty())
+  if (!should_notify_extensions_)
     return CONTINUE;
 
   delegate_->NotifyExtensions(download_, virtual_path_,
       base::Bind(&DownloadTargetDeterminer::NotifyExtensionsDone,
                  weak_ptr_factory_.GetWeakPtr()));
   return QUIT_DOLOOP;
 }
 
 void DownloadTargetDeterminer::NotifyExtensionsDone(
     const base::FilePath& suggested_path,
@@ skipping 130 matching lines @@
 DownloadTargetDeterminer::Result
     DownloadTargetDeterminer::DoCheckVisitedReferrerBefore() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   next_state_ = STATE_DETERMINE_INTERMEDIATE_PATH;
 
   // Checking if there are prior visits to the referrer is only necessary if the
   // danger level of the download depends on the file type. This excludes cases
   // where the download has already been deemed dangerous, or where the user is
   // going to be prompted or where this is a programmatic download.
-  if (danger_type_ != content::DOWNLOAD_DANGER_TYPE_NOT_DANGEROUS ||
-      should_prompt_ ||
-      !download_->GetForcedFilePath().empty()) {

[Randy Smith (Not in Mondays), 2013/05/24 01:53:55]

Sorry, confused.  Why remove the other two checks?

[asanka, 2013/05/29 22:30:11]

The checks were moved to IsDangerousFile().

+  if (danger_type_ != content::DOWNLOAD_DANGER_TYPE_NOT_DANGEROUS)
     return CONTINUE;
-  }
 
   // Assume that:
   // IsDangerousFile(VISITED_REFERRER) => IsDangerousFile(NO_VISITS_...)
   // I.e. having visited a referrer only lowers a file's danger level.
   if (IsDangerousFile(NO_VISITS_TO_REFERRER)) {
     // Only need to ping the history DB if the download would be considered safe
     // if there are prior visits and is considered dangerous otherwise.
     if (!IsDangerousFile(VISITED_REFERRER)) {
       // HistoryServiceFactory redirects incognito profiles to on-record
       // profiles.  There's no history for on-record profiles in unit_tests.
@@ skipping 26 matching lines @@
     danger_type_ = content::DOWNLOAD_DANGER_TYPE_DANGEROUS_FILE;
   DoLoop();
 }
 
 DownloadTargetDeterminer::Result
     DownloadTargetDeterminer::DoDetermineIntermediatePath() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DCHECK(!virtual_path_.empty());
   DCHECK(!local_path_.empty());
   DCHECK(intermediate_path_.empty());
+  DCHECK(!virtual_path_.MatchesExtension(FILE_PATH_LITERAL(".crdownload")));
+  DCHECK(!local_path_.MatchesExtension(FILE_PATH_LITERAL(".crdownload")));
 
   next_state_ = STATE_NONE;
 
   // Note that the intermediate filename is always uniquified (i.e. if a file by
   // the same name exists, it is never overwritten). Therefore the code below
   // does not attempt to find a name that doesn't conflict with an existing
   // file.
 
   // If the actual target of the download is a virtual path, then the local path
   // is considered to point to a temporary path. A separate intermediate path is
@@ skipping 46 matching lines @@
   DCHECK(download_);
   DVLOG(20) << "Scheduling callback. Virtual:" << virtual_path_.AsUTF8Unsafe()
             << " Local:" << local_path_.AsUTF8Unsafe()
             << " Intermediate:" << intermediate_path_.AsUTF8Unsafe()
             << " Should prompt:" << should_prompt_
             << " Danger type:" << danger_type_;
   MessageLoop::current()->PostTask(
       FROM_HERE,
       base::Bind(completion_callback_,
                  local_path_,
-                 (should_prompt_ ? DownloadItem::TARGET_DISPOSITION_PROMPT :
-                                   DownloadItem::TARGET_DISPOSITION_OVERWRITE),
+                 (HasPromptedForPath()
+                  ? DownloadItem::TARGET_DISPOSITION_PROMPT
+                  : DownloadItem::TARGET_DISPOSITION_OVERWRITE),
                  danger_type_,
                  intermediate_path_));
   completion_callback_.Reset();
   delete this;
 }
 
 void DownloadTargetDeterminer::CancelOnFailureAndDeleteSelf() {
   // Path substitution failed.
   virtual_path_.clear();
   local_path_.clear();
   intermediate_path_.clear();
   ScheduleCallbackAndDeleteSelf();
 }
 
