Skip to content

gh-122356: restore the position of a file-like object after zipfile.is_zipfile #122397

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 4 commits into from
Nov 24, 2024
Merged

gh-122356: restore the position of a file-like object after zipfile.is_zipfile #122397

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
4989d50
Ensure that `zipfile.is_zipfile` does not modify a file object.
picnixz Jul 29, 2024
76a8e4a
add tests
picnixz Jul 29, 2024
ca77c4d
blurb
picnixz Jul 29, 2024
0410d36
Merge branch 'main' into feat-restore-pos-after-is-zipfile
picnixz Nov 15, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
10 changes: 8 additions & 2 deletions Lib/test/test_zipfile/test_core.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down
2 changes: 2 additions & 0 deletions Lib/zipfile/__init__.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -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)
Comment on lines +244 to +246
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I'm guessing that a user will never call is_zipfile on a non-seekable stream (e.g. a web response stream)... but if they did, this change would break those cases. Oh, I just checked, and the current check already relies on a seekable fp, so this change has no effect on that behavior.

else:
with open(filename, "rb") as fp:
result = _check_zipfile(fp)
Expand Down
3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Library/2024-07-29-15-20-30.gh-issue-122356.wKCmFx.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -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.
Loading