New POSIX xlocale implementation written from scratch.

Complete in the sense that all POSIX *locale(3) and *_l(3) functions
are included, but in OpenBSD, we of course only really care about
LC_CTYPE and we only support ASCII and UTF-8.

With important help from kettenis@, guenther@, and jca@.
Repeated testing in ports bulk builds by naddy@.
Additional testing by jca@, sebastia@, dcoppa@, and others.
OK kettenis@ dcoppa@, and guenther@ on an earlier version.
Riding guenther@'s libc/librthread major bump.

11 files changed, 396 insertions, 96 deletions

diff --git a/lib/libc/string/Makefile.inc b/lib/libc/string/Makefile.inc
index 95eb93006b8..a1b1934aad0 100644
--- a/lib/libc/string/Makefile.inc
+++ b/lib/libc/string/Makefile.inc
@@ -1,17 +1,17 @@
-#	$OpenBSD: Makefile.inc,v 1.38 2016/03/30 06:38:41 jmc Exp $
+#	$OpenBSD: Makefile.inc,v 1.39 2017/09/05 03:16:13 schwarze Exp $
 
 # string sources
 .PATH: ${LIBCSRCDIR}/arch/${MACHINE_CPU}/string ${LIBCSRCDIR}/string
 
 SRCS+=	explicit_bzero.c memccpy.c memmem.c memrchr.c stpcpy.c stpncpy.c \
-	strcasecmp.c strcasestr.c strcoll.c strdup.c \
-	strerror.c strerror_r.c strmode.c strndup.c strnlen.c \
-	strsignal.c strtok.c strxfrm.c \
+	strcasecmp.c strcasecmp_l.c strcasestr.c strcoll.c strcoll_l.c \
+	strdup.c strerror.c strerror_l.c strerror_r.c strmode.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
+	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/lib/libc/string/strcasecmp.3 b/lib/libc/string/strcasecmp.3
index 38703622160..bb39df895a0 100644
--- a/lib/libc/string/strcasecmp.3
+++ b/lib/libc/string/strcasecmp.3
@@ -1,7 +1,8 @@
-.\"	$OpenBSD: strcasecmp.3,v 1.13 2015/11/24 09:14:35 daniel Exp $
+.\"	$OpenBSD: strcasecmp.3,v 1.14 2017/09/05 03:16:13 schwarze Exp $
 .\"
 .\" Copyright (c) 1990, 1991, 1993
 .\"	The Regents of the University of California.  All rights reserved.
+.\" Copyright (c) 2017 Ingo Schwarze <schwarze@openbsd.org>
 .\"
 .\" This code is derived from software contributed to Berkeley by
 .\" Chris Torek.
@@ -31,25 +32,43 @@
 .\"
 .\"     @(#)strcasecmp.3	8.1 (Berkeley) 6/9/93
 .\"
-.Dd $Mdocdate: November 24 2015 $
+.Dd $Mdocdate: September 5 2017 $
 .Dt STRCASECMP 3
 .Os
 .Sh NAME
 .Nm strcasecmp ,
-.Nm strncasecmp
+.Nm strcasecmp_l ,
+.Nm strncasecmp ,
+.Nm strncasecmp_l
 .Nd compare strings, ignoring case
 .Sh SYNOPSIS
 .In strings.h
 .Ft int
-.Fn strcasecmp "const char *s1" "const char *s2"
+.Fo strcasecmp
+.Fa "const char *s1"
+.Fa "const char *s2"
+.Fc
 .Ft int
-.Fn strncasecmp "const char *s1" "const char *s2" "size_t len"
+.Fo strcasecmp_l
+.Fa "const char *s1"
+.Fa "const char *s2"
+.Fa "locale_t locale"
+.Fc
+.Ft int
+.Fo strncasecmp
+.Fa "const char *s1"
+.Fa "const char *s2"
+.Fa "size_t len"
+.Fc
+.Ft int
+.Fo strncasecmp_l
+.Fa "const char *s1"
+.Fa "const char *s2"
+.Fa "size_t len"
+.Fa "locale_t locale"
+.Fc
 .Sh DESCRIPTION
-The
-.Fn strcasecmp
-and
-.Fn strncasecmp
-functions compare the NUL-terminated strings
+These functions compare the NUL-terminated strings
 .Fa s1
 and
 .Fa s2
@@ -66,27 +85,44 @@ is greater than
 .Ql \e0 .
