lib/libc/stdlib/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  * $FreeBSD: src/lib/libc/stdlib/atexit.c,v 1.3.6.1 2002/03/10 20:28:40 tegge Exp $
  37  * $DragonFly: src/lib/libc/stdlib/atexit.c,v 1.7 2006/08/03 16:40:46 swildner Exp $
  38  *
  39  * @(#)atexit.c 8.2 (Berkeley) 7/3/94
  40  */
  41
  42 #include <stddef.h>
  43 #include <stdlib.h>
  44 #include <unistd.h>
  45 #include "atexit.h"
  46
  47 #include "libc_private.h"
  48 #include "spinlock.h"
  49
  50 #define         ATEXIT_FN_EMPTY 0
  51 #define         ATEXIT_FN_STD   1
  52 #define         ATEXIT_FN_CXA   2
  53
  54 static spinlock_t thread_lock = _SPINLOCK_INITIALIZER;
  55
  56 #define THREAD_LOCK()           if (__isthreaded) _SPINLOCK(&thread_lock);
  57 #define THREAD_UNLOCK()         if (__isthreaded) _SPINUNLOCK(&thread_lock);
  58
  59 struct atexit {
  60         struct atexit *next;                    /* next in list */
  61         int ind;                                /* next index in this table */
  62         struct atexit_fn {
  63                 int fn_type;                    /* ATEXIT_? from above */
  64                 union {
  65                         void (*std_func)(void);
  66                         void (*cxa_func)(void *);
  67                 } fn_ptr;                       /* function pointer */
  68                 void *fn_arg;                   /* argument for CXA callback */
  69                 void *fn_dso;                   /* shared module handle */
  70         } fns[ATEXIT_SIZE];                     /* the table itself */
  71 };
  72
  73 static struct atexit *__atexit;         /* points to head of LIFO stack */
  74
  75 /*
  76  * Register the function described by 'fptr' to be called at application
  77  * exit or owning shared object unload time. This is a helper function
  78  * for atexit and __cxa_atexit.
  79  */
  80 static int
  81 atexit_register(struct atexit_fn *fptr)
  82 {
  83         static struct atexit __atexit0; /* one guaranteed table */
  84         struct atexit *p;
  85
  86         THREAD_LOCK();
  87         if ((p = __atexit) == NULL)
  88                 __atexit = p = &__atexit0;
  89         else while (p->ind >= ATEXIT_SIZE) {
  90                 struct atexit *old__atexit;
  91                 old__atexit = __atexit;
  92                 THREAD_UNLOCK();
  93                 if ((p = (struct atexit *)malloc(sizeof(*p))) == NULL)
  94                         return (-1);
  95                 THREAD_LOCK();
  96                 if (old__atexit != __atexit) {
  97                         /* Lost race, retry operation */
  98                         THREAD_UNLOCK();
  99                         free(p);
 100                         THREAD_LOCK();
 101                         p = __atexit;
 102                         continue;
 103                 }
 104                 p->ind = 0;
 105                 p->next = __atexit;
 106                 __atexit = p;
 107         }
 108         p->fns[p->ind++] = *fptr;
 109         THREAD_UNLOCK();
 110         return (0);
 111 }
 112
 113 /*
 114  * Register a function to be performed at exit.
 115  */
 116 int
 117 atexit(void (*func)(void))
 118 {
 119         struct atexit_fn fn;
 120         int error;
 121
 122         fn.fn_type = ATEXIT_FN_STD;
 123         fn.fn_ptr.std_func = func;
 124         fn.fn_arg = NULL;
 125         fn.fn_dso = NULL;
 126
 127         error = atexit_register(&fn);
 128         return (error);
 129 }
 130
 131 /*
 132  * Register a function to be performed at exit or when an shared object
 133  * with given dso handle is unloaded dynamically.
 134  */
 135 int
 136 __cxa_atexit(void (*func)(void *), void *arg, void *dso)
 137 {
 138         struct atexit_fn fn;
 139         int error;
 140
 141         fn.fn_type = ATEXIT_FN_CXA;
 142         fn.fn_ptr.cxa_func = func;
 143         fn.fn_arg = arg;
 144         fn.fn_dso = dso;
 145
 146         error = atexit_register(&fn);
 147         return (error);
 148 }
 149
 150 /*
 151  * Call all handlers registered with __cxa_atexit for the shared
 152  * object owning 'dso'.  Note: if 'dso' is NULL, then all remaining
 153  * handlers are called.
 154  */
 155 void
 156 __cxa_finalize(void *dso)
 157 {
 158         struct atexit *p;
 159         struct atexit_fn fn;
 160         int n;
 161
 162         THREAD_LOCK();
 163         for (p = __atexit; p; p = p->next) {
 164                 for (n = p->ind; --n >= 0;) {
 165                         if (p->fns[n].fn_type == ATEXIT_FN_EMPTY)
 166                                 continue; /* already been called */
 167                         if (dso != NULL && dso != p->fns[n].fn_dso)
 168                                 continue; /* wrong DSO */
 169                         fn = p->fns[n];
 170                         /*
 171                           Mark entry to indicate that this particular handler
 172                           has already been called.
 173                         */
 174                         p->fns[n].fn_type = ATEXIT_FN_EMPTY;
 175                         THREAD_UNLOCK();
 176
 177                         /* Call the function of correct type. */
 178                         if (fn.fn_type == ATEXIT_FN_CXA)
 179                                 fn.fn_ptr.cxa_func(fn.fn_arg);
 180                         else if (fn.fn_type == ATEXIT_FN_STD)
 181                                 fn.fn_ptr.std_func();
 182                         THREAD_LOCK();
 183                 }
 184         }
 185         THREAD_UNLOCK();
 186 }