new module 'mbsrtowcs'

[Bruno Haible]

Here's the replacement for a missing mbsrtowcs function.

Quite straightforward, except for a small hole in the specification:
ISO C 99 does not specify how the state is to be updated. glibc updates it
if and only if the dest argument is not NULL; this is what makes most sense.


2008-12-19  Bruno Haible  <address@hidden>

        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.

=============================== lib/mbsrtowcs.c ===============================
/* Convert string to wide string.
   Copyright (C) 2008 Free Software Foundation, Inc.
   Written by Bruno Haible <address@hidden>, 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);
  }
}
=============================== m4/mbsrtowcs.m4 ===============================
# 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], [
  :
])
============================== modules/mbsrtowcs ==============================
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

===============================================================================
--- lib/wchar.in.h.orig 2008-12-20 01:55:20.000000000 +0100
+++ lib/wchar.in.h      2008-12-19 23:48:14.000000000 +0100
@@ -151,6 +151,20 @@
 #endif
 
 
+/* Convert a string to a wide string.  */
+#if @GNULIB_MBSRTOWCS@
+# if address@hidden@
+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@
--- m4/wchar.m4.orig    2008-12-20 01:55:20.000000000 +0100
+++ m4/wchar.m4 2008-12-19 23:50:50.000000000 +0100
@@ -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])
--- modules/wchar.orig  2008-12-20 01:55:20.000000000 +0100
+++ modules/wchar       2008-12-19 23:49:38.000000000 +0100
@@ -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)' \
--- doc/posix-functions/mbsrtowcs.texi.orig     2008-12-20 01:55:20.000000000 
+0100
+++ doc/posix-functions/mbsrtowcs.texi  2008-12-19 23:55:41.000000000 +0100
@@ -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
address@hidden
+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.
address@hidden
 On Windows platforms, @code{wchar_t} is a 16-bit type and therefore cannot
 accommodate all Unicode characters.
 @end itemize