#
# ElementTree
# $Id: ElementInclude.py 1862 2004-06-18 07:31:02Z Fredrik $
#
# limited xinclude support for element trees
#
# history:
# 2003-08-15 fl created
# 2003-11-14 fl fixed default loader
#
# Copyright (c) 2003-2004 by Fredrik Lundh. All rights reserved.
#
# fredrik@pythonware.com
# http://www.pythonware.com
#
# --------------------------------------------------------------------
# The ElementTree toolkit is
#
# Copyright (c) 1999-2004 by Fredrik Lundh
#
# By obtaining, using, and/or copying this software and/or its
# associated documentation, you agree that you have read, understood,
# and will comply with the following terms and conditions:
#
# Permission to use, copy, modify, and distribute this software and
# its associated documentation for any purpose and without fee is
# hereby granted, provided that the above copyright notice appears in
# all copies, and that both that copyright notice and this permission
# notice appear in supporting documentation, and that the name of
# Secret Labs AB or the author not be used in advertising or publicity
# pertaining to distribution of the software without specific, written
# prior permission.
#
# SECRET LABS AB AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD
# TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANT-
# ABILITY AND FITNESS. IN NO EVENT SHALL SECRET LABS AB OR THE AUTHOR
# BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY
# DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
# WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
# ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
# OF THIS SOFTWARE.
# --------------------------------------------------------------------
"""
Limited XInclude support for the ElementTree package.
While lxml.etree has full support for XInclude (see
`etree.ElementTree.xinclude()`), this module provides a simpler, pure
Python, ElementTree compatible implementation that supports a simple
form of custom URL resolvers.
"""
from lxml import etree
try:
from urlparse import urljoin
from urllib2 import urlopen
except ImportError:
# Python 3
from urllib.parse import urljoin
from urllib.request import urlopen
XINCLUDE = "{http://www.w3.org/2001/XInclude}"
XINCLUDE_INCLUDE = XINCLUDE + "include"
XINCLUDE_FALLBACK = XINCLUDE + "fallback"
XINCLUDE_ITER_TAG = XINCLUDE + "*"
# For security reasons, the inclusion depth is limited to this read-only value by default.
DEFAULT_MAX_INCLUSION_DEPTH = 6
##
# Fatal include error.
[docs]class FatalIncludeError(etree.LxmlSyntaxError):
pass
[docs]class LimitedRecursiveIncludeError(FatalIncludeError):
pass
##
# ET compatible default loader.
# This loader reads an included resource from disk.
#
# @param href Resource reference.
# @param parse Parse mode. Either "xml" or "text".
# @param encoding Optional text encoding.
# @return The expanded resource. If the parse mode is "xml", this
# is an ElementTree instance. If the parse mode is "text", this
# is a Unicode string. If the loader fails, it can return None
# or raise an IOError exception.
# @throws IOError If the loader fails to load the resource.
[docs]def default_loader(href, parse, encoding=None):
file = open(href, 'rb')
if parse == "xml":
data = etree.parse(file).getroot()
else:
data = file.read()
if not encoding:
encoding = 'utf-8'
data = data.decode(encoding)
file.close()
return data
##
# Default loader used by lxml.etree - handles custom resolvers properly
#
[docs]def _lxml_default_loader(href, parse, encoding=None, parser=None):
if parse == "xml":
data = etree.parse(href, parser).getroot()
else:
if "://" in href:
f = urlopen(href)
else:
f = open(href, 'rb')
data = f.read()
f.close()
if not encoding:
encoding = 'utf-8'
data = data.decode(encoding)
return data
##
# Wrapper for ET compatibility - drops the parser
[docs]def _wrap_et_loader(loader):
def load(href, parse, encoding=None, parser=None):
return loader(href, parse, encoding)
return load
##
# Expand XInclude directives.
#
# @param elem Root element.
# @param loader Optional resource loader. If omitted, it defaults
# to {@link default_loader}. If given, it should be a callable
# that implements the same interface as <b>default_loader</b>.
# @param base_url The base URL of the original file, to resolve
# relative include file references.
# @param max_depth The maximum number of recursive inclusions.
# Limited to reduce the risk of malicious content explosion.
# Pass None to disable the limitation.
# @throws LimitedRecursiveIncludeError If the {@link max_depth} was exceeded.
# @throws FatalIncludeError If the function fails to include a given
# resource, or if the tree contains malformed XInclude elements.
# @throws IOError If the function fails to load a given resource.
# @returns the node or its replacement if it was an XInclude node
[docs]def include(elem, loader=None, base_url=None,
max_depth=DEFAULT_MAX_INCLUSION_DEPTH):
if max_depth is None:
max_depth = -1
elif max_depth < 0:
raise ValueError("expected non-negative depth or None for 'max_depth', got %r" % max_depth)
if base_url is None:
if hasattr(elem, 'getroot'):
tree = elem
elem = elem.getroot()
else:
tree = elem.getroottree()
if hasattr(tree, 'docinfo'):
base_url = tree.docinfo.URL
elif hasattr(elem, 'getroot'):
elem = elem.getroot()
_include(elem, loader, base_url, max_depth)
[docs]def _include(elem, loader=None, base_url=None,
max_depth=DEFAULT_MAX_INCLUSION_DEPTH, _parent_hrefs=None):
if loader is not None:
load_include = _wrap_et_loader(loader)
else:
load_include = _lxml_default_loader
if _parent_hrefs is None:
_parent_hrefs = set()
parser = elem.getroottree().parser
include_elements = list(
elem.iter(XINCLUDE_ITER_TAG))
for e in include_elements:
if e.tag == XINCLUDE_INCLUDE:
# process xinclude directive
href = urljoin(base_url, e.get("href"))
parse = e.get("parse", "xml")
parent = e.getparent()
if parse == "xml":
if href in _parent_hrefs:
raise FatalIncludeError(
"recursive include of %r detected" % href
)
if max_depth == 0:
raise LimitedRecursiveIncludeError(
"maximum xinclude depth reached when including file %s" % href)
node = load_include(href, parse, parser=parser)
if node is None:
raise FatalIncludeError(
"cannot load %r as %r" % (href, parse)
)
node = _include(node, loader, href, max_depth - 1, {href} | _parent_hrefs)
if e.tail:
node.tail = (node.tail or "") + e.tail
if parent is None:
return node # replaced the root node!
parent.replace(e, node)
elif parse == "text":
text = load_include(href, parse, encoding=e.get("encoding"))
if text is None:
raise FatalIncludeError(
"cannot load %r as %r" % (href, parse)
)
predecessor = e.getprevious()
if predecessor is not None:
predecessor.tail = (predecessor.tail or "") + text
elif parent is None:
return text # replaced the root node!
else:
parent.text = (parent.text or "") + text + (e.tail or "")
parent.remove(e)
else:
raise FatalIncludeError(
"unknown parse type in xi:include tag (%r)" % parse
)
elif e.tag == XINCLUDE_FALLBACK:
parent = e.getparent()
if parent is not None and parent.tag != XINCLUDE_INCLUDE:
raise FatalIncludeError(
"xi:fallback tag must be child of xi:include (%r)" % e.tag
)
else:
raise FatalIncludeError(
"Invalid element found in XInclude namespace (%r)" % e.tag
)
return elem