Honor explicit NUP compression for .zs members #456

Merged

klimovich008 merged 1 commit from codex/nup-explicit-codec into main

2026-11-08 08:19:57 +00:00

klimovich008 commented

2026-11-08 03:45:06 +00:00

(Migrated from github.com)

What this fixes

Extracting a NUP can silently corrupt .zs textures while producing files of the expected size. This happens when the package compresses a member whose decoded payload is not another Zstd frame.

Why merge

Honor the explicit compression codec before guessing from the filename or payload.
Keep reads inside the stored extent and reject incomplete frames; retain the decoded-size check.
Preserve legacy compression detection and existing extraction paths.

Change

nx2/nup.py: read the codec byte, use it to select package decompression and enforce its stored extent.
nx2/test_nup_codec.py: check compressed .zs plaintext, raw game Zstd, legacy detection and a truncated extent.

Tested

python -I -B nx2/test_nup_codec.py exercises the actual constructor and copy routine using synthetic packages.
Fails on the old code, passes now.
Windows: a fresh extraction of 186,587 members has three incorrect hashes before the fix and zero afterward.
Existing source checks pass in Windows and Linux CI; the AppImage build passes.

Not covered

Existing same-size cached files are reused; extract into a fresh folder to repair them.
Runtime use of the three affected textures has not been tested.

No game data is included.

## What this fixes Extracting a NUP can silently corrupt `.zs` textures while producing files of the expected size. This happens when the package compresses a member whose decoded payload is not another Zstd frame. ## Why merge - Honor the explicit compression codec before guessing from the filename or payload. - Keep reads inside the stored extent and reject incomplete frames; retain the decoded-size check. - Preserve legacy compression detection and existing extraction paths. ## Change - `nx2/nup.py`: read the codec byte, use it to select package decompression and enforce its stored extent. - `nx2/test_nup_codec.py`: check compressed `.zs` plaintext, raw game Zstd, legacy detection and a truncated extent. ## Tested - `python -I -B nx2/test_nup_codec.py` exercises the actual constructor and copy routine using synthetic packages. - Fails on the old code, passes now. - Windows: a fresh extraction of 186,587 members has three incorrect hashes before the fix and zero afterward. - Existing source checks pass in Windows and Linux CI; the AppImage build passes. ## Not covered - Existing same-size cached files are reused; extract into a fresh folder to repair them. - Runtime use of the three affected textures has not been tested. No game data is included.

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