1/*-
2 * Copyright (c) 1990, 1993
3 *	The Regents of the University of California.  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 * 4. Neither the name of the University nor the names of its contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33#if defined(LIBC_SCCS) && !defined(lint)
34static char sccsid[] = "@(#)fflush.c	8.1 (Berkeley) 6/4/93";
35#endif /* LIBC_SCCS and not lint */
36#include <sys/cdefs.h>
37__FBSDID("$FreeBSD$");
38
39#include "namespace.h"
40#include <errno.h>
41#include <stdio.h>
42#include "un-namespace.h"
43#include "libc_private.h"
44#include "local.h"
45
46static int	sflush_locked(FILE *);
47
48/*
49 * Flush a single file, or (if fp is NULL) all files.
50 * MT-safe version
51 */
52int
53fflush(FILE *fp)
54{
55	int retval;
56
57	if (fp == NULL)
58		return (_fwalk(sflush_locked));
59	FLOCKFILE(fp);
60
61	/*
62	 * There is disagreement about the correct behaviour of fflush()
63	 * when passed a file which is not open for reading.  According to
64	 * the ISO C standard, the behaviour is undefined.
65	 * Under linux, such an fflush returns success and has no effect;
66	 * under Windows, such an fflush is documented as behaving instead
67	 * as fpurge().
68	 * Given that applications may be written with the expectation of
69	 * either of these two behaviours, the only safe (non-astonishing)
70	 * option is to return EBADF and ask that applications be fixed.
71	 */
72	if ((fp->_flags & (__SWR | __SRW)) == 0) {
73		errno = EBADF;
74		retval = EOF;
75	} else
76		retval = __sflush(fp);
77	FUNLOCKFILE(fp);
78	return (retval);
79}
80
81/*
82 * Flush a single file, or (if fp is NULL) all files.
83 * Non-MT-safe version
84 */
85int
86__fflush(FILE *fp)
87{
88	int retval;
89
90	if (fp == NULL)
91		return (_fwalk(sflush_locked));
92	if ((fp->_flags & (__SWR | __SRW)) == 0) {
93		errno = EBADF;
94		retval = EOF;
95	} else
96		retval = __sflush(fp);
97	return (retval);
98}
99
100int
101__sflush(FILE *fp)
102{
103	unsigned char *p;
104	int n, t;
105
106	t = fp->_flags;
107	if ((t & __SWR) == 0)
108		return (0);
109
110	if ((p = fp->_bf._base) == NULL)
111		return (0);
112
113	n = fp->_p - p;		/* write this much */
114
115	/*
116	 * Set these immediately to avoid problems with longjmp and to allow
117	 * exchange buffering (via setvbuf) in user write function.
118	 */
119	fp->_p = p;
120	fp->_w = t & (__SLBF|__SNBF) ? 0 : fp->_bf._size;
121
122	for (; n > 0; n -= t, p += t) {
123		t = _swrite(fp, (char *)p, n);
124		if (t <= 0) {
125			fp->_flags |= __SERR;
126			return (EOF);
127		}
128	}
129	return (0);
130}
131
132static int
133sflush_locked(FILE *fp)
134{
135	int	ret;
136
137	FLOCKFILE(fp);
138	ret = __sflush(fp);
139	FUNLOCKFILE(fp);
140	return (ret);
141}
142