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414 lines
13 KiB
Python
414 lines
13 KiB
Python
#
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# XML API wrappers
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#
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# This work is licensed under the GNU GPLv2 or later.
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# See the COPYING file in the top-level directory.
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import libxml2
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from . import xmlutil
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# pylint: disable=protected-access
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class _XPathSegment(object):
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"""
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Class representing a single 'segment' of an xpath string. For example,
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the xpath:
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./qemu:foo/bar[1]/baz[@somepro='someval']/@finalprop
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will be split into the following segments:
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#1: nodename=., fullsegment=.
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#2: nodename=foo, nsname=qemu, fullsegment=qemu:foo
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#3: nodename=bar, condition_num=1, fullsegment=bar[1]
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#4: nodename=baz, condition_prop=somepro, condition_val=someval,
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fullsegment=baz[@somepro='somval']
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#5: nodename=finalprop, is_prop=True, fullsegment=@finalprop
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"""
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def __init__(self, fullsegment):
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self.fullsegment = fullsegment
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self.nodename = fullsegment
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self.condition_prop = None
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self.condition_val = None
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self.condition_num = None
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if "[" in self.nodename:
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self.nodename, cond = self.nodename.strip("]").split("[")
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if "=" in cond:
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(cprop, cval) = cond.split("=")
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self.condition_prop = cprop.strip("@")
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self.condition_val = cval.strip("'")
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elif cond.isdigit():
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self.condition_num = int(cond)
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self.is_prop = self.nodename.startswith("@")
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if self.is_prop:
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self.nodename = self.nodename[1:]
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self.nsname = None
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if ":" in self.nodename:
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self.nsname, self.nodename = self.nodename.split(":")
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class _XPath(object):
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"""
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Helper class for performing manipulations of XPath strings. Splits
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the xpath into segments.
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"""
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def __init__(self, fullxpath):
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self.fullxpath = fullxpath
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self.segments = []
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for s in self.fullxpath.split("/"):
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if s == "..":
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# Resolve and flatten .. in xpaths
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self.segments = self.segments[:-1]
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continue
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self.segments.append(_XPathSegment(s))
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self.is_prop = self.segments[-1].is_prop
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self.propname = (self.is_prop and self.segments[-1].nodename or None)
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if self.is_prop:
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self.segments = self.segments[:-1]
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self.xpath = self.join(self.segments)
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@staticmethod
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def join(segments):
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return "/".join(s.fullsegment for s in segments)
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def parent_xpath(self):
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return self.join(self.segments[:-1])
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class _XMLBase(object):
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NAMESPACES = {}
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@classmethod
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def register_namespace(cls, nsname, uri):
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cls.NAMESPACES[nsname] = uri
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def copy_api(self):
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raise NotImplementedError()
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def count(self, xpath):
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raise NotImplementedError()
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def _find(self, fullxpath):
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raise NotImplementedError()
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def _node_tostring(self, node):
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raise NotImplementedError()
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def _node_get_text(self, node):
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raise NotImplementedError()
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def _node_set_text(self, node, setval):
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raise NotImplementedError()
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def _node_get_property(self, node, propname):
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raise NotImplementedError()
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def _node_set_property(self, node, propname, setval):
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raise NotImplementedError()
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def _node_new(self, xpathseg, parentnode):
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raise NotImplementedError()
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def _node_add_child(self, parentxpath, parentnode, newnode):
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raise NotImplementedError()
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def _node_remove_child(self, parentnode, childnode):
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raise NotImplementedError()
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def _node_replace_child(self, xpath, newnode):
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raise NotImplementedError()
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def _node_from_xml(self, xml):
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raise NotImplementedError()
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def _node_has_content(self, node):
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raise NotImplementedError()
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def _node_get_name(self, node):
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raise NotImplementedError()
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def node_clear(self, xpath):
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raise NotImplementedError()
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def _sanitize_xml(self, xml):
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raise NotImplementedError()
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def get_xml(self, xpath):
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node = self._find(xpath)
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if node is None:
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return ""
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return self._sanitize_xml(self._node_tostring(node))
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def get_xpath_content(self, xpath, is_bool):
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node = self._find(xpath)
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if node is None:
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return None
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if is_bool:
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return True
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xpathobj = _XPath(xpath)
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if xpathobj.is_prop:
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return self._node_get_property(node, xpathobj.propname)
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return self._node_get_text(node)
