[3.9] bpo-42369: Fix thread safety of zipfile._SharedFile.tell (GH-26974) #32008
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The
_SharedFile
tracks its own virtual position into the file asself._pos
and updates it after reading or seeking.tell()
shouldreturn this position instead of calling into the underlying file object,
since if multiple
_SharedFile
instances are being used concurrently onthe same file, another one may have moved the real file position.
Additionally, calling into the underlying
tell
may expose threadsafety issues in the underlying file object because it was called
without taking the lock.
(cherry picked from commit e730ae7)
Co-authored-by: Kevin Mehall [email protected]
https://bugs.python.org/issue42369