Handle PermissionError nicely

openlp/core/common/handlers.py

@@ -0,0 +1,48 @@
+# -*- coding: utf-8 -*-
+
+##########################################################################
+# OpenLP - Open Source Lyrics Projection                                 #
+# ---------------------------------------------------------------------- #
+# Copyright (c) 2008-2022 OpenLP Developers                              #
+# ---------------------------------------------------------------------- #
+# This program is free software: you can redistribute it and/or modify   #
+# it under the terms of the GNU General Public License as published by   #
+# the Free Software Foundation, either version 3 of the License, or      #
+# (at your option) any later version.                                    #
+#                                                                        #
+# This program is distributed in the hope that it will be useful,        #
+# but WITHOUT ANY WARRANTY; without even the implied warranty of         #
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the          #
+# GNU General Public License for more details.                           #
+#                                                                        #
+# You should have received a copy of the GNU General Public License      #
+# along with this program.  If not, see <https://www.gnu.org/licenses/>. #
+##########################################################################
+"""
+Some exception handling functions
+"""
+import logging
+from contextlib import contextmanager
+from pathlib import Path
+from typing import Optional
+
+from PyQt5 import QtWidgets
+
+from openlp.core.common.i18n import translate
+
+
+log = logging.getLogger(__name__)
+
+
+@contextmanager
+def handle_permission_error(filepath: Path, parent: Optional[QtWidgets.QWidget] = None):
+    try:
+        yield
+    except PermissionError:
+        log.exception(f'Permission denied when accessing {filepath}')
+        QtWidgets.QMessageBox.critical(
+            parent,
+            translate('OpenLP.Handlers', 'Permission Error'),
+            translate('OpenLP.Handlers', 'There was a permissions error when trying to access '
+                      '{filename}').format(filename=filepath)
+        )

openlp/plugins/songs/forms/songimportform.py

@@ -25,6 +25,7 @@ import logging
 
 from PyQt5 import QtCore, QtWidgets, QtGui
 
+from openlp.core.common.handlers import handle_permission_error
 from openlp.core.common.i18n import UiStrings, translate
 from openlp.core.common.mixins import RegistryProperties
 from openlp.core.lib.ui import critical_error_message_box
@@ -496,7 +497,8 @@ class SongImportSourcePage(QtWidgets.QWizardPage):
                     return True
             else:
                 file_path = wizard.format_widgets[this_format]['path_edit'].path
-                if file_path:
+                if file_path and file_path.exists():
+                    with handle_permission_error(file_path):
                         if select_mode == SongFormatSelect.SingleFile and file_path.is_file():
                             return True
                         elif select_mode == SongFormatSelect.SingleFolder and file_path.is_dir():

tests/openlp_core/common/test_handlers.py

@@ -0,0 +1,45 @@
+# -*- coding: utf-8 -*-
+
+##########################################################################
+# OpenLP - Open Source Lyrics Projection                                 #
+# ---------------------------------------------------------------------- #
+# Copyright (c) 2008-2022 OpenLP Developers                              #
+# ---------------------------------------------------------------------- #
+# This program is free software: you can redistribute it and/or modify   #
+# it under the terms of the GNU General Public License as published by   #
+# the Free Software Foundation, either version 3 of the License, or      #
+# (at your option) any later version.                                    #
+#                                                                        #
+# This program is distributed in the hope that it will be useful,        #
+# but WITHOUT ANY WARRANTY; without even the implied warranty of         #
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the          #
+# GNU General Public License for more details.                           #
+#                                                                        #
+# You should have received a copy of the GNU General Public License      #
+# along with this program.  If not, see <https://www.gnu.org/licenses/>. #
+##########################################################################
+"""
+Test the exception handling functions
+"""
+from unittest.mock import patch
+
+from openlp.core.common.handlers import handle_permission_error
+
+
+@patch('openlp.core.common.handlers.QtWidgets.QMessageBox')
+def test_handle_permission_error(MockQMessageBox):
+    """Test the handle_permission_error() function to make sure it catches PermissionError"""
+    # GIVEN: A mocked QMessageBox class and a file path
+    file_path = 'mocked_file_path'
+
+    # WHEN: the handle_permission_error() context manager is used
+    try:
+        with handle_permission_error(file_path):
+            raise PermissionError('Bad mojo')
+    except PermissionError:
+        assert False, 'PermissionError was not caught'
+
+    MockQMessageBox.critical.assert_called_once_with(
+        None, 'Permission Error',
+        'There was a permissions error when trying to access mocked_file_path'
+    )