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132 lines
3.7 KiB
Groff
132 lines
3.7 KiB
Groff
.\" Copyright (c) 1990, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" Chris Torek and the American National Standards Committee X3,
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.\" on Information Processing Systems.
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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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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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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.\" @(#)ferror.3 8.2 (Berkeley) 4/19/94
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.\" $FreeBSD$
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.\"
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.Dd January 28, 2009
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.Dt FERROR 3
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.Os
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.Sh NAME
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.Nm clearerr ,
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.Nm clearerr_unlocked ,
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.Nm feof ,
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.Nm feof_unlocked ,
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.Nm ferror ,
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.Nm ferror_unlocked ,
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.Nm fileno ,
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.Nm fileno_unlocked
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.Nd check and reset stream status
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In stdio.h
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.Ft void
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.Fn clearerr "FILE *stream"
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.Ft void
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.Fn clearerr_unlocked "FILE *stream"
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.Ft int
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.Fn feof "FILE *stream"
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.Ft int
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.Fn feof_unlocked "FILE *stream"
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.Ft int
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.Fn ferror "FILE *stream"
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.Ft int
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.Fn ferror_unlocked "FILE *stream"
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.Ft int
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.Fn fileno "FILE *stream"
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.Ft int
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.Fn fileno_unlocked "FILE *stream"
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.Sh DESCRIPTION
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The function
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.Fn clearerr
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clears the end-of-file and error indicators for the stream pointed
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to by
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.Fa stream .
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.Pp
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The function
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.Fn feof
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tests the end-of-file indicator for the stream pointed to by
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.Fa stream ,
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returning non-zero if it is set.
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The end-of-file indicator may be cleared by explicitly calling
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.Fn clearerr ,
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or as a side-effect of other operations, e.g.\&
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.Fn fseek .
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.Pp
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The function
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.Fn ferror
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tests the error indicator for the stream pointed to by
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.Fa stream ,
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returning non-zero if it is set.
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.Pp
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The function
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.Fn fileno
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examines the argument
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.Fa stream
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and returns its integer descriptor.
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.Pp
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The
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.Fn clearerr_unlocked ,
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.Fn feof_unlocked ,
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.Fn ferror_unlocked ,
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and
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.Fn fileno_unlocked
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functions are equivalent to
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.Fn clearerr ,
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.Fn feof ,
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.Fn ferror ,
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and
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.Fn fileno
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respectively, except that the caller is responsible for locking the stream
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with
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.Xr flockfile 3
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before calling them.
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These functions may be used to avoid the overhead of locking the stream
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and to prevent races when multiple threads are operating on the same stream.
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.Sh ERRORS
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These functions should not fail and do not set the external
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variable
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.Va errno .
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.Sh SEE ALSO
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.Xr open 2 ,
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.Xr fdopen 3 ,
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.Xr flockfile 3 ,
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.Xr stdio 3
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.Sh STANDARDS
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The functions
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.Fn clearerr ,
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.Fn feof ,
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and
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.Fn ferror
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conform to
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.St -isoC .
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