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from __future__ import absolute_import
import hashlib
from pip.exceptions import HashMismatch, HashMissing, InstallationError
from pip.utils import read_chunks
from pip._vendor.six import iteritems, iterkeys, itervalues
# 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):
"""
:param hashes: A dict of algorithm names pointing to lists of allowed
hex digests
"""
self._allowed = {} if hashes is None else hashes
def check_against_chunks(self, chunks):
"""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: %s' % 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):
raise HashMismatch(self._allowed, gots)
def check_against_file(self, file):
"""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):
with open(path, 'rb') as file:
return self.check_against_file(file)
def __nonzero__(self):
"""Return whether I know any known-good hashes."""
return bool(self._allowed)
def __bool__(self):
return self.__nonzero__()
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):
"""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):
raise HashMissing(gots[FAVORITE_HASH].hexdigest())
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