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fflush.c revision 1.2 
      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  * PATCHES MAGIC                LEVEL   PATCH THAT GOT US HERE
     37  * --------------------         -----   ----------------------
     38  * CURRENT PATCH LEVEL:         1       00047
     39  * --------------------         -----   ----------------------
     40  *
     41  * 27 Nov 1992	Dave Rivers		Fixed fflush() to use correct flags.
     42  */
     43 
     44 #if defined(LIBC_SCCS) && !defined(lint)
     45 static char sccsid[] = "@(#)fflush.c	5.1 (Berkeley) 1/20/91";
     46 #endif /* LIBC_SCCS and not lint */
     47 
     48 #include <sys/errno.h>
     49 #include <stdio.h>
     50 #include "local.h"
     51 
     52 /* Flush a single file, or (if fp is NULL) all files.  */
     53 fflush(fp)
     54 	register FILE *fp;
     55 {
     56 	if (fp == NULL)
     57 		return (_fwalk(__sflush));
     58 
     59 	if ((fp->_flags & (__SWR | __SRW)) == 0) {
     60 		errno = EBADF;
     61 		return (EOF);
     62 	}
     63 	return (__sflush(fp));
     64 }
     65 
     66 __sflush(fp)
     67 	register FILE *fp;
     68 {
     69 	register unsigned char *p;
     70 	register int n, t;
     71 
     72 	t = fp->_flags;
     73 	if ((t & __SWR) == 0)
     74 		return (0);
     75 
     76 	if ((p = fp->_bf._base) == NULL)
     77 		return (0);
     78 
     79 	n = fp->_p - p;		/* write this much */
     80 
     81 	/*
     82 	 * Set these immediately to avoid problems with longjmp and to allow
     83 	 * exchange buffering (via setvbuf) in user write function.
     84 	 */
     85 	fp->_p = p;
     86 	fp->_w = t & (__SLBF|__SNBF) ? 0 : fp->_bf._size;
     87 
     88 	for (; n > 0; n -= t, p += t) {
     89 		t = (*fp->_write)(fp->_cookie, (char *)p, n);
     90 		if (t <= 0) {
     91 			fp->_flags |= __SERR;
     92 			return (EOF);
     93 		}
     94 	}
     95 	return (0);
     96 }
     97