--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+2008-12-19  Bruno Haible  <bruno@clisp.org>
+
+	New module 'mbsrtowcs'.
+	* lib/wchar.in.h (mbsrtowcs): New declaration.
+	* lib/mbsrtowcs.c: New file.
+	* m4/mbsrtowcs.m4: New file.
+	* modules/mbsrtowcs: New file.
+	* m4/wchar.m4 (gl_WCHAR_H_DEFAULTS): Initialize GNULIB_MBSRTOWCS and
+	HAVE_MBSRTOWCS.
+	* modules/wchar (Makefile.am): Substitute GNULIB_MBSRTOWCS and
+	HAVE_MBSRTOWCS.
+	* doc/posix-functions/mbsrtowcs.texi: Document the new module.
+
 2008-12-19  Bruno Haible  <bruno@clisp.org>
 
 	New module 'mbrlen'.

--- a/doc/posix-functions/mbsrtowcs.texi
+++ b/doc/posix-functions/mbsrtowcs.texi
@@ -4,18 +4,18 @@
 
 POSIX specification: @url{http://www.opengroup.org/onlinepubs/9699919799/functions/mbsrtowcs.html}
 
-Gnulib module: ---
+Gnulib module: mbsrtowcs
 
 Portability problems fixed by Gnulib:
 @itemize
+@item
+This function is missing on some platforms:
+HP-UX 11, IRIX 6.5, Solaris 2.6, mingw, Interix 3.5.
 @end itemize
 
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on some platforms:
-HP-UX 11, IRIX 6.5, Solaris 2.6, mingw, Interix 3.5.
-@item
 On Windows platforms, @code{wchar_t} is a 16-bit type and therefore cannot
 accommodate all Unicode characters.
 @end itemize

new file mode 100644
--- /dev/null
+++ b/lib/mbsrtowcs.c
@@ -0,0 +1,136 @@
+/* Convert string to wide string.
+   Copyright (C) 2008 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2008.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <wchar.h>
+
+#include <errno.h>
+#include <limits.h>
+#include <stdlib.h>
+
+#include "strnlen1.h"
+
+
+static mbstate_t internal_state;
+
+size_t
+mbsrtowcs (wchar_t *dest, const char **srcp, size_t len, mbstate_t *ps)
+{
+  if (ps == NULL)
+    ps = &internal_state;
+  {
+    const char *src = *srcp;
+
+    if (dest != NULL)
+      {
+	wchar_t *destptr = dest;
+
+	for (; len > 0; destptr++, len--)
+	  {
+	    size_t src_avail;
+	    size_t ret;
+
+	    /* An optimized variant of
+	       src_avail = strnlen1 (src, MB_LEN_MAX);  */
+	    if (src[0] == '\0')
+	      src_avail = 1;
+	    else if (src[1] == '\0')
+	      src_avail = 2;
+	    else if (src[2] == '\0')
+	      src_avail = 3;
+	    else if (MB_LEN_MAX <= 4 || src[3] == '\0')
+	      src_avail = 4;
+	    else
+	      src_avail = 4 + strnlen1 (src + 4, MB_LEN_MAX - 4);
+
+	    /* Parse the next multibyte character.  */
+	    ret = mbrtowc (destptr, src, src_avail, ps);
+
+	    if (ret == (size_t)(-2))
+	      /* Encountered a multibyte character that extends past a '\0' byte
+		 or that is longer than MB_LEN_MAX bytes.  Cannot happen.  */
+	      abort ();
+
+	    if (ret == (size_t)(-1))
+	      goto bad_input;
+	    if (ret == 0)
+	      {
+		src = NULL;
+		/* Here mbsinit (ps).  */
+		break;
+	      }
+	    src += ret;
+	  }
+
+	*srcp = src;
+	return destptr - dest;
+      }
+    else
+      {
+	/* Ignore dest and len, don't store *srcp at the end, and
+	   don't clobber *ps.  */
+	mbstate_t state = *ps;
+	size_t totalcount = 0;
+
+	for (;; totalcount++)
+	  {
+	    size_t src_avail;
+	    size_t ret;
+
+	    /* An optimized variant of
+	       src_avail = strnlen1 (src, MB_LEN_MAX);  */
+	    if (src[0] == '\0')
+	      src_avail = 1;
+	    else if (src[1] == '\0')
+	      src_avail = 2;
+	    else if (src[2] == '\0')
+	      src_avail = 3;
+	    else if (MB_LEN_MAX <= 4 || src[3] == '\0')
+	      src_avail = 4;
+	    else
+	      src_avail = 4 + strnlen1 (src + 4, MB_LEN_MAX - 4);
+
+	    /* Parse the next multibyte character.  */
+	    ret = mbrtowc (NULL, src, src_avail, &state);
+
+	    if (ret == (size_t)(-2))
+	      /* Encountered a multibyte character that extends past a '\0' byte
+		 or that is longer than MB_LEN_MAX bytes.  Cannot happen.  */
+	      abort ();
+
+	    if (ret == (size_t)(-1))
+	      goto bad_input2;
+	    if (ret == 0)
+	      {
+		/* Here mbsinit (&state).  */
+		break;
+	      }
+	    src += ret;
+	  }
+
+	return totalcount;
+      }
+
+   bad_input:
+    *srcp = src;
+   bad_input2:
+    errno = EILSEQ;
+    return (size_t)(-1);
+  }
+}

