launch: libvirt: Don't crash if shutdown_libvirt is called early in launch.

The assert (conn != NULL) was being triggered with this
stack trace:

    at launch-libvirt.c:1305
    fd=<optimized out>, error_if_eof=error_if_eof@entry=0) at proto.c:222
    size_rtn=size_rtn@entry=0x7fffffffdb34,
    buf_rtn=buf_rtn@entry=0x7fffffffdb58) at proto.c:548
    libvirt_uri=<optimized out>) at launch-libvirt.c:391

1 files changed, 13 insertions, 8 deletions

diff --git a/src/launch-libvirt.c b/src/launch-libvirt.c
index f5f641a4..760c99f2 100644
--- a/src/launch-libvirt.c
+++ b/src/launch-libvirt.c
@@ -1302,16 +1302,21 @@ shutdown_libvirt (guestfs_h *g)
   virDomainPtr dom = g->virt.domv;
   int ret = 0;
 
-  assert (conn != NULL);
-  assert (dom != NULL);
+  /* Note that we can be called back very early in launch (specifically
+   * from launch_libvirt itself), when conn and dom might be NULL.
+   */
 
-  /* XXX Need to be graceful? */
-  if (virDomainDestroyFlags (dom, 0) == -1) {
-    libvirt_error (g, _("could not destroy libvirt domain"));
-    ret = -1;
+  if (dom != NULL) {
+    /* XXX Need to be graceful? */
+    if (virDomainDestroyFlags (dom, 0) == -1) {
+      libvirt_error (g, _("could not destroy libvirt domain"));
+      ret = -1;
+    }
+    virDomainFree (dom);
   }
-  virDomainFree (dom);
-  virConnectClose (conn);
+
+  if (conn != NULL)
+    virConnectClose (conn);
 
   g->virt.connv = g->virt.domv = NULL;