86a16ada1e
otherwise the data is just dropped. Check for current position equal to the buffer base at the entry of the function; if not equal, setvbuf() was done from the write method and it is not our business to override the decision. PR: 76398 Reviewed by: markj Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D34007
160 lines
4.3 KiB
C
160 lines
4.3 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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*
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* Copyright (c) 1990, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Chris Torek.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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static char sccsid[] = "@(#)fflush.c 8.1 (Berkeley) 6/4/93";
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#endif /* LIBC_SCCS and not lint */
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "namespace.h"
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#include <errno.h>
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#include <stdio.h>
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#include "un-namespace.h"
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#include "libc_private.h"
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#include "local.h"
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static int sflush_locked(FILE *);
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/*
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* Flush a single file, or (if fp is NULL) all files.
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* MT-safe version
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*/
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int
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fflush(FILE *fp)
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{
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int retval;
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if (fp == NULL)
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return (_fwalk(sflush_locked));
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FLOCKFILE_CANCELSAFE(fp);
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/*
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* There is disagreement about the correct behaviour of fflush()
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* when passed a file which is not open for writing. According to
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* the ISO C standard, the behaviour is undefined.
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* Under linux, such an fflush returns success and has no effect;
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* under Windows, such an fflush is documented as behaving instead
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* as fpurge().
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* Given that applications may be written with the expectation of
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* either of these two behaviours, the only safe (non-astonishing)
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* option is to return EBADF and ask that applications be fixed.
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* SUSv3 now requires that fflush() returns success on a read-only
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* stream.
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*
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*/
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if ((fp->_flags & (__SWR | __SRW)) == 0)
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retval = 0;
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else
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retval = __sflush(fp);
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FUNLOCKFILE_CANCELSAFE();
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return (retval);
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}
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/*
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* Flush a single file, or (if fp is NULL) all files.
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* Non-MT-safe version
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*/
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int
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__fflush(FILE *fp)
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{
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int retval;
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if (fp == NULL)
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return (_fwalk(sflush_locked));
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if ((fp->_flags & (__SWR | __SRW)) == 0)
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retval = 0;
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else
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retval = __sflush(fp);
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return (retval);
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}
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__weak_reference(__fflush, fflush_unlocked);
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int
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__sflush(FILE *fp)
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{
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unsigned char *p, *old_p;
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int n, t, old_w;
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t = fp->_flags;
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if ((t & __SWR) == 0)
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return (0);
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if ((p = fp->_bf._base) == NULL)
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return (0);
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n = fp->_p - p; /* write this much */
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/*
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* Set these immediately to avoid problems with longjmp and to allow
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* exchange buffering (via setvbuf) in user write function.
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*/
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old_p = fp->_p;
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fp->_p = p;
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old_w = fp->_w;
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fp->_w = t & (__SLBF|__SNBF) ? 0 : fp->_bf._size;
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for (; n > 0; n -= t, p += t) {
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t = _swrite(fp, (char *)p, n);
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if (t <= 0) {
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/* Reset _p and _w. */
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if (p > fp->_p) {
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/* Some was written. */
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memmove(fp->_p, p, n);
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fp->_p += n;
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if ((fp->_flags & (__SLBF | __SNBF)) == 0)
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fp->_w -= n;
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} else if (p == fp->_p) { /* cond. to handle setvbuf */
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fp->_p = old_p;
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fp->_w = old_w;
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}
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fp->_flags |= __SERR;
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return (EOF);
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}
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}
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return (0);
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}
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static int
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sflush_locked(FILE *fp)
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{
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int ret;
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FLOCKFILE_CANCELSAFE(fp);
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ret = __sflush(fp);
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FUNLOCKFILE_CANCELSAFE();
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return (ret);
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}
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