ui/base/dragdrop/os_exchange_data_provider_win.cc

// 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 "ui/base/dragdrop/os_exchange_data_provider_win.h"

#include <coml2api.h>
#include <objbase.h>
#include <objidl.h>
#include <shlobj.h>
#include <shobjidl.h>
#include <stdint.h>
#include <wrl/client.h>

#include <algorithm>
#include <iterator>

#include "base/callback.h"
#include "base/containers/span.h"
#include "base/files/file_path.h"
#include "base/i18n/file_util_icu.h"
#include "base/logging.h"
#include "base/no_destructor.h"
#include "base/pickle.h"
#include "base/stl_util.h"
#include "base/strings/utf_string_conversions.h"
#include "base/win/scoped_hdc.h"
#include "base/win/scoped_hglobal.h"
#include "base/win/shlwapi.h"
#include "net/base/filename_util.h"
#include "skia/ext/skia_utils_win.h"
#include "third_party/skia/include/core/SkBitmap.h"
#include "ui/base/clipboard/clipboard_format_type.h"
#include "ui/base/clipboard/clipboard_util_win.h"
#include "ui/base/dragdrop/file_info.h"
#include "ui/base/l10n/l10n_util.h"
#include "ui/gfx/geometry/point.h"
#include "ui/gfx/image/image_skia.h"
#include "ui/gfx/skbitmap_operations.h"
#include "ui/strings/grit/ui_strings.h"
#include "url/gurl.h"

namespace ui {

static const ClipboardFormatType& GetRendererTaintFormatType() {
  static base::NoDestructor<ClipboardFormatType> format(
      ui::ClipboardFormatType::GetType("chromium/x-renderer-taint"));
  return *format;
}

// Creates a new STGMEDIUM object to hold the specified text. The caller
// owns the resulting object. The "Bytes" version does not NULL terminate, the
// string version does.
static STGMEDIUM* GetStorageForBytes(const void* data, size_t bytes);
template <typename T>
static STGMEDIUM* GetStorageForString(const std::basic_string<T>& data);
// Creates the contents of an Internet Shortcut file for the given URL.
static void GetInternetShortcutFileContents(const GURL& url, std::string* data);
// Creates a valid file name given a suggested title and URL.
static void CreateValidFileNameFromTitle(const GURL& url,
                                         const base::string16& title,
                                         base::string16* validated);
// Creates a new STGMEDIUM object to hold files.
static STGMEDIUM* GetStorageForFileNames(
    const std::vector<FileInfo>& filenames);
static STGMEDIUM* GetIDListStorageForFileName(const base::FilePath& path);
// Creates a File Descriptor for the creation of a file to the given URL and
// returns a handle to it.
static STGMEDIUM* GetStorageForFileDescriptor(const base::FilePath& path);

///////////////////////////////////////////////////////////////////////////////
// FormatEtcEnumerator

//
// This object implements an enumeration interface. The existence of an
// implementation of this interface is exposed to clients through
// OSExchangeData's EnumFormatEtc method. Our implementation is nobody's
// business but our own, so it lives in this file.
//
// This Windows API is truly a gem. It wants to be an enumerator but assumes
// some sort of sequential data (why not just use an array?). See comments
// throughout.
//
class FormatEtcEnumerator final : public IEnumFORMATETC {
 public:
  FormatEtcEnumerator(DataObjectImpl::StoredData::const_iterator begin,
                      DataObjectImpl::StoredData::const_iterator end);
  ~FormatEtcEnumerator();

  // IEnumFORMATETC implementation:
  HRESULT __stdcall Next(ULONG count,
                         FORMATETC* elements_array,
                         ULONG* elements_fetched) override;
  HRESULT __stdcall Skip(ULONG skip_count) override;
  HRESULT __stdcall Reset() override;
  HRESULT __stdcall Clone(IEnumFORMATETC** clone) override;

  // IUnknown implementation:
  HRESULT __stdcall QueryInterface(const IID& iid, void** object) override;
  ULONG __stdcall AddRef() override;
  ULONG __stdcall Release() override;

 private:
  // This can only be called from |CloneFromOther|, since it initializes the
  // contents_ from the other enumerator's contents.
  FormatEtcEnumerator() : cursor_(0), ref_count_(0) {
  }

  // Clone a new FormatEtc from another instance of this enumeration.
  static FormatEtcEnumerator* CloneFromOther(const FormatEtcEnumerator* other);

 private:
  // We are _forced_ to use a vector as our internal data model as Windows'
  // IEnumFORMATETC API assumes a deterministic ordering of elements through
  // methods like Next and Skip. This exposes the underlying data structure to
  // the user. Bah.
  std::vector<std::unique_ptr<FORMATETC>> contents_;

  // The cursor of the active enumeration - an index into |contents_|.
  size_t cursor_;

  LONG ref_count_;

  DISALLOW_COPY_AND_ASSIGN(FormatEtcEnumerator);
};

// Safely makes a copy of all of the relevant bits of a FORMATETC object.
static void CloneFormatEtc(FORMATETC* source, FORMATETC* clone) {
  *clone = *source;
  if (source->ptd) {
    source->ptd =
        static_cast<DVTARGETDEVICE*>(CoTaskMemAlloc(sizeof(DVTARGETDEVICE)));
    *(clone->ptd) = *(source->ptd);
  }
}

FormatEtcEnumerator::FormatEtcEnumerator(
    DataObjectImpl::StoredData::const_iterator start,
    DataObjectImpl::StoredData::const_iterator end)
    : cursor_(0), ref_count_(0) {
  // Copy FORMATETC data from our source into ourselves.
  while (start != end) {
    auto format_etc = std::make_unique<FORMATETC>();
    CloneFormatEtc(&(*start)->format_etc, format_etc.get());
    contents_.push_back(std::move(format_etc));
    ++start;
  }
}

FormatEtcEnumerator::~FormatEtcEnumerator() {
}

STDMETHODIMP FormatEtcEnumerator::Next(
    ULONG count, FORMATETC* elements_array, ULONG* elements_fetched) {
  // MSDN says |elements_fetched| is allowed to be NULL if count is 1.
  if (!elements_fetched)
    DCHECK_EQ(count, 1ul);

