695 lines
28 KiB
Python
695 lines
28 KiB
Python
# -*- coding: utf-8 -*-
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#
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# Copyright (c), 2016-2019, SISSA (International School for Advanced Studies).
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# All rights reserved.
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# This file is distributed under the terms of the MIT License.
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# See the file 'LICENSE' in the root directory of the present
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# distribution, or http://opensource.org/licenses/MIT.
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#
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# @author Davide Brunato <brunato@sissa.it>
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#
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import os.path
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import re
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import codecs
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from elementpath import iter_select, Selector
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from .compat import (
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PY3, StringIO, BytesIO, string_base_type, urlopen, urlsplit, urljoin, urlunsplit,
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pathname2url, URLError, uses_relative
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)
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from .exceptions import XMLSchemaTypeError, XMLSchemaValueError, XMLSchemaURLError, XMLSchemaOSError
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from .namespaces import get_namespace
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from .qnames import XSI_SCHEMA_LOCATION, XSI_NONS_SCHEMA_LOCATION
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from .etree import ElementTree, PyElementTree, SafeXMLParser, etree_tostring
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DEFUSE_MODES = ('always', 'remote', 'never')
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def is_remote_url(url):
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return url is not None and urlsplit(url).scheme not in ('', 'file')
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def url_path_is_directory(url):
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return os.path.isdir(urlsplit(url).path)
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def url_path_is_file(url):
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return os.path.isfile(urlsplit(url).path)
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def normalize_url(url, base_url=None, keep_relative=False):
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"""
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Returns a normalized URL doing a join with a base URL. URL scheme defaults to 'file' and
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backslashes are replaced with slashes. For file paths the os.path.join is used instead of
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urljoin.
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:param url: a relative or absolute URL.
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:param base_url: the reference base URL for construct the normalized URL from the argument. \
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For compatibility between "os.path.join" and "urljoin" a trailing '/' is added to not empty paths.
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:param keep_relative: if set to `True` keeps relative file paths, which would not strictly \
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conformant to URL format specification.
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:return: A normalized URL.
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"""
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def add_trailing_slash(r):
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return urlunsplit((r[0], r[1], r[2] + '/' if r[2] and r[2][-1] != '/' else r[2], r[3], r[4]))
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if base_url is not None:
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base_url = base_url.replace('\\', '/')
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while base_url.startswith('//'):
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base_url = base_url.replace('//', '/', 1)
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base_url_parts = urlsplit(base_url)
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base_url = add_trailing_slash(base_url_parts)
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if base_url_parts.scheme not in uses_relative:
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base_url_parts = urlsplit('file:///{}'.format(base_url))
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else:
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base_url_parts = urlsplit(base_url)
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if base_url_parts.scheme not in ('', 'file'):
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url = urljoin(base_url, url)
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else:
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url_parts = urlsplit(url)
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if url_parts.scheme not in ('', 'file'):
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url = urljoin(base_url, url)
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elif not url_parts.netloc or base_url_parts.netloc == url_parts.netloc:
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# Join paths only if host parts (netloc) are equal, using the os.path.join
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# instead of urljoin for path normalization.
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url = urlunsplit((
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'',
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base_url_parts.netloc,
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os.path.normpath(os.path.join(base_url_parts.path, url_parts.path)),
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url_parts.query,
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url_parts.fragment,
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))
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# Add 'file' scheme if '//' prefix is added
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if base_url_parts.netloc and not url.startswith(base_url_parts.netloc) and url.startswith('//'):
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url = 'file:' + url
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url = url.replace('\\', '/')
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while url.startswith('//'):
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url = url.replace('//', '/', 1)
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url_parts = urlsplit(url, scheme='file')
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if url_parts.scheme not in uses_relative:
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return 'file:///{}'.format(url_parts.geturl()) # Eg. k:/Python/lib/....
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elif url_parts.scheme != 'file':
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return urlunsplit((
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url_parts.scheme,
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url_parts.netloc,
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pathname2url(url_parts.path),
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url_parts.query,
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url_parts.fragment,
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))
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elif os.path.isabs(url_parts.path):
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return url_parts.geturl()
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elif keep_relative:
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# Can't use urlunsplit with a scheme because it converts relative paths to absolute ones.
