storage: allow interleave in volume XML

The RNG grammar did not allow arbitrary interleaving, which makes
it harder than necessary to create a new volume from handwritten XML.
(Compare also to commit caf516db for pools).

* docs/schemas/storagevol.rng: Support interleaving.
* tests/storagevolxml2xmlin/vol-file-backing.xml: Test it.
Signed-off-by: NEric Blake <eblake@redhat.com>

docs/schemas/storagevol.rng

@@ -13,6 +13,7 @@
 
   <define name='vol'>
     <element name='volume'>
+      <interleave>
         <element name='name'>
           <ref name='volName'/>
         </element>
@@ -29,10 +30,12 @@
         <optional>
           <ref name='backingStore'/>
         </optional>
+      </interleave>
     </element>
   </define>
 
   <define name='sizing'>
+    <interleave>
       <optional>
         <element name='capacity'>
           <ref name='scaledInteger'/>
@@ -43,11 +46,13 @@
           <ref name='scaledInteger'/>
         </element>
       </optional>
+    </interleave>
   </define>
 
   <define name='permissions'>
     <optional>
       <element name='permissions'>
+        <interleave>
           <element name='mode'>
             <ref name='octalMode'/>
           </element>
@@ -62,6 +67,7 @@
               <text/>
             </element>
           </optional>
+        </interleave>
       </element>
     </optional>
   </define>
@@ -103,6 +109,7 @@
 
   <define name='target'>
     <element name='target'>
+      <interleave>
         <optional>
           <element name='path'>
             <choice>
@@ -123,16 +130,19 @@
         <optional>
           <ref name='fileFormatFeatures'/>
         </optional>
+      </interleave>
     </element>
   </define>
 
   <define name='backingStore'>
     <element name='backingStore'>
+      <interleave>
         <element name='path'>
           <ref name='absFilePath'/>
         </element>
         <ref name='format'/>
         <ref name='permissions'/>
+      </interleave>
     </element>
   </define>
 

tests/storagevolxml2xmlin/vol-file-backing.xml

 <volume>
-  <name>sparse.img</name>
+  <!-- lines scrambled to test interleaves -->
   <key>/var/lib/libvirt/images/sparse.img</key>
-  <source/>
   <capacity unit='GB'>10</capacity>
-  <allocation unit='MiB'>0</allocation>
+  <source/>
   <target>
-    <path>/var/lib/libvirt/images/sparse.img</path>
     <permissions>
-      <mode>0</mode>
       <owner>0744</owner>
+      <mode>0</mode>
       <group>0</group>
     </permissions>
+    <path>/var/lib/libvirt/images/sparse.img</path>
   </target>
+  <allocation unit='MiB'>0</allocation>
   <backingStore>
-    <path>/var/lib/virt/images/master.img</path>
     <format type='vmdk'/>
+    <path>/var/lib/virt/images/master.img</path>
     <permissions>
       <mode>0744</mode>
+      <label>virt_image_t</label>
       <owner>1</owner>
       <group>1</group>
-      <label>virt_image_t</label>
     </permissions>
   </backingStore>
+  <name>sparse.img</name>
 </volume>