Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2276 insertions, 0 deletions

diff --git a/widget/windows/nsDataObj.cpp b/widget/windows/nsDataObj.cpp
new file mode 100644
index 0000000000..88a2a2ad09
--- /dev/null
+++ b/widget/windows/nsDataObj.cpp
@@ -0,0 +1,2276 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/TextUtils.h"
+
+#include <ole2.h>
+#include <shlobj.h>
+
+#include "nsComponentManagerUtils.h"
+#include "nsDataObj.h"
+#include "nsArrayUtils.h"
+#include "nsClipboard.h"
+#include "nsReadableUtils.h"
+#include "nsICookieJarSettings.h"
+#include "nsIHttpChannel.h"
+#include "nsISupportsPrimitives.h"
+#include "nsITransferable.h"
+#include "IEnumFE.h"
+#include "nsPrimitiveHelpers.h"
+#include "nsString.h"
+#include "nsCRT.h"
+#include "nsPrintfCString.h"
+#include "nsIStringBundle.h"
+#include "nsEscape.h"
+#include "nsIURL.h"
+#include "nsNetUtil.h"
+#include "mozilla/Components.h"
+#include "mozilla/SpinEventLoopUntil.h"
+#include "mozilla/Unused.h"
+#include "nsProxyRelease.h"
+#include "nsIObserverService.h"
+#include "nsIOutputStream.h"
+#include "nscore.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsITimer.h"
+#include "nsThreadUtils.h"
+#include "mozilla/Preferences.h"
+#include "nsContentUtils.h"
+#include "nsIPrincipal.h"
+#include "nsNativeCharsetUtils.h"
+#include "nsMimeTypes.h"
+#include "nsIMIMEService.h"
+#include "imgIEncoder.h"
+#include "imgITools.h"
+#include "WinUtils.h"
+#include "nsLocalFile.h"
+
+#include "mozilla/LazyIdleThread.h"
+#include <algorithm>
+
+using namespace mozilla;
+using namespace mozilla::glue;
+using namespace mozilla::widget;
+
+#define BFH_LENGTH 14
+#define DEFAULT_THREAD_TIMEOUT_MS 30000
+
+//-----------------------------------------------------------------------------
+// CStreamBase implementation
+nsDataObj::CStreamBase::CStreamBase() : mStreamRead(0) {}
+
+//-----------------------------------------------------------------------------
+nsDataObj::CStreamBase::~CStreamBase() {}
+
+NS_IMPL_ISUPPORTS(nsDataObj::CStream, nsIStreamListener)
+
+//-----------------------------------------------------------------------------
+// CStream implementation
+nsDataObj::CStream::CStream() : mChannelRead(false) {}
+
+//-----------------------------------------------------------------------------
+nsDataObj::CStream::~CStream() {}
+
+//-----------------------------------------------------------------------------
+// helper - initializes the stream
+nsresult nsDataObj::CStream::Init(nsIURI* pSourceURI,
+                                  nsContentPolicyType aContentPolicyType,
+                                  nsIPrincipal* aRequestingPrincipal,
+                                  nsICookieJarSettings* aCookieJarSettings,
+                                  nsIReferrerInfo* aReferrerInfo) {
+  // we can not create a channel without a requestingPrincipal
+  if (!aRequestingPrincipal) {
+    return NS_ERROR_FAILURE;
+  }
+  nsresult rv;
+  rv = NS_NewChannel(getter_AddRefs(mChannel), pSourceURI, aRequestingPrincipal,
+                     nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_INHERITS_SEC_CONTEXT,
+                     aContentPolicyType, aCookieJarSettings,
+                     nullptr,  // PerformanceStorage
+                     nullptr,  // loadGroup
+                     nullptr,  // aCallbacks
+                     nsIRequest::LOAD_FROM_CACHE);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (nsCOMPtr<nsIHttpChannel> httpChannel = do_QueryInterface(mChannel)) {
+    rv = httpChannel->SetReferrerInfo(aReferrerInfo);
+    Unused << NS_WARN_IF(NS_FAILED(rv));
+  }
+
+  rv = mChannel->AsyncOpen(this);
+  NS_ENSURE_SUCCESS(rv, rv);
+  return NS_OK;
+}
+
+//-----------------------------------------------------------------------------
+// IUnknown's QueryInterface, nsISupport's AddRef and Release are shared by
+// IUnknown and nsIStreamListener.
+STDMETHODIMP nsDataObj::CStream::QueryInterface(REFIID refiid,
+                                                void** ppvResult) {
+  *ppvResult = nullptr;
+  if (IID_IUnknown == refiid || refiid == IID_IStream)
+
+  {
+    *ppvResult = this;
+  }
+
+  if (nullptr != *ppvResult) {
+    ((LPUNKNOWN)*ppvResult)->AddRef();
+    return S_OK;
+  }
+
+  return E_NOINTERFACE;
+}
+
+// nsIStreamListener implementation
+NS_IMETHODIMP
+nsDataObj::CStream::OnDataAvailable(
+    nsIRequest* aRequest, nsIInputStream* aInputStream,
+    uint64_t aOffset,  // offset within the stream
+    uint32_t aCount)   // bytes available on this call
+{
+  // If we've been asked to read zero bytes, call `Read` once, just to ensure
+  // any side-effects take place, and return immediately.
+  if (aCount == 0) {
+    char buffer[1] = {0};
+    uint32_t bytesReadByCall = 0;
+    nsresult rv = aInputStream->Read(buffer, 0, &bytesReadByCall);
+    MOZ_ASSERT(bytesReadByCall == 0);
+    return rv;
+  }
+
+  // Extend the write buffer for the incoming data.
+  size_t oldLength = mChannelData.Length();
+  char* buffer =
+      reinterpret_cast<char*>(mChannelData.AppendElements(aCount, fallible));
+  if (!buffer) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  MOZ_ASSERT(mChannelData.Length() == (aOffset + aCount),
+             "stream length mismatch w/write buffer");
+
+  // Read() may not return aCount on a single call, so loop until we've
+  // accumulated all the data OnDataAvailable has promised.
+  uint32_t bytesRead = 0;
+  while (bytesRead < aCount) {
+    uint32_t bytesReadByCall = 0;
+    nsresult rv = aInputStream->Read(buffer + bytesRead, aCount - bytesRead,
+                                     &bytesReadByCall);
+    bytesRead += bytesReadByCall;
+
+    if (bytesReadByCall == 0) {
+      // A `bytesReadByCall` of zero indicates EOF without failure... but we
+      // were promised `aCount` elements and haven't gotten them. Return a
+      // generic failure.
+      rv = NS_ERROR_FAILURE;
+    }
+
+    if (NS_FAILED(rv)) {
+      // Drop any trailing uninitialized elements before erroring out.
+      mChannelData.RemoveElementsAt(oldLength + bytesRead, aCount - bytesRead);
+      return rv;
+    }
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsDataObj::CStream::OnStartRequest(nsIRequest* aRequest) {
+  mChannelResult = NS_OK;
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsDataObj::CStream::OnStopRequest(nsIRequest* aRequest,
+                                                nsresult aStatusCode) {
+  mChannelRead = true;
+  mChannelResult = aStatusCode;
+  return NS_OK;
+}
+
+// Pumps thread messages while waiting for the async listener operation to
+// complete. Failing this call will fail the stream incall from Windows
+// and cancel the operation.
+nsresult nsDataObj::CStream::WaitForCompletion() {
+  // We are guaranteed OnStopRequest will get called, so this should be ok.
+  SpinEventLoopUntil("widget:nsDataObj::CStream::WaitForCompletion"_ns,
+                     [&]() { return mChannelRead; });
+
+  if (!mChannelData.Length()) mChannelResult = NS_ERROR_FAILURE;
+
+  return mChannelResult;
+}
+
+//-----------------------------------------------------------------------------
+// IStream
+STDMETHODIMP nsDataObj::CStreamBase::Clone(IStream** ppStream) {
+  return E_NOTIMPL;
+}
+
+//-----------------------------------------------------------------------------
+STDMETHODIMP nsDataObj::CStreamBase::Commit(DWORD dwFrags) { return E_NOTIMPL; }
+
+//-----------------------------------------------------------------------------
+STDMETHODIMP nsDataObj::CStreamBase::CopyTo(IStream* pDestStream,
+                                            ULARGE_INTEGER nBytesToCopy,
+                                            ULARGE_INTEGER* nBytesRead,
+                                            ULARGE_INTEGER* nBytesWritten) {
+  return E_NOTIMPL;
+}
+
+//-----------------------------------------------------------------------------
+STDMETHODIMP nsDataObj::CStreamBase::LockRegion(ULARGE_INTEGER nStart,
+                                                ULARGE_INTEGER nBytes,
+                                                DWORD dwFlags) {
+  return E_NOTIMPL;
+}
+
+//-----------------------------------------------------------------------------
+STDMETHODIMP nsDataObj::CStream::Read(void* pvBuffer, ULONG nBytesToRead,
+                                      ULONG* nBytesRead) {
+  // Wait for the write into our buffer to complete via the stream listener.
+  // We can't respond to this by saying "call us back later".
