highlighter: when subtracting char, cast to unsigned

Windows.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

diff --git a/contrib/highlighter/highlighter.c b/contrib/highlighter/highlighter.c
index 171a84c97066a4e8fa1f9a046660a0d5b65080eb..1913e3591c7d92c30f811bba55a425a675e60440 100644 (file)
--- a/contrib/highlighter/highlighter.c
+++ b/contrib/highlighter/highlighter.c
@@ -166,9 +166,9 @@ static bool is_valid_uint(string_span_t s, bool support_hex, uint64_t min, uint6
 
        if (support_hex && s.len > 2 && s.s[0] == '0' && s.s[1] == 'x') {
                for (size_t i = 2; i < s.len; ++i) {
-                       if (s.s[i] - '0' < 10)
+                       if ((unsigned)s.s[i] - '0' < 10)
                                val = 16 * val + (s.s[i] - '0');
-                       else if ((s.s[i] | 32) - 'a' < 6)
+                       else if (((unsigned)s.s[i] | 32) - 'a' < 6)
                                val = 16 * val + (s.s[i] | 32) - 'a' + 10;
                        else
                                return false;