Preview: hashes.py
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/opt/alt/python27/lib/python2.7/site-packages/pip/_internal/utils/hashes.py
from __future__ import absolute_import
import hashlib
from pip._vendor.six import iteritems, iterkeys, itervalues
from pip._internal.exceptions import HashMismatch, HashMissing, InstallationError
from pip._internal.utils.misc import read_chunks
from pip._internal.utils.typing import MYPY_CHECK_RUNNING
if MYPY_CHECK_RUNNING:
from typing import BinaryIO, Dict, Iterator, List, NoReturn
from pip._vendor.six import PY3
if PY3:
from hashlib import _Hash
else:
from hashlib import _hash as _Hash
# The recommended hash algo of the moment. Change this whenever the state of
# the art changes; it won't hurt backward compatibility.
FAVORITE_HASH = 'sha256'
# Names of hashlib algorithms allowed by the --hash option and ``pip hash``
# Currently, those are the ones at least as collision-resistant as sha256.
STRONG_HASHES = ['sha256', 'sha384', 'sha512']
class Hashes(object):
"""A wrapper that builds multiple hashes at once and checks them against
known-good values
"""
def __init__(self, hashes=None):
# type: (Dict[str, List[str]]) -> None
"""
:param hashes: A dict of algorithm names pointing to lists of allowed
hex digests
"""
allowed = {}
if hashes is not None:
for alg, keys in hashes.items():
# Make sure values are always sorted (to ease equality checks)
allowed[alg] = sorted(keys)
self._allowed = allowed
def __and__(self, other):
# type: (Hashes) -> Hashes
if not isinstance(other, Hashes):
return NotImplemented
# If either of the Hashes object is entirely empty (i.e. no hash
# specified at all), all hashes from the other object are allowed.
if not other:
return self
if not self:
return other
# Otherwise only hashes that present in both objects are allowed.
new = {}
for alg, values in iteritems(other._allowed):
if alg not in self._allowed:
continue
new[alg] = [v for v in values if v in self._allowed[alg]]
return Hashes(new)
@property
def digest_count(self):
# type: () -> int
return sum(len(digests) for digests in self._allowed.values())
def is_hash_allowed(
self,
hash_name, # type: str
hex_digest, # type: str
):
# type: (...) -> bool
"""Return whether the given hex digest is allowed."""
return hex_digest in self._allowed.get(hash_name, [])
def check_against_chunks(self, chunks):
# type: (Iterator[bytes]) -> None
"""Check good hashes against ones built from iterable of chunks of
data.
Raise HashMismatch if none match.
"""
gots = {}
for hash_name in iterkeys(self._allowed):
try:
gots[hash_name] = hashlib.new(hash_name)
except (ValueError, TypeError):
raise InstallationError(
'Unknown hash name: {}'.format(hash_name)
)
for chunk in chunks:
for hash in itervalues(gots):
hash.update(chunk)
for hash_name, got in iteritems(gots):
if got.hexdigest() in self._allowed[hash_name]:
return
self._raise(gots)
def _raise(self, gots):
# type: (Dict[str, _Hash]) -> NoReturn
raise HashMismatch(self._allowed, gots)
def check_against_file(self, file):
# type: (BinaryIO) -> None
"""Check good hashes against a file-like object
Raise HashMismatch if none match.
"""
return self.check_against_chunks(read_chunks(file))
def check_against_path(self, path):
# type: (str) -> None
with open(path, 'rb') as file:
return self.check_against_file(file)
def __nonzero__(self):
# type: () -> bool
"""Return whether I know any known-good hashes."""
return bool(self._allowed)
def __bool__(self):
# type: () -> bool
return self.__nonzero__()
def __eq__(self, other):
# type: (object) -> bool
if not isinstance(other, Hashes):
return NotImplemented
return self._allowed == other._allowed
def __hash__(self):
# type: () -> int
return hash(
",".join(sorted(
":".join((alg, digest))
for alg, digest_list in self._allowed.items()
for digest in digest_list
))
)
class MissingHashes(Hashes):
"""A workalike for Hashes used when we're missing a hash for a requirement
It computes the actual hash of the requirement and raises a HashMissing
exception showing it to the user.
"""
def __init__(self):
# type: () -> None
"""Don't offer the ``hashes`` kwarg."""
# Pass our favorite hash in to generate a "gotten hash". With the
# empty list, it will never match, so an error will always raise.
super(MissingHashes, self).__init__(hashes={FAVORITE_HASH: []})
def _raise(self, gots):
# type: (Dict[str, _Hash]) -> NoReturn
raise HashMissing(gots[FAVORITE_HASH].hexdigest())
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