stdlib/FreeBSD/atexit.c

   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
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37 #if defined(LIBC_SCCS) && !defined(lint)
  38 static char sccsid[] = "@(#)atexit.c    8.2 (Berkeley) 7/3/94";
  39 #endif /* LIBC_SCCS and not lint */
  40 #include <sys/cdefs.h>
  41 __FBSDID("$FreeBSD: src/lib/libc/stdlib/atexit.c,v 1.6 2002/03/22 21:53:09 obrien Exp $");
  42
  43 #include "namespace.h"
  44 #include <stddef.h>
  45 #include <stdlib.h>
  46 #include <unistd.h>
  47 #include <pthread.h>
  48 #include "atexit.h"
  49 #include "un-namespace.h"
  50
  51 #include "libc_private.h"
  52
  53 static pthread_mutex_t atexit_mutex = PTHREAD_MUTEX_INITIALIZER;
  54
  55 #define _MUTEX_LOCK(x)          if (__isthreaded) _pthread_mutex_lock(x)
  56 #define _MUTEX_UNLOCK(x)        if (__isthreaded) _pthread_mutex_unlock(x)
  57
  58 struct atexit *__atexit;        /* points to head of LIFO stack */
  59
  60 /*
  61  * Register a function to be performed at exit.
  62  */
  63 int
  64 atexit(fn)
  65         void (*fn)();
  66 {
  67         static struct atexit __atexit0; /* one guaranteed table */
  68         struct atexit *p;
  69
  70         _MUTEX_LOCK(&atexit_mutex);
  71         if ((p = __atexit) == NULL)
  72                 __atexit = p = &__atexit0;
  73         else while (p->ind >= ATEXIT_SIZE) {
  74                 struct atexit *old__atexit;
  75                 old__atexit = __atexit;
  76                 _MUTEX_UNLOCK(&atexit_mutex);
  77                 if ((p = (struct atexit *)malloc(sizeof(*p))) == NULL)
  78                         return (-1);
  79                 _MUTEX_LOCK(&atexit_mutex);
  80                 if (old__atexit != __atexit) {
  81                         /* Lost race, retry operation */
  82                         _MUTEX_UNLOCK(&atexit_mutex);
  83                         free(p);
  84                         _MUTEX_LOCK(&atexit_mutex);
  85                         p = __atexit;
  86                         continue;
  87                 }
  88                 p->ind = 0;
  89                 p->next = __atexit;
  90                 __atexit = p;
  91         }
  92         p->fns[p->ind++] = fn;
  93         _MUTEX_UNLOCK(&atexit_mutex);
  94         return (0);
  95 }