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return 'file:{}'.format(urlunsplit(('',) + url_parts[1:]))
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else:
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return urlunsplit((
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url_parts.scheme,
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url_parts.netloc,
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os.path.abspath(url_parts.path),
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url_parts.query,
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url_parts.fragment,
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))
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def fetch_resource(location, base_url=None, timeout=30):
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"""
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Fetch a resource trying to accessing it. If the resource is accessible
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returns the URL, otherwise raises an error (XMLSchemaURLError).
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:param location: an URL or a file path.
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:param base_url: reference base URL for normalizing local and relative URLs.
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:param timeout: the timeout in seconds for the connection attempt in case of remote data.
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:return: a normalized URL.
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"""
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if not location:
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raise XMLSchemaValueError("'location' argument must contains a not empty string.")
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url = normalize_url(location, base_url)
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try:
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resource = urlopen(url, timeout=timeout)
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except URLError as err:
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# fallback joining the path without a base URL
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url = normalize_url(location)
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try:
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resource = urlopen(url, timeout=timeout)
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except URLError:
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raise XMLSchemaURLError(reason=err.reason)
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else:
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resource.close()
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return url
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else:
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resource.close()
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return url
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def fetch_schema_locations(source, locations=None, **resource_options):
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"""
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Fetches the schema URL for the source's root of an XML data source and a list of location hints.
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If an accessible schema location is not found raises a ValueError.
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:param source: an Element or an Element Tree with XML data or an URL or a file-like object.
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:param locations: a dictionary or dictionary items with Schema location hints.
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:param resource_options: keyword arguments for providing :class:`XMLResource` class init options.
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:return: A tuple with the URL referring to the first reachable schema resource, a list \
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of dictionary items with normalized location hints.
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"""
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base_url = resource_options.pop('base_url', None)
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timeout = resource_options.pop('timeout', 30)
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if not isinstance(source, XMLResource):
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resource = XMLResource(source, base_url, timeout=timeout, **resource_options)
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else:
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resource = source
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base_url = resource.base_url
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namespace = resource.namespace
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locations = resource.get_locations(locations)
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for ns, url in filter(lambda x: x[0] == namespace, locations):
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try:
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return fetch_resource(url, base_url, timeout), locations
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except XMLSchemaURLError:
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pass
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raise XMLSchemaValueError("not found a schema for XML data resource %r (namespace=%r)." % (source, namespace))
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def fetch_schema(source, locations=None, **resource_options):
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"""
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Fetches the schema URL for the source's root of an XML data source.
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If an accessible schema location is not found raises a ValueError.
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:param source: An an Element or an Element Tree with XML data or an URL or a file-like object.
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:param locations: A dictionary or dictionary items with schema location hints.
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:param resource_options: keyword arguments for providing :class:`XMLResource` class init options.
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:return: An URL referring to a reachable schema resource.
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"""
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return fetch_schema_locations(source, locations, **resource_options)[0]
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def fetch_namespaces(source, **resource_options):
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"""
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Extracts namespaces with related prefixes from the XML data source. If the source is
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an lxml's ElementTree/Element returns the nsmap attribute of the root. If a duplicate
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prefix declaration is encountered then adds the namespace using a different prefix,
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but only in the case if the namespace URI is not already mapped by another prefix.
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:param source: a string containing the XML document or file path or an url \
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or a file like object or an ElementTree or Element.
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:param resource_options: keyword arguments for providing :class:`XMLResource` init options.
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:return: A dictionary for mapping namespace prefixes to full URI.
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"""
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timeout = resource_options.pop('timeout', 30)
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return XMLResource(source, timeout=timeout, **resource_options).get_namespaces()
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def load_xml_resource(source, element_only=True, **resource_options):
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"""
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Load XML data source into an Element tree, returning the root Element, the XML text and an
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url, if available. Usable for XML data files of small or medium sizes, as XSD schemas.
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:param source: an URL, a filename path or a file-like object.
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:param element_only: if True the function returns only the root Element of the tree.
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:param resource_options: keyword arguments for providing :class:`XMLResource` init options.
