avoid (size_t)--

The decrements overflow and these variables remain ~0 when leaving the
while loops.  They are not fatal by accident, but better replace with
ordinal for loops.

See also: https://travis-ci.org/ruby/ruby/jobs/452218871#L3246


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65624 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

st.c

@@ -2036,8 +2036,9 @@ int
 st_locale_insensitive_strncasecmp(const char *s1, const char *s2, size_t n)
 {
     char c1, c2;
+    int i;
 
-    while (n--) {
+    for (i = 0; i < n; i++) {
         c1 = *s1++;
         c2 = *s2++;
         if (c1 == '\0' || c2 == '\0') {

util.c

@@ -35,8 +35,12 @@ ruby_scan_oct(const char *start, size_t len, size_t *retlen)
 {
     register const char *s = start;
     register unsigned long retval = 0;
+    size_t i;
 
-    while (len-- && *s >= '0' && *s <= '7') {
+    for (i = 0; i < len; i++) {
+        if ((s[0] < '0') || ('7' <= s[0])) {
+            break;
+        }
 	retval <<= 3;
 	retval |= *s++ - '0';
     }