blob: d35d7862c8995805d2380029a8ef2196b9f506dd [file] [log] [blame]
// Copyright (c) 2012 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 "components/download/public/common/download_path_reservation_tracker.h"
#include <stddef.h>
#include <map>
#include <string>
#include "base/bind.h"
#include "base/callback.h"
#include "base/files/file_path.h"
#include "base/files/file_util.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/memory/ptr_util.h"
#include "base/sequenced_task_runner.h"
#include "base/stl_util.h"
#include "base/strings/string_util.h"
#include "base/strings/stringprintf.h"
#include "base/task/lazy_task_runner.h"
#include "base/task/post_task.h"
#include "base/task_runner_util.h"
#include "base/third_party/icu/icu_utf.h"
#include "base/time/time.h"
#include "build/build_config.h"
#include "components/download/public/common/download_features.h"
#include "components/download/public/common/download_item.h"
#include "components/filename_generation/filename_generation.h"
#include "net/base/filename_util.h"
#include "url/gurl.h"
#if defined(OS_ANDROID)
#include "components/download/internal/common/android/download_collection_bridge.h"
namespace download {
namespace {
typedef DownloadItem* ReservationKey;
typedef std::map<ReservationKey, base::FilePath> ReservationMap;
// The length of the suffix string we append for an intermediate file name.
// In the file name truncation, we keep the margin to append the suffix.
// TODO(kinaba): remove the margin. The user should be able to set maximum
// possible filename.
const size_t kIntermediateNameSuffixLength = sizeof(".crdownload") - 1;
#if defined(OS_WIN)
// On windows, zone identifier is appended to the downloaded file name during
// annotation. That increases the length of the final target path.
const size_t kZoneIdentifierLength = sizeof(":Zone.Identifier") - 1;
#endif // defined(OS_WIN)
// Map of download path reservations. Each reserved path is associated with a
// ReservationKey=DownloadItem*. This object is destroyed in |Revoke()| when
// there are no more reservations.
ReservationMap* g_reservation_map = NULL;
base::LazySequencedTaskRunner g_sequenced_task_runner =
base::TaskTraits(base::ThreadPool(), base::MayBlock()));
// Observes a DownloadItem for changes to its target path and state. Updates or
// revokes associated download path reservations as necessary. Created, invoked
// and destroyed on the UI thread.
class DownloadItemObserver : public DownloadItem::Observer,
public base::SupportsUserData::Data {
explicit DownloadItemObserver(DownloadItem* download_item);
~DownloadItemObserver() override;
// DownloadItem::Observer
void OnDownloadUpdated(DownloadItem* download) override;
void OnDownloadDestroyed(DownloadItem* download) override;
DownloadItem* download_item_;
// Last known target path for the download.
base::FilePath last_target_path_;
static const int kUserDataKey;
// Returns true if the given path is in use by a path reservation.
bool IsPathReserved(const base::FilePath& path) {
// No reservation map => no reservations.
if (g_reservation_map == NULL)
return false;
// We only expect a small number of concurrent downloads at any given time, so
// going through all of them shouldn't be too slow.
for (ReservationMap::const_iterator iter = g_reservation_map->begin();
iter != g_reservation_map->end(); ++iter) {
if (base::FilePath::CompareEqualIgnoreCase(iter->second.value(),
return true;
return false;
// Returns true if the given file name is in use by any path reservation or the
// file system. Called on the task runner returned by
// DownloadPathReservationTracker::GetTaskRunner().
bool IsFileNameInUse(const base::FilePath& path) {
#if defined(OS_ANDROID)
// If there is a reservation, then the path is in use.
if (IsPathReserved(path.BaseName()))
return true;
if (DownloadCollectionBridge::FileNameExists(path.BaseName()))
return true;
return false;
// Returns true if the given path is in use by a path reservation,
// and has a different key then the item arg.
bool IsAdditionalPathReserved(const base::FilePath& path, DownloadItem* item) {
if (!g_reservation_map)
return false;
for (ReservationMap::const_iterator iter = g_reservation_map->begin();
iter != g_reservation_map->end(); ++iter) {
if (iter->first != item && base::FilePath::CompareEqualIgnoreCase(
iter->second.value(), path.value()))
return true;
return false;
// Returns true if the given path is in use by any path reservation or the
// file system. Called on the task runner returned by
// DownloadPathReservationTracker::GetTaskRunner().
