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feat(core)!: report ZIP entries whose xl extra field gives another file type than the central attributes - #689
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…le type than the central attributes A local or central xl (0x6c78) extra field overrides the entry type for libarchive readers, so an entry listed as a regular file could be written as a symlink or directory by a reader that honours the field. verify, list and extract now reject such archives under Enforce with ZipInconsistency::XlTypeDivergence, derived with the reader's own precedence (local over central) and final-name rules. BREAKING CHANGE: ZIP archives carrying an xl extra whose type differs from the central attributes are rejected under Enforce.
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This was referenced Oct 21, 2026
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Summary
libarchive honours the `xl` (0x6c78) extra field of a local header, and of a central record when it reads from a seekable file. Such a field can turn an entry that the central directory lists as a regular file into a symlink or a directory, so `verify` passed archives that `bsdtar` extracts differently.
`verify`, `list` and `extract` now reject these archives under `Enforce` with `ZipInconsistency::XlTypeDivergence` (category `HiddenEntry`):
Live checks with bsdtar 3.5.3 on a file and on a real pipe: a local `xl` symlink is applied by both readers, a central `xl` link or directory only by the file reader. All three are rejected. The 21-archive ZIP corpus and real symlink archives still pass. Measured cost on a 10000-entry archive: list +1.6%, verify +2.8%.
`skills/exarch-cli/SKILL.md` and spec 017 are updated.
Closes #686