 .Pp
 .Fn strncasecmp
-compares at most
+and
+.Fn strncasecmp_l
+compare at most
 .Fa len
 characters.
+.Pp
+On
+.Ox ,
+these functions always use the C locale and ignore
+the global locale, the thread-specific locale, and the
+.Fa locale
+argument.
+.Sh ENVIRONMENT
+On other operating systems, the behaviour of
+.Fn strcasecmp
+and
+.Fn strncasecmp
+may depend on the
+.Dv LC_CTYPE
+.Xr locale 1 .
 .Sh SEE ALSO
-.Xr bcmp 3 ,
-.Xr memcmp 3 ,
 .Xr strcmp 3 ,
 .Xr strcoll 3 ,
 .Xr strxfrm 3 ,
 .Xr wcscasecmp 3
 .Sh STANDARDS
-The
-.Fn strcasecmp
-and
-.Fn strncasecmp
-functions conform to
+These functions conform to
 .St -p1003.1-2008 .
 .Sh HISTORY
 The
 .Fn strcasecmp
 and
 .Fn strncasecmp
-functions first appeared in
-.Bx 4.3 Tahoe .
+functions have been available since
+.Bx 4.3 Tahoe ,
+and
+.Fn strcasecmp_l
+and
+.Fn strncasecmp_l
+since
+.Ox 6.2 .
diff --git a/lib/libc/string/strcasecmp_l.c b/lib/libc/string/strcasecmp_l.c
new file mode 100644
index 00000000000..a9543dda118
--- /dev/null
+++ b/lib/libc/string/strcasecmp_l.c
@@ -0,0 +1,21 @@
+/*	$OpenBSD: strcasecmp_l.c,v 1.1 2017/09/05 03:16:13 schwarze Exp $ */
+/*
+ * Written in 2017 by Ingo Schwarze <schwarze@openbsd.org>.
+ * Released into the public domain.
+ */
+
+#include <string.h>
+
+int
+strcasecmp_l(const char *s1, const char *s2,
+    locale_t locale __attribute__((__unused__)))
+{
+	return strcasecmp(s1, s2);
+}
+
+int
+strncasecmp_l(const char *s1, const char *s2, size_t n,
+    locale_t locale __attribute__((__unused__)))
+{
+	return strncasecmp(s1, s2, n);
+}
diff --git a/lib/libc/string/strcoll.3 b/lib/libc/string/strcoll.3
index d421200b628..4ba1f226776 100644
--- a/lib/libc/string/strcoll.3
+++ b/lib/libc/string/strcoll.3
@@ -1,4 +1,7 @@
+.\"	$OpenBSD: strcoll.3,v 1.10 2017/09/05 03:16:13 schwarze Exp $
+.\"
 .\" Copyright (c) 1990, 1991 The Regents of the University of California.
+.\" Copyright (c) 2017 Ingo Schwarze <schwarze@openbsd.org>
 .\" All rights reserved.
 .\"
 .\" This code is derived from software contributed to Berkeley by
@@ -29,45 +32,69 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.\"	$OpenBSD: strcoll.3,v 1.9 2013/06/05 03:39:23 tedu Exp $
-.\"
-.Dd $Mdocdate: June 5 2013 $
+.Dd $Mdocdate: September 5 2017 $
 .Dt STRCOLL 3
 .Os
 .Sh NAME
-.Nm strcoll
+.Nm strcoll ,
+.Nm strcoll_l
 .Nd compare strings according to current collation
 .Sh SYNOPSIS
 .In string.h
 .Ft int
 .Fn strcoll "const char *s1" "const char *s2"
+.Ft int
+.Fn strcoll_l "const char *s1" "const char *s2" "locale_t locale"
 .Sh DESCRIPTION
 The
 .Fn strcoll
-function lexicographically compares the NUL-terminated strings
+and
+.Fn strcoll_l
+functions lexicographically compare the NUL-terminated strings
 .Fa s1
 and
 .Fa s2
 according to the current locale collation
-and returns an integer greater than, equal to, or less than 0,
+and return an integer greater than, equal to, or less than 0,
 according to whether
 .Fa s1
 is greater than, equal to, or less than
 .Fa s2 .
+.Pp
+On
+.Ox ,
+they have the same effect as
+.Xr strcmp 3 ,
+and the global locale, the thread-specific locale, and the
+.Fa locale
+argument are ignored.