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:return: a tuple with three items (root Element, XML text and XML URL) or \
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only the root Element if 'element_only' argument is True.
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"""
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lazy = resource_options.pop('lazy', False)
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source = XMLResource(source, lazy=lazy, **resource_options)
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if element_only:
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return source.root
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else:
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source.load()
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return source.root, source.text, source.url
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class XMLResource(object):
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"""
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XML resource reader based on ElementTree and urllib.
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:param source: a string containing the XML document or file path or an URL or a file like \
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object or an ElementTree or an Element.
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:param base_url: is an optional base URL, used for the normalization of relative paths when \
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the URL of the resource can't be obtained from the source argument.
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:param defuse: set the usage of SafeXMLParser for XML data. Can be 'always', 'remote' or 'never'. \
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Default is 'remote' that uses the defusedxml only when loading remote data.
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:param timeout: the timeout in seconds for the connection attempt in case of remote data.
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:param lazy: if set to `False` the source is fully loaded into and processed from memory. \
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Default is `True` that means that only the root element of the source is loaded. This is \
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ignored if *source* is an Element or an ElementTree.
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"""
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def __init__(self, source, base_url=None, defuse='remote', timeout=300, lazy=True):
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if base_url is not None and not isinstance(base_url, string_base_type):
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raise XMLSchemaValueError(u"'base_url' argument has to be a string: {!r}".format(base_url))
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self._root = self._document = self._url = self._text = None
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self._base_url = base_url
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self.defuse = defuse
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self.timeout = timeout
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self._lazy = lazy
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self.source = source
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def __str__(self):
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# noinspection PyCompatibility,PyUnresolvedReferences
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return unicode(self).encode("utf-8")
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def __unicode__(self):
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return self.__repr__()
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if PY3:
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__str__ = __unicode__
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def __repr__(self):
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if self._root is None:
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return u'%s()' % self.__class__.__name__
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elif self._url is None:
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return u'%s(tag=%r)' % (self.__class__.__name__, self._root.tag)
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else:
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return u'%s(tag=%r, basename=%r)' % (
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self.__class__.__name__, self._root.tag, os.path.basename(self._url)
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)
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def __setattr__(self, name, value):
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if name == 'source':
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self._root, self._document, self._text, self._url = self._fromsource(value)
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elif name == 'defuse' and value not in DEFUSE_MODES:
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raise XMLSchemaValueError(u"'defuse' attribute: {!r} is not a defuse mode.".format(value))
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elif name == 'timeout' and (not isinstance(value, int) or value <= 0):
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raise XMLSchemaValueError(u"'timeout' attribute must be a positive integer: {!r}".format(value))
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elif name == 'lazy' and not isinstance(value, bool):
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raise XMLSchemaValueError(u"'lazy' attribute must be a boolean: {!r}".format(value))
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super(XMLResource, self).__setattr__(name, value)
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def _fromsource(self, source):
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url, lazy = None, self._lazy
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if hasattr(source, 'tag'):
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self._lazy = False
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return source, None, None, None # Source is already an Element --> nothing to load
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elif isinstance(source, string_base_type):
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_url, self._url = self._url, None
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try:
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if lazy:
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# check if source is a string containing a valid XML root
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for _, root in self.iterparse(StringIO(source), events=('start',)):
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return root, None, source, None
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else:
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return self.fromstring(source), None, source, None
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except (ElementTree.ParseError, PyElementTree.ParseError, UnicodeEncodeError):
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if '\n' in source:
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raise
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finally:
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self._url = _url
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url = normalize_url(source) if '\n' not in source else None
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elif isinstance(source, StringIO):
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_url, self._url = self._url, None
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try:
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if lazy:
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for _, root in self.iterparse(source, events=('start',)):
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return root, None, source.getvalue(), None
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else:
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document = self.parse(source)
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return document.getroot(), document, source.getvalue(), None
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finally:
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self._url = _url
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elif hasattr(source, 'read'):
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# source should be a file-like object
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try:
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if hasattr(source, 'url'):
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url = source.url
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else:
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url = normalize_url(source.name)
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except AttributeError:
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pass
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else:
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_url, self._url = self._url, url
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try:
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if lazy:
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for _, root in self.iterparse(source, events=('start',)):
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return root, None, None, url
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else:
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document = self.parse(source)
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return document.getroot(), document, None, url
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finally:
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self._url = _url
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else:
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# Try ElementTree object at last
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try:
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root = source.getroot()
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except (AttributeError, TypeError):
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pass
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else:
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if hasattr(root, 'tag'):
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self._lazy = False
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return root, source, None, None
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if url is None:
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raise XMLSchemaTypeError(
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"wrong type %r for 'source' attribute: an ElementTree object or an Element instance or a "
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"string containing XML data or an URL or a file-like object is required." % type(source)
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)
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else:
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resource = urlopen(url, timeout=self.timeout)
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_url, self._url = self._url, url
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try:
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if lazy:
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for _, root in self.iterparse(resource, events=('start',)):
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return root, None, None, url
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else:
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document = self.parse(resource)
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root = document.getroot()
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return root, document, None, url
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finally:
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self._url = _url
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resource.close()
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@property
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def root(self):
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"""The XML tree root Element."""