bool IsPathInUse(const base::FilePath& path) {
// If there is a reservation, then the path is in use.
if (IsPathReserved(path))
return true;
// If the path exists in the file system, then the path is in use.
if (base::PathExists(path))
return true;
return false;
// Create a unique filename by appending a uniquifier. Modifies |path| in place
// if successful and returns true. Otherwise |path| is left unmodified and
// returns false. If |check_file_name_only| is true, this method will only check
// the name of the file to guarantee that it is unique.
bool CreateUniqueFilename(int max_path_component_length,
const base::Time& download_start_time,
base::FilePath* path,
bool check_file_name_only) {
// Try every numeric uniquifier. Then make one attempt with the timestamp.
for (int uniquifier = 1;
uniquifier <= DownloadPathReservationTracker::kMaxUniqueFiles + 1;
++uniquifier) {
// Append uniquifier.
std::string suffix(base::StringPrintf(" (%d)", uniquifier));
// After we've tried all the unique numeric indices, make one attempt using
// the timestamp.
if (uniquifier > DownloadPathReservationTracker::kMaxUniqueFiles) {
// Generate an ISO8601 compliant local timestamp suffix that avoids
// reserved characters that are forbidden on some OSes like Windows.
base::Time::Exploded exploded;
suffix = base::StringPrintf(
" - %04d-%02d-%02dT%02d%02d%02d.%03d", exploded.year, exploded.month,
exploded.day_of_month, exploded.hour, exploded.minute,
exploded.second, exploded.millisecond);
base::FilePath path_to_check(*path);
// If the name length limit is available (max_length != -1), and the
// the current name exceeds the limit, truncate.
if (max_path_component_length != -1) {
#if defined(OS_WIN)
int limit =
max_path_component_length -
std::max(kIntermediateNameSuffixLength, kZoneIdentifierLength) -
int limit = max_path_component_length - kIntermediateNameSuffixLength -
#endif // defined(OS_WIN)
// If truncation failed, give up uniquification.
if (limit <= 0 ||
!filename_generation::TruncateFilename(&path_to_check, limit))
path_to_check = path_to_check.InsertBeforeExtensionASCII(suffix);
if ((check_file_name_only && !IsFileNameInUse(path_to_check)) ||
(!check_file_name_only && !IsPathInUse(path_to_check))) {
*path = path_to_check;
return true;
return false;
struct CreateReservationInfo {
ReservationKey key;
base::FilePath source_path;
base::FilePath suggested_path;
base::FilePath default_download_path;
base::FilePath temporary_path;
base::FilePath fallback_directory; // directory to use when target path
// cannot be used.
bool create_target_directory;
base::Time start_time;
DownloadPathReservationTracker::FilenameConflictAction conflict_action;
DownloadPathReservationTracker::ReservedPathCallback completion_callback;
// Check if |target_path| is writable.
bool IsPathWritable(const CreateReservationInfo& info,
const base::FilePath& target_path) {
if (base::PathIsWritable(target_path.DirName()))
return true;
// If a temporary file is already created under the same dir as |target_path|,
// return true. This is to avoid the windows network share issue. See
return !info.temporary_path.empty() &&
info.temporary_path.DirName() == target_path.DirName();
// Called when reservation conflicts happen. Returns the result on whether the
// conflict can be resolved, and uniquifying the file name if necessary. If
// |check_file_name_only| is true, this method will only check the name of the
// file to guarantee that it is unique.
PathValidationResult ResolveReservationConflicts(
const CreateReservationInfo& info,
int max_path_component_length,
base::FilePath* target_path,
bool check_file_name_only) {
switch (info.conflict_action) {
case DownloadPathReservationTracker::UNIQUIFY:
return CreateUniqueFilename(max_path_component_length, info.start_time,
target_path, check_file_name_only)
? PathValidationResult::SUCCESS
: PathValidationResult::CONFLICT;
case DownloadPathReservationTracker::OVERWRITE:
if (base::FeatureList::IsEnabled(
features::kPreventDownloadsWithSamePath) &&
IsPathReserved(*target_path)) {
return PathValidationResult::CONFLICT;
return PathValidationResult::SUCCESS;
case DownloadPathReservationTracker::PROMPT:
return PathValidationResult::CONFLICT;
return PathValidationResult::SUCCESS;
// Verify that |target_path| can be written to and also resolve any conflicts if
// necessary by uniquifying the filename.
