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+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\" GNU glibc-2 source code and manual
+.\" Dinkumware C library reference http://www.dinkumware.com/
+.\" OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"
+.TH mbsnrtowcs 3 2023-07-20 "Linux man-pages 6.05.01"
+.SH NAME
+mbsnrtowcs \- convert a multibyte string to a wide-character string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.PP
+.BI "size_t mbsnrtowcs(wchar_t " dest "[restrict ." len "], const char **restrict " src ,
+.BI " size_t " nms ", size_t " len \
+", mbstate_t *restrict " ps );
+.fi
+.PP
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.PP
+.BR mbsnrtowcs ():
+.nf
+ Since glibc 2.10:
+ _POSIX_C_SOURCE >= 200809L
+ Before glibc 2.10:
+ _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR mbsnrtowcs ()
+function is like the
+.BR mbsrtowcs (3)
+function, except that
+the number of bytes to be converted, starting at
+.IR *src ,
+is limited to at most
+.I nms
+bytes.
+.PP
+If
+.I dest
+is not NULL, the
+.BR mbsnrtowcs ()
+function converts at
+most
+.I nms
+bytes from the
+multibyte string
+.I *src
+to a wide-character string starting at
+.IR dest .
+At most
+.I len
+wide characters are written to
+.IR dest .
+The shift state
+.I *ps
+is updated.
+The conversion is effectively performed by repeatedly
+calling
+.I "mbrtowc(dest, *src, n, ps)"
+where
+.I n
+is some
+positive number, as long as this call succeeds, and then incrementing
+.I dest
+by one and
+.I *src
+by the number of bytes consumed.
+The
+conversion can stop for three reasons:
+.IP \[bu] 3
+An invalid multibyte sequence has been encountered.
+In this case,
+.I *src
+is left pointing to the invalid multibyte sequence,
+.I (size_t)\ \-1
+is returned,
+and
+.I errno
+is set to
+.BR EILSEQ .
+.IP \[bu]
+The
+.I nms
+limit forces a stop,
+or
+.I len
+non-L\[aq]\e0\[aq] wide characters
+have been stored at
+.IR dest .
+In this case,
+.I *src
+is left pointing to the
+next multibyte sequence to be converted, and the number of wide characters
+written to
+.I dest
+is returned.
+.IP \[bu]
+The multibyte string has been completely converted, including the
+terminating null wide character (\[aq]\e0\[aq])
+(which has the side effect of bringing back
+.I *ps
+to the
+initial state).
+In this case,
+.I *src
+is set to NULL, and the number of wide
+characters written to
+.IR dest ,
+excluding the terminating null wide character,
+is returned.
+.PP
+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.
+.PP
+If
+.I dest
+is NULL,
+.I 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.
+.PP
+In both of the above cases, if
+.I ps
+is NULL, a static anonymous
+state known only to the
+.BR mbsnrtowcs ()
+function is used instead.
+.PP
+The programmer must ensure that there is room for at least
+.I len
+wide
+characters at
+.IR dest .
+.SH RETURN VALUE
+The
+.BR 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,
+.I (size_t)\ \-1
+is returned, and
+.I errno
+set to
+.BR EILSEQ .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface Attribute Value
+T{
+.na
+.nh
+.BR mbsnrtowcs ()
+T} Thread safety T{
+.na
+.nh
+MT-Unsafe race:mbsnrtowcs/!ps
+T}
+.TE
+.sp 1
+.SH STANDARDS
+POSIX.1-2008.
+.SH NOTES
+The behavior of
+.BR mbsnrtowcs ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.PP
+Passing NULL as
+.I ps
+is not multithread safe.
+.SH SEE ALSO
+.BR iconv (3),
+.BR mbrtowc (3),
+.BR mbsinit (3),
+.BR mbsrtowcs (3)