linux-kernel - [PATCH 3.16 17/99] lib/string.c: remove duplicated function

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Date:   Tue, 02 Apr 2019 14:38:27 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Linus Torvalds" <torvalds@...ux-foundation.org>,
        "Andi Kleen" <ak@...ux.intel.com>,
        "Dan Carpenter" <dan.carpenter@...cle.com>,
        "Rasmus Villemoes" <linux@...musvillemoes.dk>,
        "H. Peter Anvin" <hpa@...ux.intel.com>,
        "Grant Likely" <grant.likely@...aro.org>
Subject: [PATCH 3.16 17/99] lib/string.c: remove duplicated function

3.16.65-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Rasmus Villemoes <linux@...musvillemoes.dk>

commit cd514e727b18ff4d189b8e268db13729a4175091 upstream.

lib/string.c contains two functions, strnicmp and strncasecmp, which do
roughly the same thing, namely compare two strings case-insensitively up
to a given bound.  They have slightly different implementations, but the
only important difference is that strncasecmp doesn't handle len==0
appropriately; it effectively becomes strcasecmp in that case.  strnicmp
correctly says that two strings are always equal in their first 0
characters.

strncasecmp is the POSIX name for this functionality.  So rename the
non-broken function to the standard name.  To minimize the impact on the
rest of the kernel (and since both are exported to modules), make strnicmp
a wrapper for strncasecmp.

Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>
Cc: Grant Likely <grant.likely@...aro.org>
Cc: Andi Kleen <ak@...ux.intel.com>
Cc: Dan Carpenter <dan.carpenter@...cle.com>
Cc: "H. Peter Anvin" <hpa@...ux.intel.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 lib/string.c | 27 ++++++++++-----------------
 1 file changed, 10 insertions(+), 17 deletions(-)

--- a/lib/string.c
+++ b/lib/string.c
@@ -31,14 +31,14 @@
 #include <asm/word-at-a-time.h>
 #include <asm/page.h>
 
-#ifndef __HAVE_ARCH_STRNICMP
+#ifndef __HAVE_ARCH_STRNCASECMP
 /**
- * strnicmp - Case insensitive, length-limited string comparison
+ * strncasecmp - Case insensitive, length-limited string comparison
  * @s1: One string
  * @s2: The other string
  * @len: the maximum number of characters to compare
  */
-int strnicmp(const char *s1, const char *s2, size_t len)
+int strncasecmp(const char *s1, const char *s2, size_t len)
 {
 	/* Yes, Virginia, it had better be unsigned */
 	unsigned char c1, c2;
@@ -60,6 +60,13 @@ int strnicmp(const char *s1, const char
 	} while (--len);
 	return (int)c1 - (int)c2;
 }
+EXPORT_SYMBOL(strncasecmp);
+#endif
+#ifndef __HAVE_ARCH_STRNICMP
+int strnicmp(const char *s1, const char *s2, size_t len)
+{
+	return strncasecmp(s1, s2, len);
+}
 EXPORT_SYMBOL(strnicmp);
 #endif
 
@@ -77,20 +84,6 @@ int strcasecmp(const char *s1, const cha
 EXPORT_SYMBOL(strcasecmp);
 #endif
 
-#ifndef __HAVE_ARCH_STRNCASECMP
-int strncasecmp(const char *s1, const char *s2, size_t n)
-{
-	int c1, c2;
-
-	do {
-		c1 = tolower(*s1++);
-		c2 = tolower(*s2++);
-	} while ((--n > 0) && c1 == c2 && c1 != 0);
-	return c1 - c2;
-}
-EXPORT_SYMBOL(strncasecmp);
-#endif
-
 #ifndef __HAVE_ARCH_STRCPY
 /**
  * strcpy - Copy a %NUL terminated string