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_ZipRepacker.repack() updates ZipInfo.header_offset for each member before moving that member's bytes, so a failing _copy_bytes() left the in-memory offsets describing a layout that was never written. remove() has already set _didModify, so a later close() committed a central directory built from those offsets, and the archive became unreadable even though the caller had handled the error. ZipFile.repack() now snapshots the offsets of the surviving and the removed entries and restores them if the repack raises. The copy only ever moves data to lower offsets, so a partial move never overwrites its own source and the archive falls back to the state of a remove() with no repack().
Restoring every offset after a failed repack() is wrong once an entry has been moved over its old position: the restored offset then points at overwritten data. Instead, set each entry's header_offset only after its bytes have been copied, so entries that finished moving or were never touched stay readable. This also drops the list(removed) copy, which was only needed because the rollback read removed a second time.
fedonman
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repack() failsrepack()
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_ZipRepacker.repack()set each entry'sheader_offsetbefore moving its bytes, so after a failed move a laterclose()wrote a central directory pointing at data that was never moved. Each offset is now set only after that entry has been moved, so entries that finished moving or were never touched stay readable.ZipFile.close()writes wrong offsets after a failedrepack()#156434