+.Sh ENVIRONMENT
+On other operating systems, the behaviour of
+.Fn strcoll
+may depend on the
+.Dv LC_CTYPE
+.Xr locale 1 .
 .Sh SEE ALSO
-.Xr bcmp 3 ,
-.Xr memcmp 3 ,
+.Xr newlocale 3 ,
 .Xr setlocale 3 ,
-.Xr strcasecmp 3 ,
 .Xr strcmp 3 ,
-.Xr strxfrm 3
+.Xr strxfrm 3 ,
+.Xr wcscoll 3
 .Sh STANDARDS
 The
 .Fn strcoll
 function conforms to
-.St -ansiC .
+.St -ansiC ,
+and
+.Fn strcoll_l
+to
+.St -p1003.1-2008 .
 .Sh HISTORY
 The
 .Fn strcoll
-function first appeared in
-.Bx 4.3 Reno .
+function has been available since
+.Bx 4.3 Reno ,
+and
+.Fn strcoll_l
+since
+.Ox 6.2 .
diff --git a/lib/libc/string/strcoll_l.c b/lib/libc/string/strcoll_l.c
new file mode 100644
index 00000000000..bcd5b0f4177
--- /dev/null
+++ b/lib/libc/string/strcoll_l.c
@@ -0,0 +1,14 @@
+/*	$OpenBSD: strcoll_l.c,v 1.1 2017/09/05 03:16:13 schwarze Exp $ */
+/*
+ * Written in 2017 by Ingo Schwarze <schwarze@openbsd.org>.
+ * Released into the public domain.
+ */
+
+#include <string.h>
+
+int
+strcoll_l(const char *s1, const char *s2,
+    locale_t locale __attribute__((__unused__)))
+{
+	return strcmp(s1, s2);
+}
diff --git a/lib/libc/string/strerror.3 b/lib/libc/string/strerror.3
index 8b2d32ea75a..0d4f084e5e0 100644
--- a/lib/libc/string/strerror.3
+++ b/lib/libc/string/strerror.3
@@ -1,4 +1,7 @@
+.\"	$OpenBSD: strerror.3,v 1.15 2017/09/05 03:16:13 schwarze Exp $
+.\"
 .\" Copyright (c) 1980, 1991 Regents of the University of California.
+.\" Copyright (c) 2017 Ingo Schwarze <schwarze@openbsd.org>
 .\" All rights reserved.
 .\"
 .\" This code is derived from software contributed to Berkeley by
@@ -29,46 +32,61 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.\"	$OpenBSD: strerror.3,v 1.14 2014/11/30 21:21:59 schwarze Exp $
-.\"
-.Dd $Mdocdate: November 30 2014 $
+.Dd $Mdocdate: September 5 2017 $
 .Dt STRERROR 3
 .Os
 .Sh NAME
 .Nm strerror ,
+.Nm strerror_l ,
 .Nm strerror_r
 .Nd get error message string
 .Sh SYNOPSIS
 .In string.h
 .Ft char *
 .Fn strerror "int errnum"
+.Ft char *
+.Fn strerror_l "int errnum" "locale_t locale"
 .Ft int
 .Fn strerror_r "int errnum" "char *strerrbuf" "size_t buflen"
 .Sh DESCRIPTION
-The
-.Fn strerror
-and
-.Fn strerror_r
-functions map the error number
+These functions map the error number
 .Fa errnum
-to a language-dependent error message string.
+to an error message string.
 .Pp
 .Fn strerror
-returns a string containing a maximum of
+and
+.Fn strerror_l
+return a string containing a maximum of
 .Dv NL_TEXTMAX
 characters, including the trailing NUL.
-This string is not to be modified by the calling program,
-but may be overwritten by subsequent calls to
-.Fn strerror .
+This string is not to be modified by the calling program.
+The string returned by
+.Fn strerror
+may be overwritten by subsequent calls to
+.Fn strerror
+in any thread.
+The string returned by
+.Fn strerror_l
+may be overwritten by subsequent calls to
+.Fn strerror_l
+in the same thread.
 .Pp
 .Fn strerror_r
 is a thread safe version of
 .Fn strerror
 that places the error message in the specified buffer
 .Fa strerrbuf .
+.Pp
+On
+.Ox ,
+the global locale, the thread-specific locale, and the
+.Fa locale
+argument are ignored.