  // This method copies count elements into |elements_array|.
  ULONG index = 0;
  while (cursor_ < contents_.size() && index < count) {
    CloneFormatEtc(contents_[cursor_].get(), &elements_array[index]);
    ++cursor_;
    ++index;
  }
  // The out param is for how many we actually copied.
  if (elements_fetched)
    *elements_fetched = index;

  // If the two don't agree, then we fail.
  return index == count ? S_OK : S_FALSE;
}

STDMETHODIMP FormatEtcEnumerator::Skip(ULONG skip_count) {
  cursor_ += skip_count;
  // MSDN implies it's OK to leave the enumerator trashed.
  // "Whatever you say, boss"
  return cursor_ <= contents_.size() ? S_OK : S_FALSE;
}

STDMETHODIMP FormatEtcEnumerator::Reset() {
  cursor_ = 0;
  return S_OK;
}

STDMETHODIMP FormatEtcEnumerator::Clone(IEnumFORMATETC** clone) {
  // Clone the current enumerator in its exact state, including cursor.
  FormatEtcEnumerator* e = CloneFromOther(this);
  e->AddRef();
  *clone = e;
  return S_OK;
}

STDMETHODIMP FormatEtcEnumerator::QueryInterface(const IID& iid,
                                                 void** object) {
  *object = NULL;
  if (IsEqualIID(iid, IID_IUnknown) || IsEqualIID(iid, IID_IEnumFORMATETC)) {
    *object = this;
  } else {
    return E_NOINTERFACE;
  }
  AddRef();
  return S_OK;
}

ULONG FormatEtcEnumerator::AddRef() {
  return InterlockedIncrement(&ref_count_);
}

ULONG FormatEtcEnumerator::Release() {
  if (InterlockedDecrement(&ref_count_) == 0) {
    ULONG copied_refcnt = ref_count_;
    delete this;
    return copied_refcnt;
  }
  return ref_count_;
}

// static
FormatEtcEnumerator* FormatEtcEnumerator::CloneFromOther(
    const FormatEtcEnumerator* other) {
  FormatEtcEnumerator* e = new FormatEtcEnumerator;
  // Copy FORMATETC data from our source into ourselves.
  std::transform(other->contents_.cbegin(), other->contents_.cend(),
                 std::back_inserter(e->contents_),
                 [](const std::unique_ptr<FORMATETC>& format_etc) {
                   auto clone = std::make_unique<FORMATETC>();
                   CloneFormatEtc(format_etc.get(), clone.get());
                   return clone;
                 });
  // Carry over
  e->cursor_ = other->cursor_;
  return e;
}

///////////////////////////////////////////////////////////////////////////////
// OSExchangeDataProviderWin, public:

// static
bool OSExchangeDataProviderWin::HasPlainTextURL(IDataObject* source) {
  base::string16 plain_text;
  return (ClipboardUtil::GetPlainText(source, &plain_text) &&
          !plain_text.empty() && GURL(plain_text).is_valid());
}

// static
bool OSExchangeDataProviderWin::GetPlainTextURL(IDataObject* source,
                                                GURL* url) {
  base::string16 plain_text;
  if (ClipboardUtil::GetPlainText(source, &plain_text) &&
      !plain_text.empty()) {
    GURL gurl(plain_text);
    if (gurl.is_valid()) {
      *url = gurl;
      return true;
    }
  }
  return false;
}

// static
DataObjectImpl* OSExchangeDataProviderWin::GetDataObjectImpl(
    const OSExchangeData& data) {
  return static_cast<const OSExchangeDataProviderWin*>(&data.provider())->
      data_.get();
}

// static
IDataObject* OSExchangeDataProviderWin::GetIDataObject(
    const OSExchangeData& data) {
  return static_cast<const OSExchangeDataProviderWin*>(&data.provider())->
      data_object();
}

// static
IDataObjectAsyncCapability* OSExchangeDataProviderWin::GetIAsyncOperation(
    const OSExchangeData& data) {
  return static_cast<const OSExchangeDataProviderWin*>(&data.provider())->
      async_operation();
}

OSExchangeDataProviderWin::OSExchangeDataProviderWin(IDataObject* source)
    : data_(new DataObjectImpl()),
      source_object_(source) {
}

OSExchangeDataProviderWin::OSExchangeDataProviderWin()
    : data_(new DataObjectImpl()),
      source_object_(data_.get()) {
}

OSExchangeDataProviderWin::~OSExchangeDataProviderWin() {
}

std::unique_ptr<OSExchangeData::Provider>
OSExchangeDataProviderWin::Clone() const {
  return std::make_unique<OSExchangeDataProviderWin>(data_object());
}

void OSExchangeDataProviderWin::MarkOriginatedFromRenderer() {
  STGMEDIUM* storage = GetStorageForString(std::string());
  data_->contents_.push_back(std::make_unique<DataObjectImpl::StoredDataInfo>(
      GetRendererTaintFormatType().ToFormatEtc(), storage));
}

bool OSExchangeDataProviderWin::DidOriginateFromRenderer() const {
  return HasCustomFormat(GetRendererTaintFormatType());
}

void OSExchangeDataProviderWin::SetString(const base::string16& data) {
  STGMEDIUM* storage = GetStorageForString(data);
  data_->contents_.push_back(std::make_unique<DataObjectImpl::StoredDataInfo>(
      ClipboardFormatType::GetPlainTextWType().ToFormatEtc(), storage));

  // Also add the UTF8-encoded version.
  storage = GetStorageForString(base::UTF16ToUTF8(data));
  data_->contents_.push_back(std::make_unique<DataObjectImpl::StoredDataInfo>(
      ClipboardFormatType::GetPlainTextType().ToFormatEtc(), storage));
}

void OSExchangeDataProviderWin::SetURL(const GURL& url,
                                       const base::string16& title) {
  // NOTE WELL:
  // Every time you change the order of the first two CLIPFORMATS that get
  // added here, you need to update the EnumerationViaCOM test case in
  // the _unittest.cc file to reflect the new arrangement otherwise that test
  // will fail! It assumes an insertion order.