--- a/lib/wchar.in.h
+++ b/lib/wchar.in.h
@@ -151,6 +151,20 @@
 #endif
 
 
+/* Convert a string to a wide string.  */
+#if @GNULIB_MBSRTOWCS@
+# if !@HAVE_MBSRTOWCS@
+extern size_t mbsrtowcs (wchar_t *dest, const char **srcp, size_t len, mbstate_t *ps);
+# endif
+#elif defined GNULIB_POSIXCHECK
+# undef mbsrtowcs
+# define mbsrtowcs(d,s,l,p) \
+    (GL_LINK_WARNING ("mbsrtowcs is unportable - " \
+                      "use gnulib module mbsrtowcs for portability"), \
+     mbsrtowcs (d, s, l, p))
+#endif
+
+
 /* Return the number of screen columns needed for WC.  */
 #if @GNULIB_WCWIDTH@
 # if @REPLACE_WCWIDTH@

new file mode 100644
--- /dev/null
+++ b/m4/mbsrtowcs.m4
@@ -0,0 +1,24 @@
+# mbsrtowcs.m4 serial 1
+dnl Copyright (C) 2008 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_FUNC_MBSRTOWCS],
+[
+  AC_REQUIRE([gl_WCHAR_H_DEFAULTS])
+
+  AC_REQUIRE([AC_TYPE_MBSTATE_T])
+  AC_CHECK_FUNCS_ONCE([mbsrtowcs])
+  if test $ac_cv_func_mbsrtowcs = no; then
+    HAVE_MBSRTOWCS=0
+    gl_REPLACE_WCHAR_H
+    AC_LIBOBJ([mbsrtowcs])
+    gl_PREREQ_MBSRTOWCS
+  fi
+])
+
+# Prerequisites of lib/mbsrtowcs.c.
+AC_DEFUN([gl_PREREQ_MBSRTOWCS], [
+  :
+])

--- a/m4/wchar.m4
+++ b/m4/wchar.m4
@@ -7,7 +7,7 @@
 
 dnl Written by Eric Blake.
 
