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  * 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  * @(#)atexit.c 8.2 (Berkeley) 7/3/94
  33  * $FreeBSD: src/lib/libc/stdlib/atexit.c,v 1.8 2007/01/09 00:28:09 imp Exp $
  34  * $DragonFly: src/lib/libc/stdlib/atexit.c,v 1.7 2006/08/03 16:40:46 swildner Exp $
  35  */
  36
  37 #include "namespace.h"
  38 #include <stddef.h>
  39 #include <stdlib.h>
  40 #include <unistd.h>
  41 #include <pthread.h>
  42 #include "atexit.h"
  43 #include "un-namespace.h"
  44
  45 #include "libc_private.h"
  46
  47 #define ATEXIT_FN_EMPTY 0
  48 #define ATEXIT_FN_STD   1
  49 #define ATEXIT_FN_CXA   2
  50
  51 static pthread_mutex_t atexit_mutex = PTHREAD_MUTEX_INITIALIZER;
  52
  53 #define _MUTEX_LOCK(x)          if (__isthreaded) _pthread_mutex_lock(x)
  54 #define _MUTEX_UNLOCK(x)        if (__isthreaded) _pthread_mutex_unlock(x)
  55
  56 struct atexit {
  57         struct atexit *next;                    /* next in list */
  58         int ind;                                /* next index in this table */
  59         struct atexit_fn {
  60                 int fn_type;                    /* ATEXIT_? from above */
  61                 union {
  62                         void (*std_func)(void);
  63                         void (*cxa_func)(void *);
  64                 } fn_ptr;                       /* function pointer */
  65                 void *fn_arg;                   /* argument for CXA callback */
  66                 void *fn_dso;                   /* shared module handle */
  67         } fns[ATEXIT_SIZE];                     /* the table itself */
  68 };
  69
  70 static struct atexit *__atexit;         /* points to head of LIFO stack */
  71
  72 /*
  73  * Register the function described by 'fptr' to be called at application
  74  * exit or owning shared object unload time. This is a helper function
  75  * for atexit and __cxa_atexit.
  76  */
  77 static int
  78 atexit_register(struct atexit_fn *fptr)
  79 {
  80         static struct atexit __atexit0; /* one guaranteed table */
  81         struct atexit *p;
  82
  83         _MUTEX_LOCK(&atexit_mutex);
  84         if ((p = __atexit) == NULL)
  85                 __atexit = p = &__atexit0;
  86         else while (p->ind >= ATEXIT_SIZE) {
  87                 struct atexit *old__atexit;
  88                 old__atexit = __atexit;
  89                 _MUTEX_UNLOCK(&atexit_mutex);
  90                 if ((p = (struct atexit *)malloc(sizeof(*p))) == NULL)
  91                         return (-1);
  92                 _MUTEX_LOCK(&atexit_mutex);
  93                 if (old__atexit != __atexit) {
  94                         /* Lost race, retry operation */
  95                         _MUTEX_UNLOCK(&atexit_mutex);
  96                         free(p);
  97                         _MUTEX_LOCK(&atexit_mutex);
  98                         p = __atexit;
  99                         continue;
 100                 }
 101                 p->ind = 0;
 102                 p->next = __atexit;
 103                 __atexit = p;
 104         }
 105         p->fns[p->ind++] = *fptr;
 106         _MUTEX_UNLOCK(&atexit_mutex);
 107         return (0);
 108 }
 109
 110 /*
 111  * Register a function to be performed at exit.
 112  */
 113 int
 114 atexit(void (*func)(void))
 115 {
 116         struct atexit_fn fn;
 117         int error;
 118
 119         fn.fn_type = ATEXIT_FN_STD;
 120         fn.fn_ptr.std_func = func;
 121         fn.fn_arg = NULL;
 122         fn.fn_dso = NULL;
 123
 124         error = atexit_register(&fn);
 125         return (error);
 126 }
 127
 128 /*
 129  * Register a function to be performed at exit or when an shared object
 130  * with given dso handle is unloaded dynamically.
 131  */
 132 int
 133 __cxa_atexit(void (*func)(void *), void *arg, void *dso)
 134 {
 135         struct atexit_fn fn;
 136         int error;
 137
 138         fn.fn_type = ATEXIT_FN_CXA;
 139         fn.fn_ptr.cxa_func = func;
 140         fn.fn_arg = arg;
 141         fn.fn_dso = dso;
 142
 143         error = atexit_register(&fn);
 144         return (error);
 145 }
 146
 147 /*
 148  * Call all handlers registered with __cxa_atexit for the shared
 149  * object owning 'dso'.  Note: if 'dso' is NULL, then all remaining
 150  * handlers are called.
 151  */
 152 void
 153 __cxa_finalize(void *dso)
 154 {
 155         struct atexit *p;
 156         struct atexit_fn fn;
 157         int n;
 158
 159         _MUTEX_LOCK(&atexit_mutex);
 160         for (p = __atexit; p; p = p->next) {
 161                 for (n = p->ind; --n >= 0;) {
 162                         if (p->fns[n].fn_type == ATEXIT_FN_EMPTY)
 163                                 continue; /* already been called */
 164                         if (dso != NULL && dso != p->fns[n].fn_dso)
 165                                 continue; /* wrong DSO */
 166                         fn = p->fns[n];
 167                         /*
 168                           Mark entry to indicate that this particular handler
 169                           has already been called.
 170                         */
 171                         p->fns[n].fn_type = ATEXIT_FN_EMPTY;
 172                         _MUTEX_UNLOCK(&atexit_mutex);
 173
 174                         /* Call the function of correct type. */
 175                         if (fn.fn_type == ATEXIT_FN_CXA)
 176                                 fn.fn_ptr.cxa_func(fn.fn_arg);
 177                         else if (fn.fn_type == ATEXIT_FN_STD)
 178                                 fn.fn_ptr.std_func();
 179                         _MUTEX_LOCK(&atexit_mutex);
 180                 }
 181         }
 182         _MUTEX_UNLOCK(&atexit_mutex);
 183 }