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 * 3. 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)
34 static 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
46 static int sflush_locked(FILE *);
47
48 /*
49 * Flush a single file, or (if fp is NULL) all files.
50 * MT-safe version
51 */
52 int
fflush(FILE * fp)53 fflush(FILE *fp)
54 {
55 int retval;
56
57 if (fp == NULL)
58 return (_fwalk(sflush_locked));
59 FLOCKFILE_CANCELSAFE(fp);
60
61 /*
62 * There is disagreement about the correct behaviour of fflush()
63 * when passed a file which is not open for writing. 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 * SUSv3 now requires that fflush() returns success on a read-only
72 * stream.
73 *
74 */
75 if ((fp->_flags & (__SWR | __SRW)) == 0)
76 retval = 0;
77 else
78 retval = __sflush(fp);
79 FUNLOCKFILE_CANCELSAFE();
80 return (retval);
81 }
82
83 /*
84 * Flush a single file, or (if fp is NULL) all files.
85 * Non-MT-safe version
86 */
87 int
__fflush(FILE * fp)88 __fflush(FILE *fp)
89 {
90 int retval;
91
92 if (fp == NULL)
93 return (_fwalk(sflush_locked));
94 if ((fp->_flags & (__SWR | __SRW)) == 0)
95 retval = 0;
96 else
97 retval = __sflush(fp);
98 return (retval);
99 }
100
101 __weak_reference(__fflush, fflush_unlocked);
102
103 int
__sflush(FILE * fp)104 __sflush(FILE *fp)
105 {
106 unsigned char *p;
107 int n, t;
108
109 t = fp->_flags;
110 if ((t & __SWR) == 0)
111 return (0);
112
113 if ((p = fp->_bf._base) == NULL)
114 return (0);
115
116 n = fp->_p - p; /* write this much */
117
118 /*
119 * Set these immediately to avoid problems with longjmp and to allow
120 * exchange buffering (via setvbuf) in user write function.
121 */
122 fp->_p = p;
123 fp->_w = t & (__SLBF|__SNBF) ? 0 : fp->_bf._size;
124
125 for (; n > 0; n -= t, p += t) {
126 t = _swrite(fp, (char *)p, n);
127 if (t <= 0) {
128 /* Reset _p and _w. */
129 if (p > fp->_p) {
130 /* Some was written. */
131 memmove(fp->_p, p, n);
132 fp->_p += n;
133 if ((fp->_flags & (__SLBF | __SNBF)) == 0)
134 fp->_w -= n;
135 }
136 fp->_flags |= __SERR;
137 return (EOF);
138 }
139 }
140 return (0);
141 }
142
143 static int
sflush_locked(FILE * fp)144 sflush_locked(FILE *fp)
145 {
146 int ret;
147
148 FLOCKFILE_CANCELSAFE(fp);
149 ret = __sflush(fp);
150 FUNLOCKFILE_CANCELSAFE();
151 return (ret);
152 }
153