mbsnrtowcs(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

MBSNRTOWCS(3)           Linux Programmer's Manual          MBSNRTOWCS(3)

NAME         top

       mbsnrtowcs - convert a multibyte string to a wide-character
       string

SYNOPSIS         top

       #include <wchar.h>

       size_t mbsnrtowcs(wchar_t *restrict dest, const char **restrict src,
                         size_t nms, size_t len, mbstate_t *restrict ps);

   Feature Test Macro Requirements for glibc (see
   feature_test_macros(7)):

       mbsnrtowcs():
           Since glibc 2.10:
               _POSIX_C_SOURCE >= 200809L
           Before glibc 2.10:
               _GNU_SOURCE

DESCRIPTION         top

       The mbsnrtowcs() function is like the mbsrtowcs(3) function,
       except that the number of bytes to be converted, starting at
       *src, is limited to at most nms bytes.

       If dest is not NULL, the mbsnrtowcs() function converts at most
       nms bytes from the multibyte string *src to a wide-character
       string starting at dest.  At most len wide characters are written
       to dest.  The shift state *ps is updated.  The conversion is
       effectively performed by repeatedly calling mbrtowc(dest, *src,
       n, ps) where n is some positive number, as long as this call
       succeeds, and then incrementing dest by one and *src by the
       number of bytes consumed.  The conversion can stop for three
       reasons:

       1. An invalid multibyte sequence has been encountered.  In this
          case, *src is left pointing to the invalid multibyte sequence,
          (size_t) -1 is returned, and errno is set to EILSEQ.

       2. The nms limit forces a stop, or len non-L'\0' wide characters
          have been stored at dest.  In this case, *src is left pointing
          to the next multibyte sequence to be converted, and the number
          of wide characters written to dest is returned.

       3. The multibyte string has been completely converted, including
          the terminating null wide character ('\0') (which has the side
          effect of bringing back *ps to the initial state).  In this
          case, *src is set to NULL, and the number of wide characters
          written to dest, excluding the terminating null wide
          character, is returned.

       According to POSIX.1, if the input buffer ends with an incomplete
       character, it is unspecified whether conversion stops at the end
       of the previous character (if any), or at the end of the input
       buffer.  The glibc implementation adopts the former behavior.

       If dest is NULL, len is ignored, and the conversion proceeds as
       above, except that the converted wide characters are not written
       out to memory, and that no destination length limit exists.

       In both of the above cases, if ps is NULL, a static anonymous
       state known only to the mbsnrtowcs() function is used instead.

       The programmer must ensure that there is room for at least len
       wide characters at dest.

RETURN VALUE         top

       The mbsnrtowcs() function returns the number of wide characters
       that make up the converted part of the wide-character string, not
       including the terminating null wide character.  If an invalid
       multibyte sequence was encountered, (size_t) -1 is returned, and
       errno set to EILSEQ.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       attributes(7).

       ┌─────────────┬───────────────┬──────────────────────────────────┐
       │Interface    Attribute     Value                            │
       ├─────────────┼───────────────┼──────────────────────────────────┤
       │mbsnrtowcs() │ Thread safety │ MT-Unsafe race:mbsnrtowcs/!ps    │
       └─────────────┴───────────────┴──────────────────────────────────┘

CONFORMING TO         top

       POSIX.1-2008.

NOTES         top

       The behavior of mbsnrtowcs() depends on the LC_CTYPE category of
       the current locale.

       Passing NULL as ps is not multithread safe.

SEE ALSO         top

       iconv(3), mbrtowc(3), mbsinit(3), mbsrtowcs(3)

COLOPHON         top

       This page is part of release 5.12 of the Linux man-pages project.
       A description of the project, information about reporting bugs,
       and the latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.

GNU                            2021-03-22                  MBSNRTOWCS(3)

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