Function multi_checksums

src/commoncode/hash.py:283–308

Return a mapping of hexdigest checksum strings keyed by checksum algorithm name from hashing the content of the file at ``location``. Use the ``checksum_names`` list of checksum names. The mapping is guaranted to contains all the requested names as keys. If the location is not a file,

(location, checksum_names=("md5", "sha1", "sha256", "sha512", "sha1_git"))

def multi_checksums(location, checksum_names=("md5", "sha1", "sha256", "sha512", "sha1_git")):
    """
    Return a mapping of hexdigest checksum strings keyed by checksum algorithm name from hashing the
    content of the file at ``location``. Use the ``checksum_names`` list of checksum names. The
    mapping is guaranted to contains all the requested names as keys. If the location is not a file,
    or if the file is empty, the values are None.

    The purpose of this function is to avoid read the same file multiple times
    to compute different checksums.
    """
    if not filetype.is_file(location):
        return {name: None for name in checksum_names}
    file_size = get_file_size(location)
    if file_size == 0:
        return {name: None for name in checksum_names}

    hashers = {
        name: get_hasher_instance_by_name(name=name, total_length=file_size)
        for name in checksum_names
    }

    for chunk in binary_chunks(location):
        for hasher in hashers.values():
            hasher.update(msg=chunk)

    return {name: hasher.hexdigest() for name, hasher in hashers.items()}