gecko-dev/widget/windows/nsFilePicker.cpp

/* -*- 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 "nsFilePicker.h"

#include <shlobj.h>
#include <shlwapi.h>
#include <cderr.h>

#include "mozilla/BackgroundHangMonitor.h"
#include "mozilla/mscom/EnsureMTA.h"
#include "mozilla/UniquePtr.h"
#include "mozilla/WindowsVersion.h"
#include "nsReadableUtils.h"
#include "nsNetUtil.h"
#include "nsWindow.h"
#include "nsILoadContext.h"
#include "nsIServiceManager.h"
#include "nsIURL.h"
#include "nsIStringBundle.h"
#include "nsEnumeratorUtils.h"
#include "nsCRT.h"
#include "nsString.h"
#include "nsToolkit.h"
#include "WinUtils.h"
#include "nsPIDOMWindow.h"
#include "GeckoProfiler.h"

using mozilla::IsWin8OrLater;
using mozilla::MakeUnique;
using mozilla::UniquePtr;
using mozilla::mscom::EnsureMTA;
using namespace mozilla::widget;

char16_t* nsFilePicker::mLastUsedUnicodeDirectory;
char nsFilePicker::mLastUsedDirectory[MAX_PATH + 1] = {0};

static const unsigned long kDialogTimerTimeout = 300;

#define MAX_EXTENSION_LENGTH 10
#define FILE_BUFFER_SIZE 4096

typedef DWORD FILEOPENDIALOGOPTIONS;

///////////////////////////////////////////////////////////////////////////////
// Helper classes

// Manages matching SuppressBlurEvents calls on the parent widget.
class AutoSuppressEvents {
 public:
  explicit AutoSuppressEvents(nsIWidget* aWidget)
      : mWindow(static_cast<nsWindow*>(aWidget)) {
    SuppressWidgetEvents(true);
  }

  ~AutoSuppressEvents() { SuppressWidgetEvents(false); }

 private:
  void SuppressWidgetEvents(bool aFlag) {
    if (mWindow) {
      mWindow->SuppressBlurEvents(aFlag);
    }
  }
  RefPtr<nsWindow> mWindow;
};

// Manages the current working path.
class AutoRestoreWorkingPath {
 public:
  AutoRestoreWorkingPath() {
    DWORD bufferLength = GetCurrentDirectoryW(0, nullptr);
    mWorkingPath = MakeUnique<wchar_t[]>(bufferLength);
    if (GetCurrentDirectoryW(bufferLength, mWorkingPath.get()) == 0) {
      mWorkingPath = nullptr;
    }
  }

  ~AutoRestoreWorkingPath() {
    if (HasWorkingPath()) {
      ::SetCurrentDirectoryW(mWorkingPath.get());
    }
  }

  inline bool HasWorkingPath() const { return mWorkingPath != nullptr; }

 private:
  UniquePtr<wchar_t[]> mWorkingPath;
};

// Manages NS_NATIVE_TMP_WINDOW child windows. NS_NATIVE_TMP_WINDOWs are
// temporary child windows of mParentWidget created to address RTL issues
// in picker dialogs. We are responsible for destroying these.
class AutoDestroyTmpWindow {
 public:
  explicit AutoDestroyTmpWindow(HWND aTmpWnd) : mWnd(aTmpWnd) {}

  ~AutoDestroyTmpWindow() {
    if (mWnd) DestroyWindow(mWnd);
  }

  inline HWND get() const { return mWnd; }

 private:
  HWND mWnd;
};

// Manages matching PickerOpen/PickerClosed calls on the parent widget.
class AutoWidgetPickerState {
 public:
  explicit AutoWidgetPickerState(nsIWidget* aWidget)
      : mWindow(static_cast<nsWindow*>(aWidget)) {
    PickerState(true);
  }

