StdLib: Fix pointer arithmetic issues in the strncasecmp function.

The original Linux code tried to be too fancy so the internal pointers got out of sync.
Rewrote the function to at least be more clear.
Regardless, it now works properly.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Daryl McDaniel <daryl.mcdaniel@intel.com>
Reviewed by: matthew.stanbro@intel.com
Reviewed by: erik.c.bjorge@intel.com


git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@14664 6f19259b-4bc3-4df7-8a09-765794883524

1 files changed, 22 insertions, 19 deletions

diff --git a/StdLib/LibC/String/strncasecmp.c b/StdLib/LibC/String/strncasecmp.c
index b3f6d05965..9cc1851ee2 100644
--- a/StdLib/LibC/String/strncasecmp.c
+++ b/StdLib/LibC/String/strncasecmp.c
@@ -1,4 +1,4 @@
-/** @file 

+/** @file

   strncasecmp implementation

 

   Copyright (c) 2011, Intel Corporation. All rights reserved.<BR>

@@ -11,7 +11,7 @@
   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

 

  * Copyright (c) 1987, 1993

- *	The Regents of the University of California.  All rights reserved.

+ *  The Regents of the University of California.  All rights reserved.

  *

  * Redistribution and use in source and binary forms, with or without

  * modification, are permitted provided that the following conditions

@@ -37,8 +37,8 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

  * SUCH DAMAGE.

 

-	$NetBSD: strncasecmp.c,v 1.2 2007/06/04 18:19:27 christos Exp $

-  strcasecmp.c	8.1 (Berkeley) 6/4/93

+  $NetBSD: strncasecmp.c,v 1.2 2007/06/04 18:19:27 christos Exp $

+  strcasecmp.c  8.1 (Berkeley) 6/4/93

 **/

 #include <LibConfig.h>

 #include <sys/cdefs.h>

@@ -55,25 +55,28 @@ __weak_alias(strncasecmp,_strncasecmp)
 #else

 #include <lib/libkern/libkern.h>

 #include <machine/limits.h>

-#endif 

+#endif

 

 int

 strncasecmp(const char *s1, const char *s2, size_t n)

 {

+  int   CompareVal;

 

-	_DIAGASSERT(s1 != NULL);

-	_DIAGASSERT(s2 != NULL);

-

-	if (n != 0) {

-		const unsigned char *us1 = (const unsigned char *)s1,

-				*us2 = (const unsigned char *)s2;

+  _DIAGASSERT(s1 != NULL);

+  _DIAGASSERT(s2 != NULL);

 

-		do {

-			if (tolower(*us1) != tolower(*us2++))

-				return (tolower(*us1) - tolower(*--us2));

-			if (*us1++ == '\0')

-				break;

-		} while (--n != 0);

-	}

-	return (0);

+  if (n != 0) {

+    do {

+      CompareVal = tolower(*s1) - tolower(*s2);

+      if (CompareVal != 0) {

+        return (CompareVal);

+      }

+      ++s1;

+      ++s2;

+      if (*s1 == '\0') {

+        break;

+      }

+    } while (--n != 0);

+  }

+  return (0);

 }