87 lines
2.6 KiB
Python
87 lines
2.6 KiB
Python
# -*- coding: utf-8 -*- #
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# Copyright 2017 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 digesting a file."""
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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 hashlib
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from googlecloudsdk.api_lib.cloudkms import base as cloudkms_base
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from googlecloudsdk.calliope import exceptions
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from googlecloudsdk.core.util import files
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_READ_SIZE = 4 * 1024 * 1024
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def _ChunkReader(file_, chunk_size=_READ_SIZE):
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while True:
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chunk = file_.read(chunk_size)
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if not chunk:
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break
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yield chunk
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_DIGEST_ALGORITHMS = {
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'sha256': hashlib.sha256,
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'sha384': hashlib.sha384,
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'sha512': hashlib.sha512,
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}
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# TODO(b/77481291) Refactor this to allow reading from stdin.
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def GetDigest(digest_algorithm, filename):
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"""Digest the file at filename based on digest_algorithm.
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Args:
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digest_algorithm: The algorithm used to digest the file, can be one of
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'sha256', 'sha384', or 'sha512'.
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filename: A valid file path over which a digest will be calculated.
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Returns:
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The digest of the provided file.
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Raises:
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InvalidArgumentException: The provided digest_algorithm is invalid.
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"""
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with files.BinaryFileReader(filename) as f:
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return GetDigestOfFile(digest_algorithm, f)
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def GetDigestOfFile(digest_algorithm, file_to_digest):
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"""Digest the file_to_digest based on digest_algorithm.
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Args:
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digest_algorithm: The algorithm used to digest the file, can be one of
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'sha256', 'sha384', or 'sha512'.
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file_to_digest: A valid file handle.
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Returns:
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The digest of the provided file.
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Raises:
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InvalidArgumentException: The provided digest_algorithm is invalid.
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"""
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messages = cloudkms_base.GetMessagesModule()
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algorithm = _DIGEST_ALGORITHMS.get(digest_algorithm)
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if not algorithm:
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raise exceptions.InvalidArgumentException('digest',
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'digest_algorithm is invalid.')
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digest = algorithm()
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for chunk in _ChunkReader(file_to_digest):
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digest.update(chunk)
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kwargs = {digest_algorithm: digest.digest()}
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return messages.Digest(**kwargs)
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