  ~AutoWidgetPickerState() { PickerState(false); }

 private:
  void PickerState(bool aFlag) {
    if (mWindow) {
      if (aFlag)
        mWindow->PickerOpen();
      else
        mWindow->PickerClosed();
    }
  }
  RefPtr<nsWindow> mWindow;
};

// Manages a simple callback timer
class AutoTimerCallbackCancel {
 public:
  AutoTimerCallbackCancel(nsFilePicker* aTarget,
                          nsTimerCallbackFunc aCallbackFunc,
                          const char* aName) {
    Init(aTarget, aCallbackFunc, aName);
  }

  ~AutoTimerCallbackCancel() {
    if (mPickerCallbackTimer) {
      mPickerCallbackTimer->Cancel();
    }
  }

 private:
  void Init(nsFilePicker* aTarget, nsTimerCallbackFunc aCallbackFunc,
            const char* aName) {
    NS_NewTimerWithFuncCallback(getter_AddRefs(mPickerCallbackTimer),
                                aCallbackFunc, aTarget, kDialogTimerTimeout,
                                nsITimer::TYPE_REPEATING_SLACK, aName);
    if (!mPickerCallbackTimer) {
      NS_WARNING("do_CreateInstance for timer failed??");
    }
  }
  nsCOMPtr<nsITimer> mPickerCallbackTimer;
};

///////////////////////////////////////////////////////////////////////////////
// nsIFilePicker

nsFilePicker::nsFilePicker()
    : mSelectedType(1), mDlgWnd(nullptr), mFDECookie(0) {
  CoInitialize(nullptr);
}

nsFilePicker::~nsFilePicker() {
  if (mLastUsedUnicodeDirectory) {
    free(mLastUsedUnicodeDirectory);
    mLastUsedUnicodeDirectory = nullptr;
  }
  CoUninitialize();
}

NS_IMPL_ISUPPORTS(nsFilePicker, nsIFilePicker)

NS_IMETHODIMP nsFilePicker::Init(mozIDOMWindowProxy* aParent,
                                 const nsAString& aTitle, int16_t aMode) {
  nsCOMPtr<nsPIDOMWindowOuter> window = do_QueryInterface(aParent);
  nsIDocShell* docShell = window ? window->GetDocShell() : nullptr;
  mLoadContext = do_QueryInterface(docShell);

  return nsBaseFilePicker::Init(aParent, aTitle, aMode);
}

STDMETHODIMP nsFilePicker::QueryInterface(REFIID refiid, void** ppvResult) {
  *ppvResult = nullptr;
  if (IID_IUnknown == refiid || refiid == IID_IFileDialogEvents) {
    *ppvResult = this;
  }

  if (nullptr != *ppvResult) {
    ((LPUNKNOWN)*ppvResult)->AddRef();
    return S_OK;
  }

  return E_NOINTERFACE;
}

/*
 * Vista+ callbacks
 */

HRESULT
nsFilePicker::OnFileOk(IFileDialog* pfd) { return S_OK; }

HRESULT
nsFilePicker::OnFolderChanging(IFileDialog* pfd, IShellItem* psiFolder) {
  return S_OK;
}

HRESULT
nsFilePicker::OnFolderChange(IFileDialog* pfd) { return S_OK; }

HRESULT
nsFilePicker::OnSelectionChange(IFileDialog* pfd) { return S_OK; }

HRESULT
nsFilePicker::OnShareViolation(IFileDialog* pfd, IShellItem* psi,
                               FDE_SHAREVIOLATION_RESPONSE* pResponse) {
  return S_OK;
}

HRESULT
nsFilePicker::OnTypeChange(IFileDialog* pfd) {
  // Failures here result in errors due to security concerns.
  RefPtr<IOleWindow> win;
  pfd->QueryInterface(IID_IOleWindow, getter_AddRefs(win));
  if (!win) {
    NS_ERROR("Could not retrieve the IOleWindow interface for IFileDialog.");
    return S_OK;
  }
  HWND hwnd = nullptr;
  win->GetWindow(&hwnd);
  if (!hwnd) {
    NS_ERROR("Could not retrieve the HWND for IFileDialog.");
    return S_OK;
  }

