Cole Robinson 18af72212b xmleditor: Add the shared code
The XML editor ui is a two tabbed notebook, one 'Details' tab
and one 'XML' tab. The latter has a gtksourceview and allows editing
the raw libvirt XML for whatever the selected object is.

API users will programmatically insert the xmleditor notebook into
their UI, with the existing UI under the details tab.
2019-06-13 07:13:43 -04:00

414 lines
13 KiB
Python

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