mirror of https://github.com/mkerrisk/man-pages
125 lines
3.7 KiB
Groff
125 lines
3.7 KiB
Groff
.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
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.\"
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.\" This is free documentation; you can redistribute it and/or
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.\" modify it under the terms of the GNU General Public License as
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.\" published by the Free Software Foundation; either version 2 of
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.\" the License, or (at your option) any later version.
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.\"
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.\" References consulted:
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.\" GNU glibc-2 source code and manual
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.\" Dinkumware C library reference http://www.dinkumware.com/
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.\" OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
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.\"
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.TH MBSNRTOWCS 3 2010-09-15 "GNU" "Linux Programmer's Manual"
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.SH NAME
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mbsnrtowcs \- convert a multibyte string to a wide-character string
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.SH SYNOPSIS
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.nf
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.B #include <wchar.h>
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.sp
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.BI "size_t mbsnrtowcs(wchar_t *" dest ", const char **" src ,
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.BI " size_t " nms ", size_t " len ", mbstate_t *" ps );
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.fi
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.sp
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.in -4n
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Feature Test Macro Requirements for glibc (see
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.BR feature_test_macros (7)):
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.in
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.sp
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.BR mbsnrtowcs ():
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.PD 0
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.ad l
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.RS 4
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.TP 4
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Since glibc 2.10:
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_XOPEN_SOURCE\ >=\ 700 || _POSIX_C_SOURCE\ >=\ 200809L
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.TP
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Before glibc 2.10:
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_GNU_SOURCE
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.RE
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.ad
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.PD
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.SH DESCRIPTION
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The
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.BR mbsnrtowcs ()
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function is like the
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.BR mbsrtowcs (3)
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function, except that
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the number of bytes to be converted, starting at \fI*src\fP, is limited to
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\fInms\fP.
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.PP
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If \fIdest\fP is not a NULL pointer, the
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.BR mbsnrtowcs ()
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function converts at
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most \fInms\fP bytes from the
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multibyte string \fI*src\fP to a wide-character string starting at \fIdest\fP.
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At most \fIlen\fP wide characters are written to \fIdest\fP.
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The shift state
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\fI*ps\fP is updated.
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The conversion is effectively performed by repeatedly
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calling
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.I "mbrtowc(dest, *src, n, ps)"
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where \fIn\fP is some
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positive number, as long as this call succeeds, and then incrementing
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\fIdest\fP by one and \fI*src\fP by the number of bytes consumed.
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The
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conversion can stop for three reasons:
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.IP 1. 3
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An invalid multibyte sequence has been encountered.
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In this case \fI*src\fP
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is left pointing to the invalid multibyte sequence,
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.I (size_t)\ \-1
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is returned,
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and \fIerrno\fP is set to \fBEILSEQ\fP.
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.IP 2.
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The \fInms\fP limit forces a stop,
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or \fIlen\fP non-L\(aq\\0\(aq wide characters
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have been stored at \fIdest\fP.
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In this case \fI*src\fP is left pointing to the
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next multibyte sequence to be converted, and the number of wide characters
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written to \fIdest\fP is returned.
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.IP 3.
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The multibyte string has been completely converted, including the
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terminating \(aq\\0\(aq
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(which has the side effect of bringing back \fI*ps\fP to the
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initial state).
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In this case \fI*src\fP is set to NULL, and the number of wide
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characters written to \fIdest\fP,
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excluding the terminating L\(aq\\0\(aq character,
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is returned.
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.PP
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If \fIdest\fP is NULL, \fIlen\fP is ignored, and the conversion proceeds as
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above, except that the converted wide characters
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are not written out to memory,
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and that no destination length limit exists.
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.PP
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In both of the above cases, if \fIps\fP is a NULL pointer, a static anonymous
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state only known to the mbsnrtowcs function is used instead.
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.PP
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The programmer must ensure that there is room for at least \fIlen\fP wide
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characters at \fIdest\fP.
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.SH "RETURN VALUE"
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The
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.BR mbsnrtowcs ()
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function returns the number of wide characters
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that make up the converted part of the wide-character string,
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not including the terminating null wide character.
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If an invalid multibyte sequence was
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encountered,
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.I (size_t)\ \-1
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is returned, and \fIerrno\fP set to \fBEILSEQ\fP.
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.SH "CONFORMING TO"
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This function is a GNU extension.
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.SH NOTES
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The behavior of
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.BR mbsnrtowcs ()
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depends on the
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.B LC_CTYPE
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category of the
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current locale.
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.PP
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Passing NULL as \fIps\fP is not multithread safe.
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.SH "SEE ALSO"
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.BR iconv (3),
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.BR mbsrtowcs (3)
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