Pillow/Tests/test_file_mpo.py
Jon Dufresne 4cd4adddc3 Improve handling of file resources
Follow Python's file object semantics. User code is responsible for
closing resources (usually through a context manager) in a deterministic
way.

To achieve this, remove __del__ functions. These functions used to
closed open file handlers in an attempt to silence Python
ResourceWarnings. However, using __del__ has the following drawbacks:

- __del__ isn't called until the object's reference count reaches 0.
  Therefore, resource handlers remain open or in use longer than
  necessary.

- The __del__ method isn't guaranteed to execute on system exit. See the
  Python documentation:

  https://docs.python.org/3/reference/datamodel.html#object.__del__

  > It is not guaranteed that __del__() methods are called for objects
  > that still exist when the interpreter exits.

- Exceptions that occur inside __del__ are ignored instead of raised.
  This has the potential of hiding bugs. This is also in the Python
  documentation:

  > Warning: Due to the precarious circumstances under which __del__()
  > methods are invoked, exceptions that occur during their execution
  > are ignored, and a warning is printed to sys.stderr instead.

Instead, always close resource handlers when they are no longer in use.
This will close the file handler at a specified point in the user's code
and not wait until the interpreter chooses to. It is always guaranteed
to run. And, if an exception occurs while closing the file handler, the
bug will not be ignored.

Now, when code receives a ResourceWarning, it will highlight an area
that is mishandling resources. It should not simply be silenced, but
fixed by closing resources with a context manager.

All warnings that were emitted during tests have been cleaned up. To
enable warnings, I passed the `-Wa` CLI option to Python. This exposed
some mishandling of resources in ImageFile.__init__() and
SpiderImagePlugin.loadImageSeries(), they too were fixed.
2019-10-12 08:27:17 -07:00

