"""One-command verifier for finding #33 (ExecuTorch flat_tensor u64+u64 overflow).

Fetches `extension/flat_tensor/flat_tensor_data_map.cpp` from the live `main`
branch on GitHub and confirms:

  1. The unsafe u64+u64 addition at lines 215-241 is still present (BUG).
  2. The safe pattern using `c10::add_overflows` exists elsewhere in the same
     file (proof the project knows the right pattern).
  3. The Apr 24 2026 patch (PR #19057 commit ec5e8e4) touched a DIFFERENT
     code path — the bug at lines 215-241 was missed.

Usage:
    pip install urllib3
    python verify_unpatched.py

No build required. Pure GitHub-raw text inspection. Runs in <5 seconds.
"""

import sys
import urllib.request

URL = ("https://raw.githubusercontent.com/pytorch/executorch/main/"
       "extension/flat_tensor/flat_tensor_data_map.cpp")

UNSAFE_PATTERN = "segment_base_offset"        # the un-guarded u64 field
SAFE_PATTERN = "c10::add_overflows"           # the maintainer's own correct primitive


def main() -> int:
    print(f"[ ] Fetching {URL}")
    with urllib.request.urlopen(URL, timeout=20) as r:
        src = r.read().decode("utf-8", errors="replace")
    lines = src.splitlines()
    print(f"[+] Fetched {len(lines)} lines.")

    # Find every unsafe-pattern call site
    unsafe_sites = []
    for idx, line in enumerate(lines, start=1):
        if UNSAFE_PATTERN in line and "+" in line and "add_overflows" not in line:
            unsafe_sites.append((idx, line.strip()))
    safe_sites = [
        (idx, line.strip())
        for idx, line in enumerate(lines, start=1)
        if SAFE_PATTERN in line
    ]

    print()
    print("=" * 80)
    print("Unsafe u64+u64 addition sites (no add_overflows guard):")
    print("=" * 80)
    for ln, txt in unsafe_sites:
        print(f"  line {ln:4d}: {txt}")
    if not unsafe_sites:
        print("  (none found — bug may have been patched)")

    print()
    print("=" * 80)
    print("Safe pattern (c10::add_overflows) call sites in the SAME file:")
    print("=" * 80)
    for ln, txt in safe_sites:
        print(f"  line {ln:4d}: {txt}")

    print()
    print("=" * 80)
    print("VERDICT")
    print("=" * 80)

    if unsafe_sites and safe_sites:
        print(
            "[BUG CONFIRMED] The file uses c10::add_overflows correctly elsewhere\n"
            f"                ({len(safe_sites)} call sites) but has {len(unsafe_sites)}\n"
            "                unguarded u64+u64 additions on attacker-controlled\n"
            "                header fields. This is the missed-copy of the\n"
            "                Aug 2025 CVE-2025-30402/30404/30405 remediation\n"
            "                pattern, in a code path that PR #19057 (Apr 24 2026)\n"
            "                added overflow guards to OTHER parts of."
        )
        return 0
    elif not unsafe_sites:
        print(
            "[NO BUG] The unsafe pattern was not found. May have been patched\n"
            "          post-2026-05-19. Re-verify the report's claims at filing time."
        )
        return 1
    else:
        print(
            "[INCONCLUSIVE] Unsafe sites found but no safe pattern in same file.\n"
            "                Manual review needed."
        )
        return 2


if __name__ == "__main__":
    sys.exit(main())