McRogueFace/tests/fuzz/fuzz_fov.py

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Add native libFuzzer fuzz harness for Python API, addresses #283 Pivots away from atheris (which lacks Python 3.14 support) to a single libFuzzer-linked executable that embeds CPython, registers mcrfpy, and dispatches each iteration to a Python fuzz_one_input(data: bytes) function loaded from tests/fuzz/fuzz_<target>.py by MCRF_FUZZ_TARGET env var. libFuzzer instruments the C++ engine code where all #258-#278 bugs live; Python drives the fuzzing logic via an in-house ByteStream replacement for atheris.FuzzedDataProvider. Python-level exceptions are caught; only ASan/UBSan signal real bugs. CMake - MCRF_FUZZER=ON builds mcrfpy_fuzz from all src/*.cpp except main.cpp plus tests/fuzz/fuzz_common.cpp, linked with -fsanitize=fuzzer,address, undefined. Asset+lib post-build copy added so the embedded interpreter finds its stdlib and default_font/default_texture load. Makefile - fuzz-build builds only mcrfpy_fuzz (fast iterate) - fuzz loops over six targets setting MCRF_FUZZ_TARGET for each - fuzz-long TARGET=x SECONDS=n for deep manual runs - fuzz-repro TARGET=x CRASH=path for crash reproduction - Shared ASAN_OPTIONS / PYTHONHOME env via FUZZ_ENV define tests/fuzz - fuzz_common.cpp: LLVMFuzzerInitialize bootstraps Python, imports target, resolves fuzz_one_input. LLVMFuzzerTestOneInput wraps bytes as PyBytes, calls target, swallows Python errors. - fuzz_common.py: ByteStream byte consumer + safe_reset() + EXPECTED_EXCEPTIONS - Six target stubs (grid_entity, property_types, anim_timer_scene, maps_procgen, fov, pathfinding_behavior) to be fleshed out in follow-up - README with build/run/triage instructions Verified end-to-end: make fuzz-build produces build-fuzz/mcrfpy_fuzz, make fuzz FUZZ_SECONDS=3 ran all six targets (~2400-9800 exec/s each, 667-1883 coverage edges), make fuzz-repro loaded and replayed a corpus input cleanly. No crashes from the stubs. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-04-10 11:05:04 -04:00
"""fuzz_fov - stub. Wave 2 agent W8 will implement.
Target: grid.compute_fov() with random origin/radius/algorithm, toggling
grid.at(x,y).transparent mid-run, grid.is_in_fov() queries on invalid coords.
Contract: define fuzz_one_input(data: bytes) -> None.
"""
import mcrfpy
from fuzz_common import ByteStream, EXPECTED_EXCEPTIONS
def fuzz_one_input(data):
stream = ByteStream(data)
try:
g = mcrfpy.Grid(grid_size=(8, 8))
g.compute_fov((0, 0), radius=3)
except EXPECTED_EXCEPTIONS:
pass