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[glibc.git] / stdlib / mblen.c
blob429048c99ceecddbf494bf1d191054b9cf2fcc2a
1 /* Copyright (C) 1991, 1997, 1998, 1999, 2000 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Library General Public License as
6 published by the Free Software Foundation; either version 2 of the
7 License, or (at your option) any later version.
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Library General Public License for more details.
14 You should have received a copy of the GNU Library General Public
15 License along with the GNU C Library; see the file COPYING.LIB. If not,
16 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
17 Boston, MA 02111-1307, USA. */
19 #include <stdlib.h>
20 #include <string.h>
21 #include <wchar.h>
22 #include <gconv.h>
23 #include <wcsmbs/wcsmbsload.h>
26 /* Internal state. */
27 static mbstate_t state;
29 /* Return the length of the multibyte character (if there is one)
30 at S which is no longer than N characters.
31 The ISO C standard says that the `mblen' function must not change
32 the state of the `mbtowc' function. */
33 int
34 mblen (const char *s, size_t n)
36 int result;
38 /* If S is NULL the function has to return null or not null
39 depending on the encoding having a state depending encoding or
40 not. */
41 if (s == NULL)
43 /* Make sure we use the correct value. */
44 update_conversion_ptrs ();
46 /* Reset the state. */
47 memset (&state, '\0', sizeof state);
49 result = __wcsmbs_gconv_fcts.towc->__stateful;
51 else if (*s == '\0')
52 /* According to the ISO C 89 standard this is the expected behaviour. */
53 result = 0;
54 else
56 memset (&state, '\0', sizeof state);
58 result = __mbrtowc (NULL, s, n, &state);
60 /* The `mbrtowc' functions tell us more than we need. Fold the -1
61 and -2 result into -1. */
62 if (result < 0)
63 result = -1;
66 return result;