Don't pass NULL to yajl_free()

Unfortunately, yajl_free() is not NOP on NULL. It really does
expect a valid pointer. Therefore, check whether the pointer we
want to pass to it is NULL or not.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>

src/util/virjson.c

@@ -1838,7 +1838,7 @@ virJSONValueFromString(const char *jsonstring)
     if (!hand) {
         virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
                        _("Unable to create JSON parser"));
-        goto cleanup;
+        return NULL;
     }
 
     /* Yajl 2 is nice enough to default to rejecting trailing garbage. */

tools/nss/libvirt_nss_leases.c

@@ -426,7 +426,8 @@ findLeases(const char *file,
         *addrs = NULL;
         *naddrs = 0;
     }
-    yajl_free(parser);
+    if (parser)
+        yajl_free(parser);
     free(parserState.entry.ipaddr);
     free(parserState.entry.macaddr);
     free(parserState.entry.hostname);

tools/nss/libvirt_nss_macs.c

@@ -278,7 +278,8 @@ findMACs(const char *file,
         *macs = NULL;
         *nmacs = 0;
     }
-    yajl_free(parser);
+    if (parser)
+        yajl_free(parser);
     for (i = 0; i < parserState.entry.nmacs; i++)
         free(parserState.entry.macs[i]);
     free(parserState.entry.macs);