virStorageVolDefFormat: Don't format empty <source>

If there are no source extents the volume XML has an empty <source>
element. Remove it if there's nothing in it by using
virXMLFormatElement.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

src/conf/storage_conf.c

@@ -1678,6 +1678,7 @@ virStorageVolDefFormat(virStoragePoolDefPtr pool,
 {
     virStorageVolOptionsPtr options;
     g_auto(virBuffer) buf = VIR_BUFFER_INITIALIZER;
+    g_auto(virBuffer) sourceChildBuf = VIR_BUFFER_INITIALIZER;
 
     options = virStorageVolOptionsForPoolType(pool->type);
     if (options == NULL)
@@ -1689,14 +1690,13 @@ virStorageVolDefFormat(virStoragePoolDefPtr pool,
 
     virBufferEscapeString(&buf, "<name>%s</name>\n", def->name);
     virBufferEscapeString(&buf, "<key>%s</key>\n", def->key);
-    virBufferAddLit(&buf, "<source>\n");
+
-    virBufferAdjustIndent(&buf, 2);
+    virBufferSetIndent(&sourceChildBuf, virBufferGetIndent(&buf) + 2);
 
     if (def->source.nextent)
-        virStorageVolDefFormatSourceExtents(&buf, def);
+        virStorageVolDefFormatSourceExtents(&sourceChildBuf, def);
 
-    virBufferAdjustIndent(&buf, -2);
+    virXMLFormatElement(&buf, "source", NULL, &sourceChildBuf);
-    virBufferAddLit(&buf, "</source>\n");
 
     virBufferAsprintf(&buf, "<capacity unit='bytes'>%llu</capacity>\n",
                       def->target.capacity);

tests/storagevolxml2xmlout/vol-file-backing.xml

@@ -1,8 +1,6 @@
 <volume type='file'>
   <name>sparse.img</name>
   <key>/var/lib/libvirt/images/sparse.img</key>
-  <source>
-  </source>
   <capacity unit='bytes'>10000000000</capacity>
   <allocation unit='bytes'>0</allocation>
   <target>

tests/storagevolxml2xmlout/vol-file-iso.xml

@@ -1,7 +1,5 @@
 <volume type='file'>
   <name>test.iso</name>
-  <source>
-  </source>
   <capacity unit='bytes'>1048576</capacity>
   <allocation unit='bytes'>1048576</allocation>
   <target>

tests/storagevolxml2xmlout/vol-file-naming.xml

@@ -1,7 +1,5 @@
 <volume type='file'>
   <name>&lt;sparse&gt;.img</name>
-  <source>
-  </source>
   <capacity unit='bytes'>1099511627776</capacity>
   <allocation unit='bytes'>0</allocation>
   <target>

tests/storagevolxml2xmlout/vol-file.xml

@@ -1,7 +1,5 @@
 <volume type='file'>
   <name>sparse.img</name>
-  <source>
-  </source>
   <capacity unit='bytes'>1099511627776</capacity>
   <allocation unit='bytes'>0</allocation>
   <target>

tests/storagevolxml2xmlout/vol-gluster-dir-neg-uid.xml

@@ -1,8 +1,6 @@
 <volume type='netdir'>
   <name>dir</name>
   <key>vol/dir</key>
-  <source>
-  </source>
   <capacity unit='bytes'>0</capacity>
   <allocation unit='bytes'>0</allocation>
   <target>

tests/storagevolxml2xmlout/vol-gluster-dir.xml

@@ -1,8 +1,6 @@
 <volume type='netdir'>
   <name>dir</name>
   <key>vol/dir</key>
-  <source>
-  </source>
   <capacity unit='bytes'>0</capacity>
   <allocation unit='bytes'>0</allocation>
   <target>

tests/storagevolxml2xmlout/vol-logical-backing.xml

@@ -1,8 +1,6 @@
 <volume type='block'>
   <name>Swap</name>
   <key>r4xkCv-MQhr-WKIT-R66x-Epn2-e8hG-1Z5gY0</key>
-  <source>
-  </source>
   <capacity unit='bytes'>2080374784</capacity>
   <allocation unit='bytes'>2080374784</allocation>
   <target>

tests/storagevolxml2xmlout/vol-logical.xml

@@ -1,8 +1,6 @@
 <volume type='block'>
   <name>Swap</name>
   <key>r4xkCv-MQhr-WKIT-R66x-Epn2-e8hG-1Z5gY0</key>
-  <source>
-  </source>
   <capacity unit='bytes'>2080374784</capacity>
   <allocation unit='bytes'>2080374784</allocation>
   <target>

