name : ElementInclude.py # # 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. # # fredrik@pythonware.com # 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 ElementTree instance. If the parse mode is "text", this # is a Unicode 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. # @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 a negative value 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 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