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// 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 <memory>
#include <string>
#include "base/files/file_path.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "base/task/cancelable_task_tracker.h"
#include "build/build_config.h"
#include "chrome/browser/download/download_target_determiner_delegate.h"
#include "chrome/browser/download/download_target_info.h"
#include "chrome/common/safe_browsing/download_file_types.pb.h"
#include "components/download/public/common/download_danger_type.h"
#include "components/download/public/common/download_item.h"
#include "components/download/public/common/download_path_reservation_tracker.h"
#include "content/public/browser/download_manager_delegate.h"
#include "ppapi/buildflags/buildflags.h"
class Profile;
class DownloadPrefs;
// Determines the target of the download.
// Terminology:
// Virtual Path: A path representing the target of the download that may or
// may not be a physical file path. E.g. if the target of the download is in
// cloud storage, then the virtual path may be relative to a logical mount
// point.
// Local Path: A local file system path where the downloads system should
// write the file to.
// Intermediate Path: Where the data should be written to during the course of
// the download. Once the download completes, the file could be renamed to
// Local Path.
// DownloadTargetDeterminer is a self owned object that performs the work of
// determining the download target. It observes the DownloadItem and aborts the
// process if the download is removed. DownloadTargetDeterminerDelegate is
// responsible for providing external dependencies and prompting the user if
// necessary.
// The only public entrypoint is the static Start() method which creates an
// instance of DownloadTargetDeterminer.
class DownloadTargetDeterminer : public download::DownloadItem::Observer {
using CompletionCallback =
// Start the process of determing the target of |download|.
// |initial_virtual_path| if non-empty, defines the initial virtual path for
// the target determination process. If one isn't specified, one will be
// generated based on the response data specified in |download| and the
// users' downloads directory.
// Note: |initial_virtual_path| is only used if download has prompted the
// user before and doesn't have a forced path.
// |download_prefs| is required and must outlive |download|. It is used for
// determining the user's preferences regarding the default downloads
// directory, prompting and auto-open behavior.
// |delegate| is required and must live until |callback| is invoked.
// |callback| will be scheduled asynchronously on the UI thread after download
// determination is complete or after |download| is destroyed.
// Start() should be called on the UI thread.
static void Start(
download::DownloadItem* download,
const base::FilePath& initial_virtual_path,
DownloadPrefs* download_prefs,
DownloadTargetDeterminerDelegate* delegate,
const CompletionCallback& callback);
// Returns a .crdownload intermediate path for the |suggested_path|.
static base::FilePath GetCrDownloadPath(const base::FilePath& suggested_path);
#if defined(OS_WIN)
// Returns true if Adobe Reader is up to date. This information refreshed
// only when Start() gets called for a PDF and Adobe Reader is the default
// System PDF viewer.
static bool IsAdobeReaderUpToDate();
// The main workflow is controlled via a set of state transitions. Each state
// has an associated handler. The handler for STATE_FOO is DoFoo. Each handler
// performs work, determines the next state to transition to and returns a
// Result indicating how the workflow should proceed. The loop ends when a
// handler returns COMPLETE.
enum State {
// Result code returned by each step of the workflow below. Controls execution
// of DoLoop().
enum Result {
// Continue processing. next_state_ is required to not be STATE_NONE.
// The DoLoop() that invoked the handler should exit. This value is
// typically returned when the handler has invoked an asynchronous operation
// and is expecting a callback. If a handler returns this value, it has
// taken responsibility for ensuring that DoLoop() is invoked. It is
// possible that the handler has invoked another DoLoop() already.
// Target determination is complete.
// Used with GetDangerLevel to indicate whether the user has visited the
// referrer URL for the download prior to today.
enum PriorVisitsToReferrer {
// Construct a DownloadTargetDeterminer object. Constraints on the arguments
// are as per Start() above.
download::DownloadItem* download,
const base::FilePath& initial_virtual_path,
DownloadPrefs* download_prefs,
DownloadTargetDeterminerDelegate* delegate,
const CompletionCallback& callback);
~DownloadTargetDeterminer() override;
// Invoke each successive handler until a handler returns QUIT_DOLOOP or
// COMPLETE. Note that as a result, this object might be deleted. So |this|
// should not be accessed after calling DoLoop().
void DoLoop();
// === Main workflow ===
// Generates an initial target path. This target is based only on the state of
// the download item.
// Next state:
// - STATE_NONE : If the download is not in progress, returns COMPLETE.
// - STATE_NOTIFY_EXTENSIONS : All other downloads.
Result DoGenerateTargetPath();
// Notifies downloads extensions. If any extension wishes to override the
// download filename, it will respond to the OnDeterminingFilename()
// notification.
// Next state:
Result DoNotifyExtensions();
// Callback invoked after extensions are notified. Updates |virtual_path_| and
// |conflict_action_|.
void NotifyExtensionsDone(
const base::FilePath& new_path,
// Invokes ReserveVirtualPath() on the delegate to acquire a reservation for
// the path. See DownloadPathReservationTracker.
// Next state:
Result DoReserveVirtualPath();
// Callback invoked after the delegate aquires a path reservation.
void ReserveVirtualPathDone(download::PathValidationResult result,
const base::FilePath& path);
// Presents a file picker to the user if necessary.
