From a7cabf16c6c579586b3b490556857dfdcda89ae5 Mon Sep 17 00:00:00 2001
From: Taylor R Campbell <campbell@mumble.net>
Date: Sun, 16 Dec 2018 01:11:58 +0000
Subject: [PATCH] Convert char to unsigned char before using islower/toupper.

Failure to do so is undefined behaviour for any negative char values.
---
 src/microcode/findprim.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/microcode/findprim.c b/src/microcode/findprim.c
index f85f5e232..93eb3c162 100644
--- a/src/microcode/findprim.c
+++ b/src/microcode/findprim.c
@@ -1206,8 +1206,8 @@ strcmp_ci (const char * s1, const char * s2)
 
   while ((length--) > 0)
     {
-      int c1 = (*s1++);
-      int c2 = (*s2++);
+      int c1 = ((unsigned char) (*s1++));
+      int c2 = ((unsigned char) (*s2++));
       if (islower (c1)) c1 = (toupper (c1));
       if (islower (c2)) c2 = (toupper (c2));
       if (c1 < c2) return (-1);
-- 
2.25.1