  // Add text/x-moz-url for drags from Firefox
  base::string16 x_moz_url_str = base::UTF8ToUTF16(url.spec());
  x_moz_url_str += '\n';
  x_moz_url_str += title;
  STGMEDIUM* storage = GetStorageForString(x_moz_url_str);
  data_->contents_.push_back(std::make_unique<DataObjectImpl::StoredDataInfo>(
      ClipboardFormatType::GetMozUrlType().ToFormatEtc(), storage));

  // Add a .URL shortcut file for dragging to Explorer.
  base::string16 valid_file_name;
  CreateValidFileNameFromTitle(url, title, &valid_file_name);
  std::string shortcut_url_file_contents;
  GetInternetShortcutFileContents(url, &shortcut_url_file_contents);
  SetFileContents(base::FilePath(valid_file_name), shortcut_url_file_contents);

  // Add a UniformResourceLocator link for apps like IE and Word.
  storage = GetStorageForString(base::UTF8ToUTF16(url.spec()));
  data_->contents_.push_back(std::make_unique<DataObjectImpl::StoredDataInfo>(
      ClipboardFormatType::GetUrlWType().ToFormatEtc(), storage));
  storage = GetStorageForString(url.spec());
  data_->contents_.push_back(std::make_unique<DataObjectImpl::StoredDataInfo>(
      ClipboardFormatType::GetUrlType().ToFormatEtc(), storage));

  // TODO(https://crbug.com/6767): add CF_HTML.

  // Also add text representations (these should be last since they're the
  // least preferable).
  SetString(base::UTF8ToUTF16(url.spec()));
}

void OSExchangeDataProviderWin::SetFilename(const base::FilePath& path) {
  SetFilenames({FileInfo(path, base::FilePath())});

  STGMEDIUM* storage = GetIDListStorageForFileName(path);
  if (!storage)
    return;
  data_->contents_.push_back(std::make_unique<DataObjectImpl::StoredDataInfo>(
      ClipboardFormatType::GetIDListType().ToFormatEtc(), storage));
}

void OSExchangeDataProviderWin::SetFilenames(
    const std::vector<FileInfo>& filenames) {
  STGMEDIUM* storage = GetStorageForFileNames(filenames);
  if (!storage)
    return;

  data_->contents_.push_back(std::make_unique<DataObjectImpl::StoredDataInfo>(
      ClipboardFormatType::GetCFHDropType().ToFormatEtc(), storage));
}

void OSExchangeDataProviderWin::SetVirtualFileContentsForTesting(
    const std::vector<std::pair<base::FilePath, std::string>>&
        filenames_and_contents,
    DWORD tymed) {
  size_t num_files = filenames_and_contents.size();
  if (!num_files)
    return;

  // Allocate storage for the file group descriptor as CFSTR_FILEDESCRIPTORW.
  // The fgd[] member of FILEGROUPDESCRIPTORW is of size one, thus sizeof
  // (FILEDESCRIPTORW) is already the correct allocation size if there is only
  // one item. Otherwise need to add room for each FILEDESCRIPTORW struct.
  const size_t total_bytes_fgd = sizeof(FILEGROUPDESCRIPTORW) +
                                 (sizeof(FILEDESCRIPTORW) * (num_files - 1));

  HANDLE hdata = ::GlobalAlloc(GPTR, total_bytes_fgd);
  if (!hdata)
    return;

  base::win::ScopedHGlobal<FILEGROUPDESCRIPTORW*> locked_mem(hdata);

  FILEGROUPDESCRIPTORW* descriptor = locked_mem.get();
  descriptor->cItems = num_files;

  STGMEDIUM* storage = new STGMEDIUM;
  storage->tymed = TYMED_HGLOBAL;
  storage->hGlobal = hdata;
  storage->pUnkForRelease = NULL;

  data_->contents_.push_back(std::make_unique<DataObjectImpl::StoredDataInfo>(
      ClipboardFormatType::GetFileDescriptorWType().ToFormatEtc(), storage));

  for (size_t i = 0; i < num_files; i++) {
    // Fill in each FILEDESCRIPTORW with file name.
    descriptor->fgd[i].dwFlags |= FD_UNICODE;
    base::string16 file_name = filenames_and_contents[i].first.value();
    wcsncpy_s(descriptor->fgd[i].cFileName, MAX_PATH, file_name.c_str(),
              std::min(file_name.size(), static_cast<size_t>(MAX_PATH - 1u)));

    // Add the contents of each file as CFSTR_FILECONTENTS.
    base::span<const uint8_t> data_buffer =
        base::make_span(reinterpret_cast<const uint8_t*>(
                            filenames_and_contents[i].second.data()),
                        filenames_and_contents[i].second.length());
    SetVirtualFileContentAtIndexForTesting(data_buffer, tymed, i);
  }
}

void OSExchangeDataProviderWin::SetVirtualFileContentAtIndexForTesting(
    base::span<const uint8_t> data_buffer,
    DWORD tymed,
    size_t index) {
  std::unique_ptr<STGMEDIUM> storage_for_contents;

  if (tymed == TYMED_ISTORAGE) {
    storage_for_contents = std::make_unique<STGMEDIUM>();
    storage_for_contents->pUnkForRelease = nullptr;

    Microsoft::WRL::ComPtr<ILockBytes> lock_bytes;
    HRESULT hr = ::CreateILockBytesOnHGlobal(
        nullptr, /* fDeleteOnRelease*/ TRUE, &lock_bytes);

    if (SUCCEEDED(hr)) {
      hr = ::StgCreateDocfileOnILockBytes(
          lock_bytes.Get(), STGM_READWRITE | STGM_SHARE_EXCLUSIVE | STGM_CREATE,
          0, &storage_for_contents->pstg);
    }

    Microsoft::WRL::ComPtr<IStream> destination_stream;
    if (SUCCEEDED(hr)) {
      hr = storage_for_contents->pstg->CreateStream(
          L"Contents", STGM_READWRITE | STGM_SHARE_EXCLUSIVE | STGM_CREATE, 0,
          0, &destination_stream);
    }

    Microsoft::WRL::ComPtr<IStream> source_stream;
    if (SUCCEEDED(hr)) {
      source_stream =
          ::SHCreateMemStream(data_buffer.data(), data_buffer.size_bytes());
    }

    if (source_stream) {
      // Copy the data to the storage stream.
      ULARGE_INTEGER bytes_to_copy;
      bytes_to_copy.QuadPart = data_buffer.size_bytes();
      hr = source_stream->CopyTo(destination_stream.Get(), bytes_to_copy,
                                 nullptr, nullptr);
    }
    if (SUCCEEDED(hr))
      hr = storage_for_contents->pstg->Commit(STGC_DEFAULT);
    if (SUCCEEDED(hr))
      storage_for_contents->tymed = TYMED_ISTORAGE;

