--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+2007-02-14  Bruno Haible  <bruno@clisp.org>
+
+	New module mbspcasecmp.
+	* modules/mbspcasecmp: New file.
+	* lib/mbspcasecmp.c: New file.
+	* lib/string_.h (strncasecmp): Change warning message.
+	(mbspcasecmp): New declaration.
+	* m4/mbspcasecmp.m4: New file.
+	* m4/string_h.m4 (gl_STRING_MODULE_INDICATOR_DEFAULTS): Initialize
+	GNULIB_MBSPCASECMP.
+	* modules/string (string.h): Also substitute GNULIB_MBSPCASECMP.
+	* MODULES.html.sh (Internationalization functions): Add mbspcasecmp.
+
 2007-02-14  Bruno Haible  <bruno@clisp.org>
 
 	* modules/mbsncasecmp-tests: New file.

--- a/MODULES.html.sh
+++ b/MODULES.html.sh
@@ -2167,6 +2167,7 @@
   func_module mbsstr
   func_module mbscasecmp
   func_module mbsncasecmp
+  func_module mbspcasecmp
   func_module mbscasestr
   func_module mbscspn
   func_module mbspbrk

new file mode 100644
--- /dev/null
+++ b/lib/mbspcasecmp.c
@@ -0,0 +1,100 @@
+/* Case-insensitive string comparison function.
+   Copyright (C) 1998-1999, 2005-2007 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2007.
+
+   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.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <string.h>
+
+#include <ctype.h>
+
+#if HAVE_MBRTOWC
+# include "mbuiter.h"
+#endif
+
+#define TOLOWER(Ch) (isupper (Ch) ? tolower (Ch) : (Ch))
+
+/* Compare the initial segment of the character string STRING consisting of
+   at most mbslen (PREFIX) characters with the character string PREFIX,
+   ignoring case, returning less than, equal to or greater than zero if this
+   initial segment is lexicographically less than, equal to or greater than
+   PREFIX.
+   Note: This function may, in multibyte locales, return 0 if STRING is of
+   smaller length than PREFIX!  */
+char *
+mbspcasecmp (const char *string, const char *prefix)
+{
+  /* This is essentially the same as
+       mbsncasecmp (string, prefix, mbslen (prefix))
+     just with small optimizations.  */
+  if (string == prefix)
+    return (char *) (string + strlen (string));
+
+  /* Be careful not to look at the entire extent of STRING or PREFIX until
+     needed.  This is useful because when two strings differ, the difference is
+     most often already in the very few first characters.  */
+#if HAVE_MBRTOWC
+  if (MB_CUR_MAX > 1)
+    {
+      mbui_iterator_t iter1;
+      mbui_iterator_t iter2;
+
+      mbui_init (iter1, string);
+      mbui_init (iter2, prefix);
+
+      while (mbui_avail (iter1) && mbui_avail (iter2))
+	{
+	  int cmp = mb_casecmp (mbui_cur (iter1), mbui_cur (iter2));
+
+	  if (cmp != 0)
+	    return NULL;
+
+	  mbui_advance (iter1);
+	  mbui_advance (iter2);
+	}
+      if (!mbui_avail (iter2))
+	/* PREFIX equals STRING or is terminated before STRING.  */
+	return (char *) mbui_cur_ptr (iter1);
+      else
+	/* STRING terminated before PREFIX.  */
+	return NULL;
+    }
+  else
+#endif
+    {
+      const unsigned char *p1 = (const unsigned char *) string;
+      const unsigned char *p2 = (const unsigned char *) prefix;
+      unsigned char c1, c2;
+
+      for (; ; p1++, p2++)
+	{
+	  c1 = TOLOWER (*p1);
+	  c2 = TOLOWER (*p2);
+
+	  if (c2 == '\0' || c1 != c2)
+	    break;
+	}
+
+      if (c2 == '\0')
+	/* PREFIX equals STRING or is terminated before STRING.  */
+	return (char *) p1;
+      else
+	/* STRING terminated before PREFIX.  */
+	return NULL;
+    }
+}

