53 lines
1.6 KiB
Python
53 lines
1.6 KiB
Python
# -*- coding: utf-8 -*- #
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# Copyright 2020 Google LLC. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""Helpers for calculating CRC32C checksums."""
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from __future__ import absolute_import
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from __future__ import division
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from __future__ import unicode_literals
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import gcloud_crcmod as crcmod
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import six
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def Crc32c(data):
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"""Calculates the CRC32C checksum of the provided data.
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Args:
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data: the bytes over which the checksum should be calculated.
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Returns:
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An int representing the CRC32C checksum of the provided bytes.
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"""
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crc32c_fun = crcmod.predefined.mkPredefinedCrcFun('crc-32c')
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return crc32c_fun(six.ensure_binary(data))
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def Crc32cMatches(data, data_crc32c):
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"""Checks that the CRC32C checksum of the provided data matches the provided checksum.
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Args:
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data: bytes over which the checksum should be calculated.
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data_crc32c: int checksum against which data's checksum will be compared.
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Returns:
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True iff both checksums match.
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"""
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return (
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Crc32c(data) == data_crc32c
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if data is not None
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else Crc32c(b'') == data_crc32c
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)
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