[Media Galleries] Filesystem interface for Mac PTP/MTP devices using ImageCaptureCore (part 3)

chrome/browser/media_gallery/mac/mtp_device_delegate_impl_mac.mm

+// 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 "chrome/browser/media_gallery/mac/mtp_device_delegate_impl_mac.h"
+
+#include "base/memory/scoped_nsobject.h"
+#include "base/sequenced_task_runner.h"
+#include "base/sequenced_task_runner_helpers.h"
+#include "base/threading/sequenced_worker_pool.h"
+#include "chrome/browser/media_gallery/mtp_device_delegate_impl.h"
+#include "chrome/browser/system_monitor/image_capture_device.h"
+#include "chrome/browser/system_monitor/image_capture_device_manager.h"
+#include "chrome/browser/system_monitor/media_storage_util.h"
+#include "content/public/browser/browser_thread.h"
+
+namespace chrome {
+
+// This class handles the UI-thread hand-offs needed to interface
+// with the ImageCapture library. It will forward callbacks to
+// its delegate on the task runner with which it is created. All
+// interactions with it are done on the UI thread, but it may be
+// created/destroyed on another thread.
+class MTPDeviceDelegateImplMac::DeviceListener
+    : public ImageCaptureDeviceListener,
+      public base::SupportsWeakPtr<DeviceListener> {
+ public:
+  DeviceListener(MTPDeviceDelegateImplMac* delegate,
+                 base::SequencedTaskRunner* task_runner)
+      : delegate_(delegate),
+        task_runner_(task_runner) {}
+  virtual ~DeviceListener() {}
+
+  void OpenCameraSession(const std::string& device_id);
+  void CloseCameraSessionAndDelete();
+
+  void DownloadFile(const std::string& name, const FilePath& local_path);
+
+  // ImageCaptureDeviceListener
+  virtual void ItemAdded(const std::string& name,
+                         const base::PlatformFileInfo& info) OVERRIDE;
+  virtual void NoMoreItems() OVERRIDE;
+  virtual void DownloadedFile(const std::string& name,
+                              base::PlatformFileError error) OVERRIDE;
+  virtual void DeviceRemoved() OVERRIDE;
+
+ private:
+  scoped_nsobject<ImageCaptureDevice> camera_device_;
+
+  // Weak pointer
+  MTPDeviceDelegateImplMac* delegate_;
+
+  // Weak pointer
+  base::SequencedTaskRunner* task_runner_;
+
+  DISALLOW_COPY_AND_ASSIGN(DeviceListener);
+};
+
+void MTPDeviceDelegateImplMac::DeviceListener::OpenCameraSession(
+    const std::string& device_id) {
+  camera_device_.reset(
+      [ImageCaptureDeviceManager::deviceForUUID(device_id) retain]);
+  [camera_device_ setListener:AsWeakPtr()];
+  [camera_device_ open];
+}
+
+void MTPDeviceDelegateImplMac::DeviceListener::CloseCameraSessionAndDelete() {
+  [camera_device_ close];
+  [camera_device_ setListener:base::WeakPtr<DeviceListener>()];
+
+  delete this;
+}
+
+void MTPDeviceDelegateImplMac::DeviceListener::DownloadFile(
+    const std::string& name,
+    const FilePath& local_path) {
+  [camera_device_ downloadFile:name localPath:local_path];
+}
+
+void MTPDeviceDelegateImplMac::DeviceListener::ItemAdded(
+    const std::string& name,
+    const base::PlatformFileInfo& info) {
+  task_runner_->PostTask(FROM_HERE,
+      base::Bind(&MTPDeviceDelegateImplMac::ItemAdded,
+                 base::Unretained(delegate_), name, info));
+}
+
+void MTPDeviceDelegateImplMac::DeviceListener::NoMoreItems() {
+  task_runner_->PostTask(FROM_HERE,
+      base::Bind(&MTPDeviceDelegateImplMac::NoMoreItems,
+                 base::Unretained(delegate_)));
+}
+
+void MTPDeviceDelegateImplMac::DeviceListener::DownloadedFile(
+    const std::string& name,
