unpaper: super syntax

Fixes #974 when used in conjunction with Python 3.10.

Reviewed other uses of TemporaryDirectory in ocrmypdf and decided it
was not worth fixing them since neither are exactly production code.

docs/release_notes.rst

@@ -18,6 +18,13 @@ tagged yet.
 
 .. |OCRmyPDF PyPI| image:: https://img.shields.io/pypi/v/ocrmypdf.svg
 
+v13.4.7
+=======
+
+-  Fixed PermissionError when cleaning up temporary files in rare cases. :issue:`974`
+-  Fixed PermissionError when calling ``os.nice`` on platforms that lack it. :issue:`973`
+-  Suppressed some warnings from libxmp during tests.
+
 v13.4.6
 =======
 

src/ocrmypdf/__main__.py

@@ -10,6 +10,7 @@ import logging
 import os
 import signal
 import sys
+from contextlib import suppress
 from multiprocessing import set_start_method
 
 from ocrmypdf import __version__
@@ -34,7 +35,7 @@ def sigbus(*args):
 def run(args=None):
     _parser, options, plugin_manager = get_parser_options_plugins(args=args)
 
-    if hasattr(os, 'nice'):
+    with suppress(AttributeError, PermissionError):
         os.nice(5)
 
     verbosity = options.verbose

src/ocrmypdf/_exec/unpaper.py

@@ -13,11 +13,11 @@
 import logging
 import os
 import shlex
+import sys
 from contextlib import contextmanager
 from decimal import Decimal
 from pathlib import Path
 from subprocess import PIPE, STDOUT
-from tempfile import TemporaryDirectory
 from typing import Iterator, List, Optional, Tuple, Union
 
 from PIL import Image
@@ -25,6 +25,23 @@ from PIL import Image
 from ocrmypdf.exceptions import MissingDependencyError, SubprocessOutputError
 from ocrmypdf.subprocess import get_version, run
 
+if sys.version_info >= (3, 10):
+    from tempfile import TemporaryDirectory
+else:
+    from tempfile import TemporaryDirectory as _TemporaryDirectory
+
+    # Consume the ignore_cleanup_errors kwarg in Python 3.9 and older, without acting
+    # on this keyword. Users who need this issue full resolved should upgrade to Python
+    # 3.10.
+    # See: https://github.com/python/cpython/pull/24793
+
+    class TemporaryDirectory(_TemporaryDirectory):
+        def __init__(self, ignore_cleanup_errors=False, **kwargs):
+            super().__init__(**kwargs)
+
+    del _TemporaryDirectory
+
+
 UNPAPER_IMAGE_PIXEL_LIMIT = 256 * 1024 * 1024
 
 DecFloat = Union[Decimal, float]
@@ -82,7 +99,7 @@ def _setup_unpaper_io(input_file: Path) -> Iterator[Tuple[Path, Path, Path]]:
             raise UnpaperImageTooLargeError(w=im.width, h=im.height)
         im, im_modified, suffix = _convert_image(im)
 
-        with TemporaryDirectory() as tmpdir:
+        with TemporaryDirectory(ignore_cleanup_errors=True) as tmpdir:
             tmppath = Path(tmpdir)
             if im_modified or input_file.suffix != '.pnm':
                 input_pnm = tmppath / 'input.pnm'

tests/test_metadata.py

@@ -6,10 +6,10 @@
 
 
 import datetime
+import warnings
 from datetime import timezone
 from os import fspath
 from shutil import copyfile
-from unittest.mock import patch
 
 import pikepdf
 import pytest
@@ -173,6 +173,19 @@ def test_creation_date_preserved(output_type, resources, infile, outpdf):
     assert seconds_between_dates(date_after, datetime.datetime.now(timezone.utc)) < 1000
 
 
+@pytest.fixture
+def libxmp_file_to_dict():
+    try:
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore", DeprecationWarning)
+            from libxmp.utils import (
+                file_to_dict,  # pylint: disable=import-outside-toplevel
+            )
+    except Exception:  # pylint: disable=broad-except
+        pytest.skip("libxmp not available or libexempi3 not installed")
+    return file_to_dict
+
+
 @pytest.mark.parametrize(
     'test_file,output_type',
     [
@@ -182,15 +195,12 @@ def test_creation_date_preserved(output_type, resources, infile, outpdf):
         ('3small.pdf', 'pdfa'),
     ],
 )
-def test_xml_metadata_preserved(test_file, output_type, resources, outpdf):
+def test_xml_metadata_preserved(
+    libxmp_file_to_dict, test_file, output_type, resources, outpdf
+):
     input_file = resources / test_file
 
-    try:
+    before = libxmp_file_to_dict(str(input_file))
-        from libxmp.utils import file_to_dict  # pylint: disable=import-outside-toplevel
-    except Exception:  # pylint: disable=broad-except
-        pytest.skip("libxmp not available or libexempi3 not installed")
-
-    before = file_to_dict(str(input_file))
 
     check_ocrmypdf(
         input_file,
@@ -202,7 +212,7 @@ def test_xml_metadata_preserved(test_file, output_type, resources, outpdf):
         'tests/plugins/tesseract_noop.py',
     )
 
-    after = file_to_dict(str(outpdf))
+    after = libxmp_file_to_dict(str(outpdf))
 
     equal_properties = [
         'dc:contributor',