guest: Add support for qemu cli passthrough

This is for xml like:

<domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
  ...
  </devices>
  <qemu:commandline>
    <qemu:arg value='-newarg'/>
    <qemu:env name='QEMU_ENV' value='VAL'/>
  </qemu:commandline>
</domain>

Requires some extensions to the xmlbuilder infrastructure

virtinst/guest.py

@@ -54,6 +54,7 @@ from .pm import PM
 from .seclabel import Seclabel
 from .sysinfo import SYSInfo
 from .xmlbuilder import XMLBuilder, XMLProperty, XMLChildProperty
+from .xmlnsqemu import XMLNSQemu
 
 
 class Guest(XMLBuilder):
@@ -188,6 +189,7 @@ class Guest(XMLBuilder):
                        validate_cb=lambda s, v: util.validate_uuid(v),
                        default_cb=_get_default_uuid)
 
+
     id = XMLProperty("./@id", is_int=True)
     type = XMLProperty("./@type", default_cb=lambda s: "xen")
     bootloader = XMLProperty("./bootloader")
@@ -214,6 +216,8 @@ class Guest(XMLBuilder):
     resource = XMLChildProperty(DomainResource, is_single=True)
     sysinfo = XMLChildProperty(SYSInfo, is_single=True)
 
+    xmlns_qemu = XMLChildProperty(XMLNSQemu, is_single=True)
+
 
     ###############################
     # Distro detection properties #

virtinst/xmlbuilder.py

@@ -42,6 +42,10 @@ _seenprops = []
 # top relavtive node in certain cases
 _top_node = None
 
+_namespaces = {
+    "qemu": "http://libvirt.org/schemas/domain/qemu/1.0",
+}
+
 
 class _DocCleanupWrapper(object):
     def __init__(self, doc):
@@ -64,6 +68,7 @@ def _make_xml_context(node):
     doc = node.doc
     ctx = _CtxCleanupWrapper(doc.xpathNewContext())
     ctx.setContextNode(node)
+    ctx.xpathRegisterNs("qemu", _namespaces["qemu"])
     return ctx
 
 
@@ -98,6 +103,13 @@ def _get_xpath_node(ctx, xpath):
     return (node and node[0] or None)
 
 
+def _add_namespace(node, nsname):
+    for ns in util.listify(node.nsDefs()):
+        if ns.name == nsname:
+            return ns
+    return node.newNs(_namespaces[nsname], nsname)
+
+
 def _add_pretty_child(parentnode, newnode):
     """
     Add 'newnode' as a child of 'parentnode', but try to preserve
@@ -206,10 +218,17 @@ def _build_xpath_node(ctx, xpath):
         # Remove conditional xpath elements for node creation. We preserved
         # them up until this point since it was needed for proper xpath
         # lookup, but they aren't valid syntax when creating the node
-        if nodename.count("["):
+        if "[" in nodename:
             nodename = nodename[:nodename.index("[")]
 
+        nsname = None
+        if ":" in nodename:
+            nsname, nodename = nodename.split(":")
+
         newnode = libxml2.newNode(nodename)
+        if nsname:
+            ns = _add_namespace(ctx.contextNode(), nsname)
+            newnode.setNs(ns)
         return _add_pretty_child(parentnode, newnode), parentpath
 
 
@@ -719,7 +738,12 @@ class _XMLState(object):
 
 
     def make_xml_stub(self):
-        return "<%s/>" % self._root_name
+        ret = "<%s" % self._root_name
+        if ":" in self._root_name:
+            ns = self._root_name.split(":")[0]
+            ret += " xmlns:%s='%s'" % (ns, _namespaces[ns])
+        ret += "/>"
+        return ret
 
     def set_relative_object_xpath(self, xpath):
         self._relative_object_xpath = xpath or ""
@@ -835,7 +859,7 @@ class XMLBuilder(object):
             for child_class in xmlprop.child_classes:
                 prop_path = xmlprop.get_prop_xpath(self, child_class)
 
-                nodecount = int(self._xmlstate.xml_node.xpathEval(
+                nodecount = int(self._xmlstate.xml_ctx.xpathEval(
                     "count(%s)" % self.fix_relative_xpath(prop_path)))
                 for idx in range(nodecount):
                     idxstr = "[%d]" % (idx + 1)

virtinst/xmlnsqemu.py

@@ -0,0 +1,52 @@
+# Copyright 2017 Red Hat, Inc.
+# Cole Robinson <crobinso@redhat.com>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+# MA 02110-1301 USA.
+
+from .xmlbuilder import XMLBuilder, XMLChildProperty, XMLProperty
+
+
+class _XMLNSQemuArg(XMLBuilder):
+    _XML_ROOT_NAME = "qemu:arg"
+
+    value = XMLProperty("./@value")
+
+
+class _XMLNSQemuEnv(XMLBuilder):
+    _XML_ROOT_NAME = "qemu:env"
+
+    name = XMLProperty("./@name")
+    value = XMLProperty("./@value")
+
+
+class XMLNSQemu(XMLBuilder):
+    """
+    Class for generating <qemu:commandline> XML
+    """
+    _XML_ROOT_NAME = "qemu:commandline"
+
+    args = XMLChildProperty(_XMLNSQemuArg)
+    def add_arg(self, value):
+        arg = _XMLNSQemuArg(conn=self.conn)
+        arg.value = value
+        self.add_child(arg)
+
+    envs = XMLChildProperty(_XMLNSQemuEnv)
+    def add_env(self, name, value):
+        env = _XMLNSQemuEnv(conn=self.conn)
+        env.name = name
+        env.value = value
+        self.add_child(env)