Windows: Use a helper process to display file open/save dialogs. This should fix most crashes caused by poorly designed shell extensions

The helper process only depends on the C runtime, no Qt/Python DLLs are
loaded.

src/calibre/gui2/__init__.py

@@ -678,15 +678,84 @@ class FileDialog(QObject):
             return tuple(os.path.abspath(unicode(i)) for i in self.fd.selectedFiles())
         return tuple(self.selected_files)
 
+has_windows_file_dialog_helper = False
+if iswindows and 'CALIBRE_NO_NATIVE_FILEDIALOGS' not in os.environ:
+    from calibre.gui2.win_file_dialogs import is_ok as has_windows_file_dialog_helper
+    has_windows_file_dialog_helper = has_windows_file_dialog_helper()
+if has_windows_file_dialog_helper:
+    from calibre.gui2.win_file_dialogs import choose_files, choose_images, choose_dir, choose_save_file
+else:
 
-def choose_dir(window, name, title, default_dir='~', no_save_dir=False):
-    fd = FileDialog(title=title, filters=[], add_all_files_filter=False,
-            parent=window, name=name, mode=QFileDialog.Directory,
-            default_dir=default_dir, no_save_dir=no_save_dir)
-    dir = fd.get_files()
-    fd.setParent(None)
-    if dir:
-        return dir[0]
+    def choose_dir(window, name, title, default_dir='~', no_save_dir=False):
+        fd = FileDialog(title=title, filters=[], add_all_files_filter=False,
+                parent=window, name=name, mode=QFileDialog.Directory,
+                default_dir=default_dir, no_save_dir=no_save_dir)
+        dir = fd.get_files()
+        fd.setParent(None)
+        if dir:
+            return dir[0]
+
+    def choose_files(window, name, title,
+                    filters=[], all_files=True, select_only_single_file=False, default_dir=u'~'):
+        '''
+        Ask user to choose a bunch of files.
+        :param name: Unique dialog name used to store the opened directory
+        :param title: Title to show in dialogs titlebar
+        :param filters: list of allowable extensions. Each element of the list
+                        must be a 2-tuple with first element a string describing
+                        the type of files to be filtered and second element a list
+                        of extensions.
+        :param all_files: If True add All files to filters.
+        :param select_only_single_file: If True only one file can be selected
+        '''
+        mode = QFileDialog.ExistingFile if select_only_single_file else QFileDialog.ExistingFiles
+        fd = FileDialog(title=title, name=name, filters=filters, default_dir=default_dir,
+                        parent=window, add_all_files_filter=all_files, mode=mode,
+                        )
+        fd.setParent(None)
+        if fd.accepted:
+            return fd.get_files()
+        return None
+
+    def choose_save_file(window, name, title, filters=[], all_files=True, initial_path=None, initial_filename=None):
+        '''
+        Ask user to choose a file to save to. Can be a non-existent file.
+        :param filters: list of allowable extensions. Each element of the list
+                        must be a 2-tuple with first element a string describing
+                        the type of files to be filtered and second element a list
+                        of extensions.
+        :param all_files: If True add All files to filters.
+        :param initial_path: The initially selected path (does not need to exist). Cannot be used with initial_filename.
+        :param initial_filename: If specified, the initially selected path is this filename in the previously used directory. Cannot be used with initial_path.
+        '''
+        kwargs = dict(title=title, name=name, filters=filters,
+                        parent=window, add_all_files_filter=all_files, mode=QFileDialog.AnyFile)
+        if initial_path is not None:
+            kwargs['no_save_dir'] = True
+            kwargs['default_dir'] = initial_path
+        elif initial_filename is not None:
+            kwargs['combine_file_and_saved_dir'] = True
+            kwargs['default_dir'] = initial_filename
+        fd = FileDialog(**kwargs)
+        fd.setParent(None)
+        ans = None
+        if fd.accepted:
+            ans = fd.get_files()
+            if ans:
+                ans = ans[0]
+        return ans
+
+    def choose_images(window, name, title, select_only_single_file=True,
+                    formats=('png', 'gif', 'jpg', 'jpeg', 'svg')):
+        mode = QFileDialog.ExistingFile if select_only_single_file else QFileDialog.ExistingFiles
+        fd = FileDialog(title=title, name=name,
+                        filters=[(_('Images'), list(formats))],
+                        parent=window, add_all_files_filter=False, mode=mode,
+                        )
+        fd.setParent(None)
+        if fd.accepted:
+            return fd.get_files()
+        return None
 
