strnlen(3) in kernel

[Jean-Yves Migeon <jeanyves.migeon%free.fr@localhost>]

Hi list,

Subject says it all. Anyone objects?

Motivation behind:
- we already have strlen(3), so having strnlen(3) in kernel is somehow
natural.
- avoids things like [1] (there are probably other possible consumers in
kernel).

http://nxr.netbsd.org/xref/src/sys/arch/usermode/usermode/copy.c#34

Comments? If no-one objects, I'll commit this at the end of the week.

-- 
Jean-Yves Migeon
jeanyves.migeon%free.fr@localhost

Index: sys/lib/libkern/libkern.h
===================================================================
RCS file: /cvsroot/src/sys/lib/libkern/libkern.h,v
retrieving revision 1.98
diff -u -p -u -p -r1.98 libkern.h
--- sys/lib/libkern/libkern.h   5 Jul 2011 01:56:45 -0000       1.98
+++ sys/lib/libkern/libkern.h   31 Aug 2011 20:25:48 -0000
@@ -277,6 +277,7 @@ void        *memset(void *, int, size_t);
 char   *strcpy(char *, const char *);
 int     strcmp(const char *, const char *);
 size_t  strlen(const char *);
+size_t  strnlen(const char *, size_t);
 char   *strsep(char **, const char *);
 #if __GNUC_PREREQ__(2, 95) && !defined(_STANDALONE)
 #define        strcpy(d, s)            __builtin_strcpy(d, s)
--- /dev/null   2011-08-31 22:45:25.000000000 +0200
+++ common/lib/libc/string/strnlen.c    2011-08-31 11:31:45.000000000 +0200
@@ -0,0 +1,51 @@
+/*     $NetBSD: strnlen.c,v 1.1 2009/05/01 17:27:01 perry Exp $        */
+
+/*-
+ * Copyright (c) 2009 David Schultz <das%FreeBSD.org@localhost>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * 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/cdefs.h>
+#if defined(LIBC_SCCS) && !defined(lint)
+__RCSID("$NetBSD: strnlen.c,v 1.1 2009/05/01 17:27:01 perry Exp $");
+#endif /* LIBC_SCCS and not lint */
+/* FreeBSD: src/lib/libc/string/strnlen.c,v 1.1 2009/02/28 06:00:58 das Exp */
+
+#if !defined(_KERNEL) && !defined(_STANDALONE)
+#include <string.h>
+#else
+#include <lib/libkern/libkern.h>
+#endif
+
+size_t
+strnlen(const char *s, size_t maxlen)
+{
+       size_t len;
+
+       for (len = 0; len < maxlen; len++, s++) {
+               if (!*s)
+                       break;
+       }
+       return (len);
+}