  } else if (tymed == TYMED_ISTREAM) {
    storage_for_contents = std::make_unique<STGMEDIUM>();
    storage_for_contents->pUnkForRelease = nullptr;
    storage_for_contents->pstm =
        ::SHCreateMemStream(data_buffer.data(), data_buffer.size_bytes());
    if (storage_for_contents->pstm) {
      // A properly implemented IDataObject::GetData moves the stream pointer
      // to end.
      const LARGE_INTEGER kZeroDisplacement = {};
      HRESULT hr = storage_for_contents->pstm->Seek(kZeroDisplacement,
                                                    STREAM_SEEK_END, nullptr);
      if (SUCCEEDED(hr))
        storage_for_contents->tymed = TYMED_ISTREAM;
    }
  } else if (tymed == TYMED_HGLOBAL) {
    storage_for_contents.reset(
        GetStorageForBytes(data_buffer.data(), data_buffer.size_bytes()));
  }
  ClipboardFormatType type =
      ClipboardFormatType::GetFileContentAtIndexType(index);
  // Pass ownership of |storage_for_contents| here.
  data_->contents_.push_back(std::make_unique<DataObjectImpl::StoredDataInfo>(
      type.ToFormatEtc(), storage_for_contents.release()));
}

void OSExchangeDataProviderWin::SetPickledData(
    const ClipboardFormatType& format,
    const base::Pickle& data) {
  STGMEDIUM* storage = GetStorageForBytes(data.data(), data.size());
  data_->contents_.push_back(std::make_unique<DataObjectImpl::StoredDataInfo>(
      format.ToFormatEtc(), storage));
}

void OSExchangeDataProviderWin::SetFileContents(
    const base::FilePath& filename,
    const std::string& file_contents) {
  // Add CFSTR_FILEDESCRIPTORW.
  STGMEDIUM* storage = GetStorageForFileDescriptor(filename);
  data_->contents_.push_back(std::make_unique<DataObjectImpl::StoredDataInfo>(
      ClipboardFormatType::GetFileDescriptorWType().ToFormatEtc(), storage));

  // Add CFSTR_FILECONTENTS.
  storage = GetStorageForBytes(file_contents.data(), file_contents.length());
  data_->contents_.push_back(std::make_unique<DataObjectImpl::StoredDataInfo>(
      ClipboardFormatType::GetFileContentZeroType().ToFormatEtc(), storage));
}

void OSExchangeDataProviderWin::SetHtml(const base::string16& html,
                                        const GURL& base_url) {
  // Add both MS CF_HTML and text/html format.  CF_HTML should be in utf-8.
  std::string utf8_html = base::UTF16ToUTF8(html);
  std::string url = base_url.is_valid() ? base_url.spec() : std::string();

  std::string cf_html = ClipboardUtil::HtmlToCFHtml(utf8_html, url);
  STGMEDIUM* storage = GetStorageForBytes(cf_html.c_str(), cf_html.size());
  data_->contents_.push_back(std::make_unique<DataObjectImpl::StoredDataInfo>(
      ClipboardFormatType::GetHtmlType().ToFormatEtc(), storage));

  STGMEDIUM* storage_plain = GetStorageForBytes(utf8_html.c_str(),
                                                utf8_html.size());
  data_->contents_.push_back(std::make_unique<DataObjectImpl::StoredDataInfo>(
      ClipboardFormatType::GetTextHtmlType().ToFormatEtc(), storage_plain));
}

bool OSExchangeDataProviderWin::GetString(base::string16* data) const {
  return ClipboardUtil::GetPlainText(source_object_.Get(), data);
}

bool OSExchangeDataProviderWin::GetURLAndTitle(
    OSExchangeData::FilenameToURLPolicy policy,
    GURL* url,
    base::string16* title) const {
  base::string16 url_str;
  bool success = ClipboardUtil::GetUrl(
      source_object_.Get(), url, title,
      policy == OSExchangeData::CONVERT_FILENAMES ? true : false);
  if (success) {
    DCHECK(url->is_valid());
    return true;
  } else if (GetPlainTextURL(source_object_.Get(), url)) {
    if (url->is_valid())
      *title = net::GetSuggestedFilename(*url, "", "", "", "", std::string());
    else
      title->clear();
    return true;
  }
  return false;
}

bool OSExchangeDataProviderWin::GetFilename(base::FilePath* path) const {
  std::vector<base::string16> filenames;
  bool success = ClipboardUtil::GetFilenames(source_object_.Get(), &filenames);
  if (success)
    *path = base::FilePath(filenames[0]);
  return success;
}

bool OSExchangeDataProviderWin::GetFilenames(
    std::vector<FileInfo>* filenames) const {
  std::vector<base::string16> filenames_local;
  bool success =
      ClipboardUtil::GetFilenames(source_object_.Get(), &filenames_local);
  if (success) {
    for (const base::string16& filename_local : filenames_local)
      filenames->push_back(
          FileInfo(base::FilePath(filename_local), base::FilePath()));
  }
  return success;
}

bool OSExchangeDataProviderWin::HasVirtualFilenames() const {
  return ClipboardUtil::HasVirtualFilenames(source_object_.Get());
}

bool OSExchangeDataProviderWin::GetVirtualFilenames(
    std::vector<FileInfo>* filenames) const {
  // ui_base_clipboard can't use FileInfo struct which is part of ui_base, so
  // use FilePath instead.
  // TODO(https://crbug.com/950360): ui_base_clipboard can't use FileInfo struct
  // which is part of ui_base (layering issue).
  std::vector<base::FilePath> display_names;
  bool success =
      ClipboardUtil::GetVirtualFilenames(source_object_.Get(), &display_names);

  if (success) {
    // On dragenter scenarios, need a placeholder file path for drag metadata
    // checks without actually creating the temp file.
    base::FilePath temp_path(FILE_PATH_LITERAL("temp.tmp"));

    for (const auto& display_name : display_names)
      filenames->push_back(FileInfo(temp_path, display_name));
  }
  return success;
}

bool OSExchangeDataProviderWin::GetVirtualFilesAsTempFiles(
    base::OnceCallback<
        void(const std::vector<std::pair<base::FilePath, base::FilePath>>&)>
        callback) const {
  return ClipboardUtil::GetVirtualFilesAsTempFiles(source_object_.Get(),
                                                   std::move(callback));
}

