NAME

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

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

       #include <wchar.h>

       size_t mbsnrtowcs(wchar_t dest[restrict .len], 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

       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:

       •  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.

       •  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.

       •  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

       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

       For an explanation of the terms used in this section, see attributes(7).
       ┌──────────────┬───────────────┬────────────────────────────────────────────────────────────────────────┐
       │ Interface    │ Attribute     │ Value                                                                  │
       ├──────────────┼───────────────┼────────────────────────────────────────────────────────────────────────┤
       │ mbsnrtowcs() │ Thread safety │ MT-Unsafe race:mbsnrtowcs/!ps                                          │
       └──────────────┴───────────────┴────────────────────────────────────────────────────────────────────────┘

STANDARDS

       POSIX.1-2008.

NOTES

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

       Passing NULL as ps is not multithread safe.

SEE ALSO

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

Linux man-pages 6.9.1                              2024-06-15                                      mbsnrtowcs(3)