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| author | Kevin Mehall <km@kevinmehall.net> | 2022-03-20 08:26:09 -0600 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2022-03-20 16:26:09 +0200 |
| commit | e730ae7effe4f13b24f1b5fb1fca005709c86acb (patch) | |
| tree | b0391ac70889fdde5ce0f2ec8de7acfa1cebb5c1 /Lib/zipfile.py | |
| parent | 3af68fc77c528d4e7749046cf6e41fd79902e6e6 (diff) | |
| download | cpython-git-e730ae7effe4f13b24f1b5fb1fca005709c86acb.tar.gz | |
bpo-42369: Fix thread safety of zipfile._SharedFile.tell (GH-26974)
The `_SharedFile` tracks its own virtual position into the file as
`self._pos` and updates it after reading or seeking. `tell()` should
return this position instead of calling into the underlying file object,
since if multiple `_SharedFile` instances are being used concurrently on
the same file, another one may have moved the real file position.
Additionally, calling into the underlying `tell` may expose thread
safety issues in the underlying file object because it was called
without taking the lock.
Diffstat (limited to 'Lib/zipfile.py')
| -rw-r--r-- | Lib/zipfile.py | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/Lib/zipfile.py b/Lib/zipfile.py index 41bf49a8fe..385adc8973 100644 --- a/Lib/zipfile.py +++ b/Lib/zipfile.py @@ -747,7 +747,9 @@ class _SharedFile: self._lock = lock self._writing = writing self.seekable = file.seekable - self.tell = file.tell + + def tell(self): + return self._pos def seek(self, offset, whence=0): with self._lock: |