mirror of
https://github.com/Druthulu/BFM-decomp
synced 2026-09-27 22:45:39 -04:00
Drew T
de7f015436
Reusable iso9660.py (Phase 2 foundation) + extract_exe.py with --list and --verify-disc. Adversarially verified: extracted EXE SHA1 143dbb89f34491258bbc27810d0a12ec8b43a8dd (413696 B), and --verify-disc confirms Track-1 SHA1 b44f0f0a19936f23b26188b658e13201a6a9c211 == redump (dump is canonical).
71 lines
3.1 KiB
Markdown
71 lines
3.1 KiB
Markdown
# bfm_extract — disc extraction tooling
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Phase 1 tooling for the Brave Fencer Musashi (PS1, SLUS-00726 USA)
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decompilation. It reads the game's MODE2/2352 data track, walks the ISO9660
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file system, and extracts + validates the main executable `SLUS_007.26`.
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## What's here
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- **`iso9660.py`** — the reusable core. `Iso9660Image` opens a raw MODE2/2352
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BIN data track, reads logical sectors (the 2048 user-data bytes at +24 inside
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each 2352-byte sector), parses the Primary Volume Descriptor and root
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directory (multi-sector directories handled generally), and exposes
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`list_files()`, `find(name)`, `extract_file(name)`, and lower-level
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`read_sector` / `read_extent`. It knows nothing about any specific file — it
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is the foundation Phase 2 will extend with the .CD / PAC / LZSS pipeline.
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- **`extract_exe.py`** — Phase 1 CLI. Locates `SLUS_007.26` via the ISO walk
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(not a hardcoded offset), writes it verbatim (PS-EXE header included, because
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`ghidra_psx_ldr` reads that header), validates the magic + five header fields
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+ the exact `0x65000` size, and prints a PASS/FAIL report with the SHA1. Also
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offers `--verify-disc`, which hashes the entire Track-1 BIN and compares it to
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redump's published values to confirm the dump is canonical.
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## Usage
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The project is **all-in-WSL** (Linux-first): everything runs inside WSL2 Ubuntu
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on a single ext4 clone. The tool is stdlib-only and OS-portable — invoke it with
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`python3` on Linux/WSL (and with `python` on a Windows host; the two behave
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identically). Run from the repo root:
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```sh
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# Extract + validate using the default dump path and gitignored output path
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python3 tools/bfm_extract/extract_exe.py
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# List the 27 root-directory entries (LBA / size / name) and exit
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python3 tools/bfm_extract/extract_exe.py --list
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# Verify the dump is the canonical redump dump (streams the whole ~348 MB BIN;
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# checks Track-1 SHA1 + CRC32) and exit
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python3 tools/bfm_extract/extract_exe.py --verify-disc
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# Override the input track and/or output path
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python3 tools/bfm_extract/extract_exe.py \
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--bin "Brave Fencer Musashi (USA)/Brave Fencer Musashi (USA) (Track 1).bin" \
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--out extracted/SLUS_007.26
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```
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The CLI exits nonzero on any validation failure, on a missing BIN, or on a BIN
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that is not shaped like a MODE2/2352 track.
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### `--verify-disc` — proving the dump is canonical
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`--verify-disc` computes the SHA1 and CRC32 of the **entire** Track-1 BIN
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(streamed in 1 MiB chunks, never loaded whole) and compares them against the
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redump-published values for SLUS-00726 (USA):
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- SHA1 `b44f0f0a19936f23b26188b658e13201a6a9c211`
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- CRC32 `c238191b`
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- reference build date `1998-08-25`
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A PASS means the local dump is byte-for-byte the canonical redump image, which
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transitively validates the extracted `SLUS_007.26` (whose own hash is not
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publicly documented). The extracted EXE's expected SHA1 is
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`143dbb89f34491258bbc27810d0a12ec8b43a8dd`.
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## Output is ROM-derived and gitignored
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The default output goes to `extracted/SLUS_007.26`. The `extracted/` directory
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is gitignored on purpose: it is derived from the game disc and must **never** be
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committed (see the ROM-content firewall in `PROJECT_CONTEXT.md`). Bring your own
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disc dump.
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