+    base::PlatformFileError error) {
+  task_runner_->PostTask(FROM_HERE,
+      base::Bind(&MTPDeviceDelegateImplMac::DownloadedFile,
+                 base::Unretained(delegate_), name, error));
+}
+
+void MTPDeviceDelegateImplMac::DeviceListener::DeviceRemoved() {
+  [camera_device_ close];
+  camera_device_.reset();
+}
+
+MTPDeviceDelegateImplMac::MTPDeviceDelegateImplMac(
+    const std::string& device_id,
+    const FilePath::StringType& synthetic_path,
+    base::SequencedTaskRunner* media_task_runner)
+    : device_id_(device_id),
+      root_path_(synthetic_path),
+      media_task_runner_(media_task_runner),
+      enumerator_(NULL),
+      file_download_event_(NULL),
+      file_download_error_(base::PLATFORM_FILE_OK),
+      received_all_files_(false) {
+
+  // Make a synthetic entry for the root of the filesystem.
+  base::PlatformFileInfo info;
+  info.is_directory = true;
+  file_info_[root_path_.value()] = info;
+
+  camera_interface_.reset(new DeviceListener(this, media_task_runner));
+  content::BrowserThread::PostTask(content::BrowserThread::UI, FROM_HERE,
+      base::Bind(&DeviceListener::OpenCameraSession,
+                 base::Unretained(camera_interface_.get()),
+                 device_id_));
+}
+
+MTPDeviceDelegateImplMac::~MTPDeviceDelegateImplMac() {
+  DCHECK(media_task_runner_->RunsTasksOnCurrentThread());
+  DCHECK(enumerator_ == NULL);
+}
+
+base::PlatformFileError MTPDeviceDelegateImplMac::GetFileInfo(
+    const FilePath& file_path,
+    base::PlatformFileInfo* file_info) {
+  base::AutoLock lock(mutex_);
+  base::hash_map<FilePath::StringType,
+                 base::PlatformFileInfo>::const_iterator i =
+      file_info_.find(file_path.value());
+  if (i == file_info_.end())
+    return base::PLATFORM_FILE_ERROR_NOT_FOUND;
+
+  *file_info = i->second;
+  return base::PLATFORM_FILE_OK;
+}
+
+scoped_ptr<fileapi::FileSystemFileUtil::AbstractFileEnumerator>
+MTPDeviceDelegateImplMac::CreateFileEnumerator(const FilePath& root,
+                                               bool recursive) {
+  base::AutoLock lock(mutex_);
+  DCHECK(!enumerator_);
+  enumerator_ = new Enumerator(this);
+  return make_scoped_ptr(enumerator_)
+      .PassAs<fileapi::FileSystemFileUtil::AbstractFileEnumerator>();
+}
+
+base::PlatformFileError MTPDeviceDelegateImplMac::CreateSnapshotFile(
+    const FilePath& device_file_path,
+    const FilePath& local_path,
+    base::PlatformFileInfo* file_info) {
+  base::PlatformFileError error = GetFileInfo(device_file_path, file_info);
+  if (error != base::PLATFORM_FILE_OK)
+    return error;
+
+  // Set up to wait for download. Callers are ensuring this particular function
+  // will not be re-entered.
+  base::WaitableEvent waiter(true, false);
+  {
+    base::AutoLock lock(mutex_);
+    DCHECK(file_download_event_ == NULL);
+    file_download_event_ = &waiter;
+  }
+
+  // Start the download in the UI thread.
+  content::BrowserThread::PostTask(content::BrowserThread::UI, FROM_HERE,
+      base::Bind(&DeviceListener::DownloadFile,
+                 base::Unretained(camera_interface_.get()),
+                 device_file_path.BaseName().value(), local_path));
+  waiter.Wait();
+  {
+    base::AutoLock lock(mutex_);
+    file_download_event_ = NULL;
+    error = file_download_error_;
+  }
+
+  // Modify the last modified time to null. This prevents the time stamp
+  // verification in LocalFileStreamReader.
+  file_info->last_modified = base::Time();
+
+  return error;
+}
+
+void MTPDeviceDelegateImplMac::CancelPendingTasksAndDeleteDelegate() {

