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/*-
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 * Copyright (c) 1990, 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.
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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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 * 3. All advertising materials mentioning features or use of this software
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 *    must display the following acknowledgement:
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 *      This product includes software developed by the University of
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 *      California, Berkeley and its contributors.
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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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#if defined(LIBC_SCCS) && !defined(lint)
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#if 0
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static char sccsid[] = "@(#)fpurge.c    8.1 (Berkeley) 6/4/93";
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#endif
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static const char rcsid[] =
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                "$\Id: fpurge.c,v 1.3 1996/06/22 10:33:16 jraynard Exp $";
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#endif /* LIBC_SCCS and not lint */
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include "local.h"
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#ifdef _THREAD_SAFE
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#include <pthread.h>
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#include "pthread_private.h"
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#endif
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/*
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 * fpurge: like fflush, but without writing anything: leave the
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 * given FILE's buffer empty.
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 */
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int
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fpurge(fp)
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        register FILE *fp;
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{
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        int retval;
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#ifdef _THREAD_SAFE
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        _thread_flockfile(fp,__FILE__,__LINE__);
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#endif
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        if (!fp->_flags) {
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                errno = EBADF;
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                retval = EOF;
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        } else {
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                if (HASUB(fp))
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                        FREEUB(fp);
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                fp->_p = fp->_bf._base;
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                fp->_r = 0;
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                fp->_w = fp->_flags & (__SLBF|__SNBF) ? 0 : fp->_bf._size;
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                retval = 0;
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        }
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#ifdef _THREAD_SAFE
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        _thread_funlockfile(fp);
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#endif
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        return (retval);
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}