 .Sh RETURN VALUES
 .Fn strerror
-returns a pointer to the error message string.
+and
+.Fn strerror_l
+return a pointer to the error message string.
 If an error occurs, the error code is stored in
 .Va errno .
 .Pp
@@ -77,11 +95,16 @@ returns zero upon successful completion.
 If an error occurs, the error code is stored in
 .Va errno
 and the error code is returned.
-.Sh ERRORS
+.Sh ENVIRONMENT
+On other operating systems, the behaviour of
 .Fn strerror
 and
 .Fn strerror_r
-may fail if:
+may depend on the
+.Dv LC_MESSAGES
+.Xr locale 1 .
+.Sh ERRORS
+All these functions may fail if:
 .Bl -tag -width Er
 .It Bq Er EINVAL
 .Fa errnum
@@ -91,7 +114,7 @@ The returned error string will consist of an error message that includes
 .El
 .Pp
 .Fn strerror_r
-may fail if:
+may also fail if:
 .Bl -tag -width Er
 .It Bq Er ERANGE
 The error message is larger than
@@ -101,6 +124,7 @@ The message will be truncated to fit.
 .El
 .Sh SEE ALSO
 .Xr intro 2 ,
+.Xr newlocale 3 ,
 .Xr perror 3 ,
 .Xr setlocale 3
 .Sh STANDARDS
@@ -109,15 +133,20 @@ The
 function conforms to
 .St -isoC-99 .
 The
+.Fn strerror_l
+and
 .Fn strerror_r
-function conforms to
+functions conform to
 .St -p1003.1-2008 .
 .Sh HISTORY
 The
 .Fn strerror
-function first appeared in
-.Bx 4.3 Reno .
-The
+function has been available since
+.Bx 4.3 Reno ,
 .Fn strerror_r
-function first appeared in
-.Ox 3.3 .
+since
+.Ox 3.3 ,
+and
+.Fn strerror_l
+since
+.Ox 6.2 .
diff --git a/lib/libc/string/strerror_l.c b/lib/libc/string/strerror_l.c
new file mode 100644
index 00000000000..c16be7a0cc2
--- /dev/null
+++ b/lib/libc/string/strerror_l.c
@@ -0,0 +1,33 @@
+/*	$OpenBSD: strerror_l.c,v 1.1 2017/09/05 03:16:13 schwarze Exp $ */
+/*
+ * Copyright (c) 2017 Ingo Schwarze <schwarze@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <limits.h>
+#include <string.h>
+
+#include "thread_private.h"
+
+char *
+strerror_l(int errnum, locale_t locale)
+{
+	static char sel_buf[NL_TEXTMAX];
+	_THREAD_PRIVATE_KEY(strerror_l);
+	char *p = _THREAD_PRIVATE(strerror_l, sel_buf, NULL);
+
+	return p == NULL ? "no buffer available in strerror_l" :
+	    strerror_r(errnum, p, sizeof(sel_buf)) ?
+	    "strerror_r failure" : p;
+}
diff --git a/lib/libc/string/strxfrm.3 b/lib/libc/string/strxfrm.3
index 481f741cb79..1a96c8512e7 100644
--- a/lib/libc/string/strxfrm.3
+++ b/lib/libc/string/strxfrm.3
@@ -1,4 +1,7 @@
+.\"	$OpenBSD: strxfrm.3,v 1.11 2017/09/05 03:16:13 schwarze Exp $
+.\"
 .\" Copyright (c) 1990, 1991 The Regents of the University of California.
+.\" Copyright (c) 2017 Ingo Schwarze <schwarze@openbsd.org>
 .\" All rights reserved.
 .\"
 .\" This code is derived from software contributed to Berkeley by
@@ -29,24 +32,27 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.\"	$OpenBSD: strxfrm.3,v 1.10 2013/06/05 03:39:23 tedu Exp $
-.\"
-.Dd $Mdocdate: June 5 2013 $
+.Dd $Mdocdate: September 5 2017 $
 .Dt STRXFRM 3
 .Os
 .Sh NAME
-.Nm strxfrm
+.Nm strxfrm ,
+.Nm strxfrm_l
 .Nd transform a string under locale
 .Sh SYNOPSIS
 .In string.h
 .Ft size_t
 .Fn strxfrm "char *dst" "const char *src" "size_t n"
+.Ft size_t
+.Fn strxfrm_l "char *dst" "const char *src" "size_t n" "locale_t locale"
 .Sh DESCRIPTION
 The idea of
 .Fn strxfrm
+and
+.Fn strxfrm_l
 is to
 .Dq un-localize
-a string: the function transforms
+a string: the functions transform
 .Ar src ,
 storing the result in
 .Ar dst ,
@@ -55,25 +61,42 @@ such that
 on transformed strings returns what
 .Xr strcoll 3
 on the original untransformed strings would return.
