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Fixed Python errors when saving a (0, 0) TIFF image #5750

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merged 1 commit into from Oct 13, 2021
Merged

Fixed Python errors when saving a (0, 0) TIFF image #5750

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7 changes: 7 additions & 0 deletions Tests/test_file_libtiff.py
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Expand Up @@ -986,3 +986,10 @@ def test_save_multistrip(self, compression, tmp_path):
with Image.open(out) as im:
# Assert that there are multiple strips
assert len(im.tag_v2[STRIPOFFSETS]) > 1

@pytest.mark.parametrize("compression", ("tiff_adobe_deflate", None))
def test_save_zero(self, compression, tmp_path):
im = Image.new("RGB", (0, 0))
out = str(tmp_path / "temp.tif")
with pytest.raises(SystemError):
im.save(out, compression=compression)
8 changes: 6 additions & 2 deletions src/PIL/TiffImagePlugin.py
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Expand Up @@ -1619,13 +1619,17 @@ def _save(im, fp, filename):
stride = len(bits) * ((im.size[0] * bits[0] + 7) // 8)
# aim for 64 KB strips when using libtiff writer
if libtiff:
rows_per_strip = min((2 ** 16 + stride - 1) // stride, im.size[1])
rows_per_strip = (
1 if stride == 0 else min((2 ** 16 + stride - 1) // stride, im.size[1])
)
# JPEG encoder expects multiple of 8 rows
if compression == "jpeg":
rows_per_strip = min(((rows_per_strip + 7) // 8) * 8, im.size[1])
else:
rows_per_strip = im.size[1]
strip_byte_counts = stride * rows_per_strip
if rows_per_strip == 0:
rows_per_strip = 1
strip_byte_counts = 1 if stride == 0 else stride * rows_per_strip
strips_per_image = (im.size[1] + rows_per_strip - 1) // rows_per_strip
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Why not just handle the problematic division instead, is it not enough?

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I set rows_per_strip to 1 since I presume that setting ROWSPERSTRIP to zero is not ideal.

I set strip_byte_counts to 1 since it is used in range later, and can't be zero.

ifd[ROWSPERSTRIP] = rows_per_strip
if strip_byte_counts >= 2 ** 16:
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