2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1990, 1993
5 * The Regents of the University of California. All rights reserved.
7 * This code is derived from software contributed to Berkeley by
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11 * modification, are permitted provided that the following conditions
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14 * notice, this list of conditions and the following disclaimer.
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17 * documentation and/or other materials provided with the distribution.
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19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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35 #if defined(LIBC_SCCS) && !defined(lint)
36 static char sccsid[] = "@(#)fflush.c 8.1 (Berkeley) 6/4/93";
37 #endif /* LIBC_SCCS and not lint */
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
41 #include "namespace.h"
44 #include "un-namespace.h"
45 #include "libc_private.h"
48 static int sflush_locked(FILE *);
51 * Flush a single file, or (if fp is NULL) all files.
60 return (_fwalk(sflush_locked));
61 FLOCKFILE_CANCELSAFE(fp);
64 * There is disagreement about the correct behaviour of fflush()
65 * when passed a file which is not open for writing. According to
66 * the ISO C standard, the behaviour is undefined.
67 * Under linux, such an fflush returns success and has no effect;
68 * under Windows, such an fflush is documented as behaving instead
70 * Given that applications may be written with the expectation of
71 * either of these two behaviours, the only safe (non-astonishing)
72 * option is to return EBADF and ask that applications be fixed.
73 * SUSv3 now requires that fflush() returns success on a read-only
77 if ((fp->_flags & (__SWR | __SRW)) == 0)
80 retval = __sflush(fp);
81 FUNLOCKFILE_CANCELSAFE();
86 * Flush a single file, or (if fp is NULL) all files.
95 return (_fwalk(sflush_locked));
96 if ((fp->_flags & (__SWR | __SRW)) == 0)
99 retval = __sflush(fp);
110 if ((t & __SWR) == 0)
113 if ((p = fp->_bf._base) == NULL)
116 n = fp->_p - p; /* write this much */
119 * Set these immediately to avoid problems with longjmp and to allow
120 * exchange buffering (via setvbuf) in user write function.
123 fp->_w = t & (__SLBF|__SNBF) ? 0 : fp->_bf._size;
125 for (; n > 0; n -= t, p += t) {
126 t = _swrite(fp, (char *)p, n);
128 /* Reset _p and _w. */
130 /* Some was written. */
131 memmove(fp->_p, p, n);
133 if ((fp->_flags & (__SLBF | __SNBF)) == 0)
136 fp->_flags |= __SERR;
144 sflush_locked(FILE *fp)
148 FLOCKFILE_CANCELSAFE(fp);
150 FUNLOCKFILE_CANCELSAFE();