xref: /netbsd-src/lib/libc/stdio/fflush.c (revision 811e6386f8c5e4a3521c7003da29ec8673e344fa)
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