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  * 4. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #if defined(LIBC_SCCS) && !defined(lint)
  34 static char sccsid[] = "@(#)atexit.c    8.2 (Berkeley) 7/3/94";
  35 #endif /* LIBC_SCCS and not lint */
  36 #include <sys/cdefs.h>
  37 __FBSDID("$FreeBSD: src/lib/libc/stdlib/atexit.c,v 1.8 2007/01/09 00:28:09 imp Exp $");
  38
  39 #include "namespace.h"
  40 #include <stddef.h>
  41 #include <stdlib.h>
  42 #include <unistd.h>
  43 #include <pthread.h>
  44 #include "atexit.h"
  45 #include "un-namespace.h"
  46
  47 #include "libc_private.h"
  48
  49 #define ATEXIT_FN_EMPTY 0
  50 #define ATEXIT_FN_STD   1
  51 #define ATEXIT_FN_CXA   2
  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 {
  59         struct atexit *next;                    /* next in list */
  60         int ind;                                /* next index in this table */
  61         struct atexit_fn {
  62                 int fn_type;                    /* ATEXIT_? from above */
  63                 union {
  64                         void (*std_func)(void);
  65                         void (*cxa_func)(void *);
  66                 } fn_ptr;                       /* function pointer */
  67                 void *fn_arg;                   /* argument for CXA callback */
  68                 void *fn_dso;                   /* shared module handle */
  69         } fns[ATEXIT_SIZE];                     /* the table itself */
  70 };
  71
  72 static struct atexit *__atexit;         /* points to head of LIFO stack */
  73
  74 /*
  75  * Register the function described by 'fptr' to be called at application
  76  * exit or owning shared object unload time. This is a helper function
  77  * for atexit and __cxa_atexit.
  78  */
  79 static int
  80 atexit_register(struct atexit_fn *fptr)
  81 {
  82         static struct atexit __atexit0; /* one guaranteed table */
  83         struct atexit *p;
  84
  85         _MUTEX_LOCK(&atexit_mutex);
  86         if ((p = __atexit) == NULL)
  87                 __atexit = p = &__atexit0;
  88         else while (p->ind >= ATEXIT_SIZE) {
  89                 struct atexit *old__atexit;
  90                 old__atexit = __atexit;
  91                 _MUTEX_UNLOCK(&atexit_mutex);
  92                 if ((p = (struct atexit *)malloc(sizeof(*p))) == NULL)
  93                         return (-1);
  94                 _MUTEX_LOCK(&atexit_mutex);
  95                 if (old__atexit != __atexit) {
  96                         /* Lost race, retry operation */
  97                         _MUTEX_UNLOCK(&atexit_mutex);
  98                         free(p);
  99                         _MUTEX_LOCK(&atexit_mutex);
 100                         p = __atexit;
 101                         continue;
 102                 }
 103                 p->ind = 0;
 104                 p->next = __atexit;
 105                 __atexit = p;
 106         }
 107         p->fns[p->ind++] = *fptr;
 108         _MUTEX_UNLOCK(&atexit_mutex);
 109         return 0;
 110 }
 111
 112 /*
 113  * Register a function to be performed at exit.
 114  */
 115 int
 116 atexit(void (*func)(void))
 117 {
 118         struct atexit_fn fn;
 119         int error;
 120
 121         fn.fn_type = ATEXIT_FN_STD;
 122         fn.fn_ptr.std_func = func;;
 123         fn.fn_arg = NULL;
 124         fn.fn_dso = NULL;
 125
 126         error = atexit_register(&fn);
 127         return (error);
 128 }
 129
 130 /*
 131  * Register a function to be performed at exit or when an shared object
 132  * with given dso handle is unloaded dynamically.
 133  */
 134 int
 135 __cxa_atexit(void (*func)(void *), void *arg, void *dso)
 136 {
 137         struct atexit_fn fn;
 138         int error;
 139
 140         fn.fn_type = ATEXIT_FN_CXA;
 141         fn.fn_ptr.cxa_func = func;;
 142         fn.fn_arg = arg;
 143         fn.fn_dso = dso;
 144
 145         error = atexit_register(&fn);
 146         return (error);
 147 }
 148
 149 /*
 150  * Call all handlers registered with __cxa_atexit for the shared
 151  * object owning 'dso'.  Note: if 'dso' is NULL, then all remaining
 152  * handlers are called.
 153  */
 154 void
 155 __cxa_finalize(void *dso)
 156 {
 157         struct atexit *p;
 158         struct atexit_fn fn;
 159         int n;
 160
 161         _MUTEX_LOCK(&atexit_mutex);
 162         for (p = __atexit; p; p = p->next) {
 163                 for (n = p->ind; --n >= 0;) {
 164                         if (p->fns[n].fn_type == ATEXIT_FN_EMPTY)
 165                                 continue; /* already been called */
 166                         if (dso != NULL && dso != p->fns[n].fn_dso)
 167                                 continue; /* wrong DSO */
 168                         fn = p->fns[n];
 169                         /*
 170                           Mark entry to indicate that this particular handler
 171                           has already been called.
 172                         */
 173                         p->fns[n].fn_type = ATEXIT_FN_EMPTY;
 174                         _MUTEX_UNLOCK(&atexit_mutex);
 175
 176                         /* Call the function of correct type. */
 177                         if (fn.fn_type == ATEXIT_FN_CXA)
 178                                 fn.fn_ptr.cxa_func(fn.fn_arg);
 179                         else if (fn.fn_type == ATEXIT_FN_STD)
 180                                 fn.fn_ptr.std_func();
 181                         _MUTEX_LOCK(&atexit_mutex);
 182                 }
 183         }
 184         _MUTEX_UNLOCK(&atexit_mutex);
 185 }