From: Samuel Just <sjust@redhat.com>
Date: Sat, 21 Dec 2019 02:11:58 +0000 (+0000)
Subject: rgw_kms: fix concat_url for empty url case
X-Git-Tag: v15.1.0~91^2
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=181d991e53c13a1add675b58c22f8f5d79fc8768;p=ceph.git

rgw_kms: fix concat_url for empty url case

Can't call back() on an empty string.  Causes unittest_rgw_kms
to fail when compiled with _GLIBCXX_ASSERTIONS.

Signed-off-by: Samuel Just <sjust@redhat.com>
---

diff --git a/src/rgw/rgw_kms.cc b/src/rgw/rgw_kms.cc
index 098edeca51bd..dd6ba062d08d 100644
--- a/src/rgw/rgw_kms.cc
+++ b/src/rgw/rgw_kms.cc
@@ -25,10 +25,11 @@ using namespace rgw;
  * empty, the URL is not changed.
  */
 static void concat_url(std::string &url, std::string path) {
+  bool url_has_slash = !url.empty() && url.back() == '/';
   if (!path.empty()) {
-    if (url.back() == '/' && path.front() == '/') {
+    if (url_has_slash && path.front() == '/') {
       url.pop_back();
-    } else if (url.back() != '/' && path.front() != '/') {
+    } else if (!url_has_slash && path.front() != '/') {
       url.push_back('/');
     }
     url.append(path);