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man:mbsnrtowcs

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

NAME

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

SYNOPSIS

     #include <wchar.h>
     size_t mbsnrtowcs(wchar_t *dest, const char **src,
                       size_t nms, size_t len, mbstate_t *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  start-
     ing  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,  exclud-
        ing the terminating null wide character, is returned.
     According to POSIX.1, if the input buffer ends with an incomplete char-
     acter, 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 mem-
     ory, 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 |
     +-------------+---------------+-------------------------------+

CONFORMING TO

     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)

COLOPHON

     This  page  is  part of release 4.16 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 2017-09-15 MBSNRTOWCS(3)

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