  SetDialogHandle(hwnd);
  return S_OK;
}

HRESULT
nsFilePicker::OnOverwrite(IFileDialog* pfd, IShellItem* psi,
                          FDE_OVERWRITE_RESPONSE* pResponse) {
  return S_OK;
}

/*
 * Close on parent close logic
 */

bool nsFilePicker::ClosePickerIfNeeded() {
  if (!mParentWidget || !mDlgWnd) return false;

  nsWindow* win = static_cast<nsWindow*>(mParentWidget.get());
  if (IsWindow(mDlgWnd) && IsWindowVisible(mDlgWnd) && win->DestroyCalled()) {
    wchar_t className[64];
    // Make sure we have the right window
    if (GetClassNameW(mDlgWnd, className, mozilla::ArrayLength(className)) &&
        !wcscmp(className, L"#32770") && DestroyWindow(mDlgWnd)) {
      mDlgWnd = nullptr;
      return true;
    }
  }
  return false;
}

void nsFilePicker::PickerCallbackTimerFunc(nsITimer* aTimer, void* aCtx) {
  nsFilePicker* picker = (nsFilePicker*)aCtx;
  if (picker->ClosePickerIfNeeded()) {
    aTimer->Cancel();
  }
}

void nsFilePicker::SetDialogHandle(HWND aWnd) {
  if (!aWnd || mDlgWnd) return;
  mDlgWnd = aWnd;
}

/*
 * Folder picker invocation
 */

/*
 * Show a folder picker.
 *
 * @param aInitialDir   The initial directory, the last used directory will be
 *                      used if left blank.
 * @return true if a file was selected successfully.
 */
bool nsFilePicker::ShowFolderPicker(const nsString& aInitialDir) {
  if (!IsWin8OrLater()) {
    // Some Windows 7 users are experiencing a race condition when some dlls
    // that are loaded by the file picker cause a crash while attempting to shut
    // down the COM multithreaded apartment. By instantiating EnsureMTA, we hold
    // an additional reference to the MTA that should prevent this race, since
    // the MTA will remain alive until shutdown.
    EnsureMTA ensureMTA;
  }

  RefPtr<IFileOpenDialog> dialog;
  if (FAILED(CoCreateInstance(CLSID_FileOpenDialog, nullptr, CLSCTX_INPROC,
                              IID_IFileOpenDialog, getter_AddRefs(dialog)))) {
    return false;
  }

  // hook up event callbacks
  dialog->Advise(this, &mFDECookie);

  // options
  FILEOPENDIALOGOPTIONS fos = FOS_PICKFOLDERS;
  dialog->SetOptions(fos);

  // initial strings
  dialog->SetTitle(mTitle.get());

  if (!mOkButtonLabel.IsEmpty()) {
    dialog->SetOkButtonLabel(mOkButtonLabel.get());
  }

  if (!aInitialDir.IsEmpty()) {
    RefPtr<IShellItem> folder;
    if (SUCCEEDED(SHCreateItemFromParsingName(aInitialDir.get(), nullptr,
                                              IID_IShellItem,
                                              getter_AddRefs(folder)))) {
      dialog->SetFolder(folder);
    }
  }

  AutoDestroyTmpWindow adtw((HWND)(
      mParentWidget.get() ? mParentWidget->GetNativeData(NS_NATIVE_TMP_WINDOW)
                          : nullptr));

  // display
  mozilla::BackgroundHangMonitor().NotifyWait();
  RefPtr<IShellItem> item;
  if (FAILED(dialog->Show(adtw.get())) ||
      FAILED(dialog->GetResult(getter_AddRefs(item))) || !item) {
    dialog->Unadvise(mFDECookie);
    return false;
  }
  dialog->Unadvise(mFDECookie);

