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Allow upgrading LONG to LONG8

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This commit is contained in:
Andrew Murray 2025-01-06 07:28:51 +11:00
parent 618339e2d2
commit a8381c619d
2 changed files with 50 additions and 15 deletions
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26
Tests/test_file_tiff.py
View File

@ -746,7 +746,7 @@ class TestFileTiff:
assert reread.n_frames == 3
def test_fixoffsets(self) -> None:
b = BytesIO(b"II\x2a\x00\x00\x00\x00\x00")
b = BytesIO(b"II\x2A\x00\x00\x00\x00\x00")
with TiffImagePlugin.AppendingTiffWriter(b) as a:
b.seek(0)
a.fixOffsets(1, isShort=True)
@ -759,6 +759,23 @@ class TestFileTiff:
with pytest.raises(RuntimeError):
a.fixOffsets(1)
b = BytesIO(b"II\x2A\x00\x00\x00\x00\x00")
with TiffImagePlugin.AppendingTiffWriter(b) as a:
a.offsetOfNewPage = 2**16
b.seek(0)
a.fixOffsets(1, isShort=True)
b = BytesIO(b"II\x2B\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00")
with TiffImagePlugin.AppendingTiffWriter(b) as a:
a.offsetOfNewPage = 2**32
b.seek(0)
a.fixOffsets(1, isShort=True)
b.seek(0)
a.fixOffsets(1, isLong=True)
def test_appending_tiff_writer_writelong(self) -> None:
data = b"II\x2A\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
b = BytesIO(data)
@ -766,6 +783,13 @@ class TestFileTiff:
a.writeLong(2**32 - 1)
assert b.getvalue() == data + b"\xff\xff\xff\xff"
def test_appending_tiff_writer_rewritelastshorttolong(self) -> None:
data = b"II\x2A\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
b = BytesIO(data)
with TiffImagePlugin.AppendingTiffWriter(b) as a:
a.rewriteLastShortToLong(2**32 - 1)
assert b.getvalue() == data[:-2] + b"\xff\xff\xff\xff"
def test_saving_icc_profile(self, tmp_path: Path) -> None:
# Tests saving TIFF with icc_profile set.
# At the time of writing this will only work for non-compressed tiffs

39
src/PIL/TiffImagePlugin.py
View File

@ -2175,17 +2175,19 @@ class AppendingTiffWriter(io.BytesIO):
msg = f"wrote only {bytes_written} bytes but wanted {expected}"
raise RuntimeError(msg)
def rewriteLastShortToLong(self, value: int) -> None:
self.f.seek(-2, os.SEEK_CUR)
bytes_written = self.f.write(struct.pack(self.longFmt, value))
self._verify_bytes_written(bytes_written, 4)
def _rewriteLast(self, value: int, field_size: int) -> None:
def _rewriteLast(
self, value: int, field_size: int, new_field_size: int = 0
) -> None:
self.f.seek(-field_size, os.SEEK_CUR)
if not new_field_size:
new_field_size = field_size
bytes_written = self.f.write(
struct.pack(self.endian + self._fmt(field_size), value)
struct.pack(self.endian + self._fmt(new_field_size), value)
)
self._verify_bytes_written(bytes_written, field_size)
self._verify_bytes_written(bytes_written, new_field_size)
def rewriteLastShortToLong(self, value: int) -> None:
self._rewriteLast(value, 2, 4)
def rewriteLastShort(self, value: int) -> None:
return self._rewriteLast(value, 2)
@ -2245,18 +2247,27 @@ class AppendingTiffWriter(io.BytesIO):
for i in range(count):
offset = self._read(field_size)
offset += self.offsetOfNewPage
if field_size == 2 and offset >= 65536:
# offset is now too large - we must convert shorts to longs
new_field_size = 0
if self._bigtiff and field_size in (2, 4) and offset >= 2**32:
# offset is now too large - we must convert long to long8
new_field_size = 8
elif field_size == 2 and offset >= 2**16:
# offset is now too large - we must convert short to long
new_field_size = 4
if new_field_size:
if count != 1:
msg = "not implemented"
raise RuntimeError(msg) # XXX TODO
# simple case - the offset is just one and therefore it is
# local (not referenced with another offset)
self.rewriteLastShortToLong(offset)
self.f.seek(-10, os.SEEK_CUR)
self.writeShort(TiffTags.LONG) # rewrite the type to LONG
self.f.seek(8, os.SEEK_CUR)
self._rewriteLast(offset, field_size, new_field_size)
# Move back past the new offset, past 'count', and before 'field_type'
rewind = -new_field_size - 4 - 2
self.f.seek(rewind, os.SEEK_CUR)
self.writeShort(new_field_size) # rewrite the type
self.f.seek(2 - rewind, os.SEEK_CUR)
else:
self._rewriteLast(offset, field_size)