From: Taylor R Campbell <campbell@mumble.net>
Date: Sun, 16 Dec 2018 01:11:58 +0000 (+0000)
Subject: Convert char to unsigned char before using islower/toupper.
X-Git-Tag: mit-scheme-pucked-10.1.9~3^2~35^2~1
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=a7cabf16c6c579586b3b490556857dfdcda89ae5;p=mit-scheme.git

Convert char to unsigned char before using islower/toupper.

Failure to do so is undefined behaviour for any negative char values.
---

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);