// Next state:
Result DoRequestConfirmation();
// Callback invoked after the file picker completes. Cancels the download if
// the user cancels the file picker.
void RequestConfirmationDone(DownloadConfirmationResult result,
const base::FilePath& virtual_path);
// Up until this point, the path that was used is considered to be a virtual
// path. This step determines the local file system path corresponding to this
// virtual path. The translation is done by invoking the DetermineLocalPath()
// method on the delegate.
// Next state:
Result DoDetermineLocalPath();
// Callback invoked when the delegate has determined local path.
void DetermineLocalPathDone(const base::FilePath& local_path);
// Determine the MIME type corresponding to the local file path. This is only
// done if the local path and the virtual path was the same. I.e. The file is
// intended for the local file system. This restriction is there because the
// resulting MIME type is only valid for determining whether the browser can
// handle the download if it were opened via a file:// URL.
// Next state:
Result DoDetermineMimeType();
// Callback invoked when the MIME type is available. Since determination of
// the MIME type can involve disk access, it is done in the blocking pool.
void DetermineMimeTypeDone(const std::string& mime_type);
// Determine if the file type can be handled safely by the browser if it were
// to be opened via a file:// URL.
// Next state:
Result DoDetermineIfHandledSafely();
// Callback invoked when a decision is available about whether the file type
// can be handled safely by the browser.
void DetermineIfHandledSafelyDone(bool is_handled_safely);
// Determine if Adobe Reader is up to date. Only do the check on Windows for
// .pdf file targets.
// Next state:
Result DoDetermineIfAdobeReaderUpToDate();
#if defined(OS_WIN)
// Callback invoked when a decision is available about whether Adobe Reader
// is up to date.
void DetermineIfAdobeReaderUpToDateDone(bool adobe_reader_up_to_date);
// Checks whether the downloaded URL is malicious. Invokes the
// DownloadProtectionService via the delegate.
// Next state:
Result DoCheckDownloadUrl();
// Callback invoked after the delegate has checked the download URL. Sets the
// danger type of the download to |danger_type|.
void CheckDownloadUrlDone(download::DownloadDangerType danger_type);
// Checks if the user has visited the referrer URL of the download prior to
// today. The actual check is only performed if it would be needed to
// determine the danger type of the download.
// Next state:
Result DoCheckVisitedReferrerBefore();
// Callback invoked after completion of history check for prior visits to
// referrer URL.
void CheckVisitedReferrerBeforeDone(bool visited_referrer_before);
// Determines the intermediate path. Once this step completes, downloads
// target determination is complete. The determination assumes that the
// intermediate file will never be overwritten (always uniquified if needed).
// Next state:
Result DoDetermineIntermediatePath();
// === End of main workflow ===
// Utilities:
// Schedules the completion callback to be run on the UI thread and deletes
// this object. The determined target info will be passed into the callback
// if |interrupt_reason| is NONE. Otherwise, only the interrupt reason will be
// passed on.
void ScheduleCallbackAndDeleteSelf(download::DownloadInterruptReason result);
Profile* GetProfile() const;
// Determine if the download requires confirmation from the user. For regular
// downloads, this determination is based on the target disposition, auto-open
// behavior, among other factors. For an interrupted download, this
// determination will be based on the interrupt reason. It is assumed that
// download interruptions always occur after the first round of download
// target determination is complete.
DownloadConfirmationReason NeedsConfirmation(
const base::FilePath& filename) const;
// Returns true if the user has been prompted for this download at least once
// prior to this target determination operation. This method is only expected
// to return true for a resuming interrupted download that has prompted the
// user before interruption. The return value does not depend on whether the
// user will be or has been prompted during the current target determination
// operation.
bool HasPromptedForPath() const;
// Returns true if this download should show the "dangerous file" warning.
// Various factors are considered, such as the type of the file, whether a
// user action initiated the download, and whether the user has explicitly
// marked the file type as "auto open". Protected virtual for testing.
// If |require_explicit_consent| is non-null then the pointed bool will be set
// to true if the download requires explicit user consent.
safe_browsing::DownloadFileType::DangerLevel GetDangerLevel(
PriorVisitsToReferrer visits) const;
// download::DownloadItem::Observer
void OnDownloadDestroyed(download::DownloadItem* download) override;
// state
State next_state_;
DownloadConfirmationReason confirmation_reason_;
bool should_notify_extensions_;
bool create_target_directory_;
download::DownloadDangerType danger_type_;
safe_browsing::DownloadFileType::DangerLevel danger_level_;
base::FilePath virtual_path_;
base::FilePath local_path_;
base::FilePath intermediate_path_;
std::string mime_type_;
bool is_filetype_handled_safely_;
#if defined(OS_ANDROID)
bool is_checking_dialog_confirmed_path_;
download::DownloadItem* download_;
const bool is_resumption_;
DownloadPrefs* download_prefs_;
DownloadTargetDeterminerDelegate* delegate_;
CompletionCallback completion_callback_;
base::CancelableTaskTracker history_tracker_;
base::WeakPtrFactory<DownloadTargetDeterminer> weak_ptr_factory_;