--- a/lib/string_.h
+++ b/lib/string_.h
@@ -152,7 +152,7 @@
    as a sequence of bytes, not of characters.  */
 # undef strncasecmp
 # define strncasecmp(a,b,n) \
-    (GL_LINK_WARNING ("strncasecmp cannot work correctly on character strings in multibyte locales - don't use it if you care about internationalization; use c_strncasecmp (from gnulib module c-strcase) if you want a locale independent function"), \
+    (GL_LINK_WARNING ("strncasecmp cannot work correctly on character strings in multibyte locales - use mbsncasecmp or mbspcasecmp if you care about internationalization, or use c_strncasecmp (from gnulib module c-strcase) if you want a locale independent function"), \
      strncasecmp (a, b, n))
 #endif
 
@@ -428,6 +428,19 @@
 extern int mbsncasecmp (const char *s1, const char *s2, size_t n);
 #endif
 
+#if @GNULIB_MBSPCASECMP@
+/* Compare the initial segment of the character string STRING consisting of
+   at most mbslen (PREFIX) characters with the character string PREFIX,
+   ignoring case, returning less than, equal to or greater than zero if this
+   initial segment is lexicographically less than, equal to or greater than
+   PREFIX.
+   Note: This function may, in multibyte locales, return 0 if STRING is of
+   smaller length than PREFIX!
+   Unlike strncasecmp(), this function works correctly in multibyte
+   locales.  */
+extern char * mbspcasecmp (const char *string, const char *prefix);
+#endif
+
 #if @GNULIB_MBSCASESTR@
 /* Find the first occurrence of the character string NEEDLE in the character
    string HAYSTACK, using case-insensitive comparison.

new file mode 100644
--- /dev/null
+++ b/m4/mbspcasecmp.m4
@@ -0,0 +1,16 @@
+# mbspcasecmp.m4 serial 1
+dnl Copyright (C) 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.
+
+AC_DEFUN([gl_FUNC_MBSPCASECMP],
+[
+  gl_PREREQ_MBSPCASECMP
+])
+
+# Prerequisites of lib/mbspcasecmp.c.
+AC_DEFUN([gl_PREREQ_MBSPCASECMP], [
+  AC_REQUIRE([gl_FUNC_MBRTOWC])
+  :
+])

--- a/m4/string_h.m4
+++ b/m4/string_h.m4
@@ -73,6 +73,7 @@
   GNULIB_MBSSTR=0;      AC_SUBST([GNULIB_MBSSTR])
   GNULIB_MBSCASECMP=0;  AC_SUBST([GNULIB_MBSCASECMP])
   GNULIB_MBSNCASECMP=0; AC_SUBST([GNULIB_MBSNCASECMP])
+  GNULIB_MBSPCASECMP=0; AC_SUBST([GNULIB_MBSPCASECMP])
   GNULIB_MBSCASESTR=0;  AC_SUBST([GNULIB_MBSCASESTR])
   GNULIB_MBSCSPN=0;     AC_SUBST([GNULIB_MBSCSPN])
   GNULIB_MBSPBRK=0;     AC_SUBST([GNULIB_MBSPBRK])

new file mode 100644
--- /dev/null
+++ b/modules/mbspcasecmp
@@ -0,0 +1,28 @@
+Description:
+mbspcasecmp() function: case-insensitive string prefix comparison.
+
+Files:
+lib/mbspcasecmp.c
+m4/mbspcasecmp.m4
+m4/mbrtowc.m4
+
+Depends-on:
+mbuiter
+string
+
+configure.ac:
+gl_FUNC_MBSPCASECMP
+gl_STRING_MODULE_INDICATOR([mbspcasecmp])
+
+Makefile.am:
+lib_SOURCES += mbspcasecmp.c
+
+Include:
+<string.h>
+
+License:
+LGPL
+
+Maintainer:
+Bruno Haible
+

--- a/modules/string
+++ b/modules/string
@@ -27,6 +27,7 @@
 	      -e 's|@''GNULIB_MBSSTR''@|$(GNULIB_MBSSTR)|g' \
 	      -e 's|@''GNULIB_MBSCASECMP''@|$(GNULIB_MBSCASECMP)|g' \
 	      -e 's|@''GNULIB_MBSNCASECMP''@|$(GNULIB_MBSNCASECMP)|g' \
+	      -e 's|@''GNULIB_MBSPCASECMP''@|$(GNULIB_MBSPCASECMP)|g' \
 	      -e 's|@''GNULIB_MBSCASESTR''@|$(GNULIB_MBSCASESTR)|g' \
 	      -e 's|@''GNULIB_MBSCSPN''@|$(GNULIB_MBSCSPN)|g' \
 	      -e 's|@''GNULIB_MBSPBRK''@|$(GNULIB_MBSPBRK)|g' \