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c6a7bdb356
* bpo-20928: bring elementtree's XInclude support en-par with the implementation in lxml by adding support for recursive includes and a base-URL. * bpo-20928: Support xincluding the same file multiple times, just not recursively. * bpo-20928: Add 'max_depth' parameter to xinclude that limits the maximum recursion depth to 6 by default. * Add news entry for updated ElementInclude support
185 lines
6.7 KiB
Python
185 lines
6.7 KiB
Python
#
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# ElementTree
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# $Id: ElementInclude.py 3375 2008-02-13 08:05:08Z fredrik $
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#
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# limited xinclude support for element trees
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#
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# history:
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# 2003-08-15 fl created
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# 2003-11-14 fl fixed default loader
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#
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# Copyright (c) 2003-2004 by Fredrik Lundh. All rights reserved.
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#
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# fredrik@pythonware.com
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# http://www.pythonware.com
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#
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# --------------------------------------------------------------------
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# The ElementTree toolkit is
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#
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# Copyright (c) 1999-2008 by Fredrik Lundh
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#
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# By obtaining, using, and/or copying this software and/or its
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# associated documentation, you agree that you have read, understood,
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# and will comply with the following terms and conditions:
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#
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# Permission to use, copy, modify, and distribute this software and
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# its associated documentation for any purpose and without fee is
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# hereby granted, provided that the above copyright notice appears in
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# all copies, and that both that copyright notice and this permission
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# notice appear in supporting documentation, and that the name of
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# Secret Labs AB or the author not be used in advertising or publicity
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# pertaining to distribution of the software without specific, written
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# prior permission.
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#
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# SECRET LABS AB AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD
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# TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANT-
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# ABILITY AND FITNESS. IN NO EVENT SHALL SECRET LABS AB OR THE AUTHOR
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# BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY
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# DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
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# WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
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# ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
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# OF THIS SOFTWARE.
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# --------------------------------------------------------------------
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# Licensed to PSF under a Contributor Agreement.
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# See http://www.python.org/psf/license for licensing details.
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##
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# Limited XInclude support for the ElementTree package.
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##
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import copy
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from . import ElementTree
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from urllib.parse import urljoin
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XINCLUDE = "{http://www.w3.org/2001/XInclude}"
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XINCLUDE_INCLUDE = XINCLUDE + "include"
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XINCLUDE_FALLBACK = XINCLUDE + "fallback"
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# For security reasons, the inclusion depth is limited to this read-only value by default.
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DEFAULT_MAX_INCLUSION_DEPTH = 6
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##
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# Fatal include error.
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class FatalIncludeError(SyntaxError):
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pass
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class LimitedRecursiveIncludeError(FatalIncludeError):
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pass
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##
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# Default loader. This loader reads an included resource from disk.
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#
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# @param href Resource reference.
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# @param parse Parse mode. Either "xml" or "text".
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# @param encoding Optional text encoding (UTF-8 by default for "text").
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# @return The expanded resource. If the parse mode is "xml", this
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# is an ElementTree instance. If the parse mode is "text", this
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# is a Unicode string. If the loader fails, it can return None
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# or raise an OSError exception.
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# @throws OSError If the loader fails to load the resource.
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def default_loader(href, parse, encoding=None):
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if parse == "xml":
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with open(href, 'rb') as file:
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data = ElementTree.parse(file).getroot()
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else:
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if not encoding:
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encoding = 'UTF-8'
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with open(href, 'r', encoding=encoding) as file:
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data = file.read()
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return data
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##
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# Expand XInclude directives.
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#
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# @param elem Root element.
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# @param loader Optional resource loader. If omitted, it defaults
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# to {@link default_loader}. If given, it should be a callable
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# that implements the same interface as <b>default_loader</b>.
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# @param base_url The base URL of the original file, to resolve
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# relative include file references.
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# @param max_depth The maximum number of recursive inclusions.
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# Limited to reduce the risk of malicious content explosion.
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# Pass a negative value to disable the limitation.
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# @throws LimitedRecursiveIncludeError If the {@link max_depth} was exceeded.
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# @throws FatalIncludeError If the function fails to include a given
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# resource, or if the tree contains malformed XInclude elements.
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# @throws IOError If the function fails to load a given resource.
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# @returns the node or its replacement if it was an XInclude node
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def include(elem, loader=None, base_url=None,
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max_depth=DEFAULT_MAX_INCLUSION_DEPTH):
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if max_depth is None:
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max_depth = -1
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elif max_depth < 0:
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raise ValueError("expected non-negative depth or None for 'max_depth', got %r" % max_depth)
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if hasattr(elem, 'getroot'):
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elem = elem.getroot()
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if loader is None:
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loader = default_loader
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_include(elem, loader, base_url, max_depth, set())
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def _include(elem, loader, base_url, max_depth, _parent_hrefs):
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# look for xinclude elements
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i = 0
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while i < len(elem):
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e = elem[i]
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if e.tag == XINCLUDE_INCLUDE:
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# process xinclude directive
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href = e.get("href")
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if base_url:
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href = urljoin(base_url, href)
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parse = e.get("parse", "xml")
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if parse == "xml":
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if href in _parent_hrefs:
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raise FatalIncludeError("recursive include of %s" % href)
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if max_depth == 0:
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raise LimitedRecursiveIncludeError(
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"maximum xinclude depth reached when including file %s" % href)
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_parent_hrefs.add(href)
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node = loader(href, parse)
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if node is None:
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raise FatalIncludeError(
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"cannot load %r as %r" % (href, parse)
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)
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node = copy.copy(node) # FIXME: this makes little sense with recursive includes
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_include(node, loader, href, max_depth - 1, _parent_hrefs)
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_parent_hrefs.remove(href)
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if e.tail:
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node.tail = (node.tail or "") + e.tail
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elem[i] = node
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elif parse == "text":
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text = loader(href, parse, e.get("encoding"))
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if text is None:
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raise FatalIncludeError(
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"cannot load %r as %r" % (href, parse)
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)
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if e.tail:
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text += e.tail
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if i:
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node = elem[i-1]
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node.tail = (node.tail or "") + text
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else:
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elem.text = (elem.text or "") + text
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del elem[i]
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continue
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else:
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raise FatalIncludeError(
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"unknown parse type in xi:include tag (%r)" % parse
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)
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elif e.tag == XINCLUDE_FALLBACK:
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raise FatalIncludeError(
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"xi:fallback tag must be child of xi:include (%r)" % e.tag
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)
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else:
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_include(e, loader, base_url, max_depth, _parent_hrefs)
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i += 1
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