61 lines
2.1 KiB
Python
61 lines
2.1 KiB
Python
#!/usr/bin/env python3
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"""Guard only arena_map_mark_used's entry locals and original operation order."""
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import re
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import sys
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from pathlib import Path
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source = Path(sys.argv[1]).read_text()
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match = re.search(
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r"\narena_map_mark_used\(uintptr_t arena_base, int is_used\)\s*\{(.*?)\n\}",
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source, re.S,
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)
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assert match, "arena_map_mark_used definition not found"
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body = re.sub(r"/\*.*?\*/", "", match.group(1), flags=re.S)
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declarations = """
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arena_map_bot_t *n_hi;
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int i3;
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int32_t tail;
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uintptr_t arena_base_next;
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arena_map_bot_t *n_lo;
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int i3_next;
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"""
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assert body.split()[:len(declarations.split())] == declarations.split(), (
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"n_hi, i3, tail, arena_base_next, n_lo, i3_next must be declared without initializers at function entry"
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)
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# Keep evaluations at their original positions: the sanity assertion precedes
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# lookup; failed lookup returns before index/tail evaluation. Lock both branches,
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# including rollback and i3_next evaluation after the n_lo NULL return.
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expected = declarations + """
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assert(HIGH_BITS(arena_base) == HIGH_BITS(&arena_map_root));
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n_hi = arena_map_get((block *)arena_base, is_used);
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if (n_hi == NULL) {
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assert(is_used);
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return 0;
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}
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i3 = MAP_BOT_INDEX((block *)arena_base);
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tail = (int32_t)(arena_base & ARENA_SIZE_MASK);
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if (tail == 0) {
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n_hi->arenas[i3].tail_hi = is_used ? -1 : 0;
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}
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else {
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n_hi->arenas[i3].tail_hi = is_used ? tail : 0;
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arena_base_next = arena_base + ARENA_SIZE;
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assert(arena_base < arena_base_next);
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n_lo = arena_map_get((block *)arena_base_next, is_used);
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if (n_lo == NULL) {
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assert(is_used);
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n_hi->arenas[i3].tail_hi = 0;
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return 0;
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}
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i3_next = MAP_BOT_INDEX(arena_base_next);
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n_lo->arenas[i3_next].tail_lo = is_used ? tail : 0;
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}
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return 1;
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"""
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assert body.split() == expected.split(), (
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"preserve original initialization/evaluation/control-flow order"
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)
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print("obmalloc arena_map_mark_used entry declarations and original operation order: PASS")
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