Better fix - just check that the upper and lower nibbles are >= 0xA.

An unsigned 8-bit integer is always <= 0xFF; that was the cause of the
warning.

To see whether a byte, when represented as hex, has letters for its
upper and lower nibbles, just check whether both nibbles are >= 0xA.
Cast the extracted nibbles to make sure there's no sign-extension.

Change-Id: If4c7717a5d2fe341c02e9309ee6b89973a6ac292
Reviewed-on: https://code.wireshark.org/review/4739
Reviewed-by: Guy Harris <guy@alum.mit.edu>

1 files changed, 5 insertions, 17 deletions

diff --git a/epan/ftypes/ftype-pcre.c b/epan/ftypes/ftype-pcre.c
index 693ea88423..947aff3047 100644
--- a/epan/ftypes/ftype-pcre.c
+++ b/epan/ftypes/ftype-pcre.c
@@ -50,27 +50,15 @@ static gboolean
 raw_flag_needed(const gchar *pattern)
 {
     gboolean found = FALSE;
-    /*
-     * gchar is neither guaranteed to be signed nor guaranteed to be
-     * unsigned.  Make s point to guint8, and use regular hex constants,
-     * to make sure the comparisons are unsigned vs. unsigned (on at
-     * least one ARM version of gcc, with char being unsigned, the
-     * comparisons before those changes warned about always being
-     * true due to the limited range of the data type).
-     */
-    const guint8 *s;
+    const gchar *s = pattern;
     size_t i, len;
 
     /* find any character whose hex value is two letters */
-    len = strlen(pattern);
-    s = (const guint8 *)pattern;
+    len = strlen(s);
     for (i = 0; i < len; i++) {
-        if ((s[i] >= 0xAA && s[i] <= 0xAF) ||
-            (s[i] >= 0xBA && s[i] <= 0xBF) ||
-            (s[i] >= 0xCA && s[i] <= 0xCF) ||
-            (s[i] >= 0xDA && s[i] <= 0xDF) ||
-            (s[i] >= 0xEA && s[i] <= 0xEF) ||
-            (s[i] >= 0xFA && s[i] <= 0xFF))
+        /* Upper and lower-nibble must be >= 0xA */
+        if ((guchar)(s[i] & 0xF0) >= 0xA0 &&
+            (guchar)(s[i] & 0x0F) >= 0x0A)
         {
             found = TRUE;
             break;