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df140f7277
be serialized. A mutex is used to protect the critical regions. sbrk() and brk() are not thread safe. Replace use of sbrk() with a call to malloc to avoid race when one thread calls atexit while another thread calls malloc. Reviewed by: deischen
96 lines
3.2 KiB
C
96 lines
3.2 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. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. 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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* $FreeBSD$
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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static char sccsid[] = "@(#)atexit.c 8.2 (Berkeley) 7/3/94";
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#endif /* LIBC_SCCS and not lint */
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#include "namespace.h"
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#include <stddef.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <pthread.h>
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#include "atexit.h"
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#include "un-namespace.h"
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#include "libc_private.h"
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static pthread_mutex_t atexit_mutex = PTHREAD_MUTEX_INITIALIZER;
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#define _MUTEX_LOCK(x) if (__isthreaded) _pthread_mutex_lock(x)
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#define _MUTEX_UNLOCK(x) if (__isthreaded) _pthread_mutex_unlock(x)
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struct atexit *__atexit; /* points to head of LIFO stack */
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/*
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* Register a function to be performed at exit.
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*/
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int
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atexit(fn)
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void (*fn)();
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{
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static struct atexit __atexit0; /* one guaranteed table */
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register struct atexit *p;
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_MUTEX_LOCK(&atexit_mutex);
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if ((p = __atexit) == NULL)
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__atexit = p = &__atexit0;
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else while (p->ind >= ATEXIT_SIZE) {
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struct atexit *old__atexit;
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old__atexit = __atexit;
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_MUTEX_UNLOCK(&atexit_mutex);
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if ((p = (struct atexit *)malloc(sizeof(*p))) == NULL)
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return (-1);
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_MUTEX_LOCK(&atexit_mutex);
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if (old__atexit != __atexit) {
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/* Lost race, retry operation */
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_MUTEX_UNLOCK(&atexit_mutex);
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free(p);
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_MUTEX_LOCK(&atexit_mutex);
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p = __atexit;
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continue;
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}
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p->ind = 0;
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p->next = __atexit;
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__atexit = p;
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}
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p->fns[p->ind++] = fn;
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_MUTEX_UNLOCK(&atexit_mutex);
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return (0);
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}
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