  // results

  // If the user chose a Win7 Library, resolve to the library's
  // default save folder.
  RefPtr<IShellItem> folderPath;
  RefPtr<IShellLibrary> shellLib;
  CoCreateInstance(CLSID_ShellLibrary, nullptr, CLSCTX_INPROC,
                   IID_IShellLibrary, getter_AddRefs(shellLib));
  if (shellLib && SUCCEEDED(shellLib->LoadLibraryFromItem(item, STGM_READ)) &&
      SUCCEEDED(shellLib->GetDefaultSaveFolder(DSFT_DETECT, IID_IShellItem,
                                               getter_AddRefs(folderPath)))) {
    item.swap(folderPath);
  }

  // get the folder's file system path
  return WinUtils::GetShellItemPath(item, mUnicodeFile);
}

/*
 * File open and save picker invocation
 */

/*
 * Show a file picker.
 *
 * @param aInitialDir   The initial directory, the last used directory will be
 *                      used if left blank.
 * @return true if a file was selected successfully.
 */
bool nsFilePicker::ShowFilePicker(const nsString& aInitialDir) {
  AUTO_PROFILER_LABEL("nsFilePicker::ShowFilePicker", OTHER);

  if (!IsWin8OrLater()) {
    // Some Windows 7 users are experiencing a race condition when some dlls
    // that are loaded by the file picker cause a crash while attempting to shut
    // down the COM multithreaded apartment. By instantiating EnsureMTA, we hold
    // an additional reference to the MTA that should prevent this race, since
    // the MTA will remain alive until shutdown.
    EnsureMTA ensureMTA;
  }

  RefPtr<IFileDialog> dialog;
  if (mMode != modeSave) {
    if (FAILED(CoCreateInstance(CLSID_FileOpenDialog, nullptr, CLSCTX_INPROC,
                                IID_IFileOpenDialog, getter_AddRefs(dialog)))) {
      return false;
    }
  } else {
    if (FAILED(CoCreateInstance(CLSID_FileSaveDialog, nullptr, CLSCTX_INPROC,
                                IID_IFileSaveDialog, getter_AddRefs(dialog)))) {
      return false;
    }
  }

  // hook up event callbacks
  dialog->Advise(this, &mFDECookie);

  // options

  FILEOPENDIALOGOPTIONS fos = 0;
  fos |= FOS_SHAREAWARE | FOS_OVERWRITEPROMPT | FOS_FORCEFILESYSTEM;

  // Handle add to recent docs settings
  if (IsPrivacyModeEnabled() || !mAddToRecentDocs) {
    fos |= FOS_DONTADDTORECENT;
  }

  // Msdn claims FOS_NOCHANGEDIR is not needed. We'll add this
  // just in case.
  AutoRestoreWorkingPath arw;

  // mode specific
  switch (mMode) {
    case modeOpen:
      fos |= FOS_FILEMUSTEXIST;
      break;

    case modeOpenMultiple:
      fos |= FOS_FILEMUSTEXIST | FOS_ALLOWMULTISELECT;
      break;

    case modeSave:
      fos |= FOS_NOREADONLYRETURN;
      // Don't follow shortcuts when saving a shortcut, this can be used
      // to trick users (bug 271732)
      if (IsDefaultPathLink()) fos |= FOS_NODEREFERENCELINKS;
      break;
  }

  dialog->SetOptions(fos);

  // initial strings

  // title
  dialog->SetTitle(mTitle.get());

  // default filename
  if (!mDefaultFilename.IsEmpty()) {
    dialog->SetFileName(mDefaultFilename.get());
  }

  // default extension to append to new files
  if (!mDefaultExtension.IsEmpty()) {
    dialog->SetDefaultExtension(mDefaultExtension.get());
  } else if (IsDefaultPathHtml()) {
    dialog->SetDefaultExtension(L"html");
  }

  // initial location
  if (!aInitialDir.IsEmpty()) {
    RefPtr<IShellItem> folder;
    if (SUCCEEDED(SHCreateItemFromParsingName(aInitialDir.get(), nullptr,
                                              IID_IShellItem,
                                              getter_AddRefs(folder)))) {
      dialog->SetFolder(folder);
    }
  }