+  if (NS_FAILED(WaitForCompletion())) return E_FAIL;
+
+  // Bytes left for Windows to read out of our buffer
+  ULONG bytesLeft = mChannelData.Length() - mStreamRead;
+  // Let Windows know what we will hand back, usually this is the entire buffer
+  *nBytesRead = std::min(bytesLeft, nBytesToRead);
+  // Copy the buffer data over
+  memcpy(pvBuffer, ((char*)mChannelData.Elements() + mStreamRead), *nBytesRead);
+  // Update our bytes read tracking
+  mStreamRead += *nBytesRead;
+  return S_OK;
+}
+
+//-----------------------------------------------------------------------------
+STDMETHODIMP nsDataObj::CStreamBase::Revert(void) { return E_NOTIMPL; }
+
+//-----------------------------------------------------------------------------
+STDMETHODIMP nsDataObj::CStreamBase::Seek(LARGE_INTEGER nMove, DWORD dwOrigin,
+                                          ULARGE_INTEGER* nNewPos) {
+  if (nNewPos == nullptr) return STG_E_INVALIDPOINTER;
+
+  if (nMove.LowPart == 0 && nMove.HighPart == 0 &&
+      (dwOrigin == STREAM_SEEK_SET || dwOrigin == STREAM_SEEK_CUR)) {
+    nNewPos->LowPart = 0;
+    nNewPos->HighPart = 0;
+    return S_OK;
+  }
+
+  return E_NOTIMPL;
+}
+
+//-----------------------------------------------------------------------------
+STDMETHODIMP nsDataObj::CStreamBase::SetSize(ULARGE_INTEGER nNewSize) {
+  return E_NOTIMPL;
+}
+
+//-----------------------------------------------------------------------------
+STDMETHODIMP nsDataObj::CStream::Stat(STATSTG* statstg, DWORD dwFlags) {
+  if (statstg == nullptr) return STG_E_INVALIDPOINTER;
+
+  if (!mChannel || NS_FAILED(WaitForCompletion())) return E_FAIL;
+
+  memset((void*)statstg, 0, sizeof(STATSTG));
+
+  if (dwFlags != STATFLAG_NONAME) {
+    nsCOMPtr<nsIURI> sourceURI;
+    if (NS_FAILED(mChannel->GetURI(getter_AddRefs(sourceURI)))) {
+      return E_FAIL;
+    }
+
+    nsAutoCString strFileName;
+    nsCOMPtr<nsIURL> sourceURL = do_QueryInterface(sourceURI);
+    sourceURL->GetFileName(strFileName);
+
+    if (strFileName.IsEmpty()) return E_FAIL;
+
+    NS_UnescapeURL(strFileName);
+    NS_ConvertUTF8toUTF16 wideFileName(strFileName);
+
+    uint32_t nMaxNameLength = (wideFileName.Length() * 2) + 2;
+    void* retBuf = CoTaskMemAlloc(nMaxNameLength);  // freed by caller
+    if (!retBuf) return STG_E_INSUFFICIENTMEMORY;
+
+    ZeroMemory(retBuf, nMaxNameLength);
+    memcpy(retBuf, wideFileName.get(), wideFileName.Length() * 2);
+    statstg->pwcsName = (LPOLESTR)retBuf;
+  }
+
+  SYSTEMTIME st;
+
+  statstg->type = STGTY_STREAM;
+
+  GetSystemTime(&st);
+  SystemTimeToFileTime((const SYSTEMTIME*)&st, (LPFILETIME)&statstg->mtime);
+  statstg->ctime = statstg->atime = statstg->mtime;
+
+  statstg->cbSize.QuadPart = mChannelData.Length();
+  statstg->grfMode = STGM_READ;
+  statstg->grfLocksSupported = LOCK_ONLYONCE;
+  statstg->clsid = CLSID_NULL;
+
+  return S_OK;
+}
+
+//-----------------------------------------------------------------------------
+STDMETHODIMP nsDataObj::CStreamBase::UnlockRegion(ULARGE_INTEGER nStart,
+                                                  ULARGE_INTEGER nBytes,
+                                                  DWORD dwFlags) {
+  return E_NOTIMPL;
+}
+
+//-----------------------------------------------------------------------------
+STDMETHODIMP nsDataObj::CStreamBase::Write(const void* pvBuffer,
+                                           ULONG nBytesToRead,
+                                           ULONG* nBytesRead) {
+  return E_NOTIMPL;
+}
+
+//-----------------------------------------------------------------------------
+HRESULT nsDataObj::CreateStream(IStream** outStream) {
+  NS_ENSURE_TRUE(outStream, E_INVALIDARG);
+
+  nsresult rv = NS_ERROR_FAILURE;
+  nsAutoString wideFileName;
+  nsCOMPtr<nsIURI> sourceURI;
+  HRESULT res;
+
+  res = GetDownloadDetails(getter_AddRefs(sourceURI), wideFileName);
+  if (FAILED(res)) return res;
+
+  nsDataObj::CStream* pStream = new nsDataObj::CStream();
+  NS_ENSURE_TRUE(pStream, E_OUTOFMEMORY);
+
+  pStream->AddRef();
+
+  // query the requestingPrincipal from the transferable and add it to the new
+  // channel
+  nsCOMPtr<nsIPrincipal> requestingPrincipal =
+      mTransferable->GetRequestingPrincipal();
+  MOZ_ASSERT(requestingPrincipal, "can not create channel without a principal");
+
+  // Note that the cookieJarSettings could be null if the data object is for the
+  // image copy. We will fix this in Bug 1690532.
+  nsCOMPtr<nsICookieJarSettings> cookieJarSettings =
+      mTransferable->GetCookieJarSettings();
+
+  // The referrer is optional.
+  nsCOMPtr<nsIReferrerInfo> referrerInfo = mTransferable->GetReferrerInfo();
+
+  nsContentPolicyType contentPolicyType = mTransferable->GetContentPolicyType();
+  rv = pStream->Init(sourceURI, contentPolicyType, requestingPrincipal,
+                     cookieJarSettings, referrerInfo);
+  if (NS_FAILED(rv)) {
+    pStream->Release();
+    return E_FAIL;
+  }
+  *outStream = pStream;
+
+  return S_OK;
+}
+
+//-----------------------------------------------------------------------------
+// AutoCloseEvent implementation
+nsDataObj::AutoCloseEvent::AutoCloseEvent()
+    : mEvent(::CreateEventW(nullptr, TRUE, FALSE, nullptr)) {}
+
+bool nsDataObj::AutoCloseEvent::IsInited() const { return !!mEvent; }
+
+void nsDataObj::AutoCloseEvent::Signal() const { ::SetEvent(mEvent); }
+
+DWORD nsDataObj::AutoCloseEvent::Wait(DWORD aMillisec) const {
+  return ::WaitForSingleObject(mEvent, aMillisec);
+}
+
+//-----------------------------------------------------------------------------
+// AutoSetEvent implementation
+nsDataObj::AutoSetEvent::AutoSetEvent(NotNull<AutoCloseEvent*> aEvent)
+    : mEvent(aEvent) {}
+
+nsDataObj::AutoSetEvent::~AutoSetEvent() { Signal(); }
+
+void nsDataObj::AutoSetEvent::Signal() const { mEvent->Signal(); }
+
+bool nsDataObj::AutoSetEvent::IsWaiting() const {
+  return mEvent->Wait(0) == WAIT_TIMEOUT;
+}
+
+//-----------------------------------------------------------------------------
+// CMemStream implementation
+Win32SRWLock nsDataObj::CMemStream::mLock;
+
+//-----------------------------------------------------------------------------
+nsDataObj::CMemStream::CMemStream(nsHGLOBAL aGlobalMem, uint32_t aTotalLength,
+                                  already_AddRefed<AutoCloseEvent> aEvent)
+    : mGlobalMem(aGlobalMem), mEvent(aEvent), mTotalLength(aTotalLength) {
+  ::CoCreateFreeThreadedMarshaler(this, getter_AddRefs(mMarshaler));
+}
+
+//-----------------------------------------------------------------------------
+nsDataObj::CMemStream::~CMemStream() {}
+
+//-----------------------------------------------------------------------------
+// IUnknown
+STDMETHODIMP nsDataObj::CMemStream::QueryInterface(REFIID refiid,
+                                                   void** ppvResult) {
+  *ppvResult = nullptr;
+  if (refiid == IID_IUnknown || refiid == IID_IStream ||
+      refiid == IID_IAgileObject) {
+    *ppvResult = this;
+  } else if (refiid == IID_IMarshal && mMarshaler) {
+    return mMarshaler->QueryInterface(refiid, ppvResult);
+  }
+
+  if (nullptr != *ppvResult) {
+    ((LPUNKNOWN)*ppvResult)->AddRef();
+    return S_OK;
+  }
+
+  return E_NOINTERFACE;
+}
+
+void nsDataObj::CMemStream::WaitForCompletion() {
+  if (!mEvent) {
+    // We are not waiting for obtaining the icon cache.
+    return;
+  }
+  if (!NS_IsMainThread()) {
+    mEvent->Wait(INFINITE);
+  } else {
+    // We should not block the main thread.
+    mEvent->Signal();
+  }
+  // mEvent will always be in the signaled state here.
+}
+
+//-----------------------------------------------------------------------------
+// IStream
+STDMETHODIMP nsDataObj::CMemStream::Read(void* pvBuffer, ULONG nBytesToRead,
+                                         ULONG* nBytesRead) {
+  // Wait until the event is signaled.
+  WaitForCompletion();
+
+  AutoExclusiveLock lock(mLock);
+  char* contents = reinterpret_cast<char*>(GlobalLock(mGlobalMem.get()));
+  if (!contents) {
+    return E_OUTOFMEMORY;
+  }
+
+  // Bytes left for Windows to read out of our buffer
+  ULONG bytesLeft = mTotalLength - mStreamRead;
+  // Let Windows know what we will hand back, usually this is the entire buffer
+  *nBytesRead = std::min(bytesLeft, nBytesToRead);
+  // Copy the buffer data over
+  memcpy(pvBuffer, contents + mStreamRead, *nBytesRead);
+  // Update our bytes read tracking
+  mStreamRead += *nBytesRead;
+
+  GlobalUnlock(mGlobalMem.get());
+  return S_OK;
+}
+
+//-----------------------------------------------------------------------------
+STDMETHODIMP nsDataObj::CMemStream::Stat(STATSTG* statstg, DWORD dwFlags) {
+  if (statstg == nullptr) return STG_E_INVALIDPOINTER;
+
+  memset((void*)statstg, 0, sizeof(STATSTG));
+
+  if (dwFlags != STATFLAG_NONAME) {
+    constexpr size_t kMaxNameLength = sizeof(wchar_t);
+    void* retBuf = CoTaskMemAlloc(kMaxNameLength);  // freed by caller
+    if (!retBuf) return STG_E_INSUFFICIENTMEMORY;
+
+    ZeroMemory(retBuf, kMaxNameLength);
+    statstg->pwcsName = (LPOLESTR)retBuf;
+  }
+
+  SYSTEMTIME st;
+
+  statstg->type = STGTY_STREAM;
+
+  GetSystemTime(&st);
+  SystemTimeToFileTime((const SYSTEMTIME*)&st, (LPFILETIME)&statstg->mtime);
+  statstg->ctime = statstg->atime = statstg->mtime;
+
+  statstg->cbSize.QuadPart = mTotalLength;
+  statstg->grfMode = STGM_READ;
+  statstg->grfLocksSupported = LOCK_ONLYONCE;
+  statstg->clsid = CLSID_NULL;
+
+  return S_OK;
+}
+
+/*
+ * Class nsDataObj
+ */
+
+//-----------------------------------------------------
+// construction
+//-----------------------------------------------------
+nsDataObj::nsDataObj(nsIURI* uri)
+    : m_cRef(0),
+      mTransferable(nullptr),
+      mIsAsyncMode(FALSE),
+      mIsInOperation(FALSE) {
+  mIOThread = new LazyIdleThread(DEFAULT_THREAD_TIMEOUT_MS, "nsDataObj",
+                                 LazyIdleThread::ManualShutdown);
+  m_enumFE = new CEnumFormatEtc();
+  m_enumFE->AddRef();
+
+  if (uri) {
+    // A URI was obtained, so pass this through to the DataObject
+    // so it can create a SourceURL for CF_HTML flavour
+    uri->GetSpec(mSourceURL);
+  }
+}
+//-----------------------------------------------------
+// destruction
+//-----------------------------------------------------
+nsDataObj::~nsDataObj() {
+  NS_IF_RELEASE(mTransferable);
+
+  mDataFlavors.Clear();
+
+  m_enumFE->Release();
+
+  // Free arbitrary system formats
+  for (uint32_t idx = 0; idx < mDataEntryList.Length(); idx++) {
+    CoTaskMemFree(mDataEntryList[idx]->fe.ptd);
+    ReleaseStgMedium(&mDataEntryList[idx]->stgm);
+    CoTaskMemFree(mDataEntryList[idx]);
+  }
+}
+
+//-----------------------------------------------------
+// IUnknown interface methods - see inknown.h for documentation
+//-----------------------------------------------------
+STDMETHODIMP nsDataObj::QueryInterface(REFIID riid, void** ppv) {
+  *ppv = nullptr;
+
+  if ((IID_IUnknown == riid) || (IID_IDataObject == riid)) {
+    *ppv = this;
+    AddRef();
+    return S_OK;
+  } else if (IID_IDataObjectAsyncCapability == riid) {
+    *ppv = static_cast<IDataObjectAsyncCapability*>(this);
+    AddRef();
+    return S_OK;
+  }
+
+  return E_NOINTERFACE;
+}
+
+//-----------------------------------------------------
+STDMETHODIMP_(ULONG) nsDataObj::AddRef() {
+  ++m_cRef;
+  NS_LOG_ADDREF(this, m_cRef, "nsDataObj", sizeof(*this));
+
+  // When the first reference is taken, hold our own internal reference.
+  if (m_cRef == 1) {
+    mKeepAlive = this;
+  }
+
+  return m_cRef;
+}
+
+namespace {
+class RemoveTempFileHelper final : public nsIObserver, public nsINamed {
+ public:
+  explicit RemoveTempFileHelper(nsIFile* aTempFile) : mTempFile(aTempFile) {
+    MOZ_ASSERT(mTempFile);
+  }
+
+  // The attach method is seperate from the constructor as we may be addref-ing
+  // ourself, and we want to be sure someone has a strong reference to us.
