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# Copyright (c) 2014 OpenStack Foundation.
#
# 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 lxml.etree
from copy import deepcopy
from pkg_resources import resource_stream # pylint: disable-msg=E0611
import six
from swift.common.utils import get_logger
from swift.common.middleware.s3api.exception import S3Exception
from swift.common.middleware.s3api.utils import camel_to_snake, \
utf8encode, utf8decode
XMLNS_S3 = 'http://s3.amazonaws.com/doc/2006-03-01/'
XMLNS_XSI = 'http://www.w3.org/2001/XMLSchema-instance'
class XMLSyntaxError(S3Exception):
pass
class DocumentInvalid(S3Exception):
pass
def cleanup_namespaces(elem):
def remove_ns(tag, ns):
if tag.startswith('{%s}' % ns):
tag = tag[len('{%s}' % ns):]
return tag
if not isinstance(elem.tag, six.string_types):
# elem is a comment element.
return
# remove s3 namespace
elem.tag = remove_ns(elem.tag, XMLNS_S3)
# remove default namespace
if elem.nsmap and None in elem.nsmap:
elem.tag = remove_ns(elem.tag, elem.nsmap[None])
for e in elem.iterchildren():
cleanup_namespaces(e)
def fromstring(text, root_tag=None, logger=None):
try:
elem = lxml.etree.fromstring(text, parser)
except lxml.etree.XMLSyntaxError as e:
if logger:
logger.debug(e)
raise XMLSyntaxError(e)
cleanup_namespaces(elem)
if root_tag is not None:
# validate XML
try:
path = 'schema/%s.rng' % camel_to_snake(root_tag)
with resource_stream(__name__, path) as rng:
lxml.etree.RelaxNG(file=rng).assertValid(elem)
except IOError as e:
# Probably, the schema file doesn't exist.
logger = logger or get_logger({}, log_route='s3api')
logger.error(e)
raise
except lxml.etree.DocumentInvalid as e:
if logger:
logger.debug(e)
raise DocumentInvalid(e)
return elem
def tostring(tree, use_s3ns=True, xml_declaration=True):
if use_s3ns:
nsmap = tree.nsmap.copy()
nsmap[None] = XMLNS_S3
root = Element(tree.tag, attrib=tree.attrib, nsmap=nsmap)
root.text = tree.text
root.extend(deepcopy(tree.getchildren()))
tree = root
return lxml.etree.tostring(tree, xml_declaration=xml_declaration,
encoding='UTF-8')
class _Element(lxml.etree.ElementBase):
"""
Wrapper Element class of lxml.etree.Element to support
a utf-8 encoded non-ascii string as a text.
Why we need this?:
Original lxml.etree.Element supports only unicode for the text.
It declines maintainability because we have to call a lot of encode/decode
methods to apply account/container/object name (i.e. PATH_INFO) to each
Element instance. When using this class, we can remove such a redundant
codes from swift.common.middleware.s3api middleware.
"""
def __init__(self, *args, **kwargs):
# pylint: disable-msg=E1002
super(_Element, self).__init__(*args, **kwargs)
@property
def text(self):
"""
utf-8 wrapper property of lxml.etree.Element.text
"""
if six.PY2:
return utf8encode(lxml.etree.ElementBase.text.__get__(self))
return lxml.etree.ElementBase.text.__get__(self)
@text.setter
def text(self, value):
lxml.etree.ElementBase.text.__set__(self, utf8decode(value))
parser_lookup = lxml.etree.ElementDefaultClassLookup(element=_Element)
parser = lxml.etree.XMLParser(resolve_entities=False, no_network=True)
parser.set_element_class_lookup(parser_lookup)
Element = parser.makeelement
SubElement = lxml.etree.SubElement
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