1MBSRTOWCS(3P) POSIX Programmer's Manual MBSRTOWCS(3P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 mbsnrtowcs, mbsrtowcs — convert a character string to a wide-character
13 string (restartable)
14
16 #include <wchar.h>
17 size_t mbsnrtowcs(wchar_t *restrict dst, const char **restrict src,
19 size_t nmc, size_t len, mbstate_t *restrict ps);
20 size_t mbsrtowcs(wchar_t *restrict dst, const char **restrict src,
21 size_t len, mbstate_t *restrict ps);
22
24 For mbsrtowcs(): The functionality described on this reference page is
25 aligned with the ISO C standard. Any conflict between the requirements
26 described here and the ISO C standard is unintentional. This volume of
27 POSIX.1‐2017 defers to the ISO C standard.
28 The mbsrtowcs() function shall convert a sequence of characters, begin‐
30 ning in the conversion state described by the object pointed to by ps,
31 from the array indirectly pointed to by src into a sequence of corre‐
32 sponding wide characters. If dst is not a null pointer, the converted
33 characters shall be stored into the array pointed to by dst. Conver‐
34 sion continues up to and including a terminating null character, which
35 shall also be stored. Conversion shall stop early in either of the fol‐
36 lowing cases:
37 * A sequence of bytes is encountered that does not form a valid char‐
39 acter.
40 * len codes have been stored into the array pointed to by dst (and
42 dst is not a null pointer).
43 Each conversion shall take place as if by a call to the mbrtowc() func‐
45 tion.
46 If dst is not a null pointer, the pointer object pointed to by src
48 shall be assigned either a null pointer (if conversion stopped due to
49 reaching a terminating null character) or the address just past the
50 last character converted (if any). If conversion stopped due to reach‐
51 ing a terminating null character, and if dst is not a null pointer, the
52 resulting state described shall be the initial conversion state.
53 If ps is a null pointer, the mbsrtowcs() function shall use its own
55 internal mbstate_t object, which is initialized at program start-up to
56 the initial conversion state. Otherwise, the mbstate_t object pointed
57 to by ps shall be used to completely describe the current conversion
58 state of the associated character sequence.
59 The mbsnrtowcs() function shall be equivalent to the mbsrtowcs() func‐
61 tion, except that the conversion of characters indirectly pointed to by
62 src is limited to at most nmc bytes (the size of the input buffer), and
63 under conditions where mbsrtowcs() would assign the address just past
64 the last character converted (if any) to the pointer object pointed to
65 by src, mbsnrtowcs() shall instead assign the address just past the
66 last byte processed (if any) to that pointer object. If the input buf‐
67 fer ends with an incomplete character, it is unspecified whether con‐
68 version stops at the end of the previous character (if any), or at the
69 end of the input buffer. In the latter case, a subsequent call to
70 mbsnrtowcs() with an input buffer that starts with the remainder of the
71 incomplete character shall correctly complete the conversion of that
72 character.
73 The behavior of these functions shall be affected by the LC_CTYPE cate‐
75 gory of the current locale.
76 The implementation shall behave as if no function defined in this vol‐
78 ume of POSIX.1‐2017 calls these functions.
79 The mbsnrtowcs() and mbsrtowcs() functions need not be thread-safe if
81 called with a NULL ps argument.
82 The mbsrtowcs() function shall not change the setting of errno if suc‐
84 cessful.
85
87 If the input conversion encounters a sequence of bytes that do not form
88 a valid character, an encoding error occurs. In this case, these func‐
89 tions shall store the value of the macro [EILSEQ] in errno and shall
90 return (size_t)-1; the conversion state is undefined. Otherwise, these
91 functions shall return the number of characters successfully converted,
92 not including the terminating null (if any).
93
95 These functions shall fail if:
96 EILSEQ An invalid character sequence is detected. In the POSIX locale
98 an [EILSEQ] error cannot occur since all byte values are valid
99 characters.
100 These functions may fail if:
102 EINVAL ps points to an object that contains an invalid conversion
104 state.
105 The following sections are informative.
107
109 None.
110
112 None.
113
115 None.
116
118 A future version may require that when the input buffer ends with an
119 incomplete character, conversion stops at the end of the input buffer.
120
122 iconv(), mbrtowc(), mbsinit()
123 The Base Definitions volume of POSIX.1‐2017, <wchar.h>
125
127 Portions of this text are reprinted and reproduced in electronic form
128 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
129 table Operating System Interface (POSIX), The Open Group Base Specifi‐
130 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
131 Electrical and Electronics Engineers, Inc and The Open Group. In the
132 event of any discrepancy between this version and the original IEEE and
133 The Open Group Standard, the original IEEE and The Open Group Standard
134 is the referee document. The original Standard can be obtained online
135 at http://www.opengroup.org/unix/online.html .
136 Any typographical or formatting errors that appear in this page are
138 most likely to have been introduced during the conversion of the source
139 files to man page format. To report such errors, see https://www.ker‐
140 nel.org/doc/man-pages/reporting_bugs.html .
141IEEE/The Open Group 2017 MBSRTOWCS(3P)