+  void Attach() {
+    // We need to listen to both the xpcom shutdown message and our timer, and
+    // fire when the first of either of these two messages is received.
+    nsresult rv;
+    rv = NS_NewTimerWithObserver(getter_AddRefs(mTimer), this, 500,
+                                 nsITimer::TYPE_ONE_SHOT);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return;
+    }
+
+    nsCOMPtr<nsIObserverService> observerService =
+        do_GetService("@mozilla.org/observer-service;1");
+    if (NS_WARN_IF(!observerService)) {
+      mTimer->Cancel();
+      mTimer = nullptr;
+      return;
+    }
+    observerService->AddObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID, false);
+  }
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIOBSERVER
+  NS_DECL_NSINAMED
+
+ private:
+  ~RemoveTempFileHelper() {
+    if (mTempFile) {
+      mTempFile->Remove(false);
+    }
+  }
+
+  nsCOMPtr<nsIFile> mTempFile;
+  nsCOMPtr<nsITimer> mTimer;
+};
+
+NS_IMPL_ISUPPORTS(RemoveTempFileHelper, nsIObserver, nsINamed);
+
+NS_IMETHODIMP
+RemoveTempFileHelper::Observe(nsISupports* aSubject, const char* aTopic,
+                              const char16_t* aData) {
+  // Let's be careful and make sure that we don't die immediately
+  RefPtr<RemoveTempFileHelper> grip = this;
+
+  // Make sure that we aren't called again by destroying references to ourself.
+  nsCOMPtr<nsIObserverService> observerService =
+      do_GetService("@mozilla.org/observer-service;1");
+  if (observerService) {
+    observerService->RemoveObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID);
+  }
+
+  if (mTimer) {
+    mTimer->Cancel();
+    mTimer = nullptr;
+  }
+
+  // Remove the tempfile
+  if (mTempFile) {
+    mTempFile->Remove(false);
+    mTempFile = nullptr;
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+RemoveTempFileHelper::GetName(nsACString& aName) {
+  aName.AssignLiteral("RemoveTempFileHelper");
+  return NS_OK;
+}
+}  // namespace
+
+//-----------------------------------------------------
+STDMETHODIMP_(ULONG) nsDataObj::Release() {
+  --m_cRef;
+
+  NS_LOG_RELEASE(this, m_cRef, "nsDataObj");
+
+  // If we hold the last reference, submit release of it to the main thread.
+  if (m_cRef == 1 && mKeepAlive) {
+    NS_ReleaseOnMainThread("nsDataObj release", mKeepAlive.forget(), true);
+  }
+
+  if (0 != m_cRef) return m_cRef;
+
+  // We have released our last ref on this object and need to delete the
+  // temp file. External app acting as drop target may still need to open the
+  // temp file. Addref a timer so it can delay deleting file and destroying
+  // this object.
+  if (mCachedTempFile) {
+    RefPtr<RemoveTempFileHelper> helper =
+        new RemoveTempFileHelper(mCachedTempFile);
+    mCachedTempFile = nullptr;
+    helper->Attach();
+  }
+
+  // In case the destructor ever AddRef/Releases, ensure we don't delete twice
+  // or take mKeepAlive as another reference.
+  m_cRef = 1;
+
+  delete this;
+
+  return 0;
+}
+
+//-----------------------------------------------------
+BOOL nsDataObj::FormatsMatch(const FORMATETC& source,
+                             const FORMATETC& target) const {
+  if ((source.cfFormat == target.cfFormat) &&
+      (source.dwAspect & target.dwAspect) && (source.tymed & target.tymed)) {
+    return TRUE;
+  } else {
+    return FALSE;
+  }
+}
+
+//-----------------------------------------------------
+// IDataObject methods
+//-----------------------------------------------------
+STDMETHODIMP nsDataObj::GetData(LPFORMATETC aFormat, LPSTGMEDIUM pSTM) {
+  if (!mTransferable) return DV_E_FORMATETC;
+
+  // Hold an extra reference in case we end up spinning the event loop.
+  RefPtr<nsDataObj> keepAliveDuringGetData(this);
+
+  uint32_t dfInx = 0;
+
+  static CLIPFORMAT fileDescriptorFlavorA =
+      ::RegisterClipboardFormat(CFSTR_FILEDESCRIPTORA);
+  static CLIPFORMAT fileDescriptorFlavorW =
+      ::RegisterClipboardFormat(CFSTR_FILEDESCRIPTORW);
+  static CLIPFORMAT uniformResourceLocatorA =
+      ::RegisterClipboardFormat(CFSTR_INETURLA);
+  static CLIPFORMAT uniformResourceLocatorW =
+      ::RegisterClipboardFormat(CFSTR_INETURLW);
+  static CLIPFORMAT fileFlavor = ::RegisterClipboardFormat(CFSTR_FILECONTENTS);
+  static CLIPFORMAT PreferredDropEffect =
+      ::RegisterClipboardFormat(CFSTR_PREFERREDDROPEFFECT);
+
+  // Arbitrary system formats are used for image feedback during drag
+  // and drop. We are responsible for storing these internally during
+  // drag operations.
+  LPDATAENTRY pde;
+  if (LookupArbitraryFormat(aFormat, &pde, FALSE)) {
+    return CopyMediumData(pSTM, &pde->stgm, aFormat, FALSE) ? S_OK
+                                                            : E_UNEXPECTED;
+  }
+
+  // Firefox internal formats
+  ULONG count;
+  FORMATETC fe;
+  m_enumFE->Reset();
+  while (NOERROR == m_enumFE->Next(1, &fe, &count) &&
+         dfInx < mDataFlavors.Length()) {
+    nsCString& df = mDataFlavors.ElementAt(dfInx);
+    if (FormatsMatch(fe, *aFormat)) {
+      pSTM->pUnkForRelease =
+          nullptr;  // caller is responsible for deleting this data
+      CLIPFORMAT format = aFormat->cfFormat;
+      switch (format) {
+        // Someone is asking for plain or unicode text
+        case CF_TEXT:
+        case CF_UNICODETEXT:
+          return GetText(df, *aFormat, *pSTM);
+
+        // Some 3rd party apps that receive drag and drop files from the browser
+        // window require support for this.
+        case CF_HDROP:
+          return GetFile(*aFormat, *pSTM);
+
+        // Someone is asking for an image
+        case CF_DIBV5:
+        case CF_DIB:
+          return GetDib(df, *aFormat, *pSTM);
+
+        default:
+          if (format == fileDescriptorFlavorA)
+            return GetFileDescriptor(*aFormat, *pSTM, false);
+          if (format == fileDescriptorFlavorW)
+            return GetFileDescriptor(*aFormat, *pSTM, true);
+          if (format == uniformResourceLocatorA)
+            return GetUniformResourceLocator(*aFormat, *pSTM, false);
+          if (format == uniformResourceLocatorW)
+            return GetUniformResourceLocator(*aFormat, *pSTM, true);
+          if (format == fileFlavor) return GetFileContents(*aFormat, *pSTM);
+          if (format == PreferredDropEffect)
+            return GetPreferredDropEffect(*aFormat, *pSTM);
+          // MOZ_LOG(gWindowsLog, LogLevel::Info,
+          //       ("***** nsDataObj::GetData - Unknown format %u\n", format));
+          return GetText(df, *aFormat, *pSTM);
+      }  // switch
+    }    // if
+    dfInx++;
+  }  // while
+
+  return DATA_E_FORMATETC;
+}
+
+//-----------------------------------------------------
+STDMETHODIMP nsDataObj::GetDataHere(LPFORMATETC pFE, LPSTGMEDIUM pSTM) {
+  return E_FAIL;
+}
+
+//-----------------------------------------------------
+// Other objects querying to see if we support a
+// particular format
+//-----------------------------------------------------
+STDMETHODIMP nsDataObj::QueryGetData(LPFORMATETC pFE) {
+  // Arbitrary system formats are used for image feedback during drag
+  // and drop. We are responsible for storing these internally during
+  // drag operations.
+  LPDATAENTRY pde;
+  if (LookupArbitraryFormat(pFE, &pde, FALSE)) return S_OK;
+
+  // Firefox internal formats
+  ULONG count;
+  FORMATETC fe;
+  m_enumFE->Reset();
+  while (NOERROR == m_enumFE->Next(1, &fe, &count)) {
+    if (fe.cfFormat == pFE->cfFormat) {
+      return S_OK;
+    }
+  }
+  return E_FAIL;
+}
+
+//-----------------------------------------------------
+STDMETHODIMP nsDataObj::GetCanonicalFormatEtc(LPFORMATETC pFEIn,
+                                              LPFORMATETC pFEOut) {
+  return E_NOTIMPL;
+}
+
+//-----------------------------------------------------
+STDMETHODIMP nsDataObj::SetData(LPFORMATETC aFormat, LPSTGMEDIUM aMedium,
+                                BOOL shouldRel) {
+  // Arbitrary system formats are used for image feedback during drag
+  // and drop. We are responsible for storing these internally during
+  // drag operations.
+  LPDATAENTRY pde;
+  if (LookupArbitraryFormat(aFormat, &pde, TRUE)) {
+    // Release the old data the lookup handed us for this format. This
+    // may have been set in CopyMediumData when we originally stored the
+    // data.
+    if (pde->stgm.tymed) {
+      ReleaseStgMedium(&pde->stgm);
+      memset(&pde->stgm, 0, sizeof(STGMEDIUM));
+    }
+
+    bool result = true;
+    if (shouldRel) {
+      // If shouldRel is TRUE, the data object called owns the storage medium
+      // after the call returns. Store the incoming data in our data array for
+      // release when we are destroyed. This is the common case with arbitrary
+      // data from explorer.
+      pde->stgm = *aMedium;
+    } else {
+      // Copy the incoming data into our data array. (AFAICT, this never gets
+      // called with arbitrary formats for drag images.)
+      result = CopyMediumData(&pde->stgm, aMedium, aFormat, TRUE);
+    }
+    pde->fe.tymed = pde->stgm.tymed;
+
+    return result ? S_OK : DV_E_TYMED;
+  }
+
+  if (shouldRel) ReleaseStgMedium(aMedium);
+
+  return S_OK;
+}
+
+bool nsDataObj::LookupArbitraryFormat(FORMATETC* aFormat,
+                                      LPDATAENTRY* aDataEntry,
+                                      BOOL aAddorUpdate) {
+  *aDataEntry = nullptr;
+
+  if (aFormat->ptd != nullptr) return false;
+
+  // See if it's already in our list. If so return the data entry.
+  for (uint32_t idx = 0; idx < mDataEntryList.Length(); idx++) {
+    if (mDataEntryList[idx]->fe.cfFormat == aFormat->cfFormat &&
+        mDataEntryList[idx]->fe.dwAspect == aFormat->dwAspect &&
+        mDataEntryList[idx]->fe.lindex == aFormat->lindex) {
+      if (aAddorUpdate || (mDataEntryList[idx]->fe.tymed & aFormat->tymed)) {
+        // If the caller requests we update, or if the
+        // medium type matches, return the entry.
+        *aDataEntry = mDataEntryList[idx];
+        return true;
+      } else {
+        // Medium does not match, not found.
+        return false;
+      }
+    }
+  }
+
+  if (!aAddorUpdate) return false;
+
+  // Add another entry to mDataEntryList
+  LPDATAENTRY dataEntry = (LPDATAENTRY)CoTaskMemAlloc(sizeof(DATAENTRY));
+  if (!dataEntry) return false;
+
+  dataEntry->fe = *aFormat;
+  *aDataEntry = dataEntry;
+  memset(&dataEntry->stgm, 0, sizeof(STGMEDIUM));
+
+  // Add this to our IEnumFORMATETC impl. so we can return it when
+  // it's requested.