bool OSExchangeDataProviderWin::GetPickledData(
    const ClipboardFormatType& format,
    base::Pickle* data) const {
  DCHECK(data);
  bool success = false;
  STGMEDIUM medium;
  FORMATETC format_etc = format.ToFormatEtc();
  if (SUCCEEDED(source_object_->GetData(&format_etc, &medium))) {
    if (medium.tymed & TYMED_HGLOBAL) {
      base::win::ScopedHGlobal<char*> c_data(medium.hGlobal);
      DCHECK_GT(c_data.Size(), 0u);
      *data = base::Pickle(c_data.get(), static_cast<int>(c_data.Size()));
      success = true;
    }
    ReleaseStgMedium(&medium);
  }
  return success;
}

bool OSExchangeDataProviderWin::GetFileContents(
    base::FilePath* filename,
    std::string* file_contents) const {
  base::string16 filename_str;
  if (!ClipboardUtil::GetFileContents(source_object_.Get(), &filename_str,
                                      file_contents)) {
    return false;
  }
  *filename = base::FilePath(filename_str);
  return true;
}

bool OSExchangeDataProviderWin::GetHtml(base::string16* html,
                                        GURL* base_url) const {
  std::string url;
  bool success = ClipboardUtil::GetHtml(source_object_.Get(), html, &url);
  if (success)
    *base_url = GURL(url);
  return success;
}

bool OSExchangeDataProviderWin::HasString() const {
  return ClipboardUtil::HasPlainText(source_object_.Get());
}

bool OSExchangeDataProviderWin::HasURL(
    OSExchangeData::FilenameToURLPolicy policy) const {
  return (ClipboardUtil::HasUrl(
              source_object_.Get(),
              policy == OSExchangeData::CONVERT_FILENAMES ? true : false) ||
          HasPlainTextURL(source_object_.Get()));
}

bool OSExchangeDataProviderWin::HasFile() const {
  return ClipboardUtil::HasFilenames(source_object_.Get());
}

bool OSExchangeDataProviderWin::HasFileContents() const {
  return ClipboardUtil::HasFileContents(source_object_.Get());
}

bool OSExchangeDataProviderWin::HasHtml() const {
  return ClipboardUtil::HasHtml(source_object_.Get());
}

bool OSExchangeDataProviderWin::HasCustomFormat(
    const ClipboardFormatType& format) const {
  FORMATETC format_etc = format.ToFormatEtc();
  return (source_object_->QueryGetData(&format_etc) == S_OK);
}

void OSExchangeDataProviderWin::SetDownloadFileInfo(
    OSExchangeData::DownloadFileInfo* download) {
  // If the filename is not provided, set storage to NULL to indicate that
  // the delay rendering will be used.
  // TODO(dcheng): Is it actually possible for filename to be empty here? I
  // think we always synthesize one in WebContentsDragWin.
  STGMEDIUM* storage = NULL;
  if (!download->filename.empty())
    GetStorageForFileNames({FileInfo(download->filename, base::FilePath())});

  // Add CF_HDROP.
  auto info = std::make_unique<DataObjectImpl::StoredDataInfo>(
      ClipboardFormatType::GetCFHDropType().ToFormatEtc(), storage);
  info->downloader = std::move(download->downloader);
  data_->contents_.push_back(std::move(info));

  // Adding a download file always enables async mode.
  data_->SetAsyncMode(VARIANT_TRUE);
}

void OSExchangeDataProviderWin::SetDragImage(
    const gfx::ImageSkia& image_skia,
    const gfx::Vector2d& cursor_offset) {
  DCHECK(!image_skia.size().IsEmpty());

  // InitializeFromBitmap() doesn't expect an alpha channel and is confused
  // by premultiplied colors, so unpremultiply the bitmap.
  SkBitmap unpremul_bitmap =
      SkBitmapOperations::UnPreMultiply(*image_skia.bitmap());
  int width = unpremul_bitmap.width();
  int height = unpremul_bitmap.height();
  size_t rowbytes = unpremul_bitmap.rowBytes();
  DCHECK_EQ(rowbytes, static_cast<size_t>(width) * 4u);

  void* bits;
  HBITMAP hbitmap;
  {
    BITMAPINFOHEADER header;
    skia::CreateBitmapHeader(width, height, &header);

    base::win::ScopedGetDC screen_dc(NULL);
    // By giving a null hSection, the |bits| will be destroyed when the
    // |hbitmap| is destroyed.
    hbitmap =
        CreateDIBSection(screen_dc, reinterpret_cast<BITMAPINFO*>(&header),
                         DIB_RGB_COLORS, &bits, NULL, 0);
  }
  if (!hbitmap)
    return;

  memcpy(bits, unpremul_bitmap.getPixels(), height * rowbytes);

  Microsoft::WRL::ComPtr<IDragSourceHelper> helper;
  HRESULT rv = CoCreateInstance(CLSID_DragDropHelper, 0, CLSCTX_INPROC_SERVER,
                                IID_PPV_ARGS(&helper));
  if (!SUCCEEDED(rv))
    return;

  // InitializeFromBitmap() takes ownership of |hbitmap|.
  SHDRAGIMAGE sdi;
  sdi.sizeDragImage.cx = width;
  sdi.sizeDragImage.cy = height;
  sdi.crColorKey = 0xFFFFFFFF;
  sdi.hbmpDragImage = hbitmap;
  sdi.ptOffset = gfx::PointAtOffsetFromOrigin(cursor_offset).ToPOINT();
  helper->InitializeFromBitmap(&sdi, data_object());
}

gfx::ImageSkia OSExchangeDataProviderWin::GetDragImage() const {
  // This class sets the image on data_object() so it shouldn't be used in
  // situations where the drag image is later queried. In that case a different
  // OSExchangeData::Provider should be used.
  NOTREACHED();
  return gfx::ImageSkia();
}

gfx::Vector2d OSExchangeDataProviderWin::GetDragImageOffset() const {
  // This class sets the image on data_object() so it shouldn't be used in
  // situations where the drag image is later queried. In that case a different
  // OSExchangeData::Provider should be used.
  NOTREACHED();
  return gfx::Vector2d();
}

///////////////////////////////////////////////////////////////////////////////
// DataObjectImpl, IDataObject implementation:

