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stbi/Lib/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 (
+        Dict, List, BinaryIO, NoReturn, Iterator
+    )
+    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
+        """
+        self._allowed = {} if hashes is None else hashes
+
+    @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__()
+
+
+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())