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
   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

   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 4.09 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/.

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