+  m_enumFE->AddFormatEtc(aFormat);
+
+  // Store a copy internally in the arbitrary formats array.
+  mDataEntryList.AppendElement(dataEntry);
+
+  return true;
+}
+
+bool nsDataObj::CopyMediumData(STGMEDIUM* aMediumDst, STGMEDIUM* aMediumSrc,
+                               LPFORMATETC aFormat, BOOL aSetData) {
+  STGMEDIUM stgmOut = *aMediumSrc;
+
+  switch (stgmOut.tymed) {
+    case TYMED_ISTREAM:
+      stgmOut.pstm->AddRef();
+      break;
+    case TYMED_ISTORAGE:
+      stgmOut.pstg->AddRef();
+      break;
+    case TYMED_HGLOBAL:
+      if (!aMediumSrc->pUnkForRelease) {
+        if (aSetData) {
+          if (aMediumSrc->tymed != TYMED_HGLOBAL) return false;
+          stgmOut.hGlobal =
+              OleDuplicateData(aMediumSrc->hGlobal, aFormat->cfFormat, 0);
+          if (!stgmOut.hGlobal) return false;
+        } else {
+          // We are returning this data from LookupArbitraryFormat, indicate to
+          // the shell we hold it and will free it.
+          stgmOut.pUnkForRelease = static_cast<IDataObject*>(this);
+        }
+      }
+      break;
+    default:
+      return false;
+  }
+
+  if (stgmOut.pUnkForRelease) stgmOut.pUnkForRelease->AddRef();
+
+  *aMediumDst = stgmOut;
+
+  return true;
+}
+
+//-----------------------------------------------------
+STDMETHODIMP nsDataObj::EnumFormatEtc(DWORD dwDir, LPENUMFORMATETC* ppEnum) {
+  switch (dwDir) {
+    case DATADIR_GET:
+      m_enumFE->Clone(ppEnum);
+      break;
+    case DATADIR_SET:
+      // fall through
+    default:
+      *ppEnum = nullptr;
+  }  // switch
+
+  if (nullptr == *ppEnum) return E_FAIL;
+
+  (*ppEnum)->Reset();
+  // Clone already AddRefed the result so don't addref it again.
+  return NOERROR;
+}
+
+//-----------------------------------------------------
+STDMETHODIMP nsDataObj::DAdvise(LPFORMATETC pFE, DWORD dwFlags,
+                                LPADVISESINK pIAdviseSink, DWORD* pdwConn) {
+  return OLE_E_ADVISENOTSUPPORTED;
+}
+
+//-----------------------------------------------------
+STDMETHODIMP nsDataObj::DUnadvise(DWORD dwConn) {
+  return OLE_E_ADVISENOTSUPPORTED;
+}
+
+//-----------------------------------------------------
+STDMETHODIMP nsDataObj::EnumDAdvise(LPENUMSTATDATA* ppEnum) {
+  return OLE_E_ADVISENOTSUPPORTED;
+}
+
+// IDataObjectAsyncCapability methods
+STDMETHODIMP nsDataObj::EndOperation(HRESULT hResult, IBindCtx* pbcReserved,
+                                     DWORD dwEffects) {
+  mIsInOperation = FALSE;
+  return S_OK;
+}
+
+STDMETHODIMP nsDataObj::GetAsyncMode(BOOL* pfIsOpAsync) {
+  *pfIsOpAsync = mIsAsyncMode;
+
+  return S_OK;
+}
+
+STDMETHODIMP nsDataObj::InOperation(BOOL* pfInAsyncOp) {
+  *pfInAsyncOp = mIsInOperation;
+
+  return S_OK;
+}
+
+STDMETHODIMP nsDataObj::SetAsyncMode(BOOL fDoOpAsync) {
+  mIsAsyncMode = fDoOpAsync;
+  return S_OK;
+}
+
+STDMETHODIMP nsDataObj::StartOperation(IBindCtx* pbcReserved) {
+  mIsInOperation = TRUE;
+  return S_OK;
+}
+
+//
+// GetDIB
+//
+// Someone is asking for a bitmap. The data in the transferable will be a
+// straight imgIContainer, so just QI it.
+//
+HRESULT
+nsDataObj::GetDib(const nsACString& inFlavor, FORMATETC& aFormat,
+                  STGMEDIUM& aSTG) {
+  nsCOMPtr<nsISupports> genericDataWrapper;
+  if (NS_FAILED(
+          mTransferable->GetTransferData(PromiseFlatCString(inFlavor).get(),
+                                         getter_AddRefs(genericDataWrapper)))) {
+    return E_FAIL;
+  }
+
+  nsCOMPtr<imgIContainer> image = do_QueryInterface(genericDataWrapper);
+  if (!image) {
+    return E_FAIL;
+  }
+
+  nsCOMPtr<imgITools> imgTools =
+      do_CreateInstance("@mozilla.org/image/tools;1");
+
+  nsAutoString options(u"bpp=32;"_ns);
+  if (aFormat.cfFormat == CF_DIBV5) {
+    options.AppendLiteral("version=5");
+  } else {
+    options.AppendLiteral("version=3");
+  }
+
+  nsCOMPtr<nsIInputStream> inputStream;
+  nsresult rv = imgTools->EncodeImage(image, nsLiteralCString(IMAGE_BMP),
+                                      options, getter_AddRefs(inputStream));
+  if (NS_FAILED(rv) || !inputStream) {
+    return E_FAIL;
+  }
+
+  nsCOMPtr<imgIEncoder> encoder = do_QueryInterface(inputStream);
+  if (!encoder) {
+    return E_FAIL;
+  }
+
+  uint32_t size = 0;
+  rv = encoder->GetImageBufferUsed(&size);
+  if (NS_FAILED(rv) || size <= BFH_LENGTH) {
+    return E_FAIL;
+  }
+
+  char* src = nullptr;
+  rv = encoder->GetImageBuffer(&src);
+  if (NS_FAILED(rv) || !src) {
+    return E_FAIL;
+  }
+
+  // We don't want the file header.
+  src += BFH_LENGTH;
+  size -= BFH_LENGTH;
+
+  HGLOBAL glob = ::GlobalAlloc(GMEM_MOVEABLE | GMEM_ZEROINIT, size);
+  if (!glob) {
+    return E_FAIL;
+  }
+
+  char* dst = (char*)::GlobalLock(glob);
+  ::CopyMemory(dst, src, size);
+  ::GlobalUnlock(glob);
+
+  aSTG.hGlobal = glob;
+  aSTG.tymed = TYMED_HGLOBAL;
+  return S_OK;
+}
+
+//
+// GetFileDescriptor
+//
+
+HRESULT
+nsDataObj ::GetFileDescriptor(FORMATETC& aFE, STGMEDIUM& aSTG,
+                              bool aIsUnicode) {
+  HRESULT res = S_OK;
+
+  // How we handle this depends on if we're dealing with an internet
+  // shortcut, since those are done under the covers.
+  if (IsFlavourPresent(kFilePromiseMime) || IsFlavourPresent(kFileMime)) {
+    if (aIsUnicode)
+      return GetFileDescriptor_IStreamW(aFE, aSTG);
+    else
+      return GetFileDescriptor_IStreamA(aFE, aSTG);
+  } else if (IsFlavourPresent(kURLMime)) {
+    if (aIsUnicode)
+      res = GetFileDescriptorInternetShortcutW(aFE, aSTG);
+    else
+      res = GetFileDescriptorInternetShortcutA(aFE, aSTG);
+  } else
+    NS_WARNING("Not yet implemented\n");
+
+  return res;
+}  // GetFileDescriptor
+
+//
+HRESULT
+nsDataObj ::GetFileContents(FORMATETC& aFE, STGMEDIUM& aSTG) {
+  HRESULT res = S_OK;
+
+  // How we handle this depends on if we're dealing with an internet
+  // shortcut, since those are done under the covers.
+  if (IsFlavourPresent(kFilePromiseMime) || IsFlavourPresent(kFileMime))
+    return GetFileContents_IStream(aFE, aSTG);
+  else if (IsFlavourPresent(kURLMime))
+    return GetFileContentsInternetShortcut(aFE, aSTG);
+  else
+    NS_WARNING("Not yet implemented\n");
+
+  return res;
+
+}  // GetFileContents
+
+// Ensure that the supplied name doesn't have invalid characters.
+static void ValidateFilename(nsString& aFilename, bool isShortcut) {
+  nsCOMPtr<nsIMIMEService> mimeService = do_GetService("@mozilla.org/mime;1");
+  if (NS_WARN_IF(!mimeService)) {
+    aFilename.Truncate();
+    return;
+  }
+
+  uint32_t flags = nsIMIMEService::VALIDATE_SANITIZE_ONLY;
+  if (isShortcut) {
+    flags |= nsIMIMEService::VALIDATE_ALLOW_INVALID_FILENAMES;
+  }
+
+  nsAutoString outFilename;
+  mimeService->ValidateFileNameForSaving(aFilename, EmptyCString(), flags,
+                                         outFilename);
+  aFilename = outFilename;
+}
+
+//
+// Given a unicode string, convert it to a valid local charset filename
+// and append the .url extension to be used for a shortcut file.
+// This ensures that we do not cut MBCS characters in the middle.
+//
+// It would seem that this is more functionality suited to being in nsIFile.
+//
+static bool CreateURLFilenameFromTextA(nsAutoString& aText, char* aFilename) {
+  if (aText.IsEmpty()) {
+    return false;
+  }
+  aText.AppendLiteral(".url");
+  ValidateFilename(aText, true);
+  if (aText.IsEmpty()) {
+    return false;
+  }
+
+  // ValidateFilename should already be checking the filename length, but do
+  // an extra check to verify for the local code page that the converted text
+  // doesn't go over MAX_PATH and just return false if it does.
+  char defaultChar = '_';
+  int currLen = WideCharToMultiByte(CP_ACP, WC_COMPOSITECHECK | WC_DEFAULTCHAR,
+                                    aText.get(), -1, aFilename, MAX_PATH,
+                                    &defaultChar, nullptr);
+  return currLen != 0;
+}
+
+// Wide character version of CreateURLFilenameFromTextA
+static bool CreateURLFilenameFromTextW(nsAutoString& aText,
+                                       wchar_t* aFilename) {
+  if (aText.IsEmpty()) {
+    return false;
+  }
+  aText.AppendLiteral(".url");
+  ValidateFilename(aText, true);
+  if (aText.IsEmpty() || aText.Length() >= MAX_PATH) {
+    return false;
+  }
+
+  wcscpy(&aFilename[0], aText.get());
+  return true;
+}
+
+#define PAGEINFO_PROPERTIES "chrome://navigator/locale/pageInfo.properties"
+
+static bool GetLocalizedString(const char* aName, nsAString& aString) {
+  nsCOMPtr<nsIStringBundleService> stringService =
+      mozilla::components::StringBundle::Service();
+  if (!stringService) return false;
+
+  nsCOMPtr<nsIStringBundle> stringBundle;
+  nsresult rv = stringService->CreateBundle(PAGEINFO_PROPERTIES,
+                                            getter_AddRefs(stringBundle));
+  if (NS_FAILED(rv)) return false;
+
+  rv = stringBundle->GetStringFromName(aName, aString);
+  return NS_SUCCEEDED(rv);
+}
+
+//
+// GetFileDescriptorInternetShortcut
+//
+// Create the special format for an internet shortcut and build up the data
+// structures the shell is expecting.