PathValidationResult ValidatePathAndResolveConflicts(
const CreateReservationInfo& info,
base::FilePath* target_path) {
// Check writability of the suggested path. If we can't write to it, use
// the |default_download_path| if it is not empty or |fallback_directory|.
// We'll prompt them in this case. No further amendments are made to the
// filename since the user is going to be prompted.
if (!IsPathWritable(info, *target_path)) {
DVLOG(1) << "Unable to write to path \"" << target_path->value() << "\"";
if (!info.default_download_path.empty() &&
target_path->DirName() != info.default_download_path) {
*target_path = info.default_download_path.Append(target_path->BaseName());
} else {
*target_path = info.fallback_directory.Append(target_path->BaseName());
return PathValidationResult::PATH_NOT_WRITABLE;
int max_path_component_length =
// Check the limit of file name length if it could be obtained. When the
// suggested name exceeds the limit, truncate or prompt the user.
if (max_path_component_length != -1) {
#if defined(OS_WIN)
int limit = max_path_component_length -
std::max(kIntermediateNameSuffixLength, kZoneIdentifierLength);
int limit = max_path_component_length - kIntermediateNameSuffixLength;
#endif // defined(OS_WIN)
if (limit <= 0 ||
!filename_generation::TruncateFilename(target_path, limit))
return PathValidationResult::NAME_TOO_LONG;
// Disallow downloading a file onto itself. Assume that downloading a file
// onto another file that differs only by case is not enough of a legitimate
// edge case to justify determining the case sensitivity of the underlying
// filesystem.
if (*target_path == info.source_path)
return PathValidationResult::SAME_AS_SOURCE;
if (!IsPathInUse(*target_path))
return PathValidationResult::SUCCESS;
return ResolveReservationConflicts(info, max_path_component_length,
target_path, false);
// Called on the task runner returned by
// DownloadPathReservationTracker::GetTaskRunner() to reserve a download path.
// This method:
// - Creates directory |default_download_path| if it doesn't exist.
// - Verifies that the parent directory of |suggested_path| exists and is
// writeable.
// - Truncates the suggested name if it exceeds the filesystem's limit.
// - Uniquifies |suggested_path| if |should_uniquify_path| is true.
// - Schedules |callback| on the UI thread with the reserved path and a flag
// indicating whether the returned path has been successfully verified.
// - Returns the result of creating the path reservation.
PathValidationResult CreateReservation(const CreateReservationInfo& info,
base::FilePath* reserved_path) {
// Create a reservation map if one doesn't exist. It will be automatically
// deleted when all the reservations are revoked.
if (g_reservation_map == NULL)
g_reservation_map = new ReservationMap;
// Erase the reservation if it already exists. This can happen during
// automatic resumption where a new target determination request may be issued
// for a DownloadItem without an intervening transition to INTERRUPTED.
// Revoking and re-acquiring the reservation forces us to re-verify the claims
// we are making about the path.
base::FilePath target_path(info.suggested_path.NormalizePathSeparators());
base::FilePath target_dir = target_path.DirName();
base::FilePath filename = target_path.BaseName();
#if defined(OS_ANDROID)
if (DownloadCollectionBridge::ShouldPublishDownload(target_path)) {
// If the download is written to a content URI, put file name in the
// reservation map as content URIs will always be different.
PathValidationResult result = PathValidationResult::SUCCESS;
if (IsFileNameInUse(filename)) {
int max_path_component_length =
result = ResolveReservationConflicts(info, max_path_component_length,
&target_path, true);
(*g_reservation_map)[info.key] = target_path.BaseName();
*reserved_path = target_path;
return result;
// Create target_dir if necessary and appropriate. target_dir may be the last
// directory that the user selected in a FilePicker; if that directory has
// since been removed, do NOT automatically re-create it. Only automatically
// create the directory if it is the default Downloads directory or if the
// caller explicitly requested automatic directory creation.
if (!base::DirectoryExists(target_dir) &&
(info.create_target_directory ||
(!info.default_download_path.empty() &&
(info.default_download_path == target_dir)))) {
PathValidationResult result =
ValidatePathAndResolveConflicts(info, &target_path);
(*g_reservation_map)[info.key] = target_path;
*reserved_path = target_path;
return result;
// Called on a background thread to update the path of the reservation
// associated with |key| to |new_path|.
void UpdateReservation(ReservationKey key, const base::FilePath& new_path) {
DCHECK(g_reservation_map != NULL);
auto iter = g_reservation_map->find(key);
if (iter != g_reservation_map->end()) {
iter->second = new_path;
} else {
// This would happen if an UpdateReservation() notification was scheduled on
// the SequencedTaskRunner before ReserveInternal(), or after a Revoke()
// call. Neither should happen.
