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fflush.c revision 1.6 
      1 /*-
      2  * Copyright (c) 1990 The Regents of the University of California.
      3  * All rights reserved.
      4  *
      5  * This code is derived from software contributed to Berkeley by
      6  * Chris Torek.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in the
     15  *    documentation and/or other materials provided with the distribution.
     16  * 3. All advertising materials mentioning features or use of this software
     17  *    must display the following acknowledgement:
     18  *	This product includes software developed by the University of
     19  *	California, Berkeley and its contributors.
     20  * 4. Neither the name of the University nor the names of its contributors
     21  *    may be used to endorse or promote products derived from this software
     22  *    without specific prior written permission.
     23  *
     24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     34  * SUCH DAMAGE.
     35  */
     36 
     37 #if defined(LIBC_SCCS) && !defined(lint)
     38 /*static char *sccsid = "from: @(#)fflush.c	5.1 (Berkeley) 1/20/91";*/
     39 static char *rcsid = "$Id: fflush.c,v 1.6 1993/12/31 19:13:58 jtc Exp $";
     40 #endif /* LIBC_SCCS and not lint */
     41 
     42 #include <sys/errno.h>
     43 #include <stdio.h>
     44 #include "local.h"
     45 
     46 /* Flush a single file, or (if fp is NULL) all files.  */
     47 int
     48 fflush(fp)
     49 	register FILE *fp;
     50 {
     51 	if (fp == NULL)
     52 		return (_fwalk(__sflush));
     53 
     54 	if ((fp->_flags & (__SWR | __SRW)) == 0) {
     55 		errno = EBADF;
     56 		return (EOF);
     57 	}
     58 	return (__sflush(fp));
     59 }
     60 
     61 int
     62 __sflush(fp)
     63 	register FILE *fp;
     64 {
     65 	register unsigned char *p;
     66 	register int n, t;
     67 
     68 	t = fp->_flags;
     69 	if ((t & __SWR) == 0)
     70 		return (0);
     71 
     72 	if ((p = fp->_bf._base) == NULL)
     73 		return (0);
     74 
     75 	n = fp->_p - p;		/* write this much */
     76 
     77 	/*
     78 	 * Set these immediately to avoid problems with longjmp and to allow
     79 	 * exchange buffering (via setvbuf) in user write function.
     80 	 */
     81 	fp->_p = p;
     82 	fp->_w = t & (__SLBF|__SNBF) ? 0 : fp->_bf._size;
     83 
     84 	for (; n > 0; n -= t, p += t) {
     85 		t = (*fp->_write)(fp->_cookie, (char *)p, n);
     86 		if (t <= 0) {
     87 			fp->_flags |= __SERR;
     88 			return (EOF);
     89 		}
     90 	}
     91 	return (0);
     92 }
     93