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def set_xpath_content(self, xpath, setval):
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node = self._find(xpath)
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if setval is False:
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# Boolean False, means remove the node entirely
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self.node_force_remove(xpath)
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elif setval is None:
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if node is not None:
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self._node_set_content(xpath, node, None)
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self._node_remove_empty(xpath)
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else:
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if node is None:
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node = self._node_make_stub(xpath)
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if setval is True:
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# Boolean property, creating the node is enough
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return
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self._node_set_content(xpath, node, setval)
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def node_add_xml(self, xml, xpath):
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newnode = self._node_from_xml(xml)
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parentnode = self._node_make_stub(xpath)
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self._node_add_child(xpath, parentnode, newnode)
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def node_replace_xml(self, xpath, xml):
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"""
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Replace the node at xpath with the passed in xml
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"""
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newnode = self._node_from_xml(xml)
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self._node_replace_child(xpath, newnode)
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def node_force_remove(self, fullxpath):
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"""
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Remove the element referenced at the passed xpath, regardless
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of whether it has children or not, and then clean up the XML
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chain
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"""
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xpathobj = _XPath(fullxpath)
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parentnode = self._find(xpathobj.parent_xpath())
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childnode = self._find(fullxpath)
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if parentnode is None or childnode is None:
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return
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self._node_remove_child(parentnode, childnode)
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def validate_root_name(self, expected_root_name):
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rootname = self._node_get_name(self._find("."))
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if rootname == expected_root_name:
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return
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raise RuntimeError(
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_("XML did not have expected root element name '%s', found '%s'") %
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(expected_root_name, rootname))
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def _node_set_content(self, xpath, node, setval):
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xpathobj = _XPath(xpath)
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if setval is not None:
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setval = str(setval)
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if xpathobj.is_prop:
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self._node_set_property(node, xpathobj.propname, setval)
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else:
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self._node_set_text(node, setval)
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def _node_make_stub(self, fullxpath):
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"""
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Build all nodes for the passed xpath. For example, if XML is <foo/>,
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and xpath=./bar/@baz, after this function the XML will be:
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<foo>
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<bar baz=''/>
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</foo>
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And the node pointing to @baz will be returned, for the caller to
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do with as they please.
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There's also special handling to ensure that setting
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xpath=./bar[@baz='foo']/frob will create
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<bar baz='foo'>
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<frob></frob>
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</bar>
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Even if <bar> didn't exist before. So we fill in the dependent property
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expression values
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"""
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xpathobj = _XPath(fullxpath)
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parentxpath = "."
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parentnode = self._find(parentxpath)
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xmlutil.raise_programming_error(not parentnode,
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"Did not find XML root node for xpath=%s" % fullxpath)
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for xpathseg in xpathobj.segments[1:]:
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oldxpath = parentxpath
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parentxpath += "/%s" % xpathseg.fullsegment
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tmpnode = self._find(parentxpath)
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if tmpnode is not None:
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# xpath node already exists, nothing to create yet
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parentnode = tmpnode
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continue
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newnode = self._node_new(xpathseg, parentnode)
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self._node_add_child(oldxpath, parentnode, newnode)
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parentnode = newnode
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# For a conditional xpath like ./foo[@bar='baz'],
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# we also want to implicitly set <foo bar='baz'/>
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if xpathseg.condition_prop:
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self._node_set_property(parentnode, xpathseg.condition_prop,
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xpathseg.condition_val)
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return parentnode
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def _node_remove_empty(self, fullxpath):
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"""
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Walk backwards up the xpath chain, and remove each element
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if it doesn't have any children or attributes, so we don't
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leave stale elements in the XML
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"""
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xpathobj = _XPath(fullxpath)
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segments = xpathobj.segments[:]
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parent = None
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while segments:
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xpath = _XPath.join(segments)
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segments.pop()
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child = parent
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parent = self._find(xpath)
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if parent is None:
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break
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if child is None:
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continue
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if self._node_has_content(child):
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break
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self._node_remove_child(parent, child)
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def node_is_text(n):
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return bool(n and n.type == "text")
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class _Libxml2API(_XMLBase):
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def __init__(self, xml):
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_XMLBase.__init__(self)
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# Use of gtksourceview in virt-manager changes this libxml
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# global setting which messes up whitespace after parsing.