 def choose_osx_app(window, name, title, default_dir='/Applications'):
     fd = FileDialog(title=title, parent=window, name=name, mode=QFileDialog.ExistingFile,
@@ -696,68 +765,6 @@ def choose_osx_app(window, name, title, default_dir='/Applications'):
     if app:
         return app
 
-def choose_files(window, name, title,
-                 filters=[], all_files=True, select_only_single_file=False, default_dir=u'~'):
-    '''
-    Ask user to choose a bunch of files.
-    :param name: Unique dialog name used to store the opened directory
-    :param title: Title to show in dialogs titlebar
-    :param filters: list of allowable extensions. Each element of the list
-                    must be a 2-tuple with first element a string describing
-                    the type of files to be filtered and second element a list
-                    of extensions.
-    :param all_files: If True add All files to filters.
-    :param select_only_single_file: If True only one file can be selected
-    '''
-    mode = QFileDialog.ExistingFile if select_only_single_file else QFileDialog.ExistingFiles
-    fd = FileDialog(title=title, name=name, filters=filters, default_dir=default_dir,
-                    parent=window, add_all_files_filter=all_files, mode=mode,
-                    )
-    fd.setParent(None)
-    if fd.accepted:
-        return fd.get_files()
-    return None
-
-def choose_save_file(window, name, title, filters=[], all_files=True, initial_path=None, initial_filename=None):
-    '''
-    Ask user to choose a file to save to. Can be a non-existent file.
-    :param filters: list of allowable extensions. Each element of the list
-                     must be a 2-tuple with first element a string describing
-                     the type of files to be filtered and second element a list
-                     of extensions.
-    :param all_files: If True add All files to filters.
-    :param initial_path: The initially selected path (does not need to exist). Cannot be used with initial_filename.
-    :param initial_filename: If specified, the initially selected path is this filename in the previously used directory. Cannot be used with initial_path.
-    '''
-    kwargs = dict(title=title, name=name, filters=filters,
-                    parent=window, add_all_files_filter=all_files, mode=QFileDialog.AnyFile)
-    if initial_path is not None:
-        kwargs['no_save_dir'] = True
-        kwargs['default_dir'] = initial_path
-    elif initial_filename is not None:
-        kwargs['combine_file_and_saved_dir'] = True
-        kwargs['default_dir'] = initial_filename
-    fd = FileDialog(**kwargs)
-    fd.setParent(None)
-    ans = None
-    if fd.accepted:
-        ans = fd.get_files()
-        if ans:
-            ans = ans[0]
-    return ans
-
-def choose_images(window, name, title, select_only_single_file=True,
-                  formats=('png', 'gif', 'jpg', 'jpeg', 'svg')):
-    mode = QFileDialog.ExistingFile if select_only_single_file else QFileDialog.ExistingFiles
-    fd = FileDialog(title=title, name=name,
-                    filters=[('Images', list(formats))],
-                    parent=window, add_all_files_filter=False, mode=mode,
-                    )
-    fd.setParent(None)
-    if fd.accepted:
-        return fd.get_files()
-    return None
-
 def pixmap_to_data(pixmap, format='JPEG', quality=90):
     '''
     Return the QPixmap pixmap as a string saved in the specified format.

src/calibre/gui2/win_file_dialogs.py

@@ -13,12 +13,17 @@ is64bit = sys.maxsize > (1 << 32)
 base = sys.extensions_location if hasattr(sys, 'new_app_layout') else os.path.dirname(sys.executable)
 HELPER = os.path.join(base, 'calibre-file-dialogs.exe')
 