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return self._root
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@property
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def document(self):
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"""
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The ElementTree document, `None` if the instance is lazy or is not created
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from another document or from an URL.
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"""
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return self._document
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@property
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def text(self):
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"""The XML text source, `None` if it's not available."""
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return self._text
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@property
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def url(self):
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"""The source URL, `None` if the instance is created from an Element tree or from a string."""
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return self._url
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@property
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def base_url(self):
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"""The base URL for completing relative locations."""
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return os.path.dirname(self._url) if self._url else self._base_url
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@property
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def namespace(self):
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"""The namespace of the XML document."""
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return get_namespace(self._root.tag) if self._root is not None else None
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@staticmethod
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def defusing(source):
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"""
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Defuse an XML source, raising an `ElementTree.ParseError` if the source contains entity
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definitions or remote entity loading.
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:param source: a filename or file object containing XML data.
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"""
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parser = SafeXMLParser(target=PyElementTree.TreeBuilder())
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try:
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for _, _ in PyElementTree.iterparse(source, ('start',), parser):
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break
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except PyElementTree.ParseError as err:
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raise ElementTree.ParseError(str(err))
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def parse(self, source):
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"""
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An equivalent of *ElementTree.parse()* that can protect from XML entities attacks. When
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protection is applied XML data are loaded and defused before building the ElementTree instance.
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:param source: a filename or file object containing XML data.
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:returns: an ElementTree instance.
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"""
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if self.defuse == 'always' or self.defuse == 'remote' and is_remote_url(self._url):
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text = source.read()
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if isinstance(text, bytes):
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self.defusing(BytesIO(text))
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return ElementTree.parse(BytesIO(text))
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else:
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self.defusing(StringIO(text))
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return ElementTree.parse(StringIO(text))
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else:
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return ElementTree.parse(source)
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def iterparse(self, source, events=None):
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"""
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An equivalent of *ElementTree.iterparse()* that can protect from XML entities attacks.
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When protection is applied the iterator yields pure-Python Element instances.
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:param source: a filename or file object containing XML data.
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:param events: a list of events to report back. If omitted, only “end” events are reported.
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"""
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if self.defuse == 'always' or self.defuse == 'remote' and is_remote_url(self._url):
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parser = SafeXMLParser(target=PyElementTree.TreeBuilder())
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try:
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return PyElementTree.iterparse(source, events, parser)
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except PyElementTree.ParseError as err:
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raise ElementTree.ParseError(str(err))
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else:
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return ElementTree.iterparse(source, events)
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def fromstring(self, text):
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"""
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An equivalent of *ElementTree.fromstring()* that can protect from XML entities attacks.
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:param text: a string containing XML data.
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:returns: the root Element instance.
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"""
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if self.defuse == 'always' or self.defuse == 'remote' and is_remote_url(self._url):
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self.defusing(StringIO(text))
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return ElementTree.fromstring(text)
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def tostring(self, indent='', max_lines=None, spaces_for_tab=4, xml_declaration=False):
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"""Generates a string representation of the XML resource."""
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return etree_tostring(self._root, self.get_namespaces(), indent, max_lines, spaces_for_tab, xml_declaration)
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def copy(self, **kwargs):
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"""Resource copy method. Change init parameters with keyword arguments."""
