[xmutantson]

A FATX directory entry holds names of up to 42 bytes (FATX_MAX_FILENAME_LEN), but fatx_create_dirent() and fatx_rename() rejected names with strlen(...) >= FATX_MAX_FILENAME_LEN, so the maximum was effectively 41. Retail games ship files whose names are exactly 42 characters (for example 10_Good_Epilogue_Comp_Sisterkilled_PAL.xmv in Fable, and over a hundred in Tony Hawk's American Wasteland's data/animsaves), and copying them with fatxfs fails with Operation not permitted.

The in-memory buffers (struct fatx_dirent, struct fatx_attr) are FATX_MAX_FILENAME_LEN + 1 bytes, and the on-disk field is FATX_MAX_FILENAME_LEN bytes with the length stored in filename_len, so a 42-character name already fits everywhere it is copied; only the three checks change from >= to >.

Added test_filename_max_length to pyfatx/tests/test.py: create, read, list and rename a 42-character name, and check that 43 characters is still refused. It fails on master and passes with this change; the rest of the suite passes either way.

This is independent of #106; both append a test to the end of test.py, so whichever lands second may need a trivial rebase.

[Copilot]

🟢 Approval recommended

There are no active review issues for the change enabling FATX’s full 42-byte filename capacity.

No open issues 🎉

What changed in this PR

Fixes an off-by-one limit in libfatx so file creation and renaming accept the full 42-byte filename capacity supported by FATX.

Changes:

• Allow names exactly FATX_MAX_FILENAME_LEN bytes long while retaining rejection of longer names.
• Add regression coverage for creating, reading, listing, and renaming 42-character names, plus rejecting 43-character names during creation.

File	Description
pyfatx/​tests/​test.py	Adds filename-length boundary regression coverage.
libfatx/​fatx_file.c	Allows 42-byte source and destination basenames during rename.
libfatx/​fatx_dir.c	Allows 42-byte basenames when creating directory entries.

_{Review effort: Balanced}

[mborgerson]

Thanks!