Current File : //opt/alt/python35/lib64/python3.5/site-packages/cryptography/hazmat/backends/__init__.py
# This file is dual licensed under the terms of the Apache License, Version
# 2.0, and the BSD License. See the LICENSE file in the root of this repository
# for complete details.
from __future__ import absolute_import, division, print_function
from cryptography.hazmat.backends.multibackend import MultiBackend
_available_backends_list = None
def _available_backends():
global _available_backends_list
if _available_backends_list is None:
# Lazy import pkg_resources here to avoid the performance issue
# on systems with many packages detailed in
# https://github.com/pypa/setuptools/issues/926
import pkg_resources
entry_point_backends = [
# DeprecatedIn16
# setuptools 11.3 deprecated support for the require parameter to
# load(), and introduced the new resolve() method instead.
# We previously removed this fallback, but users are having issues
# where Python loads an older setuptools due to various syspath
# weirdness.
ep.resolve() if hasattr(ep, "resolve") else ep.load(require=False)
for ep in pkg_resources.iter_entry_points(
"cryptography.backends"
)
]
_available_backends_list = _backend_import_fallback(
entry_point_backends
)
return _available_backends_list
def _backend_import_fallback(backends):
# If backends already exist just return them. This branch is here
# to get full line coverage from our tests.
if backends:
return backends
# if iter_entry_points fails to find any backends then manually try to
# import our current backends as a workaround for issues with application
# bundlers like pyinstaller, cx_freeze, etc
# OpenSSL is guaranteed to be present until we unbundle the backends.
from cryptography.hazmat.backends.openssl.backend import backend as be_ossl
backends = [be_ossl]
try:
from cryptography.hazmat.backends.commoncrypto.backend import (
backend as be_cc
)
except ImportError:
pass
else:
backends.append(be_cc)
return backends
_default_backend = None
def default_backend():
global _default_backend
if _default_backend is None:
_default_backend = MultiBackend(_available_backends())
return _default_backend
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