fda0a14f47
If used with fopen(3)/fdopen(3)-ed FILEs, stdio accurately uses
non-cancellable internal versions of the functions, i.e. it seems to
be fine with regard to cancellation. But if the funopen(3) and
f{r,w}open(3) functions were used to open the FILE, and corresponding
user functions create cancellation points (they typically have no
other choice), then stdio code at least leaks FILE' lock.
The change installs cleanup handler which unlocks FILE. Some minimal
restructuring of the code was required to make it use common return
place to satisfy hand-rolled pthread_cleanup_pop() requirements.
Noted by: eugen
Reviewed by: eugen, vangyzen
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D11246
151 lines
4.1 KiB
C
151 lines
4.1 KiB
C
/*-
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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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int
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__sflush(FILE *fp)
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{
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unsigned char *p;
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int n, t;
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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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fp->_p = p;
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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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}
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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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