tests/storagevolxml2xmlout/vol-luks-cipher.xml

@@ -1,8 +1,6 @@
 <volume type='file'>
   <name>LuksDemo.img</name>
   <key>/var/lib/libvirt/images/LuksDemo.img</key>
-  <source>
-  </source>
   <capacity unit='bytes'>5368709120</capacity>
   <allocation unit='bytes'>294912</allocation>
   <target>

tests/storagevolxml2xmlout/vol-luks.xml

@@ -1,8 +1,6 @@
 <volume type='file'>
   <name>LuksDemo.img</name>
   <key>/var/lib/libvirt/images/LuksDemo.img</key>
-  <source>
-  </source>
   <capacity unit='bytes'>5368709120</capacity>
   <allocation unit='bytes'>294912</allocation>
   <target>

tests/storagevolxml2xmlout/vol-partition.xml

@@ -1,8 +1,6 @@
 <volume type='block'>
   <name>sda1</name>
   <key>/dev/sda1</key>
-  <source>
-  </source>
   <capacity unit='bytes'>106896384</capacity>
   <allocation unit='bytes'>106896384</allocation>
   <target>

tests/storagevolxml2xmlout/vol-qcow2-0.10-lazy.xml

@@ -1,8 +1,6 @@
 <volume type='file'>
   <name>OtherDemo.img</name>
   <key>/var/lib/libvirt/images/OtherDemo.img</key>
-  <source>
-  </source>
   <capacity unit='bytes'>5368709120</capacity>
   <allocation unit='bytes'>294912</allocation>
   <target>

tests/storagevolxml2xmlout/vol-qcow2-1.1.xml

@@ -1,8 +1,6 @@
 <volume type='file'>
   <name>OtherDemo.img</name>
   <key>/var/lib/libvirt/images/OtherDemo.img</key>
-  <source>
-  </source>
   <capacity unit='bytes'>5368709120</capacity>
   <allocation unit='bytes'>294912</allocation>
   <target>

tests/storagevolxml2xmlout/vol-qcow2-encryption.xml

@@ -1,8 +1,6 @@
 <volume type='file'>
   <name>OtherDemo.img</name>
   <key>/var/lib/libvirt/images/OtherDemo.img</key>
-  <source>
-  </source>
   <capacity unit='bytes'>5368709120</capacity>
   <allocation unit='bytes'>294912</allocation>
   <target>

tests/storagevolxml2xmlout/vol-qcow2-lazy.xml

@@ -1,8 +1,6 @@
 <volume type='file'>
   <name>OtherDemo.img</name>
   <key>/var/lib/libvirt/images/OtherDemo.img</key>
-  <source>
-  </source>
   <capacity unit='bytes'>5368709120</capacity>
   <allocation unit='bytes'>294912</allocation>
   <target>

tests/storagevolxml2xmlout/vol-qcow2-luks.xml

@@ -1,8 +1,6 @@
 <volume type='file'>
   <name>OtherDemoLuks.img</name>
   <key>/var/lib/libvirt/images/OtherDemoLuks.img</key>
-  <source>
-  </source>
   <capacity unit='bytes'>5368709120</capacity>
   <allocation unit='bytes'>294912</allocation>
   <target>

tests/storagevolxml2xmlout/vol-qcow2-nobacking.xml

@@ -1,8 +1,6 @@
 <volume type='file'>
   <name>OtherDemo.img</name>
   <key>/var/lib/libvirt/images/OtherDemo.img</key>
-  <source>
-  </source>
   <capacity unit='bytes'>5368709120</capacity>
   <allocation unit='bytes'>294912</allocation>
   <target>

tests/storagevolxml2xmlout/vol-qcow2-nocapacity.xml

@@ -1,8 +1,6 @@
 <volume type='file'>
   <name>OtherDemo.img</name>
   <key>/var/lib/libvirt/images/OtherDemo.img</key>
-  <source>
-  </source>
   <capacity unit='bytes'>0</capacity>
   <allocation unit='bytes'>0</allocation>
   <target>

tests/storagevolxml2xmlout/vol-qcow2.xml

@@ -1,8 +1,6 @@
 <volume type='file'>
   <name>OtherDemo.img</name>
   <key>/var/lib/libvirt/images/OtherDemo.img</key>
-  <source>
-  </source>
   <capacity unit='bytes'>5368709120</capacity>
   <allocation unit='bytes'>294912</allocation>
   <target>

tests/storagevolxml2xmlout/vol-sheepdog.xml

@@ -1,7 +1,5 @@
 <volume type='network'>
   <name>test2</name>
-  <source>
-  </source>
   <capacity unit='bytes'>1024</capacity>
   <allocation unit='bytes'>0</allocation>
   <target>