1 /* Test for initial conversion state.
2 Copyright (C) 2008-2020 Free Software Foundation, Inc.
3 Written by Bruno Haible <bruno@clisp.org>, 2008.
4
5 This program is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 3 of the License, or
8 (at your option) any later version.
9
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <https://www.gnu.org/licenses/>. */
17
18 #include <config.h>
19
20 /* Specification. */
21 #include <wchar.h>
22
23 #include "verify.h"
24
25 #if GNULIB_defined_mbstate_t
26
27 /* Platforms that lack mbsinit() also lack mbrlen(), mbrtowc(), mbsrtowcs()
28 and wcrtomb(), wcsrtombs().
29 We assume that
30 - sizeof (mbstate_t) >= 4,
31 - only stateless encodings are supported (such as UTF-8 and EUC-JP, but
32 not ISO-2022 variants),
33 - for each encoding, the number of bytes for a wide character is <= 4.
34 (This maximum is attained for UTF-8, GB18030, EUC-TW.)
35 We define the meaning of mbstate_t as follows:
36 - In mb -> wc direction, mbstate_t's first byte contains the number of
37 buffered bytes (in the range 0..3), followed by up to 3 buffered bytes.
38 See mbrtowc.c.
39 - In wc -> mb direction, mbstate_t contains no information. In other
40 words, it is always in the initial state. */
41
42 verify (sizeof (mbstate_t) >= 4);
43
44 int
mbsinit(const mbstate_t * ps)45 mbsinit (const mbstate_t *ps)
46 {
47 const char *pstate = (const char *)ps;
48
49 return pstate == NULL || pstate[0] == 0;
50 }
51
52 #else
53
54 int
mbsinit(const mbstate_t * ps)55 mbsinit (const mbstate_t *ps)
56 {
57 # if defined _WIN32 && !defined __CYGWIN__
58 /* Native Windows. */
59 /* MSVC defines 'mbstate_t' as an 8-byte struct; the first 4 bytes matter.
60 On mingw, 'mbstate_t' is sometimes defined as 'int', sometimes defined as
61 an 8-byte struct, of which the first 4 bytes matter. */
62 return ps == NULL || *(const unsigned int *)ps == 0;
63 # else
64 /* Minix, HP-UX 11.00, Solaris 2.6, Interix, ... */
65 /* Maybe this definition works, maybe not... */
66 return ps == NULL || *(const char *)ps == 0;
67 # endif
68 }
69
70 #endif
71