mirror of https://github.com/mkerrisk/man-pages
110 lines
3.4 KiB
Groff
110 lines
3.4 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 WCSNRTOMBS 3 2007-07-26 "GNU" "Linux Programmer's Manual"
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.SH NAME
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wcsnrtombs \- convert a wide-character string to a multibyte string
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.SH SYNOPSIS
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.nf
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.B #define _GNU_SOURCE
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.B #include <wchar.h>
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.sp
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.BI "size_t wcsnrtombs(char *" dest ", const wchar_t **" src ", size_t " nwc ,
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.BI " size_t " len ", mbstate_t *" ps );
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.fi
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.SH DESCRIPTION
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The
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.BR wcsnrtombs ()
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function is like the
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.BR wcsrtombs (3)
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function,
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except that the number of wide characters to be converted,
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starting at \fI*src\fP, is limited to \fInwc\fP.
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.PP
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If \fIdest\fP is not a NULL pointer,
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the
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.BR wcsnrtombs ()
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function converts
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at most \fInwc\fP wide characters from
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the wide-character string \fI*src\fP to a multibyte string starting at
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\fIdest\fP.
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At most \fIlen\fP bytes 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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.IR "wcrtomb(dest, *src, ps)" ,
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as long as this call succeeds,
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and then incrementing \fIdest\fP by the
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number of bytes written and \fI*src\fP
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by one.
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The conversion can stop for three reasons:
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.PP
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1. A wide character has been encountered that can not be represented as a
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multibyte sequence (according to the current locale).
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In this case \fI*src\fP
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is left pointing to the invalid wide character,
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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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.PP
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2. \fInwc\fP wide characters have been
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converted without encountering a L'\\0',
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or the length limit forces a stop.
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In this case \fI*src\fP is left pointing
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to the next wide character to be converted, and the number of bytes written
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to \fIdest\fP is returned.
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.PP
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3. The wide-character string has been completely converted, including the
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terminating L'\\0' (which has the side effect of bringing back \fI*ps\fP
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to the initial state).
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In this case \fI*src\fP is set to NULL, and the number
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of bytes written to \fIdest\fP, excluding the terminating '\\0' byte, is
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returned.
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.PP
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If \fIdest\fP is NULL, \fIlen\fP is ignored,
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and the conversion proceeds as above,
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except that the converted bytes are not written out to memory, and that
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no destination length limit exists.
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.PP
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In both of the above cases,
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if \fIps\fP is a NULL pointer, a static anonymous
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state only known to the wcsnrtombs 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 bytes
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at \fIdest\fP.
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.SH "RETURN VALUE"
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The
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.BR wcsnrtombs ()
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function returns
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the number of bytes that make up the
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converted part of multibyte sequence,
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not including the terminating null byte.
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If a wide character was encountered which
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could not be converted,
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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 wcsnrtombs ()
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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 multi-thread safe.
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.SH "SEE ALSO"
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.BR iconv (3),
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.BR wcsrtombs (3)
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