gh-154842: Reject repack() while a reading handle is open - #154843
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serhiy-storchaka merged 2 commits intoAug 16, 2026
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ZipFile.repack() moves member data, but a ZipExtFile from an earlier open() keeps its own absolute position, so it silently returned data from the wrong place and a full read failed with a misleading CRC error. Raise ValueError while _fileRefCnt shows an open reading handle, as the writing-handle case already does.
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66 files changed ·
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| raise ValueError( | ||
| "Can't write to ZIP archive while an open writing handle exists" | ||
| ) | ||
| if self._fileRefCnt > 1: |
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Would not it be better to move all two (or even three) checks into the with self._lock block?
And maybe harmonize or consolidate the two last errors? Something like "Can't repack ZIP archive while an open handle exists".
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Both done, thanks.
The fp/_writing/_fileRefCnt checks guarded state that repack() then mutates inside `with self._lock`, so the check and the `_writing = True` it gates were not atomic. Move them into the lock. The writing-handle and reading-handle errors describe the same condition, so state it once.
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ZipFile.repack()moves member data to lower offsets, but aZipExtFilefrom an earlieropen()keeps its own absolute position, so it silently returned data from the wrong place and a full read failed withBadZipFile: Bad CRC-32. RaiseValueErrorwhile an open reading handle exists, as the writing-handle case already does.The test fails without the guard.
repack()is new in 3.16, so no NEWS entry.