def __try_read_record(self):
"""Try reading a record.
Returns:
(data, record_type) tuple.
Raises:
EOFError: when end of file was reached.
InvalidRecordError: when valid record could not be read.
"""
block_remaining = BLOCK_SIZE - self.__reader.tell() % BLOCK_SIZE
if block_remaining < HEADER_LENGTH:
return ("", RECORD_TYPE_NONE)
header = self.__reader.read(HEADER_LENGTH)
if len(header) != HEADER_LENGTH:
raise EOFError("Read %s bytes instead of %s" %
(len(header), HEADER_LENGTH))
(masked_crc, length,
record_type) = struct.unpack(HEADER_FORMAT, header)
if length + HEADER_LENGTH > block_remaining:
raise InvalidRecordError("Length is too big")
data = self.__reader.read(length)
if len(data) != length:
raise EOFError("Not enough data read. Expected: %s but got %s" %
(length, len(data)))
if record_type == RECORD_TYPE_NONE:
return ("", record_type)
if not self.no_check_crc:
actual_crc = google_crc32c.value(
record_type.to_bytes(RECORD_TYPE_LENGTH, ENDIANNESS) + data)
if actual_crc != _unmask_crc(masked_crc):
raise InvalidRecordError("Data crc does not match")
return (data, record_type)
def TestOneInput(data): val1 = google_crc32c.value(data) val2 = google_crc32c.Checksum(data)._crc assert val1 == val2
def test_update(_crc32c):
chunk = b"DEADBEEF"
helper = google_crc32c.Checksum()
helper.update(chunk)
assert helper._crc == google_crc32c.value(chunk)
def test_ctor_explicit(_crc32c):
chunk = b"DEADBEEF"
helper = google_crc32c.Checksum(chunk)
assert helper._crc == google_crc32c.value(chunk)
def test_value(chunk, expected):
assert google_crc32c.value(bytes(chunk)) == expected
def _crc32c(data):
return google_crc32c.value(data)