// The following function, DuplicateMedium, is derived from WCDataObject.cpp
// in the WebKit source code. This is the license information for the file:
/*
 * Copyright (C) 2007 Apple Inc.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
static void DuplicateMedium(CLIPFORMAT source_clipformat,
                            STGMEDIUM* source,
                            STGMEDIUM* destination) {
  switch (source->tymed) {
    case TYMED_HGLOBAL:
      destination->hGlobal =
          static_cast<HGLOBAL>(OleDuplicateData(
              source->hGlobal, source_clipformat, 0));
      break;
    case TYMED_MFPICT:
      destination->hMetaFilePict =
          static_cast<HMETAFILEPICT>(OleDuplicateData(
              source->hMetaFilePict, source_clipformat, 0));
      break;
    case TYMED_GDI:
      destination->hBitmap =
          static_cast<HBITMAP>(OleDuplicateData(
              source->hBitmap, source_clipformat, 0));
      break;
    case TYMED_ENHMF:
      destination->hEnhMetaFile =
          static_cast<HENHMETAFILE>(OleDuplicateData(
              source->hEnhMetaFile, source_clipformat, 0));
      break;
    case TYMED_FILE:
      destination->lpszFileName =
          static_cast<LPOLESTR>(OleDuplicateData(
              source->lpszFileName, source_clipformat, 0));
      break;
    case TYMED_ISTREAM:
      destination->pstm = source->pstm;
      destination->pstm->AddRef();
      break;
    case TYMED_ISTORAGE:
      destination->pstg = source->pstg;
      destination->pstg->AddRef();
      break;
  }

  destination->tymed = source->tymed;
  destination->pUnkForRelease = source->pUnkForRelease;
  if (destination->pUnkForRelease)
    destination->pUnkForRelease->AddRef();
}

DataObjectImpl::StoredDataInfo::StoredDataInfo(const FORMATETC& format_etc,
                                               STGMEDIUM* medium)
    : format_etc(format_etc), medium(medium), owns_medium(true) {}

DataObjectImpl::StoredDataInfo::~StoredDataInfo() {
  if (owns_medium) {
    ReleaseStgMedium(medium);
    delete medium;
  }
  if (downloader.get())
    downloader->Stop();
}

DataObjectImpl::DataObjectImpl()
    : is_aborting_(false),
      in_drag_loop_(false),
      in_async_mode_(false),
      async_operation_started_(false) {}

DataObjectImpl::~DataObjectImpl() {
  StopDownloads();
}

void DataObjectImpl::StopDownloads() {
  for (const std::unique_ptr<StoredDataInfo>& content : contents_) {
    if (content->downloader.get()) {
      content->downloader->Stop();
      content->downloader = 0;
    }
  }
}

void DataObjectImpl::RemoveData(const FORMATETC& format) {
  if (format.ptd)
    return;  // Don't attempt to compare target devices.

  for (StoredData::iterator i = contents_.begin(); i != contents_.end(); ++i) {
    if (!(*i)->format_etc.ptd &&
        format.cfFormat == (*i)->format_etc.cfFormat &&
        format.dwAspect == (*i)->format_etc.dwAspect &&
        format.lindex == (*i)->format_etc.lindex &&
        format.tymed == (*i)->format_etc.tymed) {
      contents_.erase(i);
      return;
    }
  }
}

void DataObjectImpl::OnDownloadCompleted(const base::FilePath& file_path) {
  for (std::unique_ptr<StoredDataInfo>& content : contents_) {
    if (content->format_etc.cfFormat == CF_HDROP) {
      // Retrieve the downloader first so it won't get destroyed.
      auto downloader = std::move(content->downloader);
      if (downloader)
        downloader->Stop();
      // Replace stored data.
      STGMEDIUM* storage =
          GetStorageForFileNames({FileInfo(file_path, base::FilePath())});
      content = std::make_unique<StoredDataInfo>(
          ClipboardFormatType::GetCFHDropType().ToFormatEtc(), storage);
      content->downloader = std::move(downloader);
      break;
    }
  }
}

void DataObjectImpl::OnDownloadAborted() {}

HRESULT DataObjectImpl::GetData(FORMATETC* format_etc, STGMEDIUM* medium) {
  if (is_aborting_)
    return DV_E_FORMATETC;

  for (const std::unique_ptr<StoredDataInfo>& content : contents_) {
    if (content->format_etc.cfFormat == format_etc->cfFormat &&
        content->format_etc.lindex == format_etc->lindex &&
        (content->format_etc.tymed & format_etc->tymed)) {
      // If medium is NULL, delay-rendering will be used.
      if (content->medium) {
        DuplicateMedium(content->format_etc.cfFormat, content->medium, medium);
        return S_OK;
      }
      // Fail all GetData() attempts for DownloadURL data if the drag and drop
      // operation is still in progress.
      if (in_drag_loop_)
        return DV_E_FORMATETC;

      bool wait_for_data = false;

      // In async mode, we do not want to start waiting for the data before
      // the async operation is started. This is because we want to postpone
      // until Shell kicks off a background thread to do the work so that
      // we do not block the UI thread.
      if (!in_async_mode_ || async_operation_started_)
        wait_for_data = true;

      if (!wait_for_data)
        return DV_E_FORMATETC;

      // Now we can start the download.
      if (content->downloader.get()) {
        content->downloader->Start(this);
        if (!content->downloader->Wait()) {
          is_aborting_ = true;
          return DV_E_FORMATETC;
        }
      }
      // The stored data should have been updated with the final version.
      // So we just need to call this function again to retrieve it.
      return GetData(format_etc, medium);
    }
  }

  return DV_E_FORMATETC;
}

HRESULT DataObjectImpl::GetDataHere(FORMATETC* format_etc,
                                    STGMEDIUM* medium) {
  return DATA_E_FORMATETC;
}

HRESULT DataObjectImpl::QueryGetData(FORMATETC* format_etc) {
  for (const std::unique_ptr<StoredDataInfo>& content : contents_) {
    if (content->format_etc.cfFormat == format_etc->cfFormat)
      return S_OK;
  }
  return DV_E_FORMATETC;
}

HRESULT DataObjectImpl::GetCanonicalFormatEtc(
    FORMATETC* format_etc, FORMATETC* result) {
  format_etc->ptd = NULL;
  return E_NOTIMPL;
}

HRESULT DataObjectImpl::SetData(
    FORMATETC* format_etc, STGMEDIUM* medium, BOOL should_release) {
  RemoveData(*format_etc);

