new file mode 100644
--- /dev/null
+++ b/m4/locale-zh.m4
@@ -0,0 +1,94 @@
+# locale-zh.m4 serial 1
+dnl Copyright (C) 2003, 2005-2007 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.
+
+dnl From Bruno Haible.
+
+dnl Determine the name of a chinese locale with GB18030 encoding.
+AC_DEFUN([gt_LOCALE_ZH_CN],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_REQUIRE([AM_LANGINFO_CODESET])
+  AC_CACHE_CHECK([for a transitional chinese locale], gt_cv_locale_zh_CN, [
+    macosx=
+    case "$host_os" in
+      darwin[56]*) ;;
+      darwin*) macosx=yes;;
+    esac
+    if test -n "$macosx"; then
+      # On Darwin 7 (MacOS X), the libc supports some locales in non-UTF-8
+      # encodings, but the kernel does not support them. The documentation
+      # says:
+      #   "... all code that calls BSD system routines should ensure
+      #    that the const *char parameters of these routines are in UTF-8
+      #    encoding. All BSD system functions expect their string
+      #    parameters to be in UTF-8 encoding and nothing else."
+      # See the comments in config.charset. Therefore we bypass the test.
+      gt_cv_locale_zh_CN=none
+    else
+      AC_LANG_CONFTEST([AC_LANG_SOURCE([
+changequote(,)dnl
+#include <locale.h>
+#include <stdlib.h>
+#include <time.h>
+#if HAVE_LANGINFO_CODESET
+# include <langinfo.h>
+#endif
+struct tm t;
+char buf[16];
+int main ()
+{
+  const char *p;
+  /* Check whether the given locale name is recognized by the system.  */
+  if (setlocale (LC_ALL, "") == NULL) return 1;
+  /* Check whether nl_langinfo(CODESET) is nonempty.
+     On MacOS X 10.3.5 (Darwin 7.5) in the fr_FR locale, nl_langinfo(CODESET)
+     is empty, and the behaviour of Tcl 8.4 in this locale is not useful.  */
+#if HAVE_LANGINFO_CODESET
+  if (nl_langinfo (CODESET) [0] == '\0') return 1;
+#endif
+  /* Check whether in a month name, no byte in the range 0x80..0x9F occurs.
+     This excludes the UTF-8 encoding.  */
+  t.tm_year = 1975 - 1900; t.tm_mon = 2 - 1; t.tm_mday = 4;
+  if (strftime (buf, sizeof (buf), "%B", &t) < 2) return 1;
+  for (p = buf; *p != '\0'; p++)
+    if ((unsigned char) *p >= 0x80 && (unsigned char) *p < 0xa0)
+      return 1;
+  /* Check whether a typical GB18030 multibyte sequence is recognized as a
+     single wide character.  This excludes the GB2312 and GBK encodings.  */
+  if (mblen ("\203\062\332\066", 5) != 4)
+    return 1;
+  return 0;
+}
+changequote([,])dnl
+        ])])
+      if AC_TRY_EVAL([ac_link]) && test -s conftest$ac_exeext; then
+        # Setting LC_ALL is not enough. Need to set LC_TIME to empty, because
+        # otherwise on MacOS X 10.3.5 the LC_TIME=C from the beginning of the
+        # configure script would override the LC_ALL setting. Likewise for
+        # LC_CTYPE, which is also set at the beginning of the configure script.
+        # Test for the locale name without encoding suffix.
+        if (LC_ALL=zh_CN LC_TIME= LC_CTYPE= ./conftest; exit) 2>/dev/null; then
+          gt_cv_locale_zh_CN=zh_CN
+        else
+          # Test for the locale name with explicit encoding suffix.
+          if (LC_ALL=zh_CN.GB18030 LC_TIME= LC_CTYPE= ./conftest; exit) 2>/dev/null; then
+            gt_cv_locale_zh_CN=zh_CN.GB18030
+          else
+            # None found.
+            gt_cv_locale_zh_CN=none
+          fi
+        fi
+      else
+        # If there was a link error, due to mblen(), the system is so old that
+        # it certainly doesn't have a chinese locale.
+        gt_cv_locale_zh_CN=none
+      fi
+      rm -fr conftest*
+    fi
+  ])
+  LOCALE_ZH_CN=$gt_cv_locale_zh_CN
+  AC_SUBST([LOCALE_ZH_CN])
+])

new file mode 100644
--- /dev/null
+++ b/modules/mbschr-tests
@@ -0,0 +1,17 @@
+Files:
+tests/test-mbschr.sh
+tests/test-mbschr.c
+m4/locale-zh.m4
+m4/codeset.m4
+
+Depends-on:
+
+configure.ac:
+gt_LOCALE_ZH_CN
+
+Makefile.am:
+TESTS += test-mbschr.sh
+TESTS_ENVIRONMENT += EXEEXT='@EXEEXT@' LOCALE_ZH_CN='@LOCALE_ZH_CN@'
+EXTRA_DIST += test-mbschr.sh
+check_PROGRAMS += test-mbschr
+

new file mode 100644
--- /dev/null
+++ b/tests/test-mbschr.c
@@ -0,0 +1,72 @@
+/* Test of searching a string for a character.
+   Copyright (C) 2007 Free Software Foundation, Inc.
+
+   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 2, 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, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2007.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <string.h>
+
+#include <locale.h>
+#include <stdlib.h>
+
+#define ASSERT(expr) if (!(expr)) abort ();
+
+int
+main ()
+{
+  /* configure should already have checked that the locale is supported.  */
+  if (setlocale (LC_ALL, "") == NULL)
+    return 1;
+
+  /* Tests with a character < 0x30.  */
+  {
+    const char input[] = "\312\276\300\375 \312\276\300\375 \312\276\300\375"; /* "示例 示例 示例" */
+    const char *result = mbschr (input, ' ');
+    ASSERT (result == input + 4);
+  }
+
+  {
+    const char input[] = "\312\276\300\375"; /* "示例" */
+    const char *result = mbschr (input, ' ');
+    ASSERT (result == NULL);
+  }
+
+  /* Tests with a character >= 0x30.  */
+  {
+    const char input[] = "\272\305123\324\313\320\320\241\243"; /* "号123运行。" */
+    const char *result = mbschr (input, '2');
+    ASSERT (result == input + 3);
+  }
+
+  /* This test shows how mbschr() is different from strchr().  */
+  {
+    const char input[] = "\203\062\332\066123\324\313\320\320\241\243"; /* "씋123运行。" */
+    const char *result = mbschr (input, '2');
+    ASSERT (result == input + 5);
+  }
+
+  {
+    const char input[] = "\312\300\275\347\304\343\272\303\243\241"; /* "世界你好！" */
+    const char *result = mbschr (input, '!');
+    ASSERT (result == NULL);
+  }
+
+  return 0;
+}

new file mode 100755
--- /dev/null
+++ b/tests/test-mbschr.sh
@@ -0,0 +1,15 @@
+#!/bin/sh
+
+# Test whether a specific GB18030 locale is installed.
+: ${LOCALE_ZH_CN=zh_CN.GB18030}
+if test $LOCALE_ZH_CN = none; then
+  if test -f /usr/bin/localedef; then
+    echo "Skipping test: no chinese GB18030 locale is installed"
+  else
+    echo "Skipping test: no chinese GB18030 locale is supported"
+  fi
+  exit 77
+fi
+
+LC_ALL=$LOCALE_ZH_CN \
+./test-mbschr${EXEEXT}