#
# ElementTree
# $Id: ElementInclude.py 3375 2008-02-13 08:05:08Z 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.
#
# [email protected]
# http://www.pythonware.com
#
# --------------------------------------------------------------------
# The ElementTree toolkit is
#
# Copyright (c) 1999-2008 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.
# --------------------------------------------------------------------
# Licensed to PSF under a Contributor Agreement.
# See https://www.python.org/psf/license for licensing details.
##
# Limited XInclude support for the ElementTree package.
##
import copy
from . import ElementTree
from urllib.parse import urljoin
XINCLUDE = "{http://www.w3.org/2001/XInclude}"
XINCLUDE_INCLUDE = XINCLUDE + "include"
XINCLUDE_FALLBACK = XINCLUDE + "fallback"
# For security reasons, the inclusion depth is limited to this read-only value by default.
DEFAULT_MAX_INCLUSION_DEPTH = 6
##
# Fatal include error.
class FatalIncludeError(SyntaxError):
pass
class LimitedRecursiveIncludeError(FatalIncludeError):
pass
##
# 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 (UTF-8 by default for "text").
# @return The expanded resource. If the parse mode is "xml", this
# is an Element instance. If the parse mode is "text", this
# is a string. If the loader fails, it can return None
# or raise an OSError exception.
# @throws OSError If the loader fails to load the resource.
def default_loader(href, parse, encoding=None):
if parse == "xml":
with open(href, 'rb') as file:
data = ElementTree.parse(file).getroot()
else:
if not encoding:
encoding = 'UTF-8'
with open(href, 'r', encoding=encoding) as file:
data = file.read()
return data
##
# Expand XInclude directives.
#
# @param elem Root Element or any ElementTree of a tree to be expanded
# @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 OSError If the function fails to load a given resource.
# @throws ValueError If negative {@link max_depth} is passed.
# @returns None. Modifies tree pointed by {@link elem}
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 hasattr(elem, 'getroot'):
elem = elem.getroot()
if loader is None:
loader = default_loader
_include(elem, loader, base_url, max_depth, set())
def _include(elem, loader, base_url, max_depth, _parent_hrefs):
# look for xinclude elements
i = 0
while i < len(elem):
e = elem[i]
if e.tag == XINCLUDE_INCLUDE:
# process xinclude directive
href = e.get("href")
if base_url:
href = urljoin(base_url, href)
parse = e.get("parse", "xml")
if parse == "xml":
if href in _parent_hrefs:
raise FatalIncludeError("recursive include of %s" % href)
if max_depth == 0:
raise LimitedRecursiveIncludeError(
"maximum xinclude depth reached when including file %s" % href)
_parent_hrefs.add(href)
node = loader(href, parse)
if node is None:
raise FatalIncludeError(
"cannot load %r as %r" % (href, parse)
)
node = copy.copy(node) # FIXME: this makes little sense with recursive includes
_include(node, loader, href, max_depth - 1, _parent_hrefs)
_parent_hrefs.remove(href)
if e.tail:
node.tail = (node.tail or "") + e.tail
elem[i] = node
elif parse == "text":
text = loader(href, parse, e.get("encoding"))
if text is None:
raise FatalIncludeError(
"cannot load %r as %r" % (href, parse)
)
if e.tail:
text += e.tail
if i:
node = elem[i-1]
node.tail = (node.tail or "") + text
else:
elem.text = (elem.text or "") + text
del elem[i]
continue
else:
raise FatalIncludeError(
"unknown parse type in xi:include tag (%r)" % parse
)
elif e.tag == XINCLUDE_FALLBACK:
raise FatalIncludeError(
"xi:fallback tag must be child of xi:include (%r)" % e.tag
)
else:
_include(e, loader, base_url, max_depth, _parent_hrefs)
i += 1
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