#!/usr/bin/env python3
"""Guard _PyMem_DebugRawFree's C89 locals and NULL-safe evaluation order."""

import re
import sys
from pathlib import Path

source = Path(sys.argv[1]).read_text()
match = re.search(
    r"\n_PyMem_DebugRawFree\(void \*ctx, void \*p\)\s*\{(.*?)\n\}",
    source, re.S,
)
assert match, "_PyMem_DebugRawFree definition not found"
body = re.sub(r"/\*.*?\*/", "", match.group(1), flags=re.S)
declarations = """
    debug_alloc_api_t *api;
    uint8_t *q;
    size_t nbytes;
"""
assert body.split()[:len(declarations.split())] == declarations.split(), (
    "_PyMem_DebugRawFree must declare api, q, and nbytes without initializers at function entry"
)

# Preserve the NULL return before either initializer is evaluated, especially
# the pointer subtraction, and retain all subsequent operations in order.
expected = declarations + """
    if (p == NULL) {
        return;
    }
    api = (debug_alloc_api_t *)ctx;
    q = (uint8_t *)p - 2*SST;
    _PyMem_DebugCheckAddress(__func__, api->api_id, p);
    nbytes = read_size_t(q);
    nbytes += PYMEM_DEBUG_EXTRA_BYTES;
    memset(q, PYMEM_DEADBYTE, nbytes);
    api->alloc.free(api->alloc.ctx, q);
"""
assert body.split() == expected.split(), (
    "preserve _PyMem_DebugRawFree assignments after the NULL return and original operation order"
)
print("obmalloc _PyMem_DebugRawFree entry declarations and NULL-safe operation order: PASS")