svn commit: r249139 - head/sys/boot/common

Andriy Gapon avg at FreeBSD.org
Fri Apr 5 09:14:31 UTC 2013


Author: avg
Date: Fri Apr  5 09:14:30 2013
New Revision: 249139
URL: http://svnweb.freebsd.org/changeset/base/249139

Log:
  strncmp for boot code: fix an off by one error
  
  Before this change strncmp would access and _compare_ n+1 characters
  in the case where the first n characters match.
  
  MFC after:	5 days

Modified:
  head/sys/boot/common/util.c

Modified: head/sys/boot/common/util.c
==============================================================================
--- head/sys/boot/common/util.c	Fri Apr  5 09:06:59 2013	(r249138)
+++ head/sys/boot/common/util.c	Fri Apr  5 09:14:30 2013	(r249139)
@@ -68,9 +68,9 @@ int
 strncmp(const char *s1, const char *s2, size_t len)
 {
 
-	for (; *s1 == *s2 && *s1 != '\0' && len > 0; len--, s1++, s2++)
+	for (; len > 0 && *s1 == *s2 && *s1 != '\0'; len--, s1++, s2++)
 		;
-	return ((unsigned char)*s1 - (unsigned char)*s2);
+	return (len == 0 ? 0 : (unsigned char)*s1 - (unsigned char)*s2);
 }
 
 void


More information about the svn-src-all mailing list