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# We can probably get away with calling this less but it
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# would take some investigation
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libxml2.keepBlanksDefault(1)
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self._doc = libxml2.parseDoc(xml)
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self._ctx = self._doc.xpathNewContext()
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self._ctx.setContextNode(self._doc.children)
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for key, val in self.NAMESPACES.items():
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self._ctx.xpathRegisterNs(key, val)
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def __del__(self):
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if not hasattr(self, "_doc"):
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# In case we error when parsing the doc
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return
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self._doc.freeDoc()
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self._doc = None
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self._ctx.xpathFreeContext()
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self._ctx = None
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def _sanitize_xml(self, xml):
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if not xml.endswith("\n") and "\n" in xml:
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xml += "\n"
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return xml
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def copy_api(self):
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return _Libxml2API(self._doc.children.serialize())
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def _find(self, fullxpath):
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xpath = _XPath(fullxpath).xpath
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node = self._ctx.xpathEval(xpath)
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return (node and node[0] or None)
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def count(self, xpath):
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return len(self._ctx.xpathEval(xpath))
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def _node_tostring(self, node):
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return node.serialize()
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def _node_from_xml(self, xml):
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return libxml2.parseDoc(xml).children
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def _node_get_text(self, node):
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return node.content
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def _node_set_text(self, node, setval):
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if setval is not None:
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setval = xmlutil.xml_escape(setval)
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node.setContent(setval)
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def _node_get_property(self, node, propname):
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prop = node.hasProp(propname)
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if prop:
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return prop.content
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def _node_set_property(self, node, propname, setval):
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if setval is None:
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prop = node.hasProp(propname)
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if prop:
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prop.unlinkNode()
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prop.freeNode()
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else:
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node.setProp(propname, xmlutil.xml_escape(setval))
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def _node_new(self, xpathseg, parentnode):
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newnode = libxml2.newNode(xpathseg.nodename)
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if not xpathseg.nsname:
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return newnode
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def _find_parent_ns():
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parent = parentnode
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while parent:
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for ns in xmlutil.listify(parent.nsDefs()):
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if ns.name == xpathseg.nsname:
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return ns
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parent = parent.get_parent()
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ns = _find_parent_ns()
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if not ns:
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ns = newnode.newNs(
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self.NAMESPACES[xpathseg.nsname], xpathseg.nsname)
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newnode.setNs(ns)
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return newnode
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def node_clear(self, xpath):
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node = self._find(xpath)
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if node:
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propnames = [p.name for p in (node.properties or [])]
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for p in propnames:
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node.unsetProp(p)
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node.setContent(None)
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def _node_has_content(self, node):
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return node.type == "element" and (node.children or node.properties)
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def _node_get_name(self, node):
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return node.name
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def _node_remove_child(self, parentnode, childnode):
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node = childnode
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# Look for preceding whitespace and remove it
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white = node.get_prev()
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if node_is_text(white):
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white.unlinkNode()
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white.freeNode()
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node.unlinkNode()
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node.freeNode()
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if all([node_is_text(n) for n in parentnode.children]):
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parentnode.setContent(None)
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def _node_add_child(self, parentxpath, parentnode, newnode):
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ignore = parentxpath
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if not node_is_text(parentnode.get_last()):
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prevsib = parentnode.get_prev()
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if node_is_text(prevsib):
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newlast = libxml2.newText(prevsib.content)
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else:
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newlast = libxml2.newText("\n")
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parentnode.addChild(newlast)
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endtext = parentnode.get_last().content
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parentnode.addChild(libxml2.newText(" "))
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parentnode.addChild(newnode)
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parentnode.addChild(libxml2.newText(endtext))
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def _node_replace_child(self, xpath, newnode):
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oldnode = self._find(xpath)
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oldnode.replaceNode(newnode)
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XMLAPI = _Libxml2API
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