  // filter types and the default index
  if (!mComFilterList.IsEmpty()) {
    dialog->SetFileTypes(mComFilterList.Length(), mComFilterList.get());
    dialog->SetFileTypeIndex(mSelectedType);
  }

  // display

  {
    AutoDestroyTmpWindow adtw((HWND)(
        mParentWidget.get() ? mParentWidget->GetNativeData(NS_NATIVE_TMP_WINDOW)
                            : nullptr));
    AutoTimerCallbackCancel atcc(this, PickerCallbackTimerFunc,
                                 "nsFilePicker::PickerCallbackTimerFunc");
    AutoWidgetPickerState awps(mParentWidget);

    mozilla::BackgroundHangMonitor().NotifyWait();
    if (FAILED(dialog->Show(adtw.get()))) {
      dialog->Unadvise(mFDECookie);
      return false;
    }
    dialog->Unadvise(mFDECookie);
  }

  // results

  // Remember what filter type the user selected
  UINT filterIdxResult;
  if (SUCCEEDED(dialog->GetFileTypeIndex(&filterIdxResult))) {
    mSelectedType = (int16_t)filterIdxResult;
  }

  // single selection
  if (mMode != modeOpenMultiple) {
    RefPtr<IShellItem> item;
    if (FAILED(dialog->GetResult(getter_AddRefs(item))) || !item) return false;
    return WinUtils::GetShellItemPath(item, mUnicodeFile);
  }

  // multiple selection
  RefPtr<IFileOpenDialog> openDlg;
  dialog->QueryInterface(IID_IFileOpenDialog, getter_AddRefs(openDlg));
  if (!openDlg) {
    // should not happen
    return false;
  }

  RefPtr<IShellItemArray> items;
  if (FAILED(openDlg->GetResults(getter_AddRefs(items))) || !items) {
    return false;
  }

  DWORD count = 0;
  items->GetCount(&count);
  for (unsigned int idx = 0; idx < count; idx++) {
    RefPtr<IShellItem> item;
    nsAutoString str;
    if (SUCCEEDED(items->GetItemAt(idx, getter_AddRefs(item)))) {
      if (!WinUtils::GetShellItemPath(item, str)) continue;
      nsCOMPtr<nsIFile> file = do_CreateInstance("@mozilla.org/file/local;1");
      if (file && NS_SUCCEEDED(file->InitWithPath(str)))
        mFiles.AppendObject(file);
    }
  }
  return true;
}

///////////////////////////////////////////////////////////////////////////////
// nsIFilePicker impl.

nsresult nsFilePicker::ShowW(int16_t* aReturnVal) {
  NS_ENSURE_ARG_POINTER(aReturnVal);

  *aReturnVal = returnCancel;

  AutoSuppressEvents supress(mParentWidget);

  nsAutoString initialDir;
  if (mDisplayDirectory) mDisplayDirectory->GetPath(initialDir);

  // If no display directory, re-use the last one.
  if (initialDir.IsEmpty()) {
    // Allocate copy of last used dir.
    initialDir = mLastUsedUnicodeDirectory;
  }

  // Clear previous file selections
  mUnicodeFile.Truncate();
  mFiles.Clear();

  // On Win10, the picker doesn't support per-monitor DPI, so we open it
  // with our context set temporarily to system-dpi-aware
  WinUtils::AutoSystemDpiAware dpiAwareness;

  bool result = false;
  if (mMode == modeGetFolder) {
    result = ShowFolderPicker(initialDir);
  } else {
    result = ShowFilePicker(initialDir);
  }

  // exit, and return returnCancel in aReturnVal
  if (!result) return NS_OK;

