Add wcsnlen(3), wcslen(3) with a max len argument

Missing function hit by fcambus@ some time ago.  ok millert@

3 files changed, 84 insertions, 7 deletions

diff --git a/src/lib/libc/string/Makefile.inc b/src/lib/libc/string/Makefile.inc
index a1b1934aad..204ca1b266 100644
--- a/src/lib/libc/string/Makefile.inc
+++ b/src/lib/libc/string/Makefile.inc
@@ -1,4 +1,4 @@
-#       $OpenBSD: Makefile.inc,v 1.39 2017/09/05 03:16:13 schwarze Exp $
+#       $OpenBSD: Makefile.inc,v 1.40 2024/07/14 09:51:18 jca Exp $
 
 # string sources
 .PATH: ${LIBCSRCDIR}/arch/${MACHINE_CPU}/string ${LIBCSRCDIR}/string
@@ -9,9 +9,9 @@ SRCS+=	explicit_bzero.c memccpy.c memmem.c memrchr.c stpcpy.c stpncpy.c \
         strndup.c strnlen.c strsignal.c strtok.c strxfrm.c strxfrm_l.c \
         timingsafe_bcmp.c timingsafe_memcmp.c \
         wcscat.c wcschr.c wcscmp.c wcscpy.c wcscspn.c wcslcat.c wcslcpy.c \
-        wcslen.c wcsncat.c wcsncmp.c wcsncpy.c wcspbrk.c wcsrchr.c wcsspn.c \
-        wcsstr.c wcstok.c wcswcs.c wcswidth.c wmemchr.c wmemcmp.c wmemcpy.c \
-        wmemmove.c wmemset.c wcsdup.c wcscasecmp.c wcscasecmp_l.c
+        wcslen.c wcsncat.c wcsncmp.c wcsncpy.c wcsnlen.c wcspbrk.c wcsrchr.c \
+        wcsspn.c wcsstr.c wcstok.c wcswcs.c wcswidth.c wmemchr.c wmemcmp.c \
+        wmemcpy.c wmemmove.c wmemset.c wcsdup.c wcscasecmp.c wcscasecmp_l.c
 
 # machine-dependent net sources
 # ../arch/ARCH/Makefile.inc must include sources for:
diff --git a/src/lib/libc/string/wcslen.3 b/src/lib/libc/string/wcslen.3
index 12f81763ba..b6d9aafc41 100644
--- a/src/lib/libc/string/wcslen.3
+++ b/src/lib/libc/string/wcslen.3
@@ -1,4 +1,4 @@
-.\"     $OpenBSD: wcslen.3,v 1.3 2013/06/05 03:39:23 tedu Exp $
+.\"     $OpenBSD: wcslen.3,v 1.4 2024/07/14 09:51:18 jca Exp $
 .\"
 .\" Copyright (c) 1990, 1991 The Regents of the University of California.
 .\" All rights reserved.
@@ -31,26 +31,50 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd $Mdocdate: June 5 2013 $
+.Dd $Mdocdate: July 14 2024 $
 .Dt WCSLEN 3
 .Os
 .Sh NAME
-.Nm wcslen
+.Nm wcslen ,
+.Nm wcsnlen
 .Nd find length of a wide string
 .Sh SYNOPSIS
 .In wchar.h
 .Ft size_t
 .Fn wcslen "const wchar_t *s"
+.Ft size_t
+.Fn wcsnlen "const wchar_t *s" "size_t maxlen"
 .Sh DESCRIPTION
 The
 .Fn wcslen
 function computes the length of the wide string
 .Fa s .
+The
+.Fn wcsnlen
+function computes the length of the wide string
+.Fa s ,
+up to
+.Fa maxlen
+wide characters.
+The
+.Fn wcsnlen
+function will never attempt to address more than
+.Fa maxlen
+wide characters, making it suitable for use with wide character arrays
+that are not guaranteed to be NUL-terminated.
 .Sh RETURN VALUES
 The
 .Fn wcslen
 function returns the number of wide characters that precede the terminating
 null wide character.
+.Pp
+The
+.Fn wcsnlen
+function returns the number of wide characters that precede the terminating
+null wide character
+or
+.Fa maxlen ,
+whichever is smaller.
 .Sh SEE ALSO
 .Xr strlen 3 ,
 .Xr wcswidth 3
@@ -61,6 +85,10 @@ function conforms to
 .St -isoC-99
 and was first introduced in
 .St -isoC-amd1 .
+The
+.Fn wcsnlen
+function conforms to
+.St -p1003.1-2008 .
 .Sh HISTORY
 The
 .Fn wcslen
@@ -68,3 +96,7 @@ function was ported from
 .Nx
 and first appeared in
 .Ox 3.8 .
+The
+.Fn wcsnlen
+function first appeared in
+.Ox 7.6 .
diff --git a/src/lib/libc/string/wcsnlen.c b/src/lib/libc/string/wcsnlen.c
new file mode 100644
index 0000000000..eb1d08e85b
--- /dev/null
+++ b/src/lib/libc/string/wcsnlen.c
@@ -0,0 +1,45 @@
+/*      $OpenBSD: wcsnlen.c,v 1.1 2024/07/14 09:51:18 jca Exp $ */
+/*      $NetBSD: wcslen.c,v 1.2 2001/01/03 14:29:36 lukem Exp $ */
+
+/*-
+ * Copyright (c)1999 Citrus Project,
+ * 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.
+ *
+ *      citrus Id: wcslen.c,v 1.1 1999/12/29 21:47:45 tshiozak Exp
+ */
+
+#include <wchar.h>
+
+size_t
+wcsnlen(const wchar_t *s, size_t maxlen)
+{
+        const wchar_t *p;
+
+        p = s;
+        while (maxlen-- && *p)
+                p++;
+
+        return p - s;
+}
+