+//
+HRESULT
+nsDataObj ::GetFileDescriptorInternetShortcutA(FORMATETC& aFE,
+                                               STGMEDIUM& aSTG) {
+  // get the title of the shortcut
+  nsAutoString title;
+  if (NS_FAILED(ExtractShortcutTitle(title))) return E_OUTOFMEMORY;
+
+  HGLOBAL fileGroupDescHandle =
+      ::GlobalAlloc(GMEM_ZEROINIT | GMEM_SHARE, sizeof(FILEGROUPDESCRIPTORA));
+  if (!fileGroupDescHandle) return E_OUTOFMEMORY;
+
+  LPFILEGROUPDESCRIPTORA fileGroupDescA =
+      reinterpret_cast<LPFILEGROUPDESCRIPTORA>(
+          ::GlobalLock(fileGroupDescHandle));
+  if (!fileGroupDescA) {
+    ::GlobalFree(fileGroupDescHandle);
+    return E_OUTOFMEMORY;
+  }
+
+  // get a valid filename in the following order: 1) from the page title,
+  // 2) localized string for an untitled page, 3) just use "Untitled.url"
+  if (!CreateURLFilenameFromTextA(title, fileGroupDescA->fgd[0].cFileName)) {
+    nsAutoString untitled;
+    if (!GetLocalizedString("noPageTitle", untitled) ||
+        !CreateURLFilenameFromTextA(untitled,
+                                    fileGroupDescA->fgd[0].cFileName)) {
+      strcpy(fileGroupDescA->fgd[0].cFileName, "Untitled.url");
+    }
+  }
+
+  // one file in the file block
+  fileGroupDescA->cItems = 1;
+  fileGroupDescA->fgd[0].dwFlags = FD_LINKUI;
+
+  ::GlobalUnlock(fileGroupDescHandle);
+  aSTG.hGlobal = fileGroupDescHandle;
+  aSTG.tymed = TYMED_HGLOBAL;
+
+  return S_OK;
+}  // GetFileDescriptorInternetShortcutA
+
+HRESULT
+nsDataObj ::GetFileDescriptorInternetShortcutW(FORMATETC& aFE,
+                                               STGMEDIUM& aSTG) {
+  // get the title of the shortcut
+  nsAutoString title;
+  if (NS_FAILED(ExtractShortcutTitle(title))) return E_OUTOFMEMORY;
+
+  HGLOBAL fileGroupDescHandle =
+      ::GlobalAlloc(GMEM_ZEROINIT | GMEM_SHARE, sizeof(FILEGROUPDESCRIPTORW));
+  if (!fileGroupDescHandle) return E_OUTOFMEMORY;
+
+  LPFILEGROUPDESCRIPTORW fileGroupDescW =
+      reinterpret_cast<LPFILEGROUPDESCRIPTORW>(
+          ::GlobalLock(fileGroupDescHandle));
+  if (!fileGroupDescW) {
+    ::GlobalFree(fileGroupDescHandle);
+    return E_OUTOFMEMORY;
+  }
+
+  // get a valid filename in the following order: 1) from the page title,
+  // 2) localized string for an untitled page, 3) just use "Untitled.url"
+  if (!CreateURLFilenameFromTextW(title, fileGroupDescW->fgd[0].cFileName)) {
+    nsAutoString untitled;
+    if (!GetLocalizedString("noPageTitle", untitled) ||
+        !CreateURLFilenameFromTextW(untitled,
+                                    fileGroupDescW->fgd[0].cFileName)) {
+      wcscpy(fileGroupDescW->fgd[0].cFileName, L"Untitled.url");
+    }
+  }
+
+  // one file in the file block
+  fileGroupDescW->cItems = 1;
+  fileGroupDescW->fgd[0].dwFlags = FD_LINKUI;
+
+  ::GlobalUnlock(fileGroupDescHandle);
+  aSTG.hGlobal = fileGroupDescHandle;
+  aSTG.tymed = TYMED_HGLOBAL;
+
+  return S_OK;
+}  // GetFileDescriptorInternetShortcutW
+
+//
+// GetFileContentsInternetShortcut
+//
+// Create the special format for an internet shortcut and build up the data
+// structures the shell is expecting.
+//
+HRESULT
+nsDataObj ::GetFileContentsInternetShortcut(FORMATETC& aFE, STGMEDIUM& aSTG) {
+  static const char* kShellIconPref = "browser.shell.shortcutFavicons";
+  nsAutoString url;
+  if (NS_FAILED(ExtractShortcutURL(url))) return E_OUTOFMEMORY;
+
+  nsCOMPtr<nsIURI> aUri;
+  nsresult rv = NS_NewURI(getter_AddRefs(aUri), url);
+  if (NS_FAILED(rv)) {
+    return E_FAIL;
+  }
+
+  nsAutoCString asciiUrl;
+  rv = aUri->GetAsciiSpec(asciiUrl);
+  if (NS_FAILED(rv)) {
+    return E_FAIL;
+  }
+
+  RefPtr<AutoCloseEvent> event;
+
+  const char* shortcutFormatStr;
+  int totalLen;
+  nsCString asciiPath;
+  if (!Preferences::GetBool(kShellIconPref, true)) {
+    shortcutFormatStr = "[InternetShortcut]\r\nURL=%s\r\n";
+    const int formatLen = strlen(shortcutFormatStr) - 2;  // don't include %s
+    totalLen = formatLen + asciiUrl.Length();  // don't include null character
+  } else {
+    nsCOMPtr<nsIFile> icoFile;
+
+    nsAutoString aUriHash;
+
+    event = new AutoCloseEvent();
+    if (!event->IsInited()) {
+      return E_FAIL;
+    }
+
+    RefPtr<AutoSetEvent> e = new AutoSetEvent(WrapNotNull(event));
+    mozilla::widget::FaviconHelper::ObtainCachedIconFile(
+        aUri, aUriHash, mIOThread, true,
+        NS_NewRunnableFunction(
+            "FaviconHelper::RefreshDesktop", [e = std::move(e)] {
+              if (e->IsWaiting()) {
+                // Unblock IStream:::Read.
+                e->Signal();
+              } else {
+                // We could not wait until the favicon was available. We have
+                // to refresh to refect the favicon.
+                SendNotifyMessage(HWND_BROADCAST, WM_SETTINGCHANGE,
+                                  SPI_SETNONCLIENTMETRICS, 0);
+              }
+            }));
+
+    rv = mozilla::widget::FaviconHelper::GetOutputIconPath(aUri, icoFile, true);
+    NS_ENSURE_SUCCESS(rv, E_FAIL);
+    nsString path;
+    rv = icoFile->GetPath(path);
+    NS_ENSURE_SUCCESS(rv, E_FAIL);
+
+    if (IsAsciiNullTerminated(static_cast<const char16_t*>(path.get()))) {
+      LossyCopyUTF16toASCII(path, asciiPath);
+      shortcutFormatStr =
+          "[InternetShortcut]\r\nURL=%s\r\n"
+          "IDList=\r\nHotKey=0\r\nIconFile=%s\r\n"
+          "IconIndex=0\r\n";
+    } else {
+      int len =
+          WideCharToMultiByte(CP_UTF7, 0, char16ptr_t(path.BeginReading()),
+                              path.Length(), nullptr, 0, nullptr, nullptr);
+      NS_ENSURE_TRUE(len > 0, E_FAIL);
+      asciiPath.SetLength(len);
+      WideCharToMultiByte(CP_UTF7, 0, char16ptr_t(path.BeginReading()),
+                          path.Length(), asciiPath.BeginWriting(), len, nullptr,
+                          nullptr);
+      shortcutFormatStr =
+          "[InternetShortcut]\r\nURL=%s\r\n"
+          "IDList=\r\nHotKey=0\r\nIconIndex=0\r\n"
+          "[InternetShortcut.W]\r\nIconFile=%s\r\n";
+    }
+    const int formatLen = strlen(shortcutFormatStr) - 2 * 2;  // no %s twice
+    totalLen = formatLen + asciiUrl.Length() +
+               asciiPath.Length();  // we don't want a null character on the end
+  }
+
+  // create a global memory area and build up the file contents w/in it
+  nsAutoGlobalMem globalMem(nsHGLOBAL(::GlobalAlloc(GMEM_SHARE, totalLen)));
+  if (!globalMem) return E_OUTOFMEMORY;
+
+  char* contents = reinterpret_cast<char*>(::GlobalLock(globalMem.get()));
+  if (!contents) {
+    return E_OUTOFMEMORY;
+  }
+
+  // NOTE: we intentionally use the Microsoft version of snprintf here because
+  // it does NOT null
+  // terminate strings which reach the maximum size of the buffer. Since we know
+  // that the formatted length here is totalLen, this call to _snprintf will
+  // format the string into the buffer without appending the null character.
+
+  if (!Preferences::GetBool(kShellIconPref, true)) {
+    _snprintf(contents, totalLen, shortcutFormatStr, asciiUrl.get());
+  } else {
+    _snprintf(contents, totalLen, shortcutFormatStr, asciiUrl.get(),
+              asciiPath.get());
+  }
+
+  ::GlobalUnlock(globalMem.get());
+
+  if (aFE.tymed & TYMED_ISTREAM) {
+    if (!mIsInOperation) {
+      // The drop target didn't initiate an async operation.
+      // We can't block CMemStream::Read.
+      event = nullptr;
+    }
+    RefPtr<IStream> stream =
+        new CMemStream(globalMem.disown(), totalLen, event.forget());
+    stream.forget(&aSTG.pstm);
+    aSTG.tymed = TYMED_ISTREAM;
+  } else {
+    if (event && event->IsInited()) {
+      event->Signal();  // We can't block reading the global memory
+    }
+    aSTG.hGlobal = globalMem.disown();
+    aSTG.tymed = TYMED_HGLOBAL;
+  }
+
+  return S_OK;
+}  // GetFileContentsInternetShortcut
+
+// check if specified flavour is present in the transferable
+bool nsDataObj ::IsFlavourPresent(const char* inFlavour) {
+  bool retval = false;
+  NS_ENSURE_TRUE(mTransferable, false);
+
+  // get the list of flavors available in the transferable
+  nsTArray<nsCString> flavors;
+  nsresult rv = mTransferable->FlavorsTransferableCanExport(flavors);
+  NS_ENSURE_SUCCESS(rv, false);
+
+  // try to find requested flavour
+  for (uint32_t i = 0; i < flavors.Length(); ++i) {
+    if (flavors[i].Equals(inFlavour)) {
+      retval = true;  // found it!
+      break;
+    }
+  }  // for each flavor
+
+  return retval;
+}
+
+HRESULT nsDataObj::GetPreferredDropEffect(FORMATETC& aFE, STGMEDIUM& aSTG) {
+  HRESULT res = S_OK;
+  aSTG.tymed = TYMED_HGLOBAL;
+  aSTG.pUnkForRelease = nullptr;
+  HGLOBAL hGlobalMemory = nullptr;
+  hGlobalMemory = ::GlobalAlloc(GMEM_MOVEABLE, sizeof(DWORD));
+  if (hGlobalMemory) {
+    DWORD* pdw = (DWORD*)GlobalLock(hGlobalMemory);
+    // The PreferredDropEffect clipboard format is only registered if a
+    // drag/drop of an image happens from Mozilla to the desktop.  We want its
+    // value to be DROPEFFECT_MOVE in that case so that the file is moved from
+    // the temporary location, not copied. This value should, ideally, be set on
+    // the data object via SetData() but our IDataObject implementation doesn't
+    // implement SetData.  It adds data to the data object lazily only when the
+    // drop target asks for it.
