vz: make output arguments in prlsdkGetDomainIds as optional

prlsdkGetDomainIds() returns name and uuid for specified instance.
Now output arguments can be NULL.
It allows to get only necessary info(name or uuid).

src/vz/vz_sdk.c

@@ -346,31 +346,37 @@ prlsdkGetDomainIds(PRL_HANDLE sdkdom,
     PRL_UINT32 len;
     PRL_RESULT pret;
 
-    len = 0;
-    /* get name length */
-    pret = PrlVmCfg_GetName(sdkdom, NULL, &len);
-    prlsdkCheckRetGoto(pret, error);
+    if (name) {
+        len = 0;
+        *name = NULL;
+        /* get name length */
+        pret = PrlVmCfg_GetName(sdkdom, NULL, &len);
+        prlsdkCheckRetGoto(pret, error);
 
-    if (VIR_ALLOC_N(*name, len) < 0)
-        goto error;
+        if (VIR_ALLOC_N(*name, len) < 0)
+            goto error;
 
-    PrlVmCfg_GetName(sdkdom, *name, &len);
-    prlsdkCheckRetGoto(pret, error);
+        pret = PrlVmCfg_GetName(sdkdom, *name, &len);
+        prlsdkCheckRetGoto(pret, error);
+    }
 
-    len = sizeof(uuidstr);
-    PrlVmCfg_GetUuid(sdkdom, uuidstr, &len);
-    prlsdkCheckRetGoto(pret, error);
+    if (uuid) {
+        len = sizeof(uuidstr);
+        pret = PrlVmCfg_GetUuid(sdkdom, uuidstr, &len);
+        prlsdkCheckRetGoto(pret, error);
 
-    if (prlsdkUUIDParse(uuidstr, uuid) < 0) {
-        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                       _("Domain UUID is malformed or empty"));
-        goto error;
+        if (prlsdkUUIDParse(uuidstr, uuid) < 0) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("Domain UUID is malformed or empty"));
+            goto error;
+        }
     }
 
     return 0;
 
  error:
-    VIR_FREE(*name);
+    if (name)
+        VIR_FREE(*name);
     return -1;
 }