  RememberLastUsedDirectory();

  int16_t retValue = returnOK;
  if (mMode == modeSave) {
    // Windows does not return resultReplace, we must check if file
    // already exists.
    nsCOMPtr<nsIFile> file(do_CreateInstance("@mozilla.org/file/local;1"));
    bool flag = false;
    if (file && NS_SUCCEEDED(file->InitWithPath(mUnicodeFile)) &&
        NS_SUCCEEDED(file->Exists(&flag)) && flag) {
      retValue = returnReplace;
    }
  }

  *aReturnVal = retValue;
  return NS_OK;
}

nsresult nsFilePicker::Show(int16_t* aReturnVal) { return ShowW(aReturnVal); }

NS_IMETHODIMP
nsFilePicker::GetFile(nsIFile** aFile) {
  NS_ENSURE_ARG_POINTER(aFile);
  *aFile = nullptr;

  if (mUnicodeFile.IsEmpty()) return NS_OK;

  nsCOMPtr<nsIFile> file(do_CreateInstance("@mozilla.org/file/local;1"));

  NS_ENSURE_TRUE(file, NS_ERROR_FAILURE);

  file->InitWithPath(mUnicodeFile);

  NS_ADDREF(*aFile = file);

  return NS_OK;
}

NS_IMETHODIMP
nsFilePicker::GetFileURL(nsIURI** aFileURL) {
  *aFileURL = nullptr;
  nsCOMPtr<nsIFile> file;
  nsresult rv = GetFile(getter_AddRefs(file));
  if (!file) return rv;

  return NS_NewFileURI(aFileURL, file);
}

NS_IMETHODIMP
nsFilePicker::GetFiles(nsISimpleEnumerator** aFiles) {
  NS_ENSURE_ARG_POINTER(aFiles);
  return NS_NewArrayEnumerator(aFiles, mFiles, NS_GET_IID(nsIFile));
}

// Get the file + path
NS_IMETHODIMP
nsBaseWinFilePicker::SetDefaultString(const nsAString& aString) {
  mDefaultFilePath = aString;

  // First, make sure the file name is not too long.
  int32_t nameLength;
  int32_t nameIndex = mDefaultFilePath.RFind("\\");
  if (nameIndex == kNotFound)
    nameIndex = 0;
  else
    nameIndex++;
  nameLength = mDefaultFilePath.Length() - nameIndex;
  mDefaultFilename.Assign(Substring(mDefaultFilePath, nameIndex));

  if (nameLength > MAX_PATH) {
    int32_t extIndex = mDefaultFilePath.RFind(".");
    if (extIndex == kNotFound) extIndex = mDefaultFilePath.Length();

    // Let's try to shave the needed characters from the name part.
    int32_t charsToRemove = nameLength - MAX_PATH;
    if (extIndex - nameIndex >= charsToRemove) {
      mDefaultFilePath.Cut(extIndex - charsToRemove, charsToRemove);
    }
  }

  // Then, we need to replace illegal characters. At this stage, we cannot
  // replace the backslash as the string might represent a file path.
  mDefaultFilePath.ReplaceChar(FILE_ILLEGAL_CHARACTERS, '-');
  mDefaultFilename.ReplaceChar(FILE_ILLEGAL_CHARACTERS, '-');

  return NS_OK;
}

NS_IMETHODIMP
nsBaseWinFilePicker::GetDefaultString(nsAString& aString) {
  return NS_ERROR_FAILURE;
}

// The default extension to use for files
NS_IMETHODIMP
nsBaseWinFilePicker::GetDefaultExtension(nsAString& aExtension) {
  aExtension = mDefaultExtension;
  return NS_OK;
}

NS_IMETHODIMP
nsBaseWinFilePicker::SetDefaultExtension(const nsAString& aExtension) {
  mDefaultExtension = aExtension;
  return NS_OK;
}

// Set the filter index
NS_IMETHODIMP
nsFilePicker::GetFilterIndex(int32_t* aFilterIndex) {
  // Windows' filter index is 1-based, we use a 0-based system.
  *aFilterIndex = mSelectedType - 1;
  return NS_OK;
}