+    *pdw = (DWORD)DROPEFFECT_MOVE;
+    GlobalUnlock(hGlobalMemory);
+  } else {
+    res = E_OUTOFMEMORY;
+  }
+  aSTG.hGlobal = hGlobalMemory;
+  return res;
+}
+
+//-----------------------------------------------------
+HRESULT nsDataObj::GetText(const nsACString& aDataFlavor, FORMATETC& aFE,
+                           STGMEDIUM& aSTG) {
+  void* data = nullptr;
+
+  const nsPromiseFlatCString& flavorStr = PromiseFlatCString(aDataFlavor);
+
+  // NOTE: CreateDataFromPrimitive creates new memory, that needs to be deleted
+  nsCOMPtr<nsISupports> genericDataWrapper;
+  nsresult rv = mTransferable->GetTransferData(
+      flavorStr.get(), getter_AddRefs(genericDataWrapper));
+  if (NS_FAILED(rv) || !genericDataWrapper) {
+    return E_FAIL;
+  }
+
+  uint32_t len;
+  nsPrimitiveHelpers::CreateDataFromPrimitive(
+      nsDependentCString(flavorStr.get()), genericDataWrapper, &data, &len);
+  if (!data) return E_FAIL;
+
+  HGLOBAL hGlobalMemory = nullptr;
+
+  aSTG.tymed = TYMED_HGLOBAL;
+  aSTG.pUnkForRelease = nullptr;
+
+  // We play games under the hood and advertise flavors that we know we
+  // can support, only they require a bit of conversion or munging of the data.
+  // Do that here.
+  //
+  // The transferable gives us data that is null-terminated, but this isn't
+  // reflected in the |len| parameter. Windoze apps expect this null to be there
+  // so bump our data buffer by the appropriate size to account for the null
+  // (one char for CF_TEXT, one char16_t for CF_UNICODETEXT).
+  DWORD allocLen = (DWORD)len;
+  if (aFE.cfFormat == CF_TEXT) {
+    // Someone is asking for text/plain; convert the unicode (assuming it's
+    // present) to text with the correct platform encoding.
+    size_t bufferSize = sizeof(char) * (len + 2);
+    char* plainTextData = static_cast<char*>(moz_xmalloc(bufferSize));
+    char16_t* castedUnicode = reinterpret_cast<char16_t*>(data);
+    int32_t plainTextLen =
+        WideCharToMultiByte(CP_ACP, 0, (LPCWSTR)castedUnicode, len / 2 + 1,
+                            plainTextData, bufferSize, NULL, NULL);
+    // replace the unicode data with our plaintext data. Recall that
+    // |plainTextLen| doesn't include the null in the length.
+    free(data);
+    if (plainTextLen) {
+      data = plainTextData;
+      allocLen = plainTextLen;
+    } else {
+      free(plainTextData);
+      NS_WARNING("Oh no, couldn't convert unicode to plain text");
+      return S_OK;
+    }
+  } else if (aFE.cfFormat == nsClipboard::GetHtmlClipboardFormat()) {
+    // Someone is asking for win32's HTML flavor. Convert our html fragment
+    // from unicode to UTF-8 then put it into a format specified by msft.
+    NS_ConvertUTF16toUTF8 converter(reinterpret_cast<char16_t*>(data));
+    char* utf8HTML = nullptr;
+    nsresult rv =
+        BuildPlatformHTML(converter.get(), &utf8HTML);  // null terminates
+
+    free(data);
+    if (NS_SUCCEEDED(rv) && utf8HTML) {
+      // replace the unicode data with our HTML data. Don't forget the null.
+      data = utf8HTML;
+      allocLen = strlen(utf8HTML) + sizeof(char);
+    } else {
+      NS_WARNING("Oh no, couldn't convert to HTML");
+      return S_OK;
+    }
+  } else if (aFE.cfFormat != nsClipboard::GetCustomClipboardFormat()) {
+    // we assume that any data that isn't caught above is unicode. This may
+    // be an erroneous assumption, but is true so far.
+    allocLen += sizeof(char16_t);
+  }
+
+  hGlobalMemory = (HGLOBAL)GlobalAlloc(GMEM_MOVEABLE, allocLen);
+
+  // Copy text to Global Memory Area
+  if (hGlobalMemory) {
+    char* dest = reinterpret_cast<char*>(GlobalLock(hGlobalMemory));
+    char* source = reinterpret_cast<char*>(data);
+    memcpy(dest, source, allocLen);  // copies the null as well
+    GlobalUnlock(hGlobalMemory);
+  }
+  aSTG.hGlobal = hGlobalMemory;
+
+  // Now, delete the memory that was created by CreateDataFromPrimitive (or our
+  // text/plain data)
+  free(data);
+
+  return S_OK;
+}
+
+//-----------------------------------------------------
+HRESULT nsDataObj::GetFile(FORMATETC& aFE, STGMEDIUM& aSTG) {
+  uint32_t dfInx = 0;
+  ULONG count;
+  FORMATETC fe;
+  m_enumFE->Reset();
+  while (NOERROR == m_enumFE->Next(1, &fe, &count) &&
+         dfInx < mDataFlavors.Length()) {
+    if (mDataFlavors[dfInx].EqualsLiteral(kNativeImageMime))
+      return DropImage(aFE, aSTG);
+    if (mDataFlavors[dfInx].EqualsLiteral(kFileMime))
+      return DropFile(aFE, aSTG);
+    if (mDataFlavors[dfInx].EqualsLiteral(kFilePromiseMime))
+      return DropTempFile(aFE, aSTG);
+    dfInx++;
+  }
+  return E_FAIL;
+}
+
+HRESULT nsDataObj::DropFile(FORMATETC& aFE, STGMEDIUM& aSTG) {
+  nsresult rv;
+  nsCOMPtr<nsISupports> genericDataWrapper;
+
+  if (NS_FAILED(mTransferable->GetTransferData(
+          kFileMime, getter_AddRefs(genericDataWrapper)))) {
+    return E_FAIL;
+  }
+  nsCOMPtr<nsIFile> file(do_QueryInterface(genericDataWrapper));
+  if (!file) return E_FAIL;
+
+  aSTG.tymed = TYMED_HGLOBAL;
+  aSTG.pUnkForRelease = nullptr;
+
+  nsAutoString path;
+  rv = file->GetPath(path);
+  if (NS_FAILED(rv)) return E_FAIL;
+
+  uint32_t allocLen = path.Length() + 2;
+  HGLOBAL hGlobalMemory = nullptr;
+  char16_t* dest;
+
+  hGlobalMemory = GlobalAlloc(GMEM_MOVEABLE,
+                              sizeof(DROPFILES) + allocLen * sizeof(char16_t));
+  if (!hGlobalMemory) return E_FAIL;
+
+  DROPFILES* pDropFile = (DROPFILES*)GlobalLock(hGlobalMemory);
+
+  // First, populate the drop file structure
+  pDropFile->pFiles = sizeof(DROPFILES);  // Offset to start of file name string
+  pDropFile->fNC = 0;
+  pDropFile->pt.x = 0;
+  pDropFile->pt.y = 0;
+  pDropFile->fWide = TRUE;
+
+  // Copy the filename right after the DROPFILES structure
+  dest = (char16_t*)(((char*)pDropFile) + pDropFile->pFiles);
+  memcpy(dest, path.get(), (allocLen - 1) * sizeof(char16_t));
+
+  // Two null characters are needed at the end of the file name.
+  // Lookup the CF_HDROP shell clipboard format for more info.
+  // Add the second null character right after the first one.
+  dest[allocLen - 1] = L'\0';
+
+  GlobalUnlock(hGlobalMemory);
+
+  aSTG.hGlobal = hGlobalMemory;
+
+  return S_OK;
+}
+
+HRESULT nsDataObj::DropImage(FORMATETC& aFE, STGMEDIUM& aSTG) {
+  nsresult rv;
+  if (!mCachedTempFile) {
+    nsCOMPtr<nsISupports> genericDataWrapper;
+
+    if (NS_FAILED(mTransferable->GetTransferData(
+            kNativeImageMime, getter_AddRefs(genericDataWrapper)))) {
+      return E_FAIL;
+    }
+    nsCOMPtr<imgIContainer> image(do_QueryInterface(genericDataWrapper));
+    if (!image) return E_FAIL;
+
+    nsCOMPtr<imgITools> imgTools =
+        do_CreateInstance("@mozilla.org/image/tools;1");
+    nsCOMPtr<nsIInputStream> inputStream;
+    rv = imgTools->EncodeImage(image, nsLiteralCString(IMAGE_BMP),
+                               u"bpp=32;version=3"_ns,
+                               getter_AddRefs(inputStream));
+    if (NS_FAILED(rv) || !inputStream) {
+      return E_FAIL;
+    }
+
+    nsCOMPtr<imgIEncoder> encoder = do_QueryInterface(inputStream);
+    if (!encoder) {
+      return E_FAIL;
+    }
+
+    uint32_t size = 0;
+    rv = encoder->GetImageBufferUsed(&size);
+    if (NS_FAILED(rv)) {
+      return E_FAIL;
+    }
+
+    char* src = nullptr;
+    rv = encoder->GetImageBuffer(&src);
+    if (NS_FAILED(rv) || !src) {
+      return E_FAIL;
+    }
+
+    // Save the bitmap to a temporary location.
+    nsCOMPtr<nsIFile> dropFile;
+    rv = NS_GetSpecialDirectory(NS_OS_TEMP_DIR, getter_AddRefs(dropFile));
+    if (!dropFile) {
+      return E_FAIL;
+    }
+
+    // Filename must be random so as not to confuse apps like
+    // Photoshop which handle multiple drags into a single window.
+    char buf[13];
+    nsCString filename;
+    NS_MakeRandomString(buf, 8);
+    memcpy(buf + 8, ".bmp", 5);
+    filename.Append(nsDependentCString(buf, 12));
+    dropFile->AppendNative(filename);
+    rv = dropFile->CreateUnique(nsIFile::NORMAL_FILE_TYPE, 0660);
+    if (NS_FAILED(rv)) {
+      return E_FAIL;
+    }
+
+    // Cache the temp file so we can delete it later and so
+    // it doesn't get recreated over and over on multiple calls
+    // which does occur from windows shell.
+    dropFile->Clone(getter_AddRefs(mCachedTempFile));
+
+    // Write the data to disk.
+    nsCOMPtr<nsIOutputStream> outStream;
+    rv = NS_NewLocalFileOutputStream(getter_AddRefs(outStream), dropFile);
+    if (NS_FAILED(rv)) {
+      return E_FAIL;
+    }
+
+    uint32_t written = 0;
+    rv = outStream->Write(src, size, &written);
+    if (NS_FAILED(rv) || written != size) {
+      return E_FAIL;
+    }
+
+    outStream->Close();
+  }
+
+  // Pass the file name back to the drop target so that it can access the file.
+  nsAutoString path;
+  rv = mCachedTempFile->GetPath(path);
+  if (NS_FAILED(rv)) return E_FAIL;
+
+  // Two null characters are needed to terminate the file name list.
+  HGLOBAL hGlobalMemory = nullptr;
+
+  uint32_t allocLen = path.Length() + 2;
+
+  aSTG.tymed = TYMED_HGLOBAL;
+  aSTG.pUnkForRelease = nullptr;
+
+  hGlobalMemory = GlobalAlloc(GMEM_MOVEABLE,
+                              sizeof(DROPFILES) + allocLen * sizeof(char16_t));
+  if (!hGlobalMemory) return E_FAIL;
+
+  DROPFILES* pDropFile = (DROPFILES*)GlobalLock(hGlobalMemory);
+
+  // First, populate the drop file structure.
+  pDropFile->pFiles =
+      sizeof(DROPFILES);  // Offset to start of file name char array.
+  pDropFile->fNC = 0;
+  pDropFile->pt.x = 0;
+  pDropFile->pt.y = 0;
+  pDropFile->fWide = TRUE;
+
+  // Copy the filename right after the DROPFILES structure.
+  char16_t* dest = (char16_t*)(((char*)pDropFile) + pDropFile->pFiles);
+  memcpy(dest, path.get(),
+         (allocLen - 1) *
+             sizeof(char16_t));  // Copies the null character in path as well.