195 lines
7.0 KiB
Python

import unittest
from io import BytesIO
from PIL import Image
from .helper import PillowTestCase, is_pypy
test_files = ["Tests/images/sugarshack.mpo", "Tests/images/frozenpond.mpo"]
class TestFileMpo(PillowTestCase):
def setUp(self):
codecs = dir(Image.core)
if "jpeg_encoder" not in codecs or "jpeg_decoder" not in codecs:
self.skipTest("jpeg support not available")
def frame_roundtrip(self, im, **options):
# Note that for now, there is no MPO saving functionality
out = BytesIO()
im.save(out, "MPO", **options)
test_bytes = out.tell()
out.seek(0)
im = Image.open(out)
im.bytes = test_bytes # for testing only
return im
def test_sanity(self):
for test_file in test_files:
with Image.open(test_file) as im:
im.load()
self.assertEqual(im.mode, "RGB")
self.assertEqual(im.size, (640, 480))
self.assertEqual(im.format, "MPO")
@unittest.skipIf(is_pypy(), "Requires CPython")
def test_unclosed_file(self):
def open():
im = Image.open(test_files[0])
im.load()
self.assert_warning(ResourceWarning, open)
def test_closed_file(self):
def open():
im = Image.open(test_files[0])
im.load()
im.close()
self.assert_warning(None, open)
def test_context_manager(self):
def open():
with Image.open(test_files[0]) as im:
im.load()
self.assert_warning(None, open)
def test_app(self):
for test_file in test_files:
# Test APP/COM reader (@PIL135)
with Image.open(test_file) as im:
self.assertEqual(im.applist[0][0], "APP1")
self.assertEqual(im.applist[1][0], "APP2")
self.assertEqual(
im.applist[1][1][:16],
b"MPF\x00MM\x00*\x00\x00\x00\x08\x00\x03\xb0\x00",
)
self.assertEqual(len(im.applist), 2)
def test_exif(self):
for test_file in test_files:
with Image.open(test_file) as im:
info = im._getexif()
self.assertEqual(info[272], "Nintendo 3DS")
self.assertEqual(info[296], 2)
self.assertEqual(info[34665], 188)
def test_frame_size(self):
# This image has been hexedited to contain a different size
# in the EXIF data of the second frame
with Image.open("Tests/images/sugarshack_frame_size.mpo") as im:
self.assertEqual(im.size, (640, 480))
im.seek(1)
self.assertEqual(im.size, (680, 480))
def test_parallax(self):
# Nintendo
with Image.open("Tests/images/sugarshack.mpo") as im:
exif = im.getexif()
self.assertEqual(
exif.get_ifd(0x927C)[0x1101]["Parallax"], -44.798187255859375
)
# Fujifilm
with Image.open("Tests/images/fujifilm.mpo") as im:
im.seek(1)
exif = im.getexif()
self.assertEqual(exif.get_ifd(0x927C)[0xB211], -3.125)
def test_mp(self):
for test_file in test_files:
with Image.open(test_file) as im:
mpinfo = im._getmp()
self.assertEqual(mpinfo[45056], b"0100")
self.assertEqual(mpinfo[45057], 2)
def test_mp_offset(self):
# This image has been manually hexedited to have an IFD offset of 10
# in APP2 data, in contrast to normal 8
with Image.open("Tests/images/sugarshack_ifd_offset.mpo") as im:
mpinfo = im._getmp()
self.assertEqual(mpinfo[45056], b"0100")
self.assertEqual(mpinfo[45057], 2)
def test_mp_attribute(self):
for test_file in test_files:
with Image.open(test_file) as im:
mpinfo = im._getmp()
frameNumber = 0
for mpentry in mpinfo[45058]:
mpattr = mpentry["Attribute"]
if frameNumber:
self.assertFalse(mpattr["RepresentativeImageFlag"])
else:
self.assertTrue(mpattr["RepresentativeImageFlag"])
self.assertFalse(mpattr["DependentParentImageFlag"])
self.assertFalse(mpattr["DependentChildImageFlag"])
self.assertEqual(mpattr["ImageDataFormat"], "JPEG")
self.assertEqual(mpattr["MPType"], "Multi-Frame Image: (Disparity)")
self.assertEqual(mpattr["Reserved"], 0)
frameNumber += 1
def test_seek(self):
for test_file in test_files:
with Image.open(test_file) as im:
self.assertEqual(im.tell(), 0)
# prior to first image raises an error, both blatant and borderline
self.assertRaises(EOFError, im.seek, -1)
self.assertRaises(EOFError, im.seek, -523)
# after the final image raises an error,
# both blatant and borderline
self.assertRaises(EOFError, im.seek, 2)
self.assertRaises(EOFError, im.seek, 523)
# bad calls shouldn't change the frame
self.assertEqual(im.tell(), 0)
# this one will work
im.seek(1)
self.assertEqual(im.tell(), 1)
# and this one, too
im.seek(0)
self.assertEqual(im.tell(), 0)
def test_n_frames(self):
with Image.open("Tests/images/sugarshack.mpo") as im:
self.assertEqual(im.n_frames, 2)
self.assertTrue(im.is_animated)
def test_eoferror(self):
with Image.open("Tests/images/sugarshack.mpo") as im:
n_frames = im.n_frames
# Test seeking past the last frame
self.assertRaises(EOFError, im.seek, n_frames)
self.assertLess(im.tell(), n_frames)
# Test that seeking to the last frame does not raise an error
im.seek(n_frames - 1)
def test_image_grab(self):
for test_file in test_files:
with Image.open(test_file) as im:
self.assertEqual(im.tell(), 0)
im0 = im.tobytes()
im.seek(1)
self.assertEqual(im.tell(), 1)
im1 = im.tobytes()
im.seek(0)
self.assertEqual(im.tell(), 0)
im02 = im.tobytes()
self.assertEqual(im0, im02)
self.assertNotEqual(im0, im1)
def test_save(self):
# Note that only individual frames can be saved at present
for test_file in test_files:
with Image.open(test_file) as im:
self.assertEqual(im.tell(), 0)
jpg0 = self.frame_roundtrip(im)
self.assert_image_similar(im, jpg0, 30)
im.seek(1)
self.assertEqual(im.tell(), 1)
jpg1 = self.frame_roundtrip(im)
self.assert_image_similar(im, jpg1, 30)