BIP-0327: avoid using sys.path[0] to find current working directory #2158

omipheo commented at 9:28 AM on May 14, 2026: contributor

Summary

bip-0327/reference.py and bip-0327/gen_vectors_helper.py both locate the test-vector JSON files via os.path.join(sys.path[0], 'vectors', '<file>.json'). As Sebastian Falbesoner noted in 4e18ee6 ("BIP-374: avoid using sys.path[0] to find current working directory"), this pattern is incompatible with any future sys.path.insert(0, ...) extension — for example, the sys.path.insert(0, str(Path(__file__).parent / "secp256k1lab/src")) shim that bip-0352 and bip-0374 use to locate their vendored secp256k1lab copies. Should bip-0327 follow the same vendoring pattern, every test-vector load would silently miss its file.

This PR switches both files to the Path(__file__).parent / 'vectors' / '...' pattern so the path is always resolved relative to the script itself, matching the BIP-374 precedent. import os and import sys are removed from reference.py (no remaining uses); gen_vectors_helper.py gets an explicit from pathlib import Path since it can no longer inherit those names through from reference import *.

Diff

Old call (×10 across 2 files)	New call
`os.path.join(sys.path[0], 'vectors', 'X.json')`	`Path(__file__).parent / 'vectors' / 'X.json'`

reference.py: 8 call sites (lines 499, 508, 532, 559, 577, 660, 717, 764). gen_vectors_helper.py: 2 call sites (lines 21, 49). Imports adjusted to match.

Verification

$ python3 bip-0327/reference.py
$ echo $?
0

$ python3 bip-0327/gen_vectors_helper.py > /dev/null
$ echo $?
0

Both scripts continue to exit 0 with all test vectors loading.

(Note: bash bip-0327/tests.sh exits non-zero on master too — current local mypy versions flag four pre-existing bytearray/bytes mismatches at reference.py:354,355,671,672 that are unrelated to this PR. CI is presumably pinned to an older mypy; the runtime tests themselves pass on both branches.)

Notes

Direct follow-up to 4e18ee6 ("BIP-374: avoid using sys.path[0]…"). Same shape, same justification, applied to the next reference implementation in the same family.
No behavior change beyond path-resolution robustness.

BIP-0327: avoid using sys.path[0] to find current working directory

`bip-0327/reference.py` and `bip-0327/gen_vectors_helper.py` both
locate the test-vector JSON files via
`os.path.join(sys.path[0], 'vectors', '<file>.json')`. As Sebastian
Falbesoner noted in 4e18ee6 ("BIP-374: avoid using sys.path[0] to
find current working directory"), this pattern is incompatible with
any future `sys.path.insert(0, ...)` extension — for example, the
`sys.path.insert(0, str(Path(__file__).parent / "secp256k1lab/src"))`
shim that bip-0352 and bip-0374 use to locate their vendored
`secp256k1lab` copies. Should bip-0327 follow the same vendoring
pattern, every test-vector load would silently miss its file.

Switch both files to the `Path(__file__).parent / 'vectors' / '...'`
pattern so the path is always resolved relative to the script
itself, matching the BIP-374 precedent. `import os` and `import sys`
are removed from `reference.py` (no remaining uses); `gen_vectors_helper.py`
gets an explicit `from pathlib import Path` since it can no longer
inherit those names through `from reference import *`.

Verified that `python3 reference.py` and `python3 gen_vectors_helper.py`
still exit 0 with all 8 (resp. 2) vector files loading correctly. No
behavior change beyond the path-resolution robustness.

86c52810c8

jonatack commented at 9:23 PM on May 14, 2026: member

ACK, it's a minor refactor but more idiomatic and robust and would serve as a better reference for developers.

jonatack commented at 9:29 PM on May 14, 2026: member

@omipheo note that BIPs 89, 328 and 340 also still use the same pattern. Maybe update them all here in one go.

BIPs 89, 328, 340: avoid using sys.path[0] to find current working directory

Same fix as the previous commit on BIP-0327, applied to the remaining
reference implementations that still use the
`os.path.join(sys.path[0], ...)` pattern: bip-0089/reference.py
(8 sites), bip-0328/reference.py (1 site), and bip-0340/reference.py
(1 site). All resolve test-vector paths via `Path(__file__).parent /
...` so future `sys.path.insert(0, ...)` extensions for vendored deps
won't silently miss the data files.

`import os` and `import sys` are dropped from each file (no remaining
uses). bip-0340/test-vectors.py imports `sys` itself for `sys.stdout`
so its wildcard `from reference import *` is unaffected by the
import cleanup in bip-0340/reference.py.

Verified: `python3 reference.py` for each of bip-0089, bip-0328,
bip-0340 still exits 0 with all test vectors loading; bip-0340's
test-vectors.py importer also still exits 0.

Per @jonatack's review note on PR #2158.

b39a896e28

omipheo commented at 11:46 PM on May 14, 2026: contributor

Done — pushed b39a896e28 extending the same fix to bip-0089/reference.py (8 sites), bip-0328/reference.py (1), and bip-0340/reference.py (1). Same pattern: os.path.join(sys.path[0], '...') → Path(__file__).parent / '...', with import os / import sys removed where they had no remaining uses.

Verified each script still runs clean:

$ for d in bip-0089 bip-0327 bip-0328 bip-0340; do (cd $d && python3 reference.py >/dev/null && echo "$d ok"); done
bip-0089 ok
bip-0327 ok
bip-0328 ok
bip-0340 ok

$ (cd bip-0327 && python3 gen_vectors_helper.py >/dev/null) && echo ok
ok

$ (cd bip-0340 && python3 test-vectors.py >/dev/null) && echo "test-vectors.py ok (wildcard importer of bip-0340/reference.py is unaffected by the os/sys removal — it imports sys itself for sys.stdout)"
test-vectors.py ok (wildcard importer of bip-0340/reference.py is unaffected by the os/sys removal — it imports sys itself for sys.stdout)

Happy to squash both commits into one if you'd prefer a single atomic change before merge.