+
+  // Two null characters are needed at the end of the file name.
+  // Lookup the CF_HDROP shell clipboard format for more info.
+  // Add the second null character right after the first one.
+  dest[allocLen - 1] = L'\0';
+
+  GlobalUnlock(hGlobalMemory);
+
+  aSTG.hGlobal = hGlobalMemory;
+
+  return S_OK;
+}
+
+HRESULT nsDataObj::DropTempFile(FORMATETC& aFE, STGMEDIUM& aSTG) {
+  nsresult rv;
+  if (!mCachedTempFile) {
+    // Tempfile will need a temporary location.
+    nsCOMPtr<nsIFile> dropFile;
+    rv = NS_GetSpecialDirectory(NS_OS_TEMP_DIR, getter_AddRefs(dropFile));
+    if (!dropFile) return E_FAIL;
+
+    // Filename must be random
+    nsCString filename;
+    nsAutoString wideFileName;
+    nsCOMPtr<nsIURI> sourceURI;
+    HRESULT res;
+    res = GetDownloadDetails(getter_AddRefs(sourceURI), wideFileName);
+    if (FAILED(res)) return res;
+    NS_CopyUnicodeToNative(wideFileName, filename);
+
+    dropFile->AppendNative(filename);
+    rv = dropFile->CreateUnique(nsIFile::NORMAL_FILE_TYPE, 0660);
+    if (NS_FAILED(rv)) return E_FAIL;
+
+    // Cache the temp file so we can delete it later and so
+    // it doesn't get recreated over and over on multiple calls
+    // which does occur from windows shell.
+    dropFile->Clone(getter_AddRefs(mCachedTempFile));
+
+    // Write the data to disk.
+    nsCOMPtr<nsIOutputStream> outStream;
+    rv = NS_NewLocalFileOutputStream(getter_AddRefs(outStream), dropFile);
+    if (NS_FAILED(rv)) return E_FAIL;
+
+    IStream* pStream = nullptr;
+    nsDataObj::CreateStream(&pStream);
+    NS_ENSURE_TRUE(pStream, E_FAIL);
+
+    char buffer[512];
+    ULONG readCount = 0;
+    uint32_t writeCount = 0;
+    while (1) {
+      HRESULT hres = pStream->Read(buffer, sizeof(buffer), &readCount);
+      if (FAILED(hres)) return E_FAIL;
+      if (readCount == 0) break;
+      rv = outStream->Write(buffer, readCount, &writeCount);
+      if (NS_FAILED(rv)) return E_FAIL;
+    }
+    outStream->Close();
+    pStream->Release();
+  }
+
+  // Pass the file name back to the drop target so that it can access the file.
+  nsAutoString path;
+  rv = mCachedTempFile->GetPath(path);
+  if (NS_FAILED(rv)) return E_FAIL;
+
+  uint32_t allocLen = path.Length() + 2;
+
+  // Two null characters are needed to terminate the file name list.
+  HGLOBAL hGlobalMemory = nullptr;
+
+  aSTG.tymed = TYMED_HGLOBAL;
+  aSTG.pUnkForRelease = nullptr;
+
+  hGlobalMemory = GlobalAlloc(GMEM_MOVEABLE,
+                              sizeof(DROPFILES) + allocLen * sizeof(char16_t));
+  if (!hGlobalMemory) return E_FAIL;
+
+  DROPFILES* pDropFile = (DROPFILES*)GlobalLock(hGlobalMemory);
+
+  // First, populate the drop file structure.
+  pDropFile->pFiles =
+      sizeof(DROPFILES);  // Offset to start of file name char array.
+  pDropFile->fNC = 0;
+  pDropFile->pt.x = 0;
+  pDropFile->pt.y = 0;
+  pDropFile->fWide = TRUE;
+
+  // Copy the filename right after the DROPFILES structure.
+  char16_t* dest = (char16_t*)(((char*)pDropFile) + pDropFile->pFiles);
+  memcpy(dest, path.get(),
+         (allocLen - 1) *
+             sizeof(char16_t));  // Copies the null character in path as well.
+
+  // Two null characters are needed at the end of the file name.
+  // Lookup the CF_HDROP shell clipboard format for more info.
+  // Add the second null character right after the first one.
+  dest[allocLen - 1] = L'\0';
+
+  GlobalUnlock(hGlobalMemory);
+
+  aSTG.hGlobal = hGlobalMemory;
+
+  return S_OK;
+}
+
+//-----------------------------------------------------
+// Registers the DataFlavor/FE pair.
+//-----------------------------------------------------
+void nsDataObj::AddDataFlavor(const char* aDataFlavor, LPFORMATETC aFE) {
+  // These two lists are the mapping to and from data flavors and FEs.
+  // Later, OLE will tell us it needs a certain type of FORMATETC (text,
+  // unicode, etc) unicode, etc), so we will look up the data flavor that
+  // corresponds to the FE and then ask the transferable for that type of data.
+  mDataFlavors.AppendElement(aDataFlavor);
+  m_enumFE->AddFormatEtc(aFE);
+}
+
+//-----------------------------------------------------
+// Sets the transferable object
+//-----------------------------------------------------
+void nsDataObj::SetTransferable(nsITransferable* aTransferable) {
+  NS_IF_RELEASE(mTransferable);
+
+  mTransferable = aTransferable;
+  if (nullptr == mTransferable) {
+    return;
+  }
+
+  NS_ADDREF(mTransferable);
+
+  return;
+}
+
+//
+// ExtractURL
+//
+// Roots around in the transferable for the appropriate flavor that indicates
+// a url and pulls out the url portion of the data. Used mostly for creating
+// internet shortcuts on the desktop. The url flavor is of the format:
+//
+//   <url> <linefeed> <page title>
+//
+nsresult nsDataObj ::ExtractShortcutURL(nsString& outURL) {
+  NS_ASSERTION(mTransferable, "We don't have a good transferable");
+  nsresult rv = NS_ERROR_FAILURE;
+
+  nsCOMPtr<nsISupports> genericURL;
+  if (NS_SUCCEEDED(mTransferable->GetTransferData(
+          kURLMime, getter_AddRefs(genericURL)))) {
+    nsCOMPtr<nsISupportsString> urlObject(do_QueryInterface(genericURL));
+    if (urlObject) {
+      nsAutoString url;
+      urlObject->GetData(url);
+      outURL = url;
+
+      // find the first linefeed in the data, that's where the url ends. trunc
+      // the result string at that point.
+      int32_t lineIndex = outURL.FindChar('\n');
+      NS_ASSERTION(lineIndex > 0,
+                   "Format for url flavor is <url> <linefeed> <page title>");
+      if (lineIndex > 0) {
+        outURL.Truncate(lineIndex);
+        rv = NS_OK;
+      }
+    }
+  } else if (NS_SUCCEEDED(mTransferable->GetTransferData(
+                 kURLDataMime, getter_AddRefs(genericURL))) ||
+             NS_SUCCEEDED(mTransferable->GetTransferData(
+                 kURLPrivateMime, getter_AddRefs(genericURL)))) {
+    nsCOMPtr<nsISupportsString> urlObject(do_QueryInterface(genericURL));
+    if (urlObject) {
+      nsAutoString url;
+      urlObject->GetData(url);
+      outURL = url;
+
+      rv = NS_OK;
+    }
+
+  }  // if found flavor
+
+  return rv;
+
+}  // ExtractShortcutURL
+
+//
+// ExtractShortcutTitle
+//
+// Roots around in the transferable for the appropriate flavor that indicates
+// a url and pulls out the title portion of the data. Used mostly for creating
+// internet shortcuts on the desktop. The url flavor is of the format:
+//
+//   <url> <linefeed> <page title>
+//
+nsresult nsDataObj ::ExtractShortcutTitle(nsString& outTitle) {
+  NS_ASSERTION(mTransferable, "We'd don't have a good transferable");
+  nsresult rv = NS_ERROR_FAILURE;
+
+  nsCOMPtr<nsISupports> genericURL;
+  if (NS_SUCCEEDED(mTransferable->GetTransferData(
+          kURLMime, getter_AddRefs(genericURL)))) {
+    nsCOMPtr<nsISupportsString> urlObject(do_QueryInterface(genericURL));
+    if (urlObject) {
+      nsAutoString url;
+      urlObject->GetData(url);
+
+      // find the first linefeed in the data, that's where the url ends. we want
+      // everything after that linefeed. FindChar() returns -1 if we can't find
+      int32_t lineIndex = url.FindChar('\n');
+      NS_ASSERTION(lineIndex != -1,
+                   "Format for url flavor is <url> <linefeed> <page title>");
+      if (lineIndex != -1) {
+        url.Mid(outTitle, lineIndex + 1, url.Length() - (lineIndex + 1));
+        rv = NS_OK;
+      }
+    }
+  }  // if found flavor
+
+  return rv;
+
+}  // ExtractShortcutTitle
+
+//
+// BuildPlatformHTML
+//
+// Munge our HTML data to win32's CF_HTML spec. Basically, put the requisite
+// header information on it. This will null-terminate |outPlatformHTML|. See
+//  https://docs.microsoft.com/en-us/windows/win32/dataxchg/html-clipboard-format
+// for details.
+//
+// We assume that |inOurHTML| is already a fragment (ie, doesn't have <HTML>
+// or <BODY> tags). We'll wrap the fragment with them to make other apps
+// happy.
+//
+nsresult nsDataObj ::BuildPlatformHTML(const char* inOurHTML,
+                                       char** outPlatformHTML) {
+  *outPlatformHTML = nullptr;
+  nsDependentCString inHTMLString(inOurHTML);
+
+  // Do we already have mSourceURL from a drag?
+  if (mSourceURL.IsEmpty()) {
+    nsAutoString url;
+    ExtractShortcutURL(url);
+
+    AppendUTF16toUTF8(url, mSourceURL);
+  }
+
+  constexpr auto kStartHTMLPrefix = "Version:0.9\r\nStartHTML:"_ns;
+  constexpr auto kEndHTMLPrefix = "\r\nEndHTML:"_ns;
+  constexpr auto kStartFragPrefix = "\r\nStartFragment:"_ns;
+  constexpr auto kEndFragPrefix = "\r\nEndFragment:"_ns;
+  constexpr auto kStartSourceURLPrefix = "\r\nSourceURL:"_ns;
+  constexpr auto kEndFragTrailer = "\r\n"_ns;
+
+  // The CF_HTML's size is embedded in the fragment, in such a way that the
+  // number of digits in the size is part of the size itself. While it _is_
+  // technically possible to compute the necessary size of the size-field
+  // precisely -- by trial and error, if nothing else -- it's simpler just to
+  // pick a rough but generous estimate and zero-pad it. (Zero-padding is
+  // explicitly permitted by the format definition.)
+  //
+  // Originally, in 2001, the "rough but generous estimate" was 8 digits. While
+  // a maximum size of (10**9 - 1) bytes probably would have covered all
+  // possible use-cases at the time, it's somewhat more likely to overflow
+  // nowadays. Nonetheless, for the sake of backwards compatibility with any
+  // misbehaving consumers of our existing CF_HTML output, we retain exactly
+  // that padding for (most) fragments where it suffices. (No such misbehaving
+  // consumers are actually known, so this is arguably paranoia.)
+  //
+  // It is now 2022. A padding size of 16 will cover up to about 8.8 petabytes,
+  // which should be enough for at least the next few years or so.