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obj = type(self)(
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source=self.source,
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base_url=kwargs.get('base_url', self.base_url),
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defuse=kwargs.get('defuse', self.defuse),
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timeout=kwargs.get('timeout', self.timeout),
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lazy=kwargs.get('lazy', self._lazy)
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)
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if obj._text is None and self._text is not None:
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obj._text = self._text
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return obj
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def open(self):
|
|
"""Returns a opened resource reader object for the instance URL."""
|
|
if self._url is None:
|
|
raise XMLSchemaValueError("can't open, the resource has no URL associated.")
|
|
try:
|
|
return urlopen(self._url, timeout=self.timeout)
|
|
except URLError as err:
|
|
raise XMLSchemaURLError(reason="cannot access to resource %r: %s" % (self._url, err.reason))
|
|
|
|
def load(self):
|
|
"""
|
|
Loads the XML text from the data source. If the data source is an Element
|
|
the source XML text can't be retrieved.
|
|
"""
|
|
if self._url is None:
|
|
return # Created from Element or text source --> already loaded
|
|
|
|
resource = self.open()
|
|
try:
|
|
data = resource.read()
|
|
except (OSError, IOError) as err:
|
|
raise XMLSchemaOSError("cannot load data from %r: %s" % (self._url, err))
|
|
finally:
|
|
resource.close()
|
|
|
|
try:
|
|
self._text = data.decode('utf-8') if PY3 else data.encode('utf-8')
|
|
except UnicodeDecodeError:
|
|
if PY3:
|
|
self._text = data.decode('iso-8859-1')
|
|
else:
|
|
with codecs.open(urlsplit(self._url).path, mode='rb', encoding='iso-8859-1') as f:
|
|
self._text = f.read().encode('iso-8859-1')
|
|
|
|
def is_lazy(self):
|
|
"""Returns `True` if the XML resource is lazy."""
|
|
return self._lazy
|
|
|
|
def is_loaded(self):
|
|
"""Returns `True` if the XML text of the data source is loaded."""
|
|
return self._text is not None
|
|
|
|
def iter(self, tag=None):
|
|
"""XML resource tree iterator."""
|
|
if not self._lazy:
|
|
for elem in self._root.iter(tag):
|
|
yield elem
|
|
return
|
|
elif self._url is not None:
|
|
resource = urlopen(self._url, timeout=self.timeout)
|
|
else:
|
|
resource = StringIO(self._text)
|
|
|
|
try:
|
|
for event, elem in self.iterparse(resource, events=('end',)):
|
|
if tag is None or elem.tag == tag:
|
|
yield elem
|
|
elem.clear()
|
|
finally:
|
|
resource.close()
|
|
|
|
def iterfind(self, path=None, namespaces=None):
|
|
"""XML resource tree iterfind selector."""
|
|
if not self._lazy:
|
|
if path is None:
|
|
yield self._root
|
|
else:
|
|
for e in iter_select(self._root, path, namespaces, strict=False):
|
|
yield e
|
|
return
|
|
elif self._url is not None:
|
|
resource = urlopen(self._url, timeout=self.timeout)
|
|
else:
|
|
self.load()
|
|
resource = StringIO(self._text)
|
|
|
|
try:
|
|
if path is None:
|
|
level = 0
|
|
for event, elem in self.iterparse(resource, events=('start', 'end')):
|
|
if event == "start":
|
|
if level == 0:
|
|
self._root.clear()
|
|
self._root = elem
|
|
level += 1
|
|
else:
|
|
level -= 1
|
|
if level == 0:
|
|
yield elem
|
|
elem.clear()
|
|
else:
|
|
selector = Selector(path, namespaces, strict=False)
|
|
level = 0
|
|
for event, elem in self.iterparse(resource, events=('start', 'end')):
|
|
if event == "start":
|
|
if level == 0:
|
|
self._root.clear()
|
|
self._root = elem
|
|
level += 1
|
|
else:
|
|
level -= 1
|
|
if elem in selector.select(self._root):
|
|
yield elem
|
|
elem.clear()
|
|
elif level == 0:
|
|
elem.clear()
|
|
finally:
|
|
resource.close()
|
|
|
|
def iter_location_hints(self):
|
|
"""Yields schema location hints from the XML tree."""
