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      1 /*	$OpenBSD: fflush.c,v 1.5 2005/08/08 08:05:36 espie Exp $ */
      2 /*-
      3  * Copyright (c) 1990, 1993
      4  *	The Regents of the University of California.  All rights reserved.
      5  *
      6  * This code is derived from software contributed to Berkeley by
      7  * Chris Torek.
      8  *
      9  * Redistribution and use in source and binary forms, with or without
     10  * modification, are permitted provided that the following conditions
     11  * are met:
     12  * 1. Redistributions of source code must retain the above copyright
     13  *    notice, this list of conditions and the following disclaimer.
     14  * 2. Redistributions in binary form must reproduce the above copyright
     15  *    notice, this list of conditions and the following disclaimer in the
     16  *    documentation and/or other materials provided with the distribution.
     17  * 3. Neither the name of the University nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  */
     33 
     34 #include <errno.h>
     35 #include <stdio.h>
     36 #include "local.h"
     37 
     38 /* Flush a single file, or (if fp is NULL) all files.  */
     39 int
     40 fflush(FILE *fp)
     41 {
     42 	int r;
     43 
     44 	if (fp == NULL)
     45 		return (_fwalk(__sflush_locked));
     46 	FLOCKFILE(fp);
     47 	if ((fp->_flags & (__SWR | __SRW)) == 0) {
     48 		errno = EBADF;
     49 		r = EOF;
     50 	} else
     51 		r = __sflush(fp);
     52 	FUNLOCKFILE(fp);
     53 	return (r);
     54 }
     55 
     56 int
     57 __sflush(FILE *fp)
     58 {
     59 	unsigned char *p;
     60 	int n, t;
     61 
     62 	t = fp->_flags;
     63 	if ((t & __SWR) == 0)
     64 		return (0);
     65 
     66 	if ((p = fp->_bf._base) == NULL)
     67 		return (0);
     68 
     69 	n = fp->_p - p;		/* write this much */
     70 
     71 	/*
     72 	 * Set these immediately to avoid problems with longjmp and to allow
     73 	 * exchange buffering (via setvbuf) in user write function.
     74 	 */
     75 	fp->_p = p;
     76 	fp->_w = t & (__SLBF|__SNBF) ? 0 : fp->_bf._size;
     77 
     78 	for (; n > 0; n -= t, p += t) {
     79 		t = (*fp->_write)(fp->_cookie, (char *)p, n);
     80 		if (t <= 0) {
     81 			fp->_flags |= __SERR;
     82 			return (EOF);
     83 		}
     84 	}
     85 	return (0);
     86 }
     87 
     88 int
     89 __sflush_locked(FILE *fp)
     90 {
     91 	int r;
     92 
     93 	FLOCKFILE(fp);
     94 	r = __sflush(fp);
     95 	FUNLOCKFILE(fp);
     96 	return (r);
     97 }
     98