1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
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 "namespace.h"
36 #include <errno.h>
37 #include <stdio.h>
38 #include "un-namespace.h"
39 #include "libc_private.h"
40 #include "local.h"
41
42 static int sflush_locked(FILE *);
43
44 /*
45 * Flush a single file, or (if fp is NULL) all files.
46 * MT-safe version
47 */
48 int
fflush(FILE * fp)49 fflush(FILE *fp)
50 {
51 int retval;
52
53 if (fp == NULL)
54 return (_fwalk(sflush_locked));
55 FLOCKFILE_CANCELSAFE(fp);
56
57 /*
58 * There is disagreement about the correct behaviour of fflush()
59 * when passed a file which is not open for writing. According to
60 * the ISO C standard, the behaviour is undefined.
61 * Under linux, such an fflush returns success and has no effect;
62 * under Windows, such an fflush is documented as behaving instead
63 * as fpurge().
64 * Given that applications may be written with the expectation of
65 * either of these two behaviours, the only safe (non-astonishing)
66 * option is to return EBADF and ask that applications be fixed.
67 * SUSv3 now requires that fflush() returns success on a read-only
68 * stream.
69 *
70 */
71 if ((fp->_flags & (__SWR | __SRW)) == 0)
72 retval = 0;
73 else
74 retval = __sflush(fp);
75 FUNLOCKFILE_CANCELSAFE();
76 return (retval);
77 }
78
79 /*
80 * Flush a single file, or (if fp is NULL) all files.
81 * Non-MT-safe version
82 */
83 int
__fflush(FILE * fp)84 __fflush(FILE *fp)
85 {
86 int retval;
87
88 if (fp == NULL)
89 return (_fwalk(sflush_locked));
90 if ((fp->_flags & (__SWR | __SRW)) == 0)
91 retval = 0;
92 else
93 retval = __sflush(fp);
94 return (retval);
95 }
96
97 __weak_reference(__fflush, fflush_unlocked);
98
99 int
__sflush(FILE * fp)100 __sflush(FILE *fp)
101 {
102 unsigned char *p;
103 int n, f, t;
104
105 f = fp->_flags;
106 if ((f & __SWR) == 0)
107 return (0);
108
109 if ((p = fp->_bf._base) == NULL)
110 return (0);
111
112 n = fp->_p - p; /* write this much */
113
114 /*
115 * Set these immediately to avoid problems with longjmp and to allow
116 * exchange buffering (via setvbuf) in user write function.
117 */
118 fp->_p = p;
119 fp->_w = f & (__SLBF|__SNBF) ? 0 : fp->_bf._size;
120
121 for (; n > 0; n -= t, p += t) {
122 t = _swrite(fp, (char *)p, n);
123 if (t <= 0) {
124 if (p > fp->_p)
125 /* Some was written. */
126 memmove(fp->_p, p, n);
127 /* Reset _p and _w. */
128 fp->_p += n;
129 if ((fp->_flags & __SNBF) == 0)
130 fp->_w -= n;
131 fp->_flags |= __SERR;
132 return (EOF);
133 }
134 }
135 return (0);
136 }
137
138 static int
sflush_locked(FILE * fp)139 sflush_locked(FILE *fp)
140 {
141 int ret;
142
143 FLOCKFILE_CANCELSAFE(fp);
144 ret = __sflush(fp);
145 FUNLOCKFILE_CANCELSAFE();
146 return (ret);
147 }
148