NS_IMETHODIMP
nsFilePicker::SetFilterIndex(int32_t aFilterIndex) {
  // Windows' filter index is 1-based, we use a 0-based system.
  mSelectedType = aFilterIndex + 1;
  return NS_OK;
}

void nsFilePicker::InitNative(nsIWidget* aParent, const nsAString& aTitle) {
  mParentWidget = aParent;
  mTitle.Assign(aTitle);
}

NS_IMETHODIMP
nsFilePicker::AppendFilter(const nsAString& aTitle, const nsAString& aFilter) {
  mComFilterList.Append(aTitle, aFilter);
  return NS_OK;
}

void nsFilePicker::RememberLastUsedDirectory() {
  nsCOMPtr<nsIFile> file(do_CreateInstance("@mozilla.org/file/local;1"));
  if (!file || NS_FAILED(file->InitWithPath(mUnicodeFile))) {
    NS_WARNING("RememberLastUsedDirectory failed to init file path.");
    return;
  }

  nsCOMPtr<nsIFile> dir;
  nsAutoString newDir;
  if (NS_FAILED(file->GetParent(getter_AddRefs(dir))) ||
      !(mDisplayDirectory = dir) ||
      NS_FAILED(mDisplayDirectory->GetPath(newDir)) || newDir.IsEmpty()) {
    NS_WARNING("RememberLastUsedDirectory failed to get parent directory.");
    return;
  }

  if (mLastUsedUnicodeDirectory) {
    free(mLastUsedUnicodeDirectory);
    mLastUsedUnicodeDirectory = nullptr;
  }
  mLastUsedUnicodeDirectory = ToNewUnicode(newDir);
}

bool nsFilePicker::IsPrivacyModeEnabled() {
  return mLoadContext && mLoadContext->UsePrivateBrowsing();
}

bool nsFilePicker::IsDefaultPathLink() {
  NS_ConvertUTF16toUTF8 ext(mDefaultFilePath);
  ext.Trim(" .", false, true);  // watch out for trailing space and dots
  ToLowerCase(ext);
  if (StringEndsWith(ext, NS_LITERAL_CSTRING(".lnk")) ||
      StringEndsWith(ext, NS_LITERAL_CSTRING(".pif")) ||
      StringEndsWith(ext, NS_LITERAL_CSTRING(".url")))
    return true;
  return false;
}

bool nsFilePicker::IsDefaultPathHtml() {
  int32_t extIndex = mDefaultFilePath.RFind(".");
  if (extIndex >= 0) {
    nsAutoString ext;
    mDefaultFilePath.Right(ext, mDefaultFilePath.Length() - extIndex);
    if (ext.LowerCaseEqualsLiteral(".htm") ||
        ext.LowerCaseEqualsLiteral(".html") ||
        ext.LowerCaseEqualsLiteral(".shtml"))
      return true;
  }
  return false;
}

void nsFilePicker::ComDlgFilterSpec::Append(const nsAString& aTitle,
                                            const nsAString& aFilter) {
  COMDLG_FILTERSPEC* pSpecForward = mSpecList.AppendElement();
  if (!pSpecForward) {
    NS_WARNING("mSpecList realloc failed.");
    return;
  }
  memset(pSpecForward, 0, sizeof(*pSpecForward));
  nsString* pStr = mStrings.AppendElement(aTitle);
  if (!pStr) {
    NS_WARNING("mStrings.AppendElement failed.");
    return;
  }
  pSpecForward->pszName = pStr->get();
  pStr = mStrings.AppendElement(aFilter);
  if (!pStr) {
    NS_WARNING("mStrings.AppendElement failed.");
    return;
  }
  if (aFilter.EqualsLiteral("..apps"))
    pStr->AssignLiteral("*.exe;*.com");
  else {
    pStr->StripWhitespace();
    if (pStr->EqualsLiteral("*")) pStr->AppendLiteral(".*");
  }
  pSpecForward->pszSpec = pStr->get();
}