rgw : add check empty for sync url

Fixes: https://tracker.ceph.com/issues/50103
Signed-off-by: caolei <halei15848934852@163.com>

diff --git a/src/rgw/rgw_rest_client.cc b/src/rgw/rgw_rest_client.cc
index a98ba3b60d824a4da9f60318bbfac1f63cd76502..938a0cb59702c6e96b1361b2d24ded7e2dd64d32 100644 (file)
--- a/src/rgw/rgw_rest_client.cc
+++ b/src/rgw/rgw_rest_client.cc
@@ -813,7 +813,7 @@ int RGWRESTStreamRWRequest::do_send_prepare(RGWAccessKey *key, map<string, strin
                                          bufferlist *send_data)
 {
   string new_url = url;
-  if (new_url[new_url.size() - 1] != '/')
+  if (!new_url.empty() && new_url.back() != '/')
     new_url.append("/");
   
   string new_resource;