replace with a correct memcmp; problem spotted by rahnds

1 files changed, 31 insertions, 18 deletions

diff --git a/sys/lib/libsa/memcmp.c b/sys/lib/libsa/memcmp.c
index babeac9c91f..7301e7c59c9 100644
--- a/sys/lib/libsa/memcmp.c
+++ b/sys/lib/libsa/memcmp.c
@@ -1,9 +1,10 @@
-/*	$OpenBSD: memcmp.c,v 1.1 1996/10/16 11:32:06 mickey Exp $	*/
-
 /*-
- * Copyright (c) 1996 Michael Shalayeff
+ * Copyright (c) 1990 The Regents of the University of California.
  * All rights reserved.
  *
+ * This code is derived from software contributed to Berkeley by
+ * Chris Torek.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
@@ -14,13 +15,15 @@
  *    documentation and/or other materials provided with the distribution.
  * 3. All advertising materials mentioning features or use of this software
  *    must display the following acknowledgement:
- *	This product includes software developed by Michael Shalayeff.
- * 4. The name of the author may not be used to endorse or promote products
- *    derived from this software without specific prior written permission.
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
  *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 
- * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
@@ -29,19 +32,29 @@
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
- *
  */
 
-#include <sys/types.h>
-#include "stand.h"
+#if defined(LIBC_SCCS) && !defined(lint)
+static char *rcsid = "$OpenBSD: memcmp.c,v 1.2 1996/10/24 23:09:09 deraadt Exp $";
+#endif /* LIBC_SCCS and not lint */
 
+#include <string.h>
+
+/*
+ * Compare memory regions.
+ */
 int
 memcmp(s1, s2, n)
-	const void *s1;
-	const void *s2;
-	size_t	n;
+	const void *s1, *s2;
+	size_t n;
 {
-	while(n-- && *(char*)s1 == *(char*)s2)
-		((char*)s1)++, ((char*)s2)++;
-	return *(char*)s1 - *(char*)s2;
+	if (n != 0) {
+		register const unsigned char *p1 = s1, *p2 = s2;
+
+		do {
+			if (*p1++ != *p2++)
+				return (*--p1 - *--p2);
+		} while (--n != 0);
+	}
+	return (0);
 }