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PdfParser: Don't use list as def in read_prev_trailer

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It's not recommended to use the empty list as default value in functions
or methods because Python interpreter evaluates during parsing, so it
will be the same list for different calls.

https://pylint.pycqa.org/en/latest/user_guide/messages/warning/dangerous-default-value.html
This commit is contained in:
Daniel Garcia Moreno 2026-05-13 11:14:41 +02:00
parent 9289863c2c
commit 78ee80a6fd
1 changed files with 3 additions and 1 deletions
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4
src/PIL/PdfParser.py
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@ -692,7 +692,7 @@ class PdfParser:
self.read_prev_trailer(self.trailer_dict[b"Prev"])
def read_prev_trailer(
self, xref_section_offset: int, processed_offsets: list[int] = []
self, xref_section_offset: int, processed_offsets: list[int] = None
) -> None:
assert self.buf is not None
trailer_offset = self.read_xref_table(xref_section_offset=xref_section_offset)
@ -708,6 +708,8 @@ class PdfParser:
)
trailer_dict = self.interpret_trailer(trailer_data)
if b"Prev" in trailer_dict:
if processed_offsets is None:
processed_offsets = []
processed_offsets.append(xref_section_offset)
check_format_condition(
trailer_dict[b"Prev"] not in processed_offsets, "trailer loop found"