stdlib/cxa_atexit.c

   1 /* Copyright (C) 1999, 2001 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <bits/libc-lock.h>
  20 #include <stdlib.h>
  21 #include "exit.h"
  22
  23 /* Register a function to be called by exit or when a shared library
  24    is unloaded.  This function is only called from code generated by
  25    the C++ compiler.  */
  26 int
  27 __cxa_atexit (void (*func) (void *), void *arg, void *d)
  28 {
  29   struct exit_function *new = __new_exitfn ();
  30
  31   if (new == NULL)
  32     return -1;
  33
  34   new->flavor = ef_cxa;
  35   new->func.cxa.fn = (void (*) (void *, int)) func;
  36   new->func.cxa.arg = arg;
  37   new->func.cxa.dso_handle = d;
  38   return 0;
  39 }
  40
  41
  42 /* We change global data, so we need locking.  */
  43 __libc_lock_define_initialized (static, lock)
  44
  45
  46 static struct exit_function_list initial;
  47 struct exit_function_list *__exit_funcs = &initial;
  48
  49 struct exit_function *
  50 __new_exitfn (void)
  51 {
  52   struct exit_function_list *l;
  53   size_t i = 0;
  54
  55   __libc_lock_lock (lock);
  56
  57   for (l = __exit_funcs; l != NULL; l = l->next)
  58     {
  59       for (i = 0; i < l->idx; ++i)
  60         if (l->fns[i].flavor == ef_free)
  61           break;
  62       if (i < l->idx)
  63         break;
  64
  65       if (l->idx < sizeof (l->fns) / sizeof (l->fns[0]))
  66         {
  67           i = l->idx++;
  68           break;
  69         }
  70     }
  71
  72   if (l == NULL)
  73     {
  74       l = (struct exit_function_list *)
  75         malloc (sizeof (struct exit_function_list));
  76       if (l != NULL)
  77         {
  78           l->next = __exit_funcs;
  79           __exit_funcs = l;
  80
  81           l->idx = 1;
  82           i = 0;
  83         }
  84     }
  85
  86   /* Mark entry as used, but we don't know the flavor now.  */
  87   if (l != NULL)
  88     l->fns[i].flavor = ef_us;
  89
  90   __libc_lock_unlock (lock);
  91
  92   return l == NULL ? NULL : &l->fns[i];
  93 }