+def is_ok():
+    return os.path.exists(HELPER)
+
 try:
     from calibre.constants import filesystem_encoding
     from calibre.utils.filenames import expanduser
+    from calibre.utils.config import dynamic
 except ImportError:
     filesystem_encoding = 'utf-8'
     expanduser = os.path.expanduser
+    dynamic = {}
 
 def get_hwnd(widget=None):
     ewid = None
@@ -52,6 +57,8 @@ def serialize_file_types(file_types):
         buf.append(struct.pack(b'=H%ds' % len(x), len(x), x))
     for name, extensions in file_types:
         add(name or _('Files'))
+        if isinstance(extensions, basestring):
+            extensions = extensions.split()
         add('; '.join('*.' + ext.lower() for ext in extensions))
     return b''.join(buf)
 
@@ -100,9 +107,10 @@ def run_file_dialog(
         file_types=()
 ):
     data = []
+    parent = parent or None
     if parent is not None:
         data.append(serialize_hwnd(get_hwnd(parent)))
-    if title is not None:
+    if title:
         data.append(serialize_string('TITLE', title))
     if no_symlinks:
         data.append(serialize_binary('NO_SYMLINKS', no_symlinks))
@@ -151,6 +159,61 @@ def run_file_dialog(
     ans = tuple((os.path.abspath(x.decode('utf-8')) for x in h.stdoutdata.split(b'\0') if x))
     return ans
 
+def get_initial_folder(name, title, default_dir='~', no_save_dir=False):
+    name = name or 'dialog_' + title
+    if no_save_dir:
+        initial_folder = expanduser(default_dir)
+    else:
+        initial_folder = dynamic.get(name, expanduser(default_dir))
+    if not initial_folder or not os.path.isdir(initial_folder):
+        initial_folder = select_initial_dir(initial_folder)
+    return name, initial_folder
+
+def choose_dir(window, name, title, default_dir='~', no_save_dir=False):
+    name, initial_folder = get_initial_folder(name, title, default_dir, no_save_dir)
+    ans = run_file_dialog(window, title, only_dirs=True, initial_folder=initial_folder)
+    if ans:
+        ans = ans[0]
+        if not no_save_dir:
+            dynamic.set(name, ans)
+        return ans
+
+def choose_files(window, name, title,
+                 filters=(), all_files=True, select_only_single_file=False, default_dir=u'~'):
+    name, initial_folder = get_initial_folder(name, title, default_dir)
+    file_types = list(filters)
+    if all_files:
+        file_types.append((_('All files'), ['*']))
+    ans = run_file_dialog(window, title, allow_multiple=not select_only_single_file, initial_folder=initial_folder, file_types=file_types)
+    if ans:
+        dynamic.set(name, os.path.dirname(ans[0]))
+        return ans
+    return None
+
+def choose_images(window, name, title, select_only_single_file=True,
+                  formats=('png', 'gif', 'jpg', 'jpeg', 'svg')):
+    file_types = [(_('Images'), list(formats))]
+    return choose_files(window, name, title, select_only_single_file=select_only_single_file, filters=file_types)
+
+def choose_save_file(window, name, title, filters=[], all_files=True, initial_path=None, initial_filename=None):
+    no_save_dir = False
+    default_dir = '~'
+    filename = initial_filename
+    if initial_path is not None:
+        no_save_dir = True
+        default_dir = select_initial_dir(initial_path)
+        filename = os.path.basename(initial_path)
+    file_types = list(filters)
+    if all_files:
+        file_types.append((_('All files'), ['*']))
+    name, initial_folder = get_initial_folder(name, title, default_dir, no_save_dir)
+    ans = run_file_dialog(window, title, save_as=True, initial_folder=initial_folder, filename=filename, file_types=file_types)
+    if ans:
+        ans = ans[0]
+        if not no_save_dir:
+            dynamic.set(name, ans)
+        return ans
+
 def test():
     p = subprocess.Popen([HELPER], stdout=subprocess.PIPE, stdin=subprocess.PIPE, stderr=subprocess.PIPE)
     echo = '\U0001f431 Hello world!'