[Libguestfs] [PATCH 2/2] v2v: -o libvirt: Check if the domain exists on the target (RHBZ#889082).

[Richard W.M. Jones]

---
 v2v/domainxml-c.c     | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++
 v2v/domainxml.ml      |  2 ++
 v2v/domainxml.mli     |  6 +++++
 v2v/output_libvirt.ml |  5 ++++
 4 files changed, 78 insertions(+)

diff --git a/v2v/domainxml-c.c b/v2v/domainxml-c.c
index 27b1389..865b18b 100644
--- a/v2v/domainxml-c.c
+++ b/v2v/domainxml-c.c
@@ -416,6 +416,71 @@ v2v_capabilities (value connv, value unitv)
   CAMLreturn (capabilitiesv);
 }
 
+value
+v2v_domain_exists (value connv, value domnamev)
+{
+  CAMLparam2 (connv, domnamev);
+  const char *conn_uri = NULL;
+  const char *domname;
+  /* We have to assemble the error on the stack because a dynamic
+   * string couldn't be freed.
+   */
+  char errmsg[256];
+  virErrorPtr err;
+  virConnectPtr conn;
+  virDomainPtr dom;
+  int domain_exists;
+
+  if (connv != Val_int (0))
+    conn_uri = String_val (Field (connv, 0)); /* Some conn */
+
+  /* We have to call the default authentication handler, not least
+   * since it handles all the PolicyKit crap.  However it also makes
+   * coding this simpler.
+   */
+  conn = virConnectOpenAuth (conn_uri, virConnectAuthPtrDefault,
+                             VIR_CONNECT_RO);
+  if (conn == NULL) {
+    if (conn_uri)
+      snprintf (errmsg, sizeof errmsg,
+                _("cannot open libvirt connection '%s'"), conn_uri);
+    else
+      snprintf (errmsg, sizeof errmsg, _("cannot open libvirt connection"));
+    caml_invalid_argument (errmsg);
+  }
+
+  /* Suppress default behaviour of printing errors to stderr.  Note
+   * you can't set this to NULL to ignore errors; setting it to NULL
+   * restores the default error handler ...
+   */
+  virConnSetErrorFunc (conn, NULL, ignore_errors);
+
+  /* Look up the domain. */
+  domname = String_val (domnamev);
+  dom = virDomainLookupByName (conn, domname);
+
+  if (dom) {
+    domain_exists = 1;
+    virDomainFree (dom);
+  }
+  else {
+    err = virGetLastError ();
+    if (err->code == VIR_ERR_NO_DOMAIN)
+      domain_exists = 0;
+    else {
+      snprintf (errmsg, sizeof errmsg,
+                _("cannot find libvirt domain '%s': %s"),
+                domname, err->message);
+      virConnectClose (conn);
+      caml_invalid_argument (errmsg);
+    }
+  }
+
+  virConnectClose (conn);
+
+  CAMLreturn (Val_bool (domain_exists));
+}
+
 #else /* !HAVE_LIBVIRT */
 
 value v2v_dumpxml (value connv, value domv) __attribute__((noreturn));
diff --git a/v2v/domainxml.ml b/v2v/domainxml.ml
index 2ac304b..a12391f 100644
--- a/v2v/domainxml.ml
+++ b/v2v/domainxml.ml
@@ -24,3 +24,5 @@ external pool_dumpxml : ?conn:string -> string -> string = "v2v_pool_dumpxml"
 external vol_dumpxml : ?conn:string -> string -> string -> string = "v2v_vol_dumpxml"
 
 external capabilities : ?conn:string -> unit -> string = "v2v_capabilities"
+
+external domain_exists : ?conn:string -> string -> bool = "v2v_domain_exists"
diff --git a/v2v/domainxml.mli b/v2v/domainxml.mli
index 11cf48e..ccbb8c8 100644
--- a/v2v/domainxml.mli
+++ b/v2v/domainxml.mli
@@ -43,3 +43,9 @@ val vol_dumpxml : ?conn:string -> string -> string -> string
 val capabilities : ?conn:string -> unit -> string
 (** [capabilities ?conn ()] returns the libvirt capabilities XML.
     The optional [?conn] parameter is the libvirt connection URI. *)
+
+val domain_exists : ?conn:string -> string -> bool
+(** [domain_exists ?conn dom] returns a boolean indicating if the
+    the libvirt XML domain [dom] exists.
+    The optional [?conn] parameter is the libvirt connection URI.
+    [dom] may be a guest name, but not a UUID. *)
diff --git a/v2v/output_libvirt.ml b/v2v/output_libvirt.ml
index 8e2337d..9a294e4 100644
--- a/v2v/output_libvirt.ml
+++ b/v2v/output_libvirt.ml
@@ -318,6 +318,11 @@ class output_libvirt verbose oc output_pool = object
   method supported_firmware = [ TargetBIOS; TargetUEFI ]
 
   method prepare_targets source targets =
+    (* Does the domain already exist on the target?  (RHBZ#889082) *)
+    if Domainxml.domain_exists ?conn:oc source.s_name then
+      error (f_"a libvirt domain called '%s' already exists on the target.\n\nUse the '-on' option for virt-v2v to use a different name, or delete the existing domain on the target using the 'virsh undefine' command.")
+            source.s_name;
+
     (* Get the capabilities from libvirt. *)
     let xml = Domainxml.capabilities ?conn:oc () in
     if verbose then printf "libvirt capabilities XML:\n%s\n%!" xml;
-- 
2.3.1