81 lines
2.3 KiB
C
81 lines
2.3 KiB
C
/*
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* Copyright (c) 1990 The Regents of the University of California.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms are permitted
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* provided that the above copyright notice and this paragraph are
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* duplicated in all such forms and that any documentation,
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* and/or other materials related to such
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* distribution and use acknowledge that the software was developed
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* by the University of California, Berkeley. The name of the
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* University may not be used to endorse or promote products derived
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* from this software without specific prior written permission.
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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*/
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/*
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FUNCTION
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<<fileno>>, <<fileno_unlocked>>---return file descriptor associated with stream
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INDEX
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fileno
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INDEX
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fileno_unlocked
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SYNOPSIS
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#include <stdio.h>
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int fileno(FILE *<[fp]>);
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#define _BSD_SOURCE
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#include <stdio.h>
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int fileno_unlocked(FILE *<[fp]>);
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DESCRIPTION
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You can use <<fileno>> to return the file descriptor identified by <[fp]>.
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<<fileno_unlocked>> is a non-thread-safe version of <<fileno>>.
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<<fileno_unlocked>> may only safely be used within a scope
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protected by flockfile() (or ftrylockfile()) and funlockfile(). This
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function may safely be used in a multi-threaded program if and only
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if they are called while the invoking thread owns the (FILE *)
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object, as is the case after a successful call to the flockfile() or
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ftrylockfile() functions. If threads are disabled, then
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<<fileno_unlocked>> is equivalent to <<fileno>>.
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RETURNS
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<<fileno>> returns a non-negative integer when successful.
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If <[fp]> is not an open stream, <<fileno>> returns -1.
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PORTABILITY
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<<fileno>> is not part of ANSI C.
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POSIX requires <<fileno>>.
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<<fileno_unlocked>> is a BSD extension also provided by GNU libc.
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Supporting OS subroutines required: none.
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*/
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#include <_ansi.h>
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#include <stdio.h>
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#include <errno.h>
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#include "local.h"
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int
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fileno (FILE * f)
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{
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int result;
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CHECK_INIT (_REENT, f);
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_newlib_flockfile_start (f);
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if (f->_flags)
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result = __sfileno (f);
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else
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{
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result = -1;
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_REENT->_errno = EBADF;
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}
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_newlib_flockfile_end (f);
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return result;
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}
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