 Profile* DownloadTargetDeterminer::GetProfile() {
   DCHECK(download_->GetBrowserContext());
   return Profile::FromBrowserContext(download_->GetBrowserContext());
 }
 
 bool DownloadTargetDeterminer::ShouldPromptForDownload(
-    const base::FilePath& filename) {
+    const base::FilePath& filename) const {
+  if (is_resumption_) {
+    // If the target disposition or prefs require prompting, the user has
+    // already been prompted. Try to respect the user's selection, unless we've
+    // discovered that the target path cannot be used for some reason.
+    content::DownloadInterruptReason reason = download_->GetLastReason();
+    return (reason == content::DOWNLOAD_INTERRUPT_REASON_FILE_ACCESS_DENIED ||
+            reason == content::DOWNLOAD_INTERRUPT_REASON_FILE_NO_SPACE ||
+            reason == content::DOWNLOAD_INTERRUPT_REASON_FILE_TOO_LARGE);
+  }
+
   // If the download path is forced, don't prompt.
   if (!download_->GetForcedFilePath().empty()) {
     // 'Save As' downloads shouldn't have a forced path.
-    DCHECK_NE(DownloadItem::TARGET_DISPOSITION_PROMPT,
-              download_->GetTargetDisposition());
+    DCHECK(is_resumption_ ||

[Randy Smith (Not in Mondays), 2013/05/24 01:53:55]

This portion of the DCHECK seems strange, since there was just a return on the
is_resumption_ test above.

[asanka, 2013/05/29 22:30:11]

Done.

+           (DownloadItem::TARGET_DISPOSITION_PROMPT !=
+            download_->GetTargetDisposition()));
     return false;
   }
 
   // Don't ask where to save if the download path is managed. Even if the user
   // wanted to be prompted for "all" downloads, or if this was a 'Save As'
   // download.
   if (download_prefs_->IsDownloadPathManaged())
     return false;
 
   // Prompt if this is a 'Save As' download.
@@ skipping 14 matching lines @@
     return true;
 
   // Otherwise, don't prompt. Note that the user might still be prompted if
   // there are unresolved conflicts during path reservation (e.g. due to the
   // target path being unwriteable or because there are too many conflicting
   // files), or if an extension signals that the user be prompted on a filename
   // conflict.
   return false;
 }
 
+bool DownloadTargetDeterminer::HasPromptedForPath() const {
+  return should_prompt_ ||
+      (is_resumption_ && download_->GetTargetDisposition() ==
+       DownloadItem::TARGET_DISPOSITION_PROMPT);
+}
+
 bool DownloadTargetDeterminer::IsDangerousFile(PriorVisitsToReferrer visits) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  // If the user has has been prompted, assume that the user has approved the
+  // download. Programmatic downloads are considered safe unless it contains

[Randy Smith (Not in Mondays), 2013/05/24 01:53:55]

nit: "it contains" -> "they contain" (or "A programmatic download is")

[asanka, 2013/05/29 22:30:11]

Done.

+  // malware.
+  if (HasPromptedForPath() || !download_->GetForcedFilePath().empty())
+    return false;
+
   const bool is_extension_download =
       download_crx_util::IsExtensionDownload(*download_);
 
   // User-initiated extension downloads from pref-whitelisted sources are not
   // considered dangerous.
   if (download_->HasUserGesture() &&
       is_extension_download &&
       download_crx_util::OffStoreInstallAllowedByPrefs(
           GetProfile(), *download_)) {
     return false;
@@ skipping 36 matching lines @@
 void DownloadTargetDeterminer::OnDownloadDestroyed(
     DownloadItem* download) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DCHECK_EQ(download_, download);
   CancelOnFailureAndDeleteSelf();
 }
 
 // static
 void DownloadTargetDeterminer::Start(
     content::DownloadItem* download,
+    const base::FilePath& initial_virtual_path,
     DownloadPrefs* download_prefs,
     const base::FilePath& last_selected_directory,
     DownloadTargetDeterminerDelegate* delegate,
     const content::DownloadTargetCallback& callback) {
   // DownloadTargetDeterminer owns itself and will self destruct when the job is
   // complete or the download item is destroyed. The callback is always invoked
   // asynchronously.
-  new DownloadTargetDeterminer(download, download_prefs,
+  new DownloadTargetDeterminer(download, initial_virtual_path, download_prefs,
                                last_selected_directory, delegate, callback);
 }
 
 // static
 base::FilePath DownloadTargetDeterminer::GetCrDownloadPath(
     const base::FilePath& suggested_path) {
   return base::FilePath(suggested_path.value() +
                         FILE_PATH_LITERAL(".crdownload"));
 }