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Merge pull request #8560 from Knio/tom/bufferedio

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Fix file position desync when calling into libtiff
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Andrew Murray 2024-11-29 13:37:33 +11:00 committed by GitHub
commit 1c152258c3
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2 changed files with 28 additions and 8 deletions
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19
Tests/test_file_libtiff.py
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@ -1098,6 +1098,25 @@ class TestFileLibTiff(LibTiffTestCase):
assert_image_similar(base_im, im, 0.7) assert_image_similar(base_im, im, 0.7)
@pytest.mark.parametrize(
"test_file",
[
"Tests/images/old-style-jpeg-compression-no-samplesperpixel.tif",
"Tests/images/old-style-jpeg-compression.tif",
],
)
def test_buffering(self, test_file: str) -> None:
# load exif first
with Image.open(open(test_file, "rb", buffering=1048576)) as im:
exif = dict(im.getexif())
# load image before exif
with Image.open(open(test_file, "rb", buffering=1048576)) as im2:
im2.load()
exif_after_load = dict(im2.getexif())
assert exif == exif_after_load
@pytest.mark.valgrind_known_error(reason="Backtrace in Python Core") @pytest.mark.valgrind_known_error(reason="Backtrace in Python Core")
def test_sampleformat_not_corrupted(self) -> None: def test_sampleformat_not_corrupted(self) -> None:
# Assert that a TIFF image with SampleFormat=UINT tag is not corrupted # Assert that a TIFF image with SampleFormat=UINT tag is not corrupted

17
src/PIL/TiffImagePlugin.py
View File

@ -1216,10 +1216,6 @@ class TiffImageFile(ImageFile.ImageFile):
def _seek(self, frame: int) -> None: def _seek(self, frame: int) -> None:
self.fp = self._fp self.fp = self._fp
# reset buffered io handle in case fp
# was passed to libtiff, invalidating the buffer
self.fp.tell()
while len(self._frame_pos) <= frame: while len(self._frame_pos) <= frame:
if not self.__next: if not self.__next:
msg = "no more images in TIFF file" msg = "no more images in TIFF file"
@ -1303,10 +1299,6 @@ class TiffImageFile(ImageFile.ImageFile):
if not self.is_animated: if not self.is_animated:
self._close_exclusive_fp_after_loading = True self._close_exclusive_fp_after_loading = True
# reset buffered io handle in case fp
# was passed to libtiff, invalidating the buffer
self.fp.tell()
# load IFD data from fp before it is closed # load IFD data from fp before it is closed
exif = self.getexif() exif = self.getexif()
for key in TiffTags.TAGS_V2_GROUPS: for key in TiffTags.TAGS_V2_GROUPS:
@ -1381,8 +1373,17 @@ class TiffImageFile(ImageFile.ImageFile):
logger.debug("have fileno, calling fileno version of the decoder.") logger.debug("have fileno, calling fileno version of the decoder.")
if not close_self_fp: if not close_self_fp:
self.fp.seek(0) self.fp.seek(0)
# Save and restore the file position, because libtiff will move it
# outside of the Python runtime, and that will confuse
# io.BufferedReader and possible others.
# NOTE: This must use os.lseek(), and not fp.tell()/fp.seek(),
# because the buffer read head already may not equal the actual
# file position, and fp.seek() may just adjust it's internal
# pointer and not actually seek the OS file handle.
pos = os.lseek(fp, 0, os.SEEK_CUR)
# 4 bytes, otherwise the trace might error out # 4 bytes, otherwise the trace might error out
n, err = decoder.decode(b"fpfp") n, err = decoder.decode(b"fpfp")
os.lseek(fp, pos, os.SEEK_SET)
else: else:
# we have something else. # we have something else.
logger.debug("don't have fileno or getvalue. just reading") logger.debug("don't have fileno or getvalue. just reading")