[Lei Zhang, 2013/01/25 23:51:20]

DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));

[Greg Billock, 2013/01/26 01:29:44]

Done.

+  // Artificially pretend that we have already gotten all items we're going
+  // to get.
+  NoMoreItems();
+
+  {
+    base::AutoLock lock(mutex_);
+    // Artificially wake up any downloads pending with an error code.
+    if (file_download_event_) {
+      file_download_error_ = base::PLATFORM_FILE_ERROR_FAILED;
+      file_download_event_->Signal();
+    }
+  }
+
+  // Schedule the camera session to be closed and the interface deleted.
+  content::BrowserThread::PostTask(content::BrowserThread::UI, FROM_HERE,
+      base::Bind(&DeviceListener::CloseCameraSessionAndDelete,
+                 base::Unretained(camera_interface_.release())));
+
+  media_task_runner_->DeleteSoon(FROM_HERE, this);
+}
+
+void MTPDeviceDelegateImplMac::ItemAdded(
+    const std::string& name, const base::PlatformFileInfo& info) {
+  base::AutoLock lock(mutex_);
+
+  // Make sure that if we're canceled and an enumerator is awake, that
+  // it will stay consistent. May need to revisit this if we need
+  // notifications of files added after we think we're done.
+  if (received_all_files_)
+    return;
+
+  // TODO(gbillock): Currently we flatten all files into a single
+  // directory. That's pretty much how PTP devices work, but if we want
+  // to support ImageCapture for USB, we need to change this.
+  if (info.is_directory)
+    return;
+
+  FilePath item_filename = root_path_.Append(name);
+  file_info_[item_filename.value()] = info;
+  file_paths_.push_back(item_filename);
+
+  if (enumerator_)
+    enumerator_->ItemsChanged();
+}
+
+void MTPDeviceDelegateImplMac::NoMoreItems() {
+  base::AutoLock lock(mutex_);
+  received_all_files_ = true;
+
+  if (enumerator_)
+    enumerator_->ItemsChanged();
+}
+
+void MTPDeviceDelegateImplMac::DownloadedFile(
+    const std::string& name, base::PlatformFileError error) {
+  // If we're cancelled and deleting, we have already signaled all enumerators.
+  if (!camera_interface_.get())
+    return;
+
+  base::AutoLock lock(mutex_);
+  file_download_error_ = error;
+  file_download_event_->Signal();
+}
+
+FilePath MTPDeviceDelegateImplMac::GetFile(size_t index) {
+  base::AutoLock lock(mutex_);
+  if (index >= file_paths_.size())
+    return FilePath();
+  else
+    return file_paths_[index];
+}
+
+bool MTPDeviceDelegateImplMac::ReceivedAllFiles() {
+  base::AutoLock lock(mutex_);
+  return received_all_files_;
+}
+
+void MTPDeviceDelegateImplMac::RemoveEnumerator(Enumerator* enumerator) {
+  base::AutoLock lock(mutex_);
+  DCHECK(enumerator_ == enumerator);
+  enumerator_ = NULL;
+}
+
+MTPDeviceDelegateImplMac::Enumerator::Enumerator(
+    MTPDeviceDelegateImplMac* delegate)
+    : delegate_(delegate),
+      position_(0),
+      done_(false),
+      wait_for_items_(false, false) {}
+
+MTPDeviceDelegateImplMac::Enumerator::~Enumerator() {
+  delegate_->RemoveEnumerator(this);
+}
+
+FilePath MTPDeviceDelegateImplMac::Enumerator::Next() {
+  FilePath next_file = delegate_->GetFile(position_);
+  while (next_file.empty() && !delegate_->ReceivedAllFiles()) {
+    wait_for_items_.Wait();
+    next_file = delegate_->GetFile(position_);
+  }
+
+  position_++;
+  if (next_file == FilePath())

[Lei Zhang, 2013/01/25 23:51:20]

You can just write this as: next_file.empty()

[Greg Billock, 2013/01/26 01:29:44]

Done.

+    done_ = true;
+
+  return next_file;
+}
+
+int64 MTPDeviceDelegateImplMac::Enumerator::Size() {
+  if (position_ <= 0 || done_)

[Lei Zhang, 2013/01/25 23:51:20]

size_t position can't ever be < 0, ditto below.

[Greg Billock, 2013/01/26 01:29:44]

Done.

+    return 0;
+
+  base::PlatformFileInfo info;
+  delegate_->GetFileInfo(delegate_->GetFile(position_ - 1), &info);
+  return info.size;
+}
+
+base::Time MTPDeviceDelegateImplMac::Enumerator::LastModifiedTime() {
+  if (position_ <= 0 || done_)
+    return base::Time();
+
+  base::PlatformFileInfo info;
+  delegate_->GetFileInfo(delegate_->GetFile(position_ - 1), &info);
+  return info.last_modified;
+}
+
+bool MTPDeviceDelegateImplMac::Enumerator::IsDirectory() {
+  if (position_ <= 0 || done_)
+    return false;
+
+  base::PlatformFileInfo info;
+  delegate_->GetFileInfo(delegate_->GetFile(position_ - 1), &info);
+  return info.is_directory;
+}
+
+void MTPDeviceDelegateImplMac::Enumerator::ItemsChanged() {
+  wait_for_items_.Signal();
+}
+
+void CreateMTPDeviceDelegate(const FilePath::StringType& device_location,
+                             base::SequencedTaskRunner* media_task_runner,
+                             const CreateMTPDeviceDelegateCallback& cb) {
+  std::string device_name = FilePath(device_location).BaseName().value();
+  std::string device_id;
+  MediaStorageUtil::Type type;
+  bool cracked = MediaStorageUtil::CrackDeviceId(device_name,
+                                                 &type, &device_id);
+  DCHECK(cracked);
+  DCHECK_EQ(MediaStorageUtil::MAC_IMAGE_CAPTURE, type);
+
+  cb.Run(new MTPDeviceDelegateImplMac(device_id, device_location,
+                                      media_task_runner));
+}
+
+}  // namespace chrome
+