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

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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: head/lib/libc/stdio/fflush.c 268924 2014-07-20 20:05:39Z pfg $");
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

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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 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(fp);
80 return (retval);
81}
82
83/*
84 * Flush a single file, or (if fp is NULL) all files.
85 * Non-MT-safe version
86 */
87int
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
101int
102__sflush(FILE *fp)
103{
104 unsigned char *p;

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118 * exchange buffering (via setvbuf) in user write function.
119 */
120 fp->_p = p;
121 fp->_w = t & (__SLBF|__SNBF) ? 0 : fp->_bf._size;
122
123 for (; n > 0; n -= t, p += t) {
124 t = _swrite(fp, (char *)p, n);
125 if (t <= 0) {
126 /* Reset _p and _w. */
127 if (p > fp->_p) /* Some was written. */
128 memmove(fp->_p, p, n);
129 fp->_p += n;
130 if ((fp->_flags & (__SLBF | __SNBF)) == 0)
131 fp->_w -= n;
132 fp->_flags |= __SERR;
133 return (EOF);
134 }
135 }
136 return (0);
137}
138
139static int
140sflush_locked(FILE *fp)
141{
142 int ret;
143
144 FLOCKFILE(fp);
145 ret = __sflush(fp);
146 FUNLOCKFILE(fp);
147 return (ret);
148}