-# wchar.m4 serial 10
+# wchar.m4 serial 11
 
 AC_DEFUN([gl_WCHAR_H],
 [
@@ -61,18 +61,20 @@
 
 AC_DEFUN([gl_WCHAR_H_DEFAULTS],
 [
-  GNULIB_BTOWC=0;   AC_SUBST([GNULIB_BTOWC])
-  GNULIB_WCTOB=0;   AC_SUBST([GNULIB_WCTOB])
-  GNULIB_MBSINIT=0; AC_SUBST([GNULIB_MBSINIT])
-  GNULIB_MBRTOWC=0; AC_SUBST([GNULIB_MBRTOWC])
-  GNULIB_MBRLEN=0;  AC_SUBST([GNULIB_MBRLEN])
-  GNULIB_WCWIDTH=0; AC_SUBST([GNULIB_WCWIDTH])
+  GNULIB_BTOWC=0;      AC_SUBST([GNULIB_BTOWC])
+  GNULIB_WCTOB=0;      AC_SUBST([GNULIB_WCTOB])
+  GNULIB_MBSINIT=0;    AC_SUBST([GNULIB_MBSINIT])
+  GNULIB_MBRTOWC=0;    AC_SUBST([GNULIB_MBRTOWC])
+  GNULIB_MBRLEN=0;     AC_SUBST([GNULIB_MBRLEN])
+  GNULIB_MBSRTOWCS=0;  AC_SUBST([GNULIB_MBSRTOWCS])
+  GNULIB_WCWIDTH=0;    AC_SUBST([GNULIB_WCWIDTH])
   dnl Assume proper GNU behavior unless another module says otherwise.
   HAVE_BTOWC=1;        AC_SUBST([HAVE_BTOWC])
   HAVE_WCTOB=1;        AC_SUBST([HAVE_WCTOB])
   HAVE_MBSINIT=1;      AC_SUBST([HAVE_MBSINIT])
   HAVE_MBRTOWC=1;      AC_SUBST([HAVE_MBRTOWC])
   HAVE_MBRLEN=1;       AC_SUBST([HAVE_MBRLEN])
+  HAVE_MBSRTOWCS=1;    AC_SUBST([HAVE_MBSRTOWCS])
   HAVE_DECL_WCWIDTH=1; AC_SUBST([HAVE_DECL_WCWIDTH])
   REPLACE_WCWIDTH=0;   AC_SUBST([REPLACE_WCWIDTH])
   WCHAR_H='';          AC_SUBST([WCHAR_H])

new file mode 100644
--- /dev/null
+++ b/modules/mbsrtowcs
@@ -0,0 +1,28 @@
+Description:
+mbsrtowcs() function: convert string to wide string.
+
+Files:
+lib/mbsrtowcs.c
+m4/mbsrtowcs.m4
+m4/mbstate_t.m4
+
+Depends-on:
+wchar
+mbrtowc
+strnlen1
+
+configure.ac:
+gl_FUNC_MBSRTOWCS
+gl_WCHAR_MODULE_INDICATOR([mbsrtowcs])
+
+Makefile.am:
+
+Include:
+<wchar.h>
+
+License:
+LGPL
+
+Maintainer:
+Bruno Haible
+

--- a/modules/wchar
+++ b/modules/wchar
@@ -30,6 +30,7 @@
 	      -e 's|@''GNULIB_MBSINIT''@|$(GNULIB_MBSINIT)|g' \
 	      -e 's|@''GNULIB_MBRTOWC''@|$(GNULIB_MBRTOWC)|g' \
 	      -e 's|@''GNULIB_MBRLEN''@|$(GNULIB_MBRLEN)|g' \
+	      -e 's|@''GNULIB_MBSRTOWCS''@|$(GNULIB_MBSRTOWCS)|g' \
 	      -e 's|@''GNULIB_WCWIDTH''@|$(GNULIB_WCWIDTH)|g' \
 	      -e 's|@''HAVE_WINT_T''@|$(HAVE_WINT_T)|g' \
 	      -e 's|@''HAVE_BTOWC''@|$(HAVE_BTOWC)|g' \
@@ -37,6 +38,7 @@
 	      -e 's|@''HAVE_MBSINIT''@|$(HAVE_MBSINIT)|g' \
 	      -e 's|@''HAVE_MBRTOWC''@|$(HAVE_MBRTOWC)|g' \
 	      -e 's|@''HAVE_MBRLEN''@|$(HAVE_MBRLEN)|g' \
+	      -e 's|@''HAVE_MBSRTOWCS''@|$(HAVE_MBSRTOWCS)|g' \
 	      -e 's|@''HAVE_DECL_WCWIDTH''@|$(HAVE_DECL_WCWIDTH)|g' \
 	      -e 's|@''REPLACE_WCWIDTH''@|$(REPLACE_WCWIDTH)|g' \
 	      -e '/definition of GL_LINK_WARNING/r $(LINK_WARNING_H)' \