devices: smartcard: Use CharSource

smartcard does the same internally for libvirt, so let's follow that
pattern, and fix the fallout

tests/testdriver.xml

@@ -483,6 +483,9 @@ Foo bar baz & yeah boii < > yeahfoo
       <source mode='bind' host='127.0.0.1' service='2001'/>
       <protocol type='raw'/>
     </smartcard>
+    <smartcard mode='passthrough' type='unix'>
+      <source mode='bind' path='/tmp/smartcard.sock'/>
+    </smartcard>
 
 
     <!-- redir devices -->

tests/xmlparse-xml/change-smartcard-in.xml

@@ -54,6 +54,13 @@
     </smartcard>
     <smartcard mode='passthrough' type='spicevmc'>
     </smartcard>
+    <smartcard mode='passthrough' type='tcp'>
+      <source mode='bind' host='127.0.0.1' service='2001'/>
+      <protocol type='raw'/>
+    </smartcard>
+    <smartcard mode='passthrough' type='unix'>
+      <source mode='bind' path='/tmp/smartcard.sock'/>
+    </smartcard>
   </devices>
   <seclabel type='static' model='selinux'>
     <label>foolabel</label>

tests/xmlparse-xml/change-smartcard-out.xml

@@ -54,6 +54,13 @@
     </smartcard>
     <smartcard mode="host">
     </smartcard>
+    <smartcard mode="passthrough" type="tcp">
+      <source mode="bind" host="127.0.0.1" service="2001"/>
+      <protocol type="raw"/>
+    </smartcard>
+    <smartcard mode="passthrough" type="unix">
+      <source mode="bind" path="/tmp/smartcard.sock"/>
+    </smartcard>
   </devices>
   <seclabel type="static" model="selinux">
     <label>foolabel</label>

tests/xmlparse.py

@@ -966,6 +966,8 @@ class XMLParseTest(unittest.TestCase):
 
         dev1 = guest.devices.smartcard[0]
         dev2 = guest.devices.smartcard[1]
+        dev3 = guest.devices.smartcard[2]
+        dev4 = guest.devices.smartcard[3]
 
         check = self._make_checker(dev1)
         check("type", None, "tcp")
@@ -974,6 +976,16 @@ class XMLParseTest(unittest.TestCase):
         check("mode", "passthrough", "host")
         check("type", "spicevmc", None)
 
+        check = self._make_checker(dev3)
+        check("type", "tcp")
+        check("source.host", "127.0.0.1")
+        check("source.service", 2001)
+
+        check = self._make_checker(dev4)
+        check("type", "unix")
+        check("source.path", "/tmp/smartcard.sock")
+        check("source.mode", "bind")
+
         self._alter_compare(guest.get_xml(), outfile)
 
     def testAlterRedirdev(self):

virtinst/devices/smartcard.py

@@ -4,8 +4,9 @@
 # This work is licensed under the GNU GPLv2 or later.
 # See the COPYING file in the top-level directory.
 
+from .char import CharSource
 from .device import Device
-from ..xmlbuilder import XMLProperty
+from ..xmlbuilder import XMLChildProperty, XMLProperty
 
 
 class DeviceSmartcard(Device):
@@ -14,6 +15,7 @@ class DeviceSmartcard(Device):
 
     mode = XMLProperty("./@mode")
     type = XMLProperty("./@type")
+    source = XMLChildProperty(CharSource, is_single=True)
 
 
     ##################