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# -*- coding: utf-8 -*-
# Copyright 2014-2016 OpenMarket Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import random
import string
import six
from six import PY2, PY3
from six.moves import range
_string_with_symbols = string.digits + string.ascii_letters + ".,;:^&*-_+=#~@"
# random_string and random_string_with_symbols are used for a range of things,
# some cryptographically important, some less so. We use SystemRandom to make sure
# we get cryptographically-secure randoms.
rand = random.SystemRandom()
def random_string(length):
return "".join(rand.choice(string.ascii_letters) for _ in range(length))
def random_string_with_symbols(length):
return "".join(rand.choice(_string_with_symbols) for _ in range(length))
def is_ascii(s):
if PY3:
if isinstance(s, bytes):
try:
s.decode("ascii").encode("ascii")
except UnicodeDecodeError:
return False
except UnicodeEncodeError:
return False
return True
try:
s.encode("ascii")
except UnicodeEncodeError:
return False
except UnicodeDecodeError:
return False
else:
return True
def to_ascii(s):
"""Converts a string to ascii if it is ascii, otherwise leave it alone.
If given None then will return None.
"""
if PY3:
return s
if s is None:
return None
try:
return s.encode("ascii")
except UnicodeEncodeError:
return s
def exception_to_unicode(e):
"""Helper function to extract the text of an exception as a unicode string
Args:
e (Exception): exception to be stringified
Returns:
unicode
"""
# urgh, this is a mess. The basic problem here is that psycopg2 constructs its
# exceptions with PyErr_SetString, with a (possibly non-ascii) argument. str() will
# then produce the raw byte sequence. Under Python 2, this will then cause another
# error if it gets mixed with a `unicode` object, as per
# https://github.com/matrix-org/synapse/issues/4252
# First of all, if we're under python3, everything is fine because it will sort this
# nonsense out for us.
if not PY2:
return str(e)
# otherwise let's have a stab at decoding the exception message. We'll circumvent
# Exception.__str__(), which would explode if someone raised Exception(u'non-ascii')
# and instead look at what is in the args member.
if len(e.args) == 0:
return ""
elif len(e.args) > 1:
return six.text_type(repr(e.args))
msg = e.args[0]
if isinstance(msg, bytes):
return msg.decode("utf-8", errors="replace")
else:
return msg
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