Function _fetch_checksums

python/copilot/_cli_download.py:115–145

Fetch and parse the SHA256SUMS.txt file. Returns a dict mapping filename → sha256 hex digest.

(version: str)

def _fetch_checksums(version: str) -> dict[str, str]:
    """Fetch and parse the SHA256SUMS.txt file.

    Returns a dict mapping filename → sha256 hex digest.
    """
    url = get_checksums_url(version)
    last_exc: Exception | None = None
    for attempt in range(_MAX_RETRIES):
        try:
            with urlopen(url, timeout=30) as response:
                text = response.read().decode("utf-8")
            break
        except (HTTPError, URLError) as exc:
            last_exc = exc
            if attempt < _MAX_RETRIES - 1:
                time.sleep(2**attempt)
    else:
        raise RuntimeError(
            f"Failed to download checksums from {url}: {last_exc}\n\n"
            "If you are in an offline or firewalled environment, set "
            "COPILOT_CLI_PATH to point to a manually-installed binary."
        ) from last_exc

    checksums: dict[str, str] = {}
    for line in text.strip().splitlines():
        parts = line.split()
        if len(parts) == 2:
            digest, filename = parts
            # Some formats use *filename (binary mode indicator)
            checksums[filename.lstrip("*")] = digest
    return checksums


def _verify_checksum(data: bytes, expected_hash: str, filename: str) -> None: