commit afffab10a4d752af24f6ea2b83a0ac1a3f2c633d
author Johan Hedberg <johan.hedberg@intel.com> Tue May 19 20:43:30 2015 +0300
committer Anas Nashif <anas.nashif@intel.com> Fri Feb 05 20:14:00 2016 -0500
tree c5b5a9d450f8f820c41c776589e045f04e3e0f2d
parent 7fc1c37c328c51965554f58cb5f5402f08f9e2c7

libc: Fix memcmp implementation

The previous implementation would read one byte past both buffers if
the buffers were equal. Make sure the pointers are not incremented
past the last byte. Also ensure that comparing zero bytes always
returns 0.

Change-Id: I5ef25d6bd2f7417b60102dc1c2602d8b23c4c1bc
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

lib/libc/minimal/source/string/string.c

diff --git a/lib/libc/minimal/source/string/string.c b/lib/libc/minimal/source/string/string.c
index 7218e33..f93f526 100644
--- a/lib/libc/minimal/source/string/string.c
+++ b/lib/libc/minimal/source/string/string.c
@@ -164,10 +164,12 @@
 	const char *c1 = m1;
 	const char *c2 = m2;
 
-	while ((n > 0) && (*c1 == *c2)) {
+	if (!n)
+		return 0;
+
+	while ((--n > 0) && (*c1 == *c2)) {
 		c1++;
 		c2++;
-		n--;
 	}
 
 	return *c1 - *c2;