https://github.com/python/cpython/commit/e0ef08f5b444950ad9e900b27f5b5dbc706f4459
commit: e0ef08f5b444950ad9e900b27f5b5dbc706f4459
branch: main
author: Bénédikt Tran <[email protected]>
committer: jaraco <[email protected]>
date: 2024-11-24T11:36:15-05:00
summary:
gh-122356: restore the position of a file-like object after
`zipfile.is_zipfile` (#122397)
files:
A Misc/NEWS.d/next/Library/2024-07-29-15-20-30.gh-issue-122356.wKCmFx.rst
M Lib/test/test_zipfile/test_core.py
M Lib/zipfile/__init__.py
diff --git a/Lib/test/test_zipfile/test_core.py
b/Lib/test/test_zipfile/test_core.py
index 36f7f542872897..c36228c033a414 100644
--- a/Lib/test/test_zipfile/test_core.py
+++ b/Lib/test/test_zipfile/test_core.py
@@ -1969,10 +1969,16 @@ def test_is_zip_valid_file(self):
zip_contents = fp.read()
# - passing a file-like object
fp = io.BytesIO()
- fp.write(zip_contents)
+ end = fp.write(zip_contents)
+ self.assertEqual(fp.tell(), end)
+ mid = end // 2
+ fp.seek(mid, 0)
self.assertTrue(zipfile.is_zipfile(fp))
- fp.seek(0, 0)
+ # check that the position is left unchanged after the call
+ # see: https://github.com/python/cpython/issues/122356
+ self.assertEqual(fp.tell(), mid)
self.assertTrue(zipfile.is_zipfile(fp))
+ self.assertEqual(fp.tell(), mid)
def test_non_existent_file_raises_OSError(self):
# make sure we don't raise an AttributeError when a
partially-constructed
diff --git a/Lib/zipfile/__init__.py b/Lib/zipfile/__init__.py
index 08c83cfb760250..6907ae6d5b7464 100644
--- a/Lib/zipfile/__init__.py
+++ b/Lib/zipfile/__init__.py
@@ -241,7 +241,9 @@ def is_zipfile(filename):
result = False
try:
if hasattr(filename, "read"):
+ pos = filename.tell()
result = _check_zipfile(fp=filename)
+ filename.seek(pos)
else:
with open(filename, "rb") as fp:
result = _check_zipfile(fp)
diff --git
a/Misc/NEWS.d/next/Library/2024-07-29-15-20-30.gh-issue-122356.wKCmFx.rst
b/Misc/NEWS.d/next/Library/2024-07-29-15-20-30.gh-issue-122356.wKCmFx.rst
new file mode 100644
index 00000000000000..0a4632ca975f6b
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-07-29-15-20-30.gh-issue-122356.wKCmFx.rst
@@ -0,0 +1,3 @@
+Guarantee that the position of a file-like object passed to
+:func:`zipfile.is_zipfile` is left untouched after the call.
+Patch by Bénédikt Tran.
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