  STGMEDIUM* local_medium = new STGMEDIUM;
  if (should_release) {
    *local_medium = *medium;
  } else {
    DuplicateMedium(format_etc->cfFormat, medium, local_medium);
  }

  auto info = std::make_unique<DataObjectImpl::StoredDataInfo>(*format_etc,
                                                               local_medium);
  info->medium->tymed = format_etc->tymed;
  info->owns_medium = !!should_release;
  // Make newly added data appear first.
  // TODO(dcheng): Make various setters agree whether elements should be
  // prioritized from front to back or back to front.
  contents_.insert(contents_.begin(), std::move(info));

  return S_OK;
}

HRESULT DataObjectImpl::EnumFormatEtc(
    DWORD direction, IEnumFORMATETC** enumerator) {
  if (direction == DATADIR_GET) {
    FormatEtcEnumerator* e =
        new FormatEtcEnumerator(contents_.begin(), contents_.end());
    e->AddRef();
    *enumerator = e;
    return S_OK;
  }
  return E_NOTIMPL;
}

HRESULT DataObjectImpl::DAdvise(
    FORMATETC* format_etc, DWORD advf, IAdviseSink* sink, DWORD* connection) {
  return OLE_E_ADVISENOTSUPPORTED;
}

HRESULT DataObjectImpl::DUnadvise(DWORD connection) {
  return OLE_E_ADVISENOTSUPPORTED;
}

HRESULT DataObjectImpl::EnumDAdvise(IEnumSTATDATA** enumerator) {
  return OLE_E_ADVISENOTSUPPORTED;
}

///////////////////////////////////////////////////////////////////////////////
// DataObjectImpl, IDataObjectAsyncCapability implementation:

HRESULT DataObjectImpl::EndOperation(
    HRESULT result, IBindCtx* reserved, DWORD effects) {
  async_operation_started_ = false;
  return S_OK;
}

HRESULT DataObjectImpl::GetAsyncMode(BOOL* is_op_async) {
  *is_op_async = in_async_mode_ ? VARIANT_TRUE : VARIANT_FALSE;
  return S_OK;
}

HRESULT DataObjectImpl::InOperation(BOOL* in_async_op) {
  *in_async_op = async_operation_started_ ? VARIANT_TRUE : VARIANT_FALSE;
  return S_OK;
}

HRESULT DataObjectImpl::SetAsyncMode(BOOL do_op_async) {
  in_async_mode_ = !!do_op_async;
  return S_OK;
}

HRESULT DataObjectImpl::StartOperation(IBindCtx* reserved) {
  async_operation_started_ = true;
  return S_OK;
}

///////////////////////////////////////////////////////////////////////////////
// DataObjectImpl, IUnknown implementation:

HRESULT DataObjectImpl::QueryInterface(const IID& iid, void** object) {
  if (!object)
    return E_POINTER;
  if (IsEqualIID(iid, IID_IDataObject) || IsEqualIID(iid, IID_IUnknown)) {
    *object = static_cast<IDataObject*>(this);
  } else if (in_async_mode_ &&
             IsEqualIID(iid, __uuidof(IDataObjectAsyncCapability))) {
    *object = static_cast<IDataObjectAsyncCapability*>(this);
  } else {
    *object = NULL;
    return E_NOINTERFACE;
  }
  AddRef();
  return S_OK;
}

ULONG DataObjectImpl::AddRef() {
  base::RefCountedThreadSafe<DownloadFileObserver>::AddRef();
  return 0;
}

ULONG DataObjectImpl::Release() {
  base::RefCountedThreadSafe<DownloadFileObserver>::Release();
  return 0;
}

///////////////////////////////////////////////////////////////////////////////
// DataObjectImpl, private:

static STGMEDIUM* GetStorageForBytes(const void* data, size_t bytes) {
  HANDLE handle = GlobalAlloc(GPTR, static_cast<int>(bytes));
  if (handle) {
    base::win::ScopedHGlobal<uint8_t*> scoped(handle);
    memcpy(scoped.get(), data, bytes);
  }

  STGMEDIUM* storage = new STGMEDIUM;
  storage->hGlobal = handle;
  storage->tymed = TYMED_HGLOBAL;
  storage->pUnkForRelease = NULL;
  return storage;
}

template <typename T>
static STGMEDIUM* GetStorageForString(const std::basic_string<T>& data) {
  return GetStorageForBytes(
      data.c_str(),
      (data.size() + 1) * sizeof(typename std::basic_string<T>::value_type));
}

static void GetInternetShortcutFileContents(const GURL& url,
                                            std::string* data) {
  DCHECK(data);
  static constexpr char kInternetShortcutFileStart[] =
      "[InternetShortcut]\r\nURL=";
  static constexpr char kInternetShortcutFileEnd[] = "\r\n";
  *data = kInternetShortcutFileStart + url.spec() + kInternetShortcutFileEnd;
}

static void CreateValidFileNameFromTitle(const GURL& url,
                                         const base::string16& title,
                                         base::string16* validated) {
  if (title.empty()) {
    if (url.is_valid()) {
      *validated = net::GetSuggestedFilename(url, "", "", "", "",
                                             std::string());
    } else {
      // Nothing else can be done, just use a default.
      *validated =
          l10n_util::GetStringUTF16(IDS_APP_UNTITLED_SHORTCUT_FILE_NAME);
    }
  } else {
    *validated = title;
    base::i18n::ReplaceIllegalCharactersInPath(validated, '-');
  }
  static const wchar_t kExtension[] = L".url";
  static const size_t kMaxLength = MAX_PATH - base::size(kExtension);
  if (validated->size() > kMaxLength)
    validated->erase(kMaxLength);
  *validated += kExtension;
}

static STGMEDIUM* GetStorageForFileNames(
    const std::vector<FileInfo>& filenames) {
  // CF_HDROP clipboard format consists of DROPFILES structure, a series of file
  // names including the terminating null character and the additional null
  // character at the tail to terminate the array.
  // For example,
  //| DROPFILES | FILENAME 1 | NULL | ... | FILENAME n | NULL | NULL |
  // For more details, please refer to
  // https://docs.microsoft.com/en-us/windows/desktop/shell/clipboard#cf_hdrop

  if (filenames.empty())
    return nullptr;

  const size_t kDropFilesHeaderSizeInBytes = sizeof(DROPFILES);
  size_t total_bytes = kDropFilesHeaderSizeInBytes;
  for (const auto& filename : filenames) {
    // Allocate memory of the filename's length including the null
    // character.
    total_bytes += (filename.path.value().length() + 1) * sizeof(wchar_t);
  }
  // |data| needs to be terminated by an additional null character.
  total_bytes += sizeof(wchar_t);

