[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 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. (cherry picked from commit e730ae7) Co-authored-by: Kevin Mehall <km@kevinmehall.net>
serhiy-storchaka
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Mar 20, 2022
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@kevinmehall and @serhiy-storchaka: Status check is done, and it's a success ✅ . |
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The
_SharedFiletracks its own virtual position into the file asself._posand updates it after reading or seeking.tell()shouldreturn this position instead of calling into the underlying file object,
since if multiple
_SharedFileinstances are being used concurrently onthe same file, another one may have moved the real file position.
Additionally, calling into the underlying
tellmay 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 km@kevinmehall.net
https://bugs.python.org/issue42369