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gh-79459 tempfile: Raise a ValueError if the prefix or suffix contains a directory component. #150477

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gh-79459 tempfile: Raise a ValueError if the prefix or suffix contains a directory component. #150477

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tempfile:
mbyrnepr2 May 26, 2026
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mbyrnepr2 May 26, 2026
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4 changes: 4 additions & 0 deletions Lib/tempfile.py
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Original file line number Diff line number Diff line change
Expand Up @@ -117,11 +117,15 @@ def _sanitize_params(prefix, suffix, dir):
output_type = _infer_return_type(prefix, suffix, dir)
if suffix is None:
suffix = output_type()
if _os.path.dirname(suffix):
raise ValueError("'suffix' can't contain a directory component")
if prefix is None:
if output_type is str:
prefix = template
else:
prefix = _os.fsencode(template)
if _os.path.dirname(prefix):
raise ValueError("'prefix' can't contain a directory component")
if dir is None:
if output_type is str:
dir = gettempdir()
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44 changes: 44 additions & 0 deletions Lib/test/test_tempfile.py
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Expand Up @@ -2054,5 +2054,49 @@ def test_delete_false(self):
self.assertTrue(os.path.exists(working_dir))
shutil.rmtree(working_dir)


class TestPrefixAndSuffix(BaseTestCase):
DATA = (
f"dir{os.sep}name",
f"{os.sep}abs_name",
os.fsencode(f"dir{os.sep}name"),
os.fsencode(f"{os.sep}abs_name"),
)
if os.altsep is not None:
DATA += (
f"dir{os.altsep}name",
f"{os.altsep}abs_name",
os.fsencode(f"dir{os.altsep}name"),
os.fsencode(f"{os.altsep}abs_name"),
)

def test_prefix_error(self):
MESSAGE = "'prefix' can't contain a directory component"

for value in self.DATA:
with self.subTest((value)):
with self.assertRaisesRegex(ValueError, MESSAGE):
tempfile.mkstemp(prefix=value)
with self.assertRaisesRegex(ValueError, MESSAGE):
os.rmdir(tempfile.mkdtemp(prefix=value))
with self.assertRaisesRegex(ValueError, MESSAGE):
tempfile.TemporaryFile(prefix=value)
with self.assertRaisesRegex(ValueError, MESSAGE):
tempfile.NamedTemporaryFile(prefix=value)

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@vstinner vstinner May 26, 2026

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You should test all functions taking prefix/suffix arguments:

  • mkstemp()
  • mkdtemp()
  • NamedTemporaryFile()
  • TemporaryFile()

Write one test for prefix and a second test for the suffix.

def test_suffix_error(self):
MESSAGE = "'suffix' can't contain a directory component"

for value in self.DATA:
with self.subTest((value)):
with self.assertRaisesRegex(ValueError, MESSAGE):
tempfile.mkstemp(suffix=value)
with self.assertRaisesRegex(ValueError, MESSAGE):
os.rmdir(tempfile.mkdtemp(suffix=value))
with self.assertRaisesRegex(ValueError, MESSAGE):
tempfile.TemporaryFile(suffix=value)
with self.assertRaisesRegex(ValueError, MESSAGE):
tempfile.NamedTemporaryFile(suffix=value)

if __name__ == "__main__":
unittest.main()
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