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fflush.c revision 1.16 
      1 /*	$NetBSD: fflush.c,v 1.16 2012/03/13 21:13:46 christos Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1990, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * This code is derived from software contributed to Berkeley by
      8  * Chris Torek.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. Neither the name of the University nor the names of its contributors
     19  *    may be used to endorse or promote products derived from this software
     20  *    without specific prior written permission.
     21  *
     22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     32  * SUCH DAMAGE.
     33  */
     34 
     35 #include <sys/cdefs.h>
     36 #if defined(LIBC_SCCS) && !defined(lint)
     37 #if 0
     38 static char sccsid[] = "@(#)fflush.c	8.1 (Berkeley) 6/4/93";
     39 #else
     40 __RCSID("$NetBSD: fflush.c,v 1.16 2012/03/13 21:13:46 christos Exp $");
     41 #endif
     42 #endif /* LIBC_SCCS and not lint */
     43 
     44 #include <stddef.h>
     45 #include <assert.h>
     46 #include <errno.h>
     47 #include <stdio.h>
     48 #include "reentrant.h"
     49 #include "local.h"
     50 
     51 #ifdef _REENTRANT
     52 extern rwlock_t __sfp_lock;
     53 #endif
     54 
     55 /* Flush a single file, or (if fp is NULL) all files.  */
     56 int
     57 fflush(fp)
     58 	FILE *fp;
     59 {
     60 	int r;
     61 
     62 	if (fp == NULL) {
     63 		rwlock_rdlock(&__sfp_lock);
     64 		r = _fwalk(__sflush);
     65 		rwlock_unlock(&__sfp_lock);
     66 		return r;
     67 	}
     68 
     69 	FLOCKFILE(fp);
     70 	if ((fp->_flags & (__SWR | __SRW)) == 0) {
     71 		errno = EBADF;
     72 		r = EOF;
     73 	} else {
     74 		r = __sflush(fp);
     75 	}
     76 	FUNLOCKFILE(fp);
     77 	return r;
     78 }
     79 
     80 int
     81 __sflush(fp)
     82 	FILE *fp;
     83 {
     84 	unsigned char *p;
     85 	int n, t;
     86 
     87 	_DIAGASSERT(fp != NULL);
     88 
     89 	t = fp->_flags;
     90 	if ((t & __SWR) == 0)
     91 		return (0);
     92 
     93 	if ((p = fp->_bf._base) == NULL)
     94 		return (0);
     95 
     96 	ptrdiff_t tp = fp->_p - p;
     97 	_DIAGASSERT(__type_fit(int, tp));
     98 	n = (int)tp;		/* write this much */
     99 
    100 	/*
    101 	 * Set these immediately to avoid problems with longjmp and to allow
    102 	 * exchange buffering (via setvbuf) in user write function.
    103 	 */
    104 	fp->_p = p;
    105 	fp->_w = t & (__SLBF|__SNBF) ? 0 : fp->_bf._size;
    106 
    107 	for (; n > 0; n -= t, p += t) {
    108 		t = (*fp->_write)(fp->_cookie, (char *)p, n);
    109 		if (t <= 0) {
    110 			fp->_flags |= __SERR;
    111 			return (EOF);
    112 		}
    113 	}
    114 	return (0);
    115 }
    116