virsh: add [--domain DOMAIN] option to domxml-to-native DOMAIN COMMAND

The option allows someone to run domain-to-native on already existing
domain without the need of supplying their XML.  It is basically
wrapper around 'virsh dumpxml  | virsh domxml-to-native /dev/stdin'.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=835476
Signed-off-by: Daniel Liu <srwx4096@gmail.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>
Reviewed-by: John Ferlan <jferlan@redhat.com>

tools/virsh-domain.c

@@ -9856,9 +9856,13 @@ static const vshCmdOptDef opts_domxmltonative[] = {
      .flags = VSH_OFLAG_REQ,
      .help = N_("target config data type format")
     },
+    {.name = "domain",
+     .type = VSH_OT_DATA,
+     .flags = VSH_OFLAG_REQ_OPT,
+     .help = N_("domain name, id or uuid")
+    },
     {.name = "xml",
      .type = VSH_OT_DATA,
-     .flags = VSH_OFLAG_REQ,
      .help = N_("xml data file to export from")
     },
     {.name = NULL}
@@ -9867,30 +9871,51 @@ static const vshCmdOptDef opts_domxmltonative[] = {
 static bool
 cmdDomXMLToNative(vshControl *ctl, const vshCmd *cmd)
 {
-    bool ret = true;
+    bool ret = false;
     const char *format = NULL;
     const char *xmlFile = NULL;
-    char *configData;
+    char *configData = NULL;
-    char *xmlData;
+    char *xmlData = NULL;
     unsigned int flags = 0;
     virshControlPtr priv = ctl->privData;
+    virDomainPtr dom = NULL;
 
     if (vshCommandOptStringReq(ctl, cmd, "format", &format) < 0 ||
         vshCommandOptStringReq(ctl, cmd, "xml", &xmlFile) < 0)
         return false;
 
-    if (virFileReadAll(xmlFile, VSH_MAX_XML_FILE, &xmlData) < 0)
+    VSH_EXCLUSIVE_OPTIONS("domain", "xml");
-        return false;
 
-    configData = virConnectDomainXMLToNative(priv->conn, format, xmlData, flags);
+    if (vshCommandOptBool(cmd, "domain") &&
-    if (configData != NULL) {
+        (!(dom = virshCommandOptDomain(ctl, cmd, NULL))))
-        vshPrint(ctl, "%s", configData);
+            return false;
-        VIR_FREE(configData);
+
+    if (dom) {
+        xmlData = virDomainGetXMLDesc(dom, flags);
+    } else if (xmlFile) {
+        if (virFileReadAll(xmlFile, VSH_MAX_XML_FILE, &xmlData) < 0)
+            goto cleanup;
     } else {
-        ret = false;
+        vshError(ctl, "%s", _("need either domain or domain XML"));
+        goto cleanup;
     }
 
+    if (!xmlData) {
+        vshError(ctl, "%s", _("failed to retrieve XML"));
+        goto cleanup;
+    }
+
+    if (!(configData = virConnectDomainXMLToNative(priv->conn, format, xmlData, flags))) {
+        goto cleanup;
+    } else {
+        vshPrint(ctl, "%s", configData);
+        ret = true;
+    }
+
+ cleanup:
+    virshDomainFree(dom);
     VIR_FREE(xmlData);
+    VIR_FREE(configData);
     return ret;
 }
 

tools/virsh.pod

@@ -1440,13 +1440,19 @@ the I<format> argument must be B<qemu-argv>. For Xen hypervisor, the
 I<format> argument may be B<xen-xm>, B<xen-xl>, or B<xen-sxpr>. For
 LXC hypervisor, the I<format> argument must be B<lxc-tools>.
 
-=item B<domxml-to-native> I<format> I<xml>
+=item B<domxml-to-native> I<format>
+{ [I<--xml>] I<xml> | I<--domain> I<domain-name-or-id-or-uuid> }
 
-Convert the file I<xml> in domain XML format to the native guest
+Convert the file I<xml> into domain XML format or convert an existing
-configuration format named by I<format>. For QEMU/KVM hypervisor,
+I<--domain> to the native guest configuration format named by I<format>.
-the I<format> argument must be B<qemu-argv>. For Xen hypervisor, the
+The I<xml> and I<--domain> arguments are mutually exclusive.
-I<format> argument may be B<xen-xm>, B<xen-xl>, or B<xen-sxpr>. For
+
-LXC hypervisor, the I<format> argument must be B<lxc-tools>.
+For the QEMU/KVM hypervisor, the I<format> argument must be B<qemu-argv>.
+
+For the Xen hypervisor, the I<format> argument may be B<xen-xm>, B<xen-xl>,
+or B<xen-sxpr>.
+
+For the LXC hypervisor, the I<format> argument must be B<lxc-tools>.
 
 =item B<dump> I<domain> I<corefilepath> [I<--bypass-cache>]
 { [I<--live>] | [I<--crash>] | [I<--reset>] } [I<--verbose>] [I<--memory-only>]