qemu: snapshot: Remove memory image if external checkpoint fails

When the disk snapshot part of an external system checkpoint fails the
memory image is retained. This patch adds code to remove the image in
such case.

src/qemu/qemu_driver.c

@@ -11376,6 +11376,7 @@ qemuDomainSnapshotCreateActiveExternal(virConnectPtr conn,
     qemuDomainObjPrivatePtr priv = vm->privateData;
     char *xml = NULL;
     bool memory = snap->def->memory == VIR_DOMAIN_SNAPSHOT_LOCATION_EXTERNAL;
+    bool memory_unlink = false;
     bool atomic = !!(flags & VIR_DOMAIN_SNAPSHOT_CREATE_ATOMIC);
     bool transaction = qemuCapsGet(priv->caps, QEMU_CAPS_TRANSACTION);
     int thaw = 0; /* 1 if freeze succeeded, -1 if freeze failed */
@@ -11443,6 +11444,9 @@ qemuDomainSnapshotCreateActiveExternal(virConnectPtr conn,
                                         QEMU_ASYNC_JOB_SNAPSHOT)) < 0)
             goto endjob;
 
+        /* the memory image was created, remove it on errors */
+        memory_unlink = true;
+
         /* forbid any further manipulation */
         qemuDomainObjSetAsyncJobMask(vm, DEFAULT_JOB_MASK);
     }
@@ -11513,6 +11517,8 @@ endjob:
 
 cleanup:
     VIR_FREE(xml);
+    if (memory_unlink && ret < 0)
+        unlink(snap->def->file);
 
     return ret;
 }