Skip to content

gh-124293: Fix tar stream seekability checks #159854

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

Open
limadog9 wants to merge 1 commit into
base: main
Choose a base branch
from
+16 −8
Open

gh-124293: Fix tar stream seekability checks #159854

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
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
3 changes: 3 additions & 0 deletions Lib/tarfile.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -543,6 +543,9 @@ def tell(self):
"""
return self.pos

def seekable(self):
return True

def seek(self, pos=0):
"""Set the stream's file pointer to pos. Negative seeking
is forbidden.
Expand Down
19 changes: 11 additions & 8 deletions Lib/test/test_tarfile.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -547,21 +547,15 @@ def test_extractfile_attrs(self):
self.assertEqual(fobj.mode, 'rb')
self.assertIs(fobj.readable(), True)
self.assertIs(fobj.writable(), False)
if self.is_stream:
self.assertRaises(AttributeError, fobj.seekable)
else:
self.assertIs(fobj.seekable(), True)
self.assertIs(fobj.seekable(), True)
self.assertIs(fobj.closed, False)
self.assertIs(fobj.closed, True)
self.assertEqual(fobj.name, 'ustar/regtype')
self.assertRaises(AttributeError, fobj.fileno)
self.assertEqual(fobj.mode, 'rb')
self.assertIs(fobj.readable(), True)
self.assertIs(fobj.writable(), False)
if self.is_stream:
self.assertRaises(AttributeError, fobj.seekable)
else:
self.assertIs(fobj.seekable(), True)
self.assertIs(fobj.seekable(), True)


class ReadSizeRecorder(io.BytesIO):
Expand Down Expand Up @@ -1003,6 +997,15 @@ class StreamReadTest(CommonReadTest, unittest.TestCase):
prefix="r|"
is_stream = True

def test_extractfile_seek_forward(self):
tarinfo = self.tar.next()
with tarfile.open(tarname) as reference:
expected = reference.extractfile(tarinfo.name).read()
with self.tar.extractfile(tarinfo) as file:
self.assertIs(file.seekable(), True)
self.assertEqual(file.seek(10), 10)
self.assertEqual(file.read(20), expected[10:30])

def test_read_through(self):
# Issue #11224: A poorly designed _FileInFile.read() method
# caused seeking errors with stream tar files.
Expand Down
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2026-10-20-04-10-00.gh-issue-124293.K9sW3e.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Fix :exc:`AttributeError` from ``seekable()`` and forward ``seek()`` calls on
file objects returned by :meth:`tarfile.TarFile.extractfile` in stream modes.
Loading