fix(vrtManager): a failed NVRAM copy aborts its libvirt streams

libvirt requires a stream that did not finish to be aborted before it is
freed. The NVRAM download of a shut-off move and upload_volume (NVRAM
upload, cloud-init seed) freed theirs after a failed send, receive or
finish without aborting, on the shared host connection. They abort now;
upload_volume opens its stream before it makes the volume, so the
cleanup has both.

vrtManager/connection.py

@@ -1039,17 +1039,20 @@ class wvmConnect(object):
         """A new raw volume in pool holding data, written through a libvirt
         stream, which every connection type carries. A failed write leaves
         no volume."""
+        stream = self.wvm.newStream(0)
         vol = pool.createXML(
             f"<volume><name>{util.xml_escape(name)}</name><capacity>{len(data)}</capacity>"
             "<target><format type='raw'/></target></volume>",
             0,
         )
         try:
-            stream = self.wvm.newStream(0)
             vol.upload(stream, 0, len(data), 0)
             stream.sendAll(lambda _stream, size, buffer: buffer.read(size), io.BytesIO(data))
             stream.finish()
         except Exception:
+            # libvirt: a stream that did not finish is aborted before it is freed
+            with contextlib.suppress(libvirtError):
+                stream.abort()
             vol.delete(0)
             raise
         return vol

vrtManager/instance.py

@@ -427,9 +427,14 @@ class wvmInstances(wvmConnect):
                 return None
             chunks = []
             stream = conn.wvm.newStream(0)
-            vol.download(stream, 0, 0, 0)
-            stream.recvAll(lambda _stream, data, out: out.append(data), chunks)
-            stream.finish()
+            try:
+                vol.download(stream, 0, 0, 0)
+                stream.recvAll(lambda _stream, data, out: out.append(data), chunks)
+                stream.finish()
+            except Exception:
+                with contextlib.suppress(libvirtError):
+                    stream.abort()
+                raise
             self.upload_volume(target, name, b"".join(chunks))
         return name
 

vrtManager/tests/test_cloud_init_seed.py

@@ -78,6 +78,7 @@ class UploadVolumeTestCase(unittest.TestCase):
         with self.assertRaises(RuntimeError):
             conn.upload_volume(pool, "a.iso", b"data")
         pool.createXML.return_value.delete.assert_called_once_with(0)
+        conn.wvm.newStream.return_value.abort.assert_called_once_with()
 
 
 class DeleteWithDisksTestCase(unittest.TestCase):

vrtManager/tests/test_migration.py

@@ -465,6 +465,14 @@ class NvramCopyTestCase(unittest.TestCase):
         copy.upload.assert_called_once_with(self.dest.wvm.newStream.return_value, 0, 4, 0)
         self.assertEqual(self.host.defined, ["<domain><name>vm</name></domain>"])
 
+    def test_a_failed_download_aborts_its_stream(self):
+        stream = self.source.wvm.newStream.return_value
+        stream.recvAll.side_effect = libvirt.libvirtError("download failed")
+        with self.assertRaises(libvirt.libvirtError):
+            self.move()
+        stream.abort.assert_called_once_with()
+        self.dest_pool.createXML.assert_not_called()
+
     def test_a_shared_directory_is_not_copied(self):
         self.shared.stop()
         with mock.patch.object(wvmInstances, "same_directory", return_value=True):