e1b3e9e6ae
Add patch support and resumeable sha Implement all actual registry methods Add a simple database generation option
96 lines
2.7 KiB
Python
96 lines
2.7 KiB
Python
import re
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import os.path
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import hashlib
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DIGEST_PATTERN = r'(tarsum\.(v[\w]+)\+)?([\w]+):([0-9a-f]+)'
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class InvalidDigestException(RuntimeError):
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pass
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class Digest(object):
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DIGEST_REGEX = re.compile(DIGEST_PATTERN)
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def __init__(self, hash_alg, hash_bytes, is_tarsum=False, tarsum_version=None):
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self._hash_alg = hash_alg
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self._hash_bytes = hash_bytes
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self._is_tarsum = is_tarsum
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self._tarsum_version = tarsum_version
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def __str__(self):
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if self._is_tarsum:
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return 'tarsum.{0}+{1}:{2}'.format(self._tarsum_version, self._hash_alg, self._hash_bytes)
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return '{0}:{1}'.format(self._hash_alg, self._hash_bytes)
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def __eq__(self, rhs):
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return isinstance(rhs, Digest) and str(self) == str(rhs)
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@staticmethod
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def parse_digest(digest):
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""" Returns the digest parsed out to its components. """
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match = Digest.DIGEST_REGEX.match(digest)
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if match is None or match.end() != len(digest):
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raise InvalidDigestException('Not a valid digest: %s', digest)
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is_tarsum = match.group(1) is not None
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return Digest(match.group(3), match.group(4), is_tarsum, match.group(2))
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@property
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def is_tarsum(self):
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return self._is_tarsum
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@property
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def tarsum_version(self):
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return self._tarsum_version
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@property
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def hash_alg(self):
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return self._hash_alg
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@property
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def hash_bytes(self):
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return self._hash_bytes
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def content_path(digest):
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""" Returns a relative path to the parsed digest. """
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parsed = Digest.parse_digest(digest)
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components = []
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if parsed.is_tarsum:
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components.extend(['tarsum', parsed.tarsum_version])
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# Generate a prefix which is always two characters, and which will be filled with leading zeros
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# if the input does not contain at least two characters. e.g. ABC -> AB, A -> 0A
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prefix = parsed.hash_bytes[0:2].zfill(2)
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components.extend([parsed.hash_alg, prefix, parsed.hash_bytes])
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return os.path.join(*components)
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def sha256_digest(content):
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""" Returns a sha256 hash of the content bytes in digest form. """
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def single_chunk_generator():
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yield content
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return sha256_digest_from_generator(single_chunk_generator())
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def sha256_digest_from_generator(content_generator):
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""" Reads all of the data from the iterator and creates a sha256 digest from the content
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"""
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digest = hashlib.sha256()
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for chunk in content_generator:
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digest.update(chunk)
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return 'sha256:{0}'.format(digest.hexdigest())
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def sha256_digest_from_hashlib(sha256_hash_obj):
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return 'sha256:{0}'.format(sha256_hash_obj.hexdigest())
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def digests_equal(lhs_digest_string, rhs_digest_string):
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""" Parse and compare the two digests, returns True if the digests are equal, False otherwise.
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"""
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return Digest.parse_digest(lhs_digest_string) == Digest.parse_digest(rhs_digest_string)
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