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. 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: head/lib/libc/stdlib/atexit.c 211894 2010-08-27 19:57:17Z kib $
  34  */
  35
  36 #include "namespace.h"
  37 #include <link.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 int __cxa_atexit(void (*)(void *), void *, void *);
  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 #define _MUTEX_DESTROY(x)       if (__isthreaded) _pthread_mutex_destroy(x)
  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 static int nested_atexit;               /* nested atexit() status */
  75
  76 #define CXA_DTORS_ITERATIONS    16      /* give up after nested iterations */
  77
  78 /*
  79  * Register the function described by 'fptr' to be called at application
  80  * exit or owning shared object unload time. This is a helper function
  81  * for atexit and __cxa_atexit.
  82  */
  83 static int
  84 atexit_register(struct atexit_fn *fptr)
  85 {
  86         static struct atexit __atexit0; /* one guaranteed table */
  87         struct atexit *p;
  88
  89         _MUTEX_LOCK(&atexit_mutex);
  90         if ((p = __atexit) == NULL)
  91                 __atexit = p = &__atexit0;
  92         else while (p->ind >= ATEXIT_SIZE) {
  93                 struct atexit *old__atexit;
  94                 old__atexit = __atexit;
  95                 _MUTEX_UNLOCK(&atexit_mutex);
  96                 if ((p = (struct atexit *)malloc(sizeof(*p))) == NULL)
  97                         return (-1);
  98                 _MUTEX_LOCK(&atexit_mutex);
  99                 if (old__atexit != __atexit) {
 100                         /* Lost race, retry operation */
 101                         _MUTEX_UNLOCK(&atexit_mutex);
 102                         free(p);
 103                         _MUTEX_LOCK(&atexit_mutex);
 104                         p = __atexit;
 105                         continue;
 106                 }
 107                 p->ind = 0;
 108                 p->next = __atexit;
 109                 __atexit = p;
 110         }
 111         p->fns[p->ind++] = *fptr;
 112         if (nested_atexit == 1)
 113                 nested_atexit = 2;
 114         _MUTEX_UNLOCK(&atexit_mutex);
 115         return 0;
 116 }
 117
 118 /*
 119  * Register a function to be performed at exit.
 120  */
 121 int
 122 atexit(void (*func)(void))
 123 {
 124         struct atexit_fn fn;
 125         int error;
 126
 127         fn.fn_type = ATEXIT_FN_STD;
 128         fn.fn_ptr.std_func = func;
 129         fn.fn_arg = NULL;
 130         fn.fn_dso = NULL;
 131
 132         error = atexit_register(&fn);
 133         return (error);
 134 }
 135
 136 /*
 137  * Register a function to be performed at exit or when an shared object
 138  * with given dso handle is unloaded dynamically.
 139  */
 140 int
 141 __cxa_atexit(void (*func)(void *), void *arg, void *dso)
 142 {
 143         struct atexit_fn fn;
 144         int error;
 145
 146         fn.fn_type = ATEXIT_FN_CXA;
 147         fn.fn_ptr.cxa_func = func;
 148         fn.fn_arg = arg;
 149         fn.fn_dso = dso;
 150
 151         error = atexit_register(&fn);
 152         return (error);
 153 }
 154
 155 #pragma weak __pthread_cxa_finalize
 156 void __pthread_cxa_finalize(const struct dl_phdr_info *);
 157
 158 static int global_exit;
 159
 160 /*
 161  * Call all handlers registered with __cxa_atexit for the shared
 162  * object owning 'dso'.  Note: if 'dso' is NULL, then all remaining
 163  * handlers are called.
 164  * Attempt to support additional static c++ destructors added from within
 165  * destructors in a LIFO manner by relooping.
 166  */
 167 void
 168 __cxa_finalize(void *dso)
 169 {
 170         struct dl_phdr_info phdr_info;
 171         struct atexit *p;
 172         struct atexit_fn fn;
 173         int n, ni, has_phdr;
 174
 175         if (dso != NULL) {
 176                 has_phdr = _rtld_addr_phdr(dso, &phdr_info);
 177         } else {
 178                 has_phdr = 0;
 179                 global_exit = 1;
 180         }
 181
 182         _MUTEX_LOCK(&atexit_mutex);
 183         ni = CXA_DTORS_ITERATIONS;
 184 again:
 185         nested_atexit = 1;
 186         for (p = __atexit; p; p = p->next) {
 187                 for (n = p->ind; --n >= 0;) {
 188                         if (p->fns[n].fn_type == ATEXIT_FN_EMPTY)
 189                                 continue; /* already been called */
 190                         fn = p->fns[n];
 191                         if (dso != NULL && dso != fn.fn_dso) {
 192                                 /* wrong DSO ? */
 193                                 if (!has_phdr || global_exit ||
 194                                     !__elf_phdr_match_addr(&phdr_info,
 195                                     fn.fn_ptr.cxa_func))
 196                                         continue;
 197                         }
 198                         /*
 199                           Mark entry to indicate that this particular handler
 200                           has already been called.
 201                         */
 202                         p->fns[n].fn_type = ATEXIT_FN_EMPTY;
 203                         _MUTEX_UNLOCK(&atexit_mutex);
 204
 205                         /* Call the function of correct type. */
 206                         if (fn.fn_type == ATEXIT_FN_CXA)
 207                                 fn.fn_ptr.cxa_func(fn.fn_arg);
 208                         else if (fn.fn_type == ATEXIT_FN_STD)
 209                                 fn.fn_ptr.std_func();
 210                         _MUTEX_LOCK(&atexit_mutex);
 211
 212                         /*
 213                          * Reloop if we got more atexit() destructors.
 214                          */
 215                         if (nested_atexit == 2 && ni > 0) {
 216                                 ni--;
 217                                 goto again;
 218                         }
 219                 }
 220         }
 221         _MUTEX_UNLOCK(&atexit_mutex);
 222         if (dso == NULL)
 223                 _MUTEX_DESTROY(&atexit_mutex);
 224
 225         if (has_phdr && !global_exit && &__pthread_cxa_finalize != NULL)
 226                 __pthread_cxa_finalize(&phdr_info);
 227 }