mbsrtowcs(3p) — Linux manual page

MBSRTOWCS(3P)           POSIX Programmer's Manual          MBSRTOWCS(3P)

PROLOG

       This manual page is part of the POSIX Programmer's Manual.  The
       Linux implementation of this interface may differ (consult the
       corresponding Linux manual page for details of Linux behavior),
       or the interface may not be implemented on Linux.

NAME

       mbsnrtowcs, mbsrtowcs — convert a character string to a wide-
       character string (restartable)

SYNOPSIS

       #include <wchar.h>

       size_t mbsnrtowcs(wchar_t *restrict dst, const char **restrict src,
           size_t nmc, size_t len, mbstate_t *restrict ps);
       size_t mbsrtowcs(wchar_t *restrict dst, const char **restrict src,
           size_t len, mbstate_t *restrict ps);

DESCRIPTION

       For mbsrtowcs(): The functionality described on this reference
       page is aligned with the ISO C standard. Any conflict between the
       requirements described here and the ISO C standard is
       unintentional. This volume of POSIX.1‐2017 defers to the ISO C
       standard.

       The mbsrtowcs() function shall convert a sequence of characters,
       beginning in the conversion state described by the object pointed
       to by ps, from the array indirectly pointed to by src into a
       sequence of corresponding wide characters. If dst is not a null
       pointer, the converted characters shall be stored into the array
       pointed to by dst.  Conversion continues up to and including a
       terminating null character, which shall also be stored.
       Conversion shall stop early in either of the following cases:

        *  A sequence of bytes is encountered that does not form a valid
           character.

        *  len codes have been stored into the array pointed to by dst
           (and dst is not a null pointer).

       Each conversion shall take place as if by a call to the mbrtowc()
       function.

       If dst is not a null pointer, the pointer object pointed to by
       src shall be assigned either a null pointer (if conversion
       stopped due to reaching a terminating null character) or the
       address just past the last character converted (if any). If
       conversion stopped due to reaching a terminating null character,
       and if dst is not a null pointer, the resulting state described
       shall be the initial conversion state.

       If ps is a null pointer, the mbsrtowcs() function shall use its
       own internal mbstate_t object, which is initialized at program
       start-up to the initial conversion state. Otherwise, the
       mbstate_t object pointed to by ps shall be used to completely
       describe the current conversion state of the associated character
       sequence.

       The mbsnrtowcs() function shall be equivalent to the mbsrtowcs()
       function, except that the conversion of characters indirectly
       pointed to by src is limited to at most nmc bytes (the size of
       the input buffer), and under conditions where mbsrtowcs() would
       assign the address just past the last character converted (if
       any) to the pointer object pointed to by src, mbsnrtowcs() shall
       instead assign the address just past the last byte processed (if
       any) to that pointer object. 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. In the latter case, a subsequent call to
       mbsnrtowcs() with an input buffer that starts with the remainder
       of the incomplete character shall correctly complete the
       conversion of that character.

       The behavior of these functions shall be affected by the LC_CTYPE
       category of the current locale.

       The implementation shall behave as if no function defined in this
       volume of POSIX.1‐2017 calls these functions.

       The mbsnrtowcs() and mbsrtowcs() functions need not be thread-
       safe if called with a NULL ps argument.

       The mbsrtowcs() function shall not change the setting of errno if
       successful.

RETURN VALUE

       If the input conversion encounters a sequence of bytes that do
       not form a valid character, an encoding error occurs. In this
       case, these functions shall store the value of the macro [EILSEQ]
       in errno and shall return (size_t)-1; the conversion state is
       undefined.  Otherwise, these functions shall return the number of
       characters successfully converted, not including the terminating
       null (if any).

ERRORS

       These functions shall fail if:

       EILSEQ An invalid character sequence is detected.  In the POSIX
              locale an [EILSEQ] error cannot occur since all byte
              values are valid characters.

       These functions may fail if:

       EINVAL ps points to an object that contains an invalid conversion
              state.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       A future version may require that when the input buffer ends with
       an incomplete character, conversion stops at the end of the input
       buffer.

SEE ALSO

       iconv(3p), mbrtowc(3p), mbsinit(3p)

       The Base Definitions volume of POSIX.1‐2017, wchar.h(0p)

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  In the event of any
       discrepancy between this version and the original IEEE and The
       Open Group Standard, the original IEEE and The Open Group
       Standard is the referee document. The original Standard can be
       obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page
       are most likely to have been introduced during the conversion of
       the source files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group               2017                     MBSRTOWCS(3P)

Pages that refer to this page: wchar.h(0p), iconv(3p), mbrtowc(3p), mbsinit(3p)

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