b6cbf7203b
This patch imports the unmodified current version of NetBSD libc. The NetBSD includes are in /nbsd_include, while the libc code itself is split between lib/nbsd_libc and common/lib/libc.
206 lines
5.6 KiB
Groff
206 lines
5.6 KiB
Groff
.\" $NetBSD: mbrlen.3,v 1.9 2008/02/28 19:36:51 tnozaki Exp $
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.\"
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.\" Copyright (c)2002 Citrus Project,
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.Dd February 3, 2002
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.Dt MBRLEN 3
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.Os
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.\" ----------------------------------------------------------------------
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.Sh NAME
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.Nm mbrlen
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.Nd get number of bytes in a multibyte character (restartable)
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.\" ----------------------------------------------------------------------
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.Sh LIBRARY
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.Lb libc
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.\" ----------------------------------------------------------------------
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.Sh SYNOPSIS
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.In wchar.h
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.Ft size_t
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.Fn mbrlen "const char * restrict s" "size_t n" "mbstate_t * restrict ps"
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.\" ----------------------------------------------------------------------
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.Sh DESCRIPTION
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The
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.Fn mbrlen
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function usually determines the number of bytes in
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a multibyte character pointed to by
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.Fa s
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and returns it.
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This function shall only examine max n bytes of the array beginning from
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.Fa s .
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.Pp
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.Fn mbrlen
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is equivalent to the following call (except
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.Fa ps
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is evaluated only once):
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.Bd -literal -offset indent
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mbrtowc(NULL, s, n, (ps != NULL) ? ps : \*[Am]internal);
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.Ed
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.Pp
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Here,
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.Fa internal
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is an internal state object.
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.Pp
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In state-dependent encodings,
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.Fa s
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may point to the special sequence bytes to change the shift-state.
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Although such sequence bytes corresponds to no individual
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wide-character code, these affect the conversion state object pointed
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to by
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.Fa ps ,
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and the
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.Fn mbrlen
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treats the special sequence bytes
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as if these are a part of the subsequent multibyte character.
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.Pp
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Unlike
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.Xr mblen 3 ,
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.Fn mbrlen
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may accept the byte sequence when it is not a complete character
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but possibly contains part of a valid character.
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In this case, this function will accept all such bytes
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and save them into the conversion state object pointed to by
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.Fa ps .
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They will be used on subsequent calls of this function to restart
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the conversion suspended.
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.Pp
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The behaviour of
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.Fn mbrlen
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is affected by the
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.Dv LC_CTYPE
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category of the current locale.
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.Pp
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These are the special cases:
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.Bl -tag -width 0123456789
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.It "s == NULL"
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.Fn mbrlen
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sets the conversion state object pointed to by
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.Fa ps
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to an initial state and always returns 0.
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Unlike
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.Xr mblen 3 ,
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the value returned does not indicate whether the current encoding of
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the locale is state-dependent.
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.Pp
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In this case,
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.Fn mbrlen
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ignores
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.Fa n .
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.It "n == 0"
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In this case,
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the first
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.Fa n
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bytes of the array pointed to by
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.Fa s
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never form a complete character.
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Thus,
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.Fn mbrlen
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always returns (size_t)-2.
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.It "ps == NULL"
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.Fn mbrlen
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uses its own internal state object to keep the conversion state,
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instead of
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.Fa ps
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mentioned in this manual page.
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.Pp
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Calling any other functions in
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.Lb libc
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never changes the internal
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state of
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.Fn mbrlen ,
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except for calling
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.Xr setlocale 3
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with a changing
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.Dv LC_CTYPE
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category of the current locale.
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Such
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.Xr setlocale 3
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calls cause the internal state of this function to be indeterminate.
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This internal state is initialized at startup time of the program.
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.El
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.\" ----------------------------------------------------------------------
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.Sh RETURN VALUES
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The
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.Fn mbrlen
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returns:
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.Bl -tag -width 0123456789
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.It "0"
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.Fa s
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points to a nul byte
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.Pq Sq \e0 .
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.It "positive"
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The value returned is
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a number of bytes for the valid multibyte character pointed to by
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.Fa s .
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There are no cases that this value is greater than
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.Fa n
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or the value of the
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.Dv MB_CUR_MAX
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macro.
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.It "(size_t)-2"
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.Fa s
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points to the byte sequence which possibly contains part of a valid
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multibyte character, but which is incomplete.
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When
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.Fa n
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is at least
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.Dv MB_CUR_MAX ,
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this case can only occur if the array pointed to by
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.Fa s
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contains a redundant shift sequence.
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.It "(size_t)-1"
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.Fa s
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points to an illegal byte sequence which does not form a valid multibyte
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character.
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In this case,
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.Fn mbrtowc
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sets
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.Va errno
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to indicate the error.
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.El
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.\" ----------------------------------------------------------------------
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.Sh ERRORS
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.Fn mbrlen
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may cause an error in the following case:
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.Bl -tag -width Er
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.It Bq Er EILSEQ
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.Fa s
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points to an invalid multibyte character.
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.It Bq Er EINVAL
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.Fa ps
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points to an invalid or uninitialized mbstate_t object.
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.El
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.\" ----------------------------------------------------------------------
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.Sh SEE ALSO
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.Xr mblen 3 ,
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.Xr mbrtowc 3 ,
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.Xr setlocale 3
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.\" ----------------------------------------------------------------------
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.Sh STANDARDS
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The
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.Fn mbrlen
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function conforms to
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.St -isoC-amd1 .
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The restrict qualifier is added at
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.St -isoC-99 .
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