+.Pp
+On
+.Ox ,
+both have the same effect as
+.Xr strlcpy 3 ,
+and the global locale, the thread-specific locale, and the
+.Fa locale
+argument are ignored.
+.Sh ENVIRONMENT
+On other operating systems, the behaviour of
+.Fn strxfrm
+may depend on the
+.Dv LC_CTYPE
+.Xr locale 1 .
 .Sh SEE ALSO
-.Xr bcmp 3 ,
-.Xr memcmp 3 ,
+.Xr newlocale 3 ,
 .Xr setlocale 3 ,
-.Xr strcasecmp 3 ,
 .Xr strcmp 3 ,
-.Xr strcoll 3
+.Xr strcoll 3 ,
+.Xr strlcpy 3 ,
+.Xr wcsxfrm 3
 .Sh STANDARDS
 The
 .Fn strxfrm
 function conforms to
-.St -ansiC .
+.St -ansiC ,
+and
+.Fn strxfrm_l
+to
+.St -p1003.1-2008 .
 .Sh HISTORY
 The
 .Fn strxfrm
-function first appeared in
-.Bx 4.3 Reno .
-.Sh BUGS
-Since locales are not fully implemented on
-.Ox ,
-.Fn strxfrm
-just returns a copy of the original string.
+function has been available since
+.Bx 4.3 Reno ,
+and
+.Fn strxfrm_l
+since
+.Ox 6.2 .
diff --git a/lib/libc/string/strxfrm_l.c b/lib/libc/string/strxfrm_l.c
new file mode 100644
index 00000000000..ff77947953b
--- /dev/null
+++ b/lib/libc/string/strxfrm_l.c
@@ -0,0 +1,14 @@
+/*	$OpenBSD: strxfrm_l.c,v 1.1 2017/09/05 03:16:14 schwarze Exp $ */
+/*
+ * Written in 2017 by Ingo Schwarze <schwarze@openbsd.org>.
+ * Released into the public domain.
+ */
+
+#include <string.h>
+
+size_t
+strxfrm_l(char *dst, const char *src, size_t n,
+    locale_t locale __attribute__((__unused__)))
+{
+	return strxfrm(dst, src, n);
+}
diff --git a/lib/libc/string/wcscasecmp.3 b/lib/libc/string/wcscasecmp.3
index daf397aecea..9db4a829b90 100644
--- a/lib/libc/string/wcscasecmp.3
+++ b/lib/libc/string/wcscasecmp.3
@@ -1,7 +1,8 @@
-.\"	$OpenBSD: wcscasecmp.3,v 1.4 2013/07/16 15:21:11 schwarze Exp $
+.\"	$OpenBSD: wcscasecmp.3,v 1.5 2017/09/05 03:16:14 schwarze Exp $
 .\"
 .\" Copyright (c) 1990, 1991, 1993
 .\"	The Regents of the University of California.  All rights reserved.
+.\" Copyright (c) 2017 Ingo Schwarze <schwarze@openbsd.org>
 .\"
 .\" This code is derived from software contributed to Berkeley by
 .\" Chris Torek.
