Fix [Bug 1631017]

2 files changed, 10 insertions, 4 deletions

diff --git a/ChangeLog b/ChangeLog
index 2ec53a9..a1eeba0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2007-01-22  Donal K. Fellows  <donal.k.fellows@man.ac.uk>
+
+	* compat/memcmp.c (memcmp): Reworked so that arithmetic is never
+	performed upon void pointers, since that is illegal. [Bug 1631017]
+
 2006-01-19  Daniel Steffen  <das@users.sourceforge.net>
 
 	* macosx/tclMacOSXNotify.c: accommodate changes to prototypes of
diff --git a/compat/memcmp.c b/compat/memcmp.c
index 09a5724..dd4cacc 100644
--- a/compat/memcmp.c
+++ b/compat/memcmp.c
@@ -48,11 +48,12 @@ memcmp(s1, s2, n)
     CONST VOID *s2;			/* Second string. */
     size_t      n;                      /* Length to compare. */
 {
-    unsigned char u1, u2;
+    VOID unsigned char *ptr1 = (VOID unsigned char *) s1;
+    VOID unsigned char *ptr2 = (VOID unsigned char *) s2;
+
+    for ( ; n-- ; ptr1++, ptr2++) {
+	unsigned char u1 = *s1, u2 = *s2;
 
-    for ( ; n-- ; s1++, s2++) {
-	u1 = * (unsigned char *) s1;
-	u2 = * (unsigned char *) s2;
 	if ( u1 != u2) {
 	    return (u1-u2);
 	}