|
|
for elem in self.iter():
|
|
try:
|
|
locations = elem.attrib[XSI_SCHEMA_LOCATION]
|
|
except KeyError:
|
|
pass
|
|
else:
|
|
locations = locations.split()
|
|
for ns, url in zip(locations[0::2], locations[1::2]):
|
|
yield ns, url
|
|
|
|
try:
|
|
locations = elem.attrib[XSI_NONS_SCHEMA_LOCATION]
|
|
except KeyError:
|
|
pass
|
|
else:
|
|
for url in locations.split():
|
|
yield '', url
|
|
|
|
def get_namespaces(self):
|
|
"""
|
|
Extracts namespaces with related prefixes from the XML resource. If a duplicate
|
|
prefix declaration is encountered then adds the namespace using a different prefix,
|
|
but only in the case if the namespace URI is not already mapped by another prefix.
|
|
|
|
:return: A dictionary for mapping namespace prefixes to full URI.
|
|
"""
|
|
def update_nsmap(prefix, uri):
|
|
if prefix not in nsmap and (prefix or not local_root):
|
|
nsmap[prefix] = uri
|
|
elif not any(uri == ns for ns in nsmap.values()):
|
|
if not prefix:
|
|
try:
|
|
prefix = re.search(r'(\w+)$', uri.strip()).group()
|
|
except AttributeError:
|
|
return
|
|
|
|
while prefix in nsmap:
|
|
match = re.search(r'(\d+)$', prefix)
|
|
if match:
|
|
index = int(match.group()) + 1
|
|
prefix = prefix[:match.span()[0]] + str(index)
|
|
else:
|
|
prefix += '2'
|
|
nsmap[prefix] = uri
|
|
|
|
local_root = self.root.tag[0] != '{'
|
|
nsmap = {}
|
|
|
|
if self._url is not None:
|
|
resource = self.open()
|
|
try:
|
|
for event, node in self.iterparse(resource, events=('start-ns', 'end')):
|
|
if event == 'start-ns':
|
|
update_nsmap(*node)
|
|
else:
|
|
node.clear()
|
|
except (ElementTree.ParseError, PyElementTree.ParseError, UnicodeEncodeError):
|
|
pass
|
|
finally:
|
|
resource.close()
|
|
elif isinstance(self._text, string_base_type):
|
|
try:
|
|
for event, node in self.iterparse(StringIO(self._text), events=('start-ns', 'end')):
|
|
if event == 'start-ns':
|
|
update_nsmap(*node)
|
|
else:
|
|
node.clear()
|
|
except (ElementTree.ParseError, PyElementTree.ParseError, UnicodeEncodeError):
|
|
pass
|
|
else:
|
|
# Warning: can extracts namespace information only from lxml etree structures
|
|
try:
|
|
for elem in self._root.iter():
|
|
for k, v in elem.nsmap.items():
|
|
update_nsmap(k if k is not None else '', v)
|
|
except (AttributeError, TypeError):
|
|
pass # Not an lxml's tree or element
|
|
|
|
return nsmap
|
|
|
|
def get_locations(self, locations=None):
|
|
"""
|
|
Returns a list of schema location hints. The locations are normalized using the
|
|
base URL of the instance. The *locations* argument can be a dictionary or a list
|
|
of namespace resources, that are inserted before the schema location hints extracted
|
|
from the XML resource.
|
|
"""
|
|
base_url = self.base_url
|
|
location_hints = []
|
|
if locations is not None:
|
|
try:
|
|
for ns, value in locations.items():
|
|
if isinstance(value, list):
|
|
location_hints.extend([(ns, normalize_url(url, base_url)) for url in value])
|
|
else:
|
|
location_hints.append((ns, normalize_url(value, base_url)))
|
|
except AttributeError:
|
|
location_hints.extend([(ns, normalize_url(url, base_url)) for ns, url in locations])
|
|
|
|
location_hints.extend([(ns, normalize_url(url, base_url)) for ns, url in self.iter_location_hints()])
|
|
return location_hints
|