  // GHND combines GMEM_MOVEABLE and GMEM_ZEROINIT, and GMEM_ZEROINIT
  // initializes memory contents to zero.
  HANDLE hdata = GlobalAlloc(GHND, total_bytes);

  base::win::ScopedHGlobal<DROPFILES*> locked_mem(hdata);
  DROPFILES* drop_files = locked_mem.get();
  drop_files->pFiles = sizeof(DROPFILES);
  drop_files->fWide = TRUE;

  wchar_t* data = reinterpret_cast<wchar_t*>(
      reinterpret_cast<BYTE*>(drop_files) + kDropFilesHeaderSizeInBytes);

  size_t next_filename_offset = 0;
  for (const auto& filename : filenames) {
    wcscpy(data + next_filename_offset, filename.path.value().c_str());
    // Skip the terminating null character of the filename.
    next_filename_offset += filename.path.value().length() + 1;
  }

  STGMEDIUM* storage = new STGMEDIUM;
  storage->tymed = TYMED_HGLOBAL;
  storage->hGlobal = hdata;
  storage->pUnkForRelease = nullptr;
  return storage;
}

static LPITEMIDLIST PIDLNext(LPITEMIDLIST pidl) {
  return reinterpret_cast<LPITEMIDLIST>(
      reinterpret_cast<BYTE*>(pidl) + pidl->mkid.cb);
}

static size_t PIDLSize(LPITEMIDLIST pidl) {
  size_t s = 0;
  while (pidl->mkid.cb > 0) {
    s += pidl->mkid.cb;
    pidl = PIDLNext(pidl);
  }
  // We add 2 because an LPITEMIDLIST is terminated by two NULL bytes.
  return 2 + s;
}

static LPITEMIDLIST GetNthPIDL(CIDA* cida, int n) {
  return reinterpret_cast<LPITEMIDLIST>(
      reinterpret_cast<LPBYTE>(cida) + cida->aoffset[n]);
}

static LPITEMIDLIST GetPidlFromPath(const base::FilePath& path) {
  LPITEMIDLIST pidl = NULL;
  LPSHELLFOLDER desktop_folder = NULL;
  LPWSTR path_str = const_cast<LPWSTR>(path.value().c_str());

  if (FAILED(SHGetDesktopFolder(&desktop_folder)))
    return NULL;

  HRESULT hr = desktop_folder->ParseDisplayName(
      NULL, NULL, path_str, NULL, &pidl, NULL);

  return SUCCEEDED(hr) ? pidl : NULL;
}

static STGMEDIUM* GetIDListStorageForFileName(const base::FilePath& path) {
  LPITEMIDLIST pidl = GetPidlFromPath(path);
  if (!pidl)
    return NULL;

  // When using CFSTR_SHELLIDLIST the hGlobal field of the STGMEDIUM is a
  // pointer to a CIDA*. A CIDA is a variable length struct that contains a PIDL
  // count (a UINT), an array of offsets of the following PIDLs (a UINT[]) and
  // then a series of PIDLs laid out contiguously in memory. A PIDL is
  // represented by an ITEMIDLIST struct, which contains a single SHITEMID.
  // Despite only containing a single SHITEMID, ITEMIDLISTs are so-named because
  // SHITEMIDs contain their own size and so given one, the next can be found by
  // looking at the section of memory after it. The end of a list is indicated
  // by two NULL bytes.
  // Here we require two PIDLs - the first PIDL is the parent folder and is
  // NULL here to indicate that the parent folder is the desktop, and the second
  // is the PIDL of |path|.
  const size_t kPIDLCountSize = sizeof(UINT);
  const size_t kPIDLOffsetsSize = 2 * sizeof(UINT);
  const size_t kFirstPIDLOffset = kPIDLCountSize + kPIDLOffsetsSize;
  const size_t kFirstPIDLSize = 2;  // Empty PIDL - 2 NULL bytes.
  const size_t kSecondPIDLSize = PIDLSize(pidl);
  const size_t kCIDASize = kFirstPIDLOffset + kFirstPIDLSize + kSecondPIDLSize;
  HANDLE hdata = GlobalAlloc(GMEM_MOVEABLE, kCIDASize);

  base::win::ScopedHGlobal<CIDA*> locked_mem(hdata);
  CIDA* cida = locked_mem.get();
  cida->cidl = 1;     // We have one PIDL (not including the 0th root PIDL).
  cida->aoffset[0] = kFirstPIDLOffset;
  cida->aoffset[1] = kFirstPIDLOffset + kFirstPIDLSize;
  LPITEMIDLIST idl = GetNthPIDL(cida, 0);
  idl->mkid.cb = 0;
  idl->mkid.abID[0] = 0;
  idl = GetNthPIDL(cida, 1);
  memcpy(idl, pidl, kSecondPIDLSize);

  STGMEDIUM* storage = new STGMEDIUM;
  storage->tymed = TYMED_HGLOBAL;
  storage->hGlobal = hdata;
  storage->pUnkForRelease = NULL;
  return storage;
}

static STGMEDIUM* GetStorageForFileDescriptor(
    const base::FilePath& path) {
  base::string16 file_name = path.value();
  DCHECK(!file_name.empty());
  HANDLE hdata = GlobalAlloc(GPTR, sizeof(FILEGROUPDESCRIPTORW));
  base::win::ScopedHGlobal<FILEGROUPDESCRIPTORW*> locked_mem(hdata);

  FILEGROUPDESCRIPTORW* descriptor = locked_mem.get();
  descriptor->cItems = 1;
  descriptor->fgd[0].dwFlags = FD_LINKUI;
  wcsncpy_s(descriptor->fgd[0].cFileName, MAX_PATH, file_name.c_str(),
            std::min(file_name.size(), static_cast<size_t>(MAX_PATH - 1u)));

  STGMEDIUM* storage = new STGMEDIUM;
  storage->tymed = TYMED_HGLOBAL;
  storage->hGlobal = hdata;
  storage->pUnkForRelease = NULL;
  return storage;
}

}  // namespace ui