83 lines
2.4 KiB
Python
83 lines
2.4 KiB
Python
import re
|
|
import os.path
|
|
import hashlib
|
|
|
|
|
|
DIGEST_PATTERN = r'([A-Za-z0-9_+.-]+):([A-Fa-f0-9]+)'
|
|
REPLACE_WITH_PATH = re.compile(r'[+.]')
|
|
REPLACE_DOUBLE_SLASHES = re.compile(r'/+')
|
|
|
|
class InvalidDigestException(RuntimeError):
|
|
pass
|
|
|
|
|
|
class Digest(object):
|
|
DIGEST_REGEX = re.compile(DIGEST_PATTERN)
|
|
|
|
def __init__(self, hash_alg, hash_bytes):
|
|
self._hash_alg = hash_alg
|
|
self._hash_bytes = hash_bytes
|
|
|
|
def __str__(self):
|
|
return '{0}:{1}'.format(self._hash_alg, self._hash_bytes)
|
|
|
|
def __eq__(self, rhs):
|
|
return isinstance(rhs, Digest) and str(self) == str(rhs)
|
|
|
|
@staticmethod
|
|
def parse_digest(digest):
|
|
""" Returns the digest parsed out to its components. """
|
|
match = Digest.DIGEST_REGEX.match(digest)
|
|
if match is None or match.end() != len(digest):
|
|
raise InvalidDigestException('Not a valid digest: %s', digest)
|
|
|
|
return Digest(match.group(1), match.group(2))
|
|
|
|
@property
|
|
def hash_alg(self):
|
|
return self._hash_alg
|
|
|
|
@property
|
|
def hash_bytes(self):
|
|
return self._hash_bytes
|
|
|
|
|
|
def content_path(digest):
|
|
""" Returns a relative path to the parsed digest. """
|
|
parsed = Digest.parse_digest(digest)
|
|
components = []
|
|
|
|
# Generate a prefix which is always two characters, and which will be filled with leading zeros
|
|
# if the input does not contain at least two characters. e.g. ABC -> AB, A -> 0A
|
|
prefix = parsed.hash_bytes[0:2].zfill(2)
|
|
pathish = REPLACE_WITH_PATH.sub('/', parsed.hash_alg)
|
|
normalized = REPLACE_DOUBLE_SLASHES.sub('/', pathish).lstrip('/')
|
|
components.extend([normalized, prefix, parsed.hash_bytes])
|
|
return os.path.join(*components)
|
|
|
|
|
|
def sha256_digest(content):
|
|
""" Returns a sha256 hash of the content bytes in digest form. """
|
|
def single_chunk_generator():
|
|
yield content
|
|
return sha256_digest_from_generator(single_chunk_generator())
|
|
|
|
|
|
def sha256_digest_from_generator(content_generator):
|
|
""" Reads all of the data from the iterator and creates a sha256 digest from the content
|
|
"""
|
|
digest = hashlib.sha256()
|
|
for chunk in content_generator:
|
|
digest.update(chunk)
|
|
return 'sha256:{0}'.format(digest.hexdigest())
|
|
|
|
|
|
def sha256_digest_from_hashlib(sha256_hash_obj):
|
|
return 'sha256:{0}'.format(sha256_hash_obj.hexdigest())
|
|
|
|
|
|
def digests_equal(lhs_digest_string, rhs_digest_string):
|
|
""" Parse and compare the two digests, returns True if the digests are equal, False otherwise.
|
|
"""
|
|
return Digest.parse_digest(lhs_digest_string) == Digest.parse_digest(rhs_digest_string)
|