// Called on the FILE thread to remove the path reservation associated with
// |key|.
void RevokeReservation(ReservationKey key) {
DCHECK(g_reservation_map != NULL);
DCHECK(base::Contains(*g_reservation_map, key));
if (g_reservation_map->size() == 0) {
// No more reservations. Delete map.
delete g_reservation_map;
g_reservation_map = NULL;
void RunGetReservedPathCallback(
const DownloadPathReservationTracker::ReservedPathCallback& callback,
const base::FilePath* reserved_path,
PathValidationResult result) {
callback.Run(result, *reserved_path);
// Gets the path reserved in the global |g_reservation_map|. For content Uri,
// file name instead of file path is used.
base::FilePath GetReservationPath(DownloadItem* download_item) {
#if defined(OS_ANDROID)
if (download_item->GetTargetFilePath().IsContentUri())
return download_item->GetFileNameToReportUser();
return download_item->GetTargetFilePath();
DownloadItemObserver::DownloadItemObserver(DownloadItem* download_item)
: download_item_(download_item),
last_target_path_(GetReservationPath(download_item)) {
download_item_->SetUserData(&kUserDataKey, base::WrapUnique(this));
DownloadItemObserver::~DownloadItemObserver() {
// DownloadItemObserver is owned by DownloadItem. It should only be getting
// destroyed because it's being removed from the UserData pool. No need to
// call DownloadItem::RemoveUserData().
void DownloadItemObserver::OnDownloadUpdated(DownloadItem* download) {
switch (download->GetState()) {
case DownloadItem::IN_PROGRESS: {
// Update the reservation.
base::FilePath new_target_path = GetReservationPath(download);
if (new_target_path != last_target_path_) {
base::BindOnce(&UpdateReservation, download, new_target_path));
last_target_path_ = new_target_path;
case DownloadItem::COMPLETE:
// If the download is complete, then it has already been renamed to the
// final name. The existence of the file on disk is sufficient to prevent
// conflicts from now on.
case DownloadItem::CANCELLED:
// We no longer need the reservation if the download is being removed.
case DownloadItem::INTERRUPTED:
// The download filename will need to be re-generated when the download is
// restarted. Holding on to the reservation now would prevent the name
// from being used for a subsequent retry attempt.
FROM_HERE, base::BindOnce(&RevokeReservation, download));
case DownloadItem::MAX_DOWNLOAD_STATE:
// Compiler appeasement.
void DownloadItemObserver::OnDownloadDestroyed(DownloadItem* download) {
// Items should be COMPLETE/INTERRUPTED/CANCELLED before being destroyed.
FROM_HERE, base::BindOnce(&RevokeReservation, download));
// static
const int DownloadItemObserver::kUserDataKey = 0;
} // namespace
// static
void DownloadPathReservationTracker::GetReservedPath(
DownloadItem* download_item,
const base::FilePath& target_path,
const base::FilePath& default_path,
const base::FilePath& fallback_directory,
bool create_directory,
FilenameConflictAction conflict_action,
const ReservedPathCallback& callback) {
// Attach an observer to the download item so that we know when the target
// path changes and/or the download is no longer active.
new DownloadItemObserver(download_item);
// DownloadItemObserver deletes itself.
base::FilePath* reserved_path = new base::FilePath;
base::FilePath source_path;
if (download_item->GetURL().SchemeIsFile())
net::FileURLToFilePath(download_item->GetURL(), &source_path);
CreateReservationInfo info = {static_cast<ReservationKey>(download_item),
GetTaskRunner().get(), FROM_HERE,
base::BindOnce(&CreateReservation, info, reserved_path),
base::BindOnce(&RunGetReservedPathCallback, callback,
// static
bool DownloadPathReservationTracker::IsPathInUseForTesting(
const base::FilePath& path) {
return IsPathInUse(path);
// static
DownloadPathReservationTracker::GetTaskRunner() {
return g_sequenced_task_runner.Get();
// static
bool DownloadPathReservationTracker::CheckDownloadPathForExistingDownload(
const base::FilePath& target_path,
DownloadItem* download_item) {
return IsAdditionalPathReserved(target_path, download_item);
} // namespace download