From 5b83a015909e5aa7e3909a3fafa0f231360a3475 Mon Sep 17 00:00:00 2001
From: Przemyslaw Skibinski <przemyslaw.skibinski@percona.com>
Date: Mon, 4 Nov 2019 13:47:21 +0100
Subject: [PATCH] PS-6052: gcc 9.2.1 reports new warnings

---
 storage/innobase/os/os0file.cc | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/storage/innobase/os/os0file.cc b/storage/innobase/os/os0file.cc
index 58b0a28b78d0..d44bfdf4b80b 100644
--- a/storage/innobase/os/os0file.cc
+++ b/storage/innobase/os/os0file.cc
@@ -1990,6 +1990,11 @@ static char *os_file_get_parent_dir(const char *path) {
     return (NULL);
   }
 
+  /* Make sure that mem_strdupl() will get non-negative "ulint len" */
+  if (last_slash - path < 0) {
+    return (NULL);
+  }
+
   /* Non-trivial directory component */
 
   return (mem_strdupl(path, last_slash - path));