+  const size_t numberLength = inHTMLString.Length() < 9999'0000 ? 8 : 16;
+
+  const size_t sourceURLLength = mSourceURL.Length();
+
+  const size_t fixedHeaderLen =
+      kStartHTMLPrefix.Length() + kEndHTMLPrefix.Length() +
+      kStartFragPrefix.Length() + kEndFragPrefix.Length() +
+      kEndFragTrailer.Length() + (4 * numberLength);
+
+  const size_t totalHeaderLen =
+      fixedHeaderLen + (sourceURLLength > 0
+                            ? kStartSourceURLPrefix.Length() + sourceURLLength
+                            : 0);
+
+  constexpr auto kHeaderString = "<html><body>\r\n<!--StartFragment-->"_ns;
+  constexpr auto kTrailingString =
+      "<!--EndFragment-->\r\n"
+      "</body>\r\n"
+      "</html>"_ns;
+
+  // calculate the offsets
+  size_t startHTMLOffset = totalHeaderLen;
+  size_t startFragOffset = startHTMLOffset + kHeaderString.Length();
+
+  size_t endFragOffset = startFragOffset + inHTMLString.Length();
+  size_t endHTMLOffset = endFragOffset + kTrailingString.Length();
+
+  // now build the final version
+  nsCString clipboardString;
+  clipboardString.SetCapacity(endHTMLOffset);
+
+  const int numberLengthInt = static_cast<int>(numberLength);
+  clipboardString.Append(kStartHTMLPrefix);
+  clipboardString.AppendPrintf("%0*zu", numberLengthInt, startHTMLOffset);
+
+  clipboardString.Append(kEndHTMLPrefix);
+  clipboardString.AppendPrintf("%0*zu", numberLengthInt, endHTMLOffset);
+
+  clipboardString.Append(kStartFragPrefix);
+  clipboardString.AppendPrintf("%0*zu", numberLengthInt, startFragOffset);
+
+  clipboardString.Append(kEndFragPrefix);
+  clipboardString.AppendPrintf("%0*zu", numberLengthInt, endFragOffset);
+
+  if (sourceURLLength > 0) {
+    clipboardString.Append(kStartSourceURLPrefix);
+    clipboardString.Append(mSourceURL);
+  }
+
+  clipboardString.Append(kEndFragTrailer);
+
+  // Assert that the positional values were correct as we pass by their
+  // corresponding positions.
+  MOZ_ASSERT(clipboardString.Length() == startHTMLOffset);
+  clipboardString.Append(kHeaderString);
+  MOZ_ASSERT(clipboardString.Length() == startFragOffset);
+  clipboardString.Append(inHTMLString);
+  MOZ_ASSERT(clipboardString.Length() == endFragOffset);
+  clipboardString.Append(kTrailingString);
+  MOZ_ASSERT(clipboardString.Length() == endHTMLOffset);
+
+  *outPlatformHTML = ToNewCString(clipboardString, mozilla::fallible);
+  if (!*outPlatformHTML) return NS_ERROR_OUT_OF_MEMORY;
+
+  return NS_OK;
+}
+
+HRESULT
+nsDataObj ::GetUniformResourceLocator(FORMATETC& aFE, STGMEDIUM& aSTG,
+                                      bool aIsUnicode) {
+  HRESULT res = S_OK;
+  if (IsFlavourPresent(kURLMime)) {
+    if (aIsUnicode)
+      res = ExtractUniformResourceLocatorW(aFE, aSTG);
+    else
+      res = ExtractUniformResourceLocatorA(aFE, aSTG);
+  } else
+    NS_WARNING("Not yet implemented\n");
+  return res;
+}
+
+HRESULT
+nsDataObj::ExtractUniformResourceLocatorA(FORMATETC& aFE, STGMEDIUM& aSTG) {
+  HRESULT result = S_OK;
+
+  nsAutoString url;
+  if (NS_FAILED(ExtractShortcutURL(url))) return E_OUTOFMEMORY;
+
+  NS_LossyConvertUTF16toASCII asciiUrl(url);
+  const int totalLen = asciiUrl.Length() + 1;
+  HGLOBAL hGlobalMemory = GlobalAlloc(GMEM_ZEROINIT | GMEM_SHARE, totalLen);
+  if (!hGlobalMemory) return E_OUTOFMEMORY;
+
+  char* contents = reinterpret_cast<char*>(GlobalLock(hGlobalMemory));
+  if (!contents) {
+    GlobalFree(hGlobalMemory);
+    return E_OUTOFMEMORY;
+  }
+
+  strcpy(contents, asciiUrl.get());
+  GlobalUnlock(hGlobalMemory);
+  aSTG.hGlobal = hGlobalMemory;
+  aSTG.tymed = TYMED_HGLOBAL;
+
+  return result;
+}
+
+HRESULT
+nsDataObj::ExtractUniformResourceLocatorW(FORMATETC& aFE, STGMEDIUM& aSTG) {
+  HRESULT result = S_OK;
+
+  nsAutoString url;
+  if (NS_FAILED(ExtractShortcutURL(url))) return E_OUTOFMEMORY;
+
+  const int totalLen = (url.Length() + 1) * sizeof(char16_t);
+  HGLOBAL hGlobalMemory = GlobalAlloc(GMEM_ZEROINIT | GMEM_SHARE, totalLen);
+  if (!hGlobalMemory) return E_OUTOFMEMORY;
+
+  wchar_t* contents = reinterpret_cast<wchar_t*>(GlobalLock(hGlobalMemory));
+  if (!contents) {
+    GlobalFree(hGlobalMemory);
+    return E_OUTOFMEMORY;
+  }
+
+  wcscpy(contents, url.get());
+  GlobalUnlock(hGlobalMemory);
+  aSTG.hGlobal = hGlobalMemory;
+  aSTG.tymed = TYMED_HGLOBAL;
+
+  return result;
+}
+
+// Gets the filename from the kFilePromiseURLMime flavour
+HRESULT nsDataObj::GetDownloadDetails(nsIURI** aSourceURI,
+                                      nsAString& aFilename) {
+  *aSourceURI = nullptr;
+
+  NS_ENSURE_TRUE(mTransferable, E_FAIL);
+
+  // get the URI from the kFilePromiseURLMime flavor
+  nsCOMPtr<nsISupports> urlPrimitive;
+  nsresult rv = mTransferable->GetTransferData(kFilePromiseURLMime,
+                                               getter_AddRefs(urlPrimitive));
+  NS_ENSURE_SUCCESS(rv, E_FAIL);
+  nsCOMPtr<nsISupportsString> srcUrlPrimitive = do_QueryInterface(urlPrimitive);
+  NS_ENSURE_TRUE(srcUrlPrimitive, E_FAIL);
+
+  nsAutoString srcUri;
+  srcUrlPrimitive->GetData(srcUri);
+  if (srcUri.IsEmpty()) return E_FAIL;
+  nsCOMPtr<nsIURI> sourceURI;
+  NS_NewURI(getter_AddRefs(sourceURI), srcUri);
+
+  nsAutoString srcFileName;
+  nsCOMPtr<nsISupports> fileNamePrimitive;
+  Unused << mTransferable->GetTransferData(kFilePromiseDestFilename,
+                                           getter_AddRefs(fileNamePrimitive));
+  nsCOMPtr<nsISupportsString> srcFileNamePrimitive =
+      do_QueryInterface(fileNamePrimitive);
+  if (srcFileNamePrimitive) {
+    srcFileNamePrimitive->GetData(srcFileName);
+  } else {
+    nsCOMPtr<nsIURL> sourceURL = do_QueryInterface(sourceURI);
+    if (!sourceURL) return E_FAIL;
+
+    nsAutoCString urlFileName;
+    sourceURL->GetFileName(urlFileName);
+    NS_UnescapeURL(urlFileName);
+    CopyUTF8toUTF16(urlFileName, srcFileName);
+  }
+
+  // make the name safe for the filesystem
+  ValidateFilename(srcFileName, false);
+  if (srcFileName.IsEmpty()) return E_FAIL;
+
+  sourceURI.swap(*aSourceURI);
+  aFilename = srcFileName;
+  return S_OK;
+}
+
+HRESULT nsDataObj::GetFileDescriptor_IStreamA(FORMATETC& aFE, STGMEDIUM& aSTG) {
+  HGLOBAL fileGroupDescHandle =
+      ::GlobalAlloc(GMEM_ZEROINIT | GMEM_SHARE, sizeof(FILEGROUPDESCRIPTORW));
+  NS_ENSURE_TRUE(fileGroupDescHandle, E_OUTOFMEMORY);
+
+  LPFILEGROUPDESCRIPTORA fileGroupDescA =
+      reinterpret_cast<LPFILEGROUPDESCRIPTORA>(GlobalLock(fileGroupDescHandle));
+  if (!fileGroupDescA) {
+    ::GlobalFree(fileGroupDescHandle);
+    return E_OUTOFMEMORY;
+  }
+
+  nsAutoString wideFileName;
+  HRESULT res;
+  nsCOMPtr<nsIURI> sourceURI;
+  res = GetDownloadDetails(getter_AddRefs(sourceURI), wideFileName);
+  if (FAILED(res)) {
+    ::GlobalFree(fileGroupDescHandle);
+    return res;
+  }
+
+  nsAutoCString nativeFileName;
+  NS_CopyUnicodeToNative(wideFileName, nativeFileName);
+
+  strncpy(fileGroupDescA->fgd[0].cFileName, nativeFileName.get(), MAX_PATH - 1);
+  fileGroupDescA->fgd[0].cFileName[MAX_PATH - 1] = '\0';
+
+  // one file in the file block
+  fileGroupDescA->cItems = 1;
+  fileGroupDescA->fgd[0].dwFlags = FD_PROGRESSUI;
+
+  GlobalUnlock(fileGroupDescHandle);
+  aSTG.hGlobal = fileGroupDescHandle;
+  aSTG.tymed = TYMED_HGLOBAL;
+
+  return S_OK;
+}
+
+HRESULT nsDataObj::GetFileDescriptor_IStreamW(FORMATETC& aFE, STGMEDIUM& aSTG) {
+  HGLOBAL fileGroupDescHandle =
+      ::GlobalAlloc(GMEM_ZEROINIT | GMEM_SHARE, sizeof(FILEGROUPDESCRIPTORW));
+  NS_ENSURE_TRUE(fileGroupDescHandle, E_OUTOFMEMORY);
+
+  LPFILEGROUPDESCRIPTORW fileGroupDescW =
+      reinterpret_cast<LPFILEGROUPDESCRIPTORW>(GlobalLock(fileGroupDescHandle));
+  if (!fileGroupDescW) {
+    ::GlobalFree(fileGroupDescHandle);
+    return E_OUTOFMEMORY;
+  }
+
+  nsAutoString wideFileName;
+  HRESULT res;
+  nsCOMPtr<nsIURI> sourceURI;
+  res = GetDownloadDetails(getter_AddRefs(sourceURI), wideFileName);
+  if (FAILED(res)) {
+    ::GlobalFree(fileGroupDescHandle);
+    return res;
+  }
+
+  wcsncpy(fileGroupDescW->fgd[0].cFileName, wideFileName.get(), MAX_PATH - 1);
+  fileGroupDescW->fgd[0].cFileName[MAX_PATH - 1] = '\0';
+  // one file in the file block
+  fileGroupDescW->cItems = 1;
+  fileGroupDescW->fgd[0].dwFlags = FD_PROGRESSUI;
+
+  GlobalUnlock(fileGroupDescHandle);
+  aSTG.hGlobal = fileGroupDescHandle;
+  aSTG.tymed = TYMED_HGLOBAL;
+
+  return S_OK;
+}
+
+HRESULT nsDataObj::GetFileContents_IStream(FORMATETC& aFE, STGMEDIUM& aSTG) {
+  IStream* pStream = nullptr;
+
+  nsDataObj::CreateStream(&pStream);
+  NS_ENSURE_TRUE(pStream, E_FAIL);
+
+  aSTG.tymed = TYMED_ISTREAM;
+  aSTG.pstm = pStream;
+  aSTG.pUnkForRelease = nullptr;
+
+  return S_OK;
+}