@@ -31,25 +32,43 @@
 .\"
 .\"     @(#)strcasecmp.3	8.1 (Berkeley) 6/9/93
 .\"
-.Dd $Mdocdate: July 16 2013 $
+.Dd $Mdocdate: September 5 2017 $
 .Dt WCSCASECMP 3
 .Os
 .Sh NAME
 .Nm wcscasecmp ,
-.Nm wcsncasecmp
+.Nm wcscasecmp_l ,
+.Nm wcsncasecmp ,
+.Nm wcsncasecmp_l
 .Nd compare wide strings, ignoring case
 .Sh SYNOPSIS
 .In wchar.h
 .Ft int
-.Fn wcscasecmp "const wchar_t *s1" "const wchar_t *s2"
+.Fo wcscasecmp
+.Fa "const wchar_t *s1"
+.Fa "const wchar_t *s2"
+.Fc
 .Ft int
-.Fn wcsncasecmp "const wchar_t *s1" "const wchar_t *s2" "size_t len"
+.Fo wcscasecmp_l
+.Fa "const wchar_t *s1"
+.Fa "const wchar_t *s2"
+.Fa "locale_t locale"
+.Fc
+.Ft int
+.Fo wcsncasecmp
+.Fa "const wchar_t *s1"
+.Fa "const wchar_t *s2"
+.Fa "size_t len"
+.Fc
+.Ft int
+.Fo wcsncasecmp_l
+.Fa "const wchar_t *s1"
+.Fa "const wchar_t *s2"
+.Fa "size_t len"
+.Fa "locale_t locale"
+.Fc
 .Sh DESCRIPTION
-The
-.Fn wcscasecmp
-and
-.Fn wcsncasecmp
-functions compare the wide strings
+These functions compare the wide strings
 .Fa s1
 and
 .Fa s2
@@ -61,28 +80,49 @@ is lexicographically greater than, equal to, or less than
 after translation of each corresponding wide character to lower case.
 The wide strings themselves are not modified.
 .Pp
+For the translation to lower case,
+.Fn wcscasecmp
+and
+.Fn wcsncasecmp
+use the thread-specific locale as defined with
+.Xr uselocale 3 ,
+falling back to the global locale defined with
+.Xr setlocale 3 .
+.Fn wcscasecmp_l
+and
+.Fn wcsncasecmp_l
+use the
+.Fa locale
+argument instead.
+.Pp
 .Fn wcsncasecmp
-compares at most
+and
+.Fn wcsncasecmp_l
+compare at most
 .Fa len
 wide characters.
 .Sh SEE ALSO
+.Xr newlocale 3 ,
+.Xr setlocale 3 ,
 .Xr strcasecmp 3 ,
 .Xr wcscmp 3 ,
 .Xr wmemcmp 3
 .Sh STANDARDS
-The
-.Fn wcscasecmp
-and
-.Fn wcsncasecmp
-functions conform to
+These functions conform to
 .St -p1003.1-2008 .
 .Sh HISTORY
 The
 .Fn wcscasecmp
 and
 .Fn wcsncasecmp
-functions first appeared in
-.Ox 5.0 .
+functions have been available since
+.Ox 5.0 ,
+and
+.Fn wcscasecmp_l
+and
+.Fn wcsncasecmp_l
+since
+.Ox 6.2 .
 .Sh AUTHORS
 The
 .Ox
diff --git a/lib/libc/string/wcscasecmp_l.c b/lib/libc/string/wcscasecmp_l.c
new file mode 100644
index 00000000000..35b99225c11
--- /dev/null
+++ b/lib/libc/string/wcscasecmp_l.c
@@ -0,0 +1,63 @@
+/*	$OpenBSD: wcscasecmp_l.c,v 1.1 2017/09/05 03:16:14 schwarze Exp $ */
+
+/*
+ * Copyright (c) 2011 Marc Espie
+ *
+ * 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 OPENBSD PROJECT 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 OPENBSD
+ * PROJECT 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 <wchar.h>
+#include <wctype.h>
+#include "locale/runetype.h"
+
+int
+wcscasecmp_l(const wchar_t *s1, const wchar_t *s2, locale_t locale)
+{
+	wchar_t l1, l2;
+
+	while ((l1 = towlower_l(*s1++, locale)) ==
+	    (l2 = towlower_l(*s2++, locale))) {
+		if (l1 == 0)
+			return (0);
+	}
+	/* XXX assumes wchar_t = int */
+	return ((rune_t)l1 - (rune_t)l2);
+}
+
+int
+wcsncasecmp_l(const wchar_t *s1, const wchar_t *s2, size_t n, locale_t locale)
+{
+	wchar_t l1, l2;
+
+	if (n == 0)
+		return (0);
+	do {
+		if (((l1 = towlower_l(*s1++, locale))) !=
+		    (l2 = towlower_l(*s2++, locale))) {
+			/* XXX assumes wchar_t = int */
+			return ((rune_t)l1 - (rune_t)l2);
+		}
+		if (l1 == 0)
+			break;
+	} while (--n != 0);
+	return (0);
+}