1/* Copyright (C) 1991-2023 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
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 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18#include <stdlib.h>
19#include <string.h>
20#include <wchar.h>
21#include <gconv.h>
22#include <wcsmbs/wcsmbsload.h>
23
24
25/* Internal state. */
26static mbstate_t state;
27
28/* Return the length of the multibyte character (if there is one)
29 at S which is no longer than N characters.
30 The ISO C standard says that the `mblen' function must not change
31 the state of the `mbtowc' function. */
32int
33mblen (const char *s, size_t n)
34{
35 int result;
36
37 /* If S is NULL the function has to return null or not null
38 depending on the encoding having a state depending encoding or
39 not. */
40 if (s == NULL)
41 {
42 const struct gconv_fcts *fcts;
43
44 /* Get the conversion functions. */
45 fcts = get_gconv_fcts (_NL_CURRENT_DATA (LC_CTYPE));
46
47 /* Reset the state. */
48 memset (&state, '\0', sizeof state);
49
50 result = fcts->towc->__stateful;
51 }
52 else if (*s == '\0')
53 /* According to the ISO C 89 standard this is the expected behaviour. */
54 result = 0;
55 else
56 {
57 memset (&state, '\0', sizeof state);
58
59 result = __mbrtowc (NULL, s, n, &state);
60
61 /* The `mbrtowc' functions tell us more than we need. Fold the -1
62 and -2 result into -1. */
